Makerere University

MAKERERE UNIVERSITY

EFFECTS OF SALT SOLUTION CONCENTRATION ON THE GERMINATION SUCCESS OF PODOCARPUS LATIFOLIUS SEEDS

ABITI MAY FRANCIS

14/U/5

214000243

A SPECIAL PROJECT REPORT SUBMITTED TO THE DEPARTMENT OF FORESTRY BIODIVERSITY AND TOURISM IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF BACHELOR OF SCIENCE DEGREE IN CONSERVATION FORESTRY AND PRODUCTS TECHNOLOGY OF MAKERERE UNIVERSITY, KAMPALA

SEPTEMBER, 2019

DECLARATION

I, Abiti May Francis, hereby declare that this research report is my original work and has never been submitted to any university or institution of higher learning in any form for an academic award.

Name: ABITI MAY FRANCIS

Signature:

Date:

SUPERVISOR’S APPROVAL

This report has been handed in with my approval as the university supervisor.

Signature:

PROF. OKULLO JOHN BOSCO LAMORIS

Department of Forestry Biodiversity and Tourism

Email: [email protected]

Date:

DEDICATION

This research report is dedicated to my lovely parents, my university supervisor and friends who have always inspired, encouraged and supported me in one way or the other through this education cycle.

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ACKNOWLEDGEMENT

First, I would like to thank the Almighty God for spiritual guidance, protection, good life and motivation He accorded me in all the stages of this research and also during the whole course of my study. I believe without the intervention of the almighty who is above all, I would not have been able to get even an inch way through my research.

My sincere heartfelt gratitude goes to my supervisor Prof. JBL. Okullo for all the time, guidance, fatherly advice and more so mentoring me into a self-stable and self-reliant Forester. Right from the first day, my supervisor always advised me to put my own efforts in everything I am doing and become my own superior. May the almighty generously reward him as he fulfils his tasks of mentoring future Foresters.

I would like to thank all the staff of National Tree Seed Centre (Namanve); especially Mr. Ochwo Joseph for the guidance, free provision of materials, space and liaising on my behalf with the NFA administration so that I could carry out my research at the NTSC laboratory. Others are Ms. Nyakecho Josephine for being such an encouraging lady ready to offer guidance at any time approached; Ms. Hanifa who always looked after the experiment whenever I was away. To all the rest of NFA staff that I can’t mention here; may the Almighty God always reward you abundantly.

Special thanks are due to the following persons: my mother and father for all the financial support, sense of respect and the importance they accorded to my research; My Bsc. CFPT classmates of 2014/2015 and not forgetting Ms. Munguci Belinda for her constant encouragement and motivation that made me reach this far, May the almighty God reward you all abundantly.

TABLE OF CONTENTS DECLARATION...... i SUPERVISOR’S APPROVAL ...... ii DEDICATION...... iii ACKNOWLEDGEMENT ...... iv ABBREVIATIONS AND ACRONYMS ...... vii LIST OF FIGURES ...... viii LIST OF TABLES ...... ix ABSTRACT ...... x CHAPTER ONE: INTRODUCTION ...... 1 1.1 Background ...... 1 1.2 Statement of the problem ...... 2 1.3.1 Objectives of the Study...... 3 1.3.1 General Objective ...... 3 1.3.2 Specific Objectives ...... 3 1.4 Research Questions and Hypotheses ...... 3 1.4.1 Research Questions ...... 3 1.4.2 Research hypotheses ...... 4 1.5 Significance of the study ...... 4 CHAPTER TWO: LITERATURE REVIEW ...... 5 2.1 The Species (Podocarpus latifolius) ...... 5 2.1.1 Taxonomy, Ecology and Geographical distribution of Podocarpus latifolius ...... 5 2.1.2 Economic Importance of Podocarpus latifolius ...... 5 2.1.3 Podocarpus latifolius Seed Morphology ...... 6 2.2 Factors Influencing Seed Dormancy ...... 7 2.3 Overcoming Seed Dormancy to Ensure Proper Germination ...... 8 2.4 Effects of Salinity on Seeds Germination and Growth ...... 10 2.5 Effects of Salinity on Soil Properties ...... 12 CHAPTER THREE: MATERIALS AND METHODS ...... 13 3.1 Materials ...... 13 3.2 Methods ...... 13 3.2.1 Research Design...... 13 3.2.2 Experimental Setup ...... 13 3.2.3 Plot layout ...... 15 3.2.4 Data Collection ...... 16

3.2.5 Data Analysis ...... 16 CHAPTER FOUR: RESULTS ...... 17 4.1 Determination of Sodium Chloride Concentration for the Shortest Germination Days of Podocarpus latifolius Seeds ...... 17 4.2 Examination of the Effects of Sodium Chloride on the Growth Responses of Podocarpus latifolius Seedlings ...... 18 4.3 Assessment of the Significant Differences in the Growth Responses of Podocarpus latifolius Seedlings Pre-Treated with the Different Salt Solution Concentrations...... 22 CHAPTER FIVE: DISCUSSIONS ...... 24 5.1 Determination of the Sodium Chloride Concentration for the Shortest Germination Days 24 5.2 Effects of Sodium Chloride on the Growth Responses of Podocarpus latifolius Seedlings ...... 25 5.3 Significant Differences in the Growth Response of Podocarpus latifolius Seedlings Pre- treated with Different Salt Solution Concentrations ...... 26 CHAPTER SIX: CONCLUSIONS AND RECOMMENDATIONS ...... 28 6.1 Conclusions ...... 28 6.2 Recommendations ...... 28 REFERENCES ...... 30 APPENDICES ...... 33

ABBREVIATIONS AND ACRONYMS

NFA National Forestry Authority

NTSC National Tree Seed Centre

NaCl Sodium Chloride

M Molar

Mt. Mountain m meter cm centimetre dS 푀−1 deciSiemens per metre pH Hydrogen Potential

P Phosphorus

Fe Iron

Mn Manganese mM millimolar kg kilogram

MGT Mean Germination Time

MGR Mean Germination Rate

ANOVA Analysis Of Variance

LSD Least Significant Difference

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LIST OF FIGURES

Figure 1: Treatment illustrations ...... 14 Figure 2: Plot layout...... 15 Figure 3: Mean germination days by sodium chloride solution concentrations and soaking time of Podocarpus latifolius seeds ...... 18 Figure 4: Mean heights of leaves formation by sodium chloride solution and soaking time for Podocarpus latifolius seedlings ...... 20 Figure 5: Mean number of true leaves by sodium chloride solution and soaking time for Podocarpus latifolius seedlings ...... 21

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LIST OF TABLES

Table 1: Number of days taken for germination of seeds of Podocarpus latifolius ...... 18 Table 2: Comparison of effects of sodium chloride solution and soaking time on days to seeds germination and germination responses of Podocarpus latifolius seedlings ...... 19 Table 3: ANOVA on effect of sodium chloride solution concentration, soaking time and their interaction on germination responses of Podocarpus latifolius seedlings ...... 22

ABSTRACT

The study was carried out to investigate the effects of sodium chloride solution on the germination success of Podocarpus latifolius seeds under nursery conditions. The aim was to find out the most appropriate salt solution concentration for enhancing germination of. Podocarpus latifolius seeds. The seeds were subjected to seven different salt solution concentrations of 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6M. Seeds were soaked for 6 hours, 12 hours and 24 hours after which seeds samples from each hour set were divided into two; one lot sown directly/ immediately after rinsing and the other first rinsed in distilled water for 6 hours and then sown. The experiments were monitored for three months during which data were collected on: Days of seed germination (Unrinsed seeds: 55.76±11.74 days; rinsed seeds: 59.72±10.31 days), height of leaf formation (Rinsed seeds: 6.6 cm; unrinsed seeds: 5.9±0.801cm), and number of leaves formed (rinsed seeds: 12±2.524 leaves; unrinsed seeds: 11±1.988 leaves). Sodium chloride salinity (p<0.05) significantly reduced the number of days and also increased the number of leaves, height of leaves formation and the number of seeds germinated for Podocarpus latifolius. There was no significant difference in the number of days taken for the seeds to germinate for the seeds soaked in 0.0 and 0.3M NaCl solution. However, significant differences were witnessed between seeds soaked in 0.0 to 0.3M category and seeds soaked in solution of concentration 0.6M. This is an indication that Podocarpus latifolius has a long salinity tolerance range with 0.3M solution being the most appropriate solution concentration for pre- treating Podocarpus latifolius seeds. The germination responses of Podocarpus latifolius seedlings in terms of (height of leaves formation, number of leaves and days to formation of leaves) were all best for seeds soaked in 0.3M of NaCl for 12 hours. The results further showed that time of soaking seeds during pretreatment, height of seedlings and number of leaves were suitable parameters for evaluating the effects of sodium chloride solution on Podocarpus latifolius seeds. Soaking Podocarpus latifolius seeds in solution concentrations more than the range within which it can germinate especially for more hours (0.6M for 24hours), will impede its germination. In general, unrinsed Podocarpus latifolius seeds had better germination rate (67.01 ±11.43 days) for their leaves to unfold compared to soaked and rinsed seeds which took 70.10±9.66 days for their leaves to unfold. These results indicate that sodium chloride can influence the growth responses of Podocarpus latifolius seedlings. The reduction in the number of leaves unfolded and lesser height at which leaves were formed for seedlings whose seeds were soaked in solutions of concentration 0.4M and above is an indication of the effect of sodium chloride solution on the growth responses of Podocarpus latifolius seedlings. Germination rate in Podocarpus latifolius, amount of biomass formed and the rate of biomass formation are higher and relatively the same within the non-lethal ranges of sodium chloride solution (0.0 to 0.3M) though any increase in NaCl solution concentration beyond optimum, leads to a reduction in amount of biomass and the rate of biomass production, implying that sodium chloride concentrations above the optimum concentrations are lethal to germination success of Podocarpus latifolius. For Podocarpus latifolius, the optimum NaCl solution concentrations that are non-lethal are 0.0 to 0.3M; moderately high concentrations are 0.4 to 0.5M and extremely lethal concentrations range from 0.6M and above. For the shortest germination days, greater amounts of biomass addition and greater rates of biomass addition, salt solution concentrations within the optimum levels of up to 0.3M solution should be considered. For the best germination results of Podocarpus latifolius, seeds should be soaked in NaCl solution of 0.3M solution for 12 hours. For the best germination responses in Podocarpus latifolius seedlings, their seeds have to soaked solution of concentration of 0.3M solution for 12 hours. Dry matter, root length, sodium chloride solution effect on the cellular component should be investigated to find out whether sodium chloride solution has significant effects on these. Further germination experiments can also be done to investigate the effects of watering with sodium chloride solution on the Podocarpus latifolius seeds.

CHAPTER ONE: INTRODUCTION 1.1 Background Podocarpus latifolius is a native species of soft wood tree in Uganda that grows between 30 to 40 m tall. The seeds are characterized by a hard seed coat that takes a very long time to disintegrate though it is water absorbent. As a result, the species has not commonly been used in plantations and also not yet recommended as a plantation species. Little research regarding best propagation procedures for the species including starting straight from germination has been done on it. Low yields may also result from various factors such as poorly adapted cultivars, production techniques, biotic stress, climatic constraints, and soil factors (Bahizire, 2007).

In spite of the above mentioned factors, any crop growth and yield is largely dependent on the success of germination and seeds establishment which are largely affected by seed quality, pest and diseases, climatic constraints, as well as soil factors such as soil pH, soil temperature, soil moisture and soil salinity. According to steer (2004), variation in salinity can lead to variation in the germination success, and yet efficient seed germination is important in forestry. This implies that successful establishment of early seedlings requires a rapid and uniform emergence and root growth. (Nabanyumya, 2015).

Germination of orthodox seeds such as those of Podocarpus latifolius has been reported to occur under three distinct phases; Phase one: seed hydration process related to passive imbibition of dry tissues associated with water movement first occurring in the apoplastic spaces; Phase two: activation phase associated with the re-establishment of metabolic activities and repairing processes at the cell level; and phase three: initiation of growing processes associated to cell elongation and leading to radicle protrusion (Lutts, 2016).

Phases one and three both involve an increase in the water content while hydration remains stable during phase two. It is commonly considered that before the end of phase two, germination remains a reversible process: the seed may be dried again and remain alive during storage and able to subsequently re-initiate germination under favorable conditions (Lutts, 2016). It is this stage of imbibition that pre-treatment with salt solution can create a state of excitement in growth once the seed is again exposed to normal conditions of non-saline water (Munns, 2002).

Factors that can enhance germination such as seed scarification, cracking of the seed coat, soaking in water, warm water treatment, burning of the seed are reported to give the high germination percentages to Podocarpus latifolius seeds, although the highest was obtained for seeds that were soaked for 24 hours in cool water (Nabanyumya, 2015). Another research from National Tree Seed Centre Uganda reports that acid scarification and halo priming using sodium chloride solution as a pretreatment can reduce the number of days for the germination of the Podocarpus latifolius seeds, but without known significant salt solution concentration.

Even if the appropriate salt solution concentration needs to be recommended to farmers as a way of enhancing seed germination, salt solution is known to be a highly osmotic solution with very low water potential that can cause living cells to loose water (Munns, 2002). In most plant species, salinity usually affects germination and development of the seedling, which is considered the developmental stage that is most sensitive and vulnerable to abiotic stresses (Miceli, 2003). Delay of germination (Li, 2011) and growth inhibition due to salinity are also caused by low external water potential, ion imbalance and specific ion toxicity (Munns, 2002) caused by an excessive absorption of ions (Manuela, 2015).

Since an appropriate salt solution concentration for germination of Podocarpus latifolius was not known, this study examined the effects of sodium chloride solution on the number of days for germination of Podocarpus latifolius seeds and their respective germination responses after the pre-treatment.

1.2 Statement of the problem Apart from a report that Podocarpus latifolius seeds take 40-70 days to germinate under normal conditions to produce a germination percentage of 60-80% (Nabanyumya, 2015), current available research by NTSC showed that of all the methods applied (acid scarification, warm water treatment, cold water treatment, complete removal of the seed coat and salt water treatment), only salt solution proved to have the best output for germinating Podocarpus latifolius seeds.

However, due to the fact that the evaluation was done for only single sample for every method, the appropriate salt solution concentration that gives the highest germination percentage within the shortest time needed to be established. That lack of information has also led to use of salt solutions 2 with concentrations too high or too low thus leading to low germination success (Hongxiang Zhang, 2010). Such a recommended method of pretreatment for Podocarpus latifolius seeds should not only aim at increasing germination success but should also be efficient and easy to apply by the local farmers and other people within the forestry enterprise.

In order to avoid use of too much salt concentrations that can lead to complete damage of a seed lots thereby incurring losses, additional time and wasted time in pretreatment (Hylton, 2009), it was thus necessary to set up an experiment geared towards determining the most appropriate concentration of sodium chloride solution for improved germination success of Podocarpus latifolius seeds.

1.3.1 Objectives of the Study 1.3.1 General Objective The general objective of this study was to come up with the most appropriate salt solution concentration for enhancing germination of Podocarpus latifolius seeds under nursery conditions.

1.3.2 Specific Objectives The specific objectives of this study were to: 1- Determine the sodium chloride concentration for shortest Podocarpus latifolius germination days. 2- Examine the effects of sodium chloride on the growth responses of Podocarpus latifolius seedlings. 3- Assess the significant difference in the growth response of Podocarpus latifolius seedlings pretreated with different salt solution concentrations.

1.4 Research Questions and Hypotheses 1.4.1 Research Questions The following research questions were posed: a) What appropriate salt solution concentration would produce the shortest germintion days for Podocarpus latifolius seeds? b) What would be the effect of sodium chloride solution on germiantion responses of Podocarpus latifolius ? 3

c) To what degree do the growth responses of Podocarpus latifolius seedlings differ in the different solution concentrations?

1.4.2 Research hypotheses The following hypothesis was tested: H0: Null hypothesis: There is no difference in the germination time of Podocarpus latifolius seeds pretreated with different salt solution concentrations. H1: Alternative hypothesis: There is a significant difference in the germination time of Podocarpus latifolius seeds pretreated with different salt solution concentrations.

1.5 Significance of the study Determining the most appropriate concentrations of sodium chloride solution for improved germination success of Podocarpus latifolius seeds under nursery conditions is a technique that is now very much needed. Once developed, such conditions would increase on the nursery germination output for this species. Such success would not only reduce on the resource wastage in terms of seeds, water, space and few seedlings within a square meter of nursery bed but also would improve on the scale of Podocarpus latifolius seedlings sales within the country and also outside the country.

This report has also been submitted in partial fulfillment of the requirements for the award of Bachelor of Science degree in Conservation Forestry and Products Technology of Makerere University. It has also enhanced my skills in handling seed germination activities under nursery conditions.

CHAPTER TWO: LITERATURE REVIEW 2.1 The Species (Podocarpus latifolius) 2.1.1 Taxonomy, Ecology and Geographical distribution of Podocarpus latifolius Podocarpus latifolius is a softwood tree that belongs to the family podocarpaceae (Adie, 2010). The common English name is the Broad-leaved Yellowwood, Real Yellowwood, True Yellowwood, and Upright Yellowwood. Podocarpaceae comprises 18 genera and about 173 species of evergreen, coniferous trees and shrubs (Fern, 2014). The synonym for Podocarpus latifolius is podocarpus milanjianus. It is native and an indigenous tree species in Uganda. It is common in the eastern region of Uganda around Mt. Elgon (Nabanyumya, 2015).

Podocarpus latifolius is an evergreen tree with a dense, narrow-branched crown that can grow up to 35 metres tall, though at higher altitudes it is more likely to be a shrub or small, stunted tree or shrub no more than 2 metres tall. The bole, which is usually straight and cylindrical, is up to 150cm in diameter, occasionally reaching 300cm, sometimes with buttresses at base. It can be branchless for up to 10 metres, occasionally for 20 metres (Fern, 2014).

Podocarpus latifolius is a canopy forest tree in the coastal, midland and montane primary forests where there is sufficient rainfall and natural protection from fires to allow such forest types to develop. In open coastal bushland and on dry, rocky mountain slopes podocarpus only grows to a stunted tree a few meters tall at most. It occurs from near sea level to 2,000 m above sea level (Fern, 2014).

In forested valleys near the coast, podocarpus can be associated with Afrocarpus falcatus and both are commonly emergent above a lower canopy of angiosperm trees, among which members of the families Celastraceae, Araliaceae and Flacourtiaceae, as well as Olea capensis are often seen (Farjon, 2013).

2.1.2 Economic Importance of Podocarpus latifolius Podocarpus latifolius heartwood is pale yellowish brown, and not demarcated from the sapwood. The grain is straight, occasionally spirally; the texture fine and even. Reddish streaks of compression wood may be present. Resin is absent, and the wood has no distinctive odor. The

5 wood is moderately lightweight; resistant to acids but not durable; easy to saw and work with machine and hand tools, having little dulling effects on cutting edges (Fern, 2014).

While Podocarpus latifolius wood can be planed to a smooth finish, it has a tendency to split upon nailing and so pre-boring is recommended. The wood of Podocarpus latifolius requires support in drilling and mortising to hold screw well because of its brittleness. The gluing, painting, varnishing and staining properties are moderately good. Steam bending gives moderate results, but turning properties are good. The peeling and slicing properties are of good-quality but with brittle veneer that can be produced from the wood. The wood of podocarpus trees from Sudan has a high lignin content and was found difficult to pulp (Fern, 2014).

Podocarpus latifolius is indigenous and has been used in afforestation on a small scale in several African countries, within and perhaps without its natural range (Adie, 2010). The tree has been used to provide shade in coffee, cocoa and banana plantations while the bark is used as waterproof cover for bee-hives. Podocarpus latifolius is an important timber tree in many parts of tropical Africa. Its wood is valued for carpentry and joinery as it is light colored, even grained and easily worked. Large trees yield good sizes of sawn timber with more specialized uses requiring high grade timber in veneer, furniture making, cabinet making, interior rim, household utensils, and wood carving (Adie, 2010).

The wood, often traded as ‘podo’, is highly valued as timber for furniture, ship building, poles, paneling, boxes, and plywood. It is popular for making butchers’ blocks because it is fairly hard, without scent, and does not chip easily. It is suitable for construction, flooring, interior trim, vehicle bodies, railway sleepers, toys, novelties, agricultural implements, musical instruments, coffins, food containers, vats, carving, pattern making, matches, turnery, hardboard and particle boards. The wood considered a high-quality pulpwood is also used for fuel (Fern, 2014).

2.1.3 Podocarpus latifolius Seed Morphology The dioecious flowers are inconspicuous and are followed by green fleshy fruits (Fern, 2014). There are male and female trees. The male cones are 10-30mm long (Farjon, 2013), maturing from July to September. The cones resemble catkins, an inflorescence adapted for wind pollination found on the exotic Betula species. The female tree usually develops round grey / blue seeds on 6 thickened fleshy stalks known as receptacles which as they mature, turn purple in December to February (Fern, 2014). There may be one or sometimes two seeds mature on each receptacle. Seeds are large, fleshy and oval 1-1.5cm maturing in December-February (Farjon, 2013).

2.2 Factors Influencing Seed Dormancy Seed dormancy is nature’s way of setting a time clock that allows seeds to initiate germination when conditions are normally favorable for germination and survival of the seedlings. For example, dogwoods produce mature seeds in the fall, but conditions are not suitable for seedling survival at that time. Thus, dogwoods have developed a mechanism that keeps the seeds dormant until spring when conditions are favorable for germination, as well as, seedling growth and survival (Yeager, 2010)

One of the external factor that influences seed dormancy and germination is water. A dormant seed is generally dehydrated and contains hardly 6-15% water in its living cells. The active cells, however, require about 75-95% of water for carrying out their metabolism. Therefore, the dormant seeds must absorb external water to become active and start to germinate. In addition to providing the necessary hydration for the vital activities of protoplasm, water softens the seed coats, causes their rupturing, increases permeability of seeds, and converts the insoluble food into soluble form for its translocation to the embryo. Water also brings in the dissolved oxygen for use by the growing embryo (Blake, 2003).

Another factor influencing germination is oxygen. Oxygen is necessary for respiration which releases the energy needed for growth. Germinating seeds respire very actively and need sufficient oxygen. The germinating seeds obtain this oxygen from the air contained in the soil. It is for this reason that most seeds sown deeper in the soil or in water-logged soils (i.e. oxygen deficient) often fail to germinate due to insufficient oxygen. Ploughing and hoeing aerate the soil and facilitate good germination (Lynn, 2006).

Suitable temperature and moderate warmth are also necessary for the vital activities of protoplasm, and, therefore, for seed germination. Though germination can take place over a wide range of temperature (5-40°C), the optimum for most of the crop plants is around 25-30°C. The germination in most cases stops at 0°C and 45°C respectively (Blake, 2003). 7

In some plants the embryo is not fully mature at the time of seed shedding which is an internal factor. Such seeds do not germinate till the embryo attains maturity. The freshly shed seed in certain plants may not have sufficient amounts of growth hormones required for the growth of embryo. These seeds require some interval of time during which the hormones get synthesized (Mohammad & Smith, 2013). This implies that, the seeds of almost all the plants remain viable or living for a specific period of time. This viability period ranges from a few weeks to many years (Blake, 2003). For instance Acacia, Gmelina, Eucalyptus, A. garckeana, Flacourtia indica, S. birrea and P. curatellifolia are some of the examples of tree species whose seeds have long viability periods (Mng’omba, 2007).

In many plants, the freshly shed seeds become dormant due to various reasons like the presence of hard, tough and impermeable seed coats, presence of growth inhibitors and the deficiency of sufficient amounts of food, minerals and enzymes (Isabelle Debeaujon, 2010).

2.3 Overcoming Seed Dormancy to Ensure Proper Germination Viable seeds that do not germinate are said to be dormant. Dormancy can be regulated by the environment or by the seed itself. If a seed is not exposed to sufficient moisture, proper temperature, oxygen, and for some species light, the seed will not germinate. In this case, the seed’s dormancy would be due to unfavorable environmental conditions (Hoyle, 2014).

On the other hand, some seeds may not germinate because of some inhibitory factor of the seed itself. This particular kind of dormancy consists of two general types: seed coat or external dormancy and internal (endogenous) dormancy (Bentsinka, 2008).

Ways of overcoming seed dormancy include hot water soaks, dry heat, scarification, acid soaking among others. Hot water soaks: This is the traditional treatment for hard-seeded species such as legumes, or seeds with waxy seed coats. Although some growers use a standard treatment period for the hot water soak, it is better to experiment with each species and seed lot because of variations in seed coat thickness. Treated seed is subject to bacteria and fungus infection, and should be sown within a few days. One problem with hot-water treated seeds is that they stick together, making them

8 difficult to use in mechanical seeders. One remedy for this is to place the treated seeds in moist peat moss for a few days (Hilhorst, 2010).

Dry Heat: Fire treatments have been used on the seeds of some woody shrubs (e.g. Arctostaphylos spp.) from fire-dependent plant communities, and for some species of Eucalyptus spp. Dry heat treatments are always not recommended, however, because the amount and duration of the heat that reaches the seed cannot be accurately controlled (Demir, 2008).

Scarification: the process of scarification involves weakening the hard seed coat just enough to allow imbibition, and several techniques are effective. Mechanical abrasion as a form of scarification is where the seed coats of small quantities of relatively large seeds can be treated by hand: nicked with a triangular file or sharp knife, rubbed against coarse sandpaper, or burned with an electric soldering iron or wood-burning tool.

Apart from ensuring that the rounded side of the seed is scarified to avoid damage to the radicle of the embryo, workers should always wear protective gloves and small seeds can be held with tweezers. To treat large seed lots, a rotating drum that is lined with sandpaper or a cement mixer filled with gravel can be used. Whatever technique is used, it is important to regularly check the seed coats to make sure that the treatment has not gone too far (EL-Khalifa, 2004).

Acid soaking is another scarification method in which the seeds are soaked in a strong acid solution which chemically digests the hard seed coat. Concentrated sulfuric acid is preferred, but growers must be aware that this is an extremely caustic material, and that safety must always be a foremost consideration (Demir 2008). Because the treatment time will vary considerably with species and seed lot, it is a good idea to conduct some small-scale trials first by removing a few seeds at regular time intervals, and cutting them to assess the thickness of the seed coat. When properly done, acid scarification is a very effective way to soften seed coats and stimulate quick germination.

Although acid-scarified seeds can be stored for a few days, it is best if they are sown immediately. It should however, be noted that the best choice of scarification treatment would depend on the biological requirements of the species and the skill and experience of the grower (EL-Khalifa, 2004). 9

Embryo or morphological dormancy is an "internal" type of dormancy which has two different causes, but in both, the cultural treatment must overcome a physiological or morphological condition within the seed itself. As was the case with seed coat dormancy, the degree of dormancy can vary considerably from species to species, as well as between ecotypes. Again, the need to try different treatments and keep good records cannot be overstressed (Dhief, 2012).

Cold moist stratification is the most common treatment used to overcome seed dormancy in commercial forest tree species. This method of stratification satisfies several important physiological functions, including: activating enzyme systems and converting starches to sugars for quick metabolism. Although the exact mechanism is unknown, stratification also changes the balance between chemical inhibitors and promoters within the seed, thereby acting as a "switch" to chemically stimulate germination. It should also be noted that even species that do not exhibit true dormancy can benefit from cold, moist stratification with faster and more complete germination (Sayed Roholla Mousavi, 2011).

Nevertheless, traditional practice of mixing seeds within a moist medium is still used for some forest and conservation species. In cases where some nurseries mix seeds with damp Sphagnum moss in a plastic bag and place it in a refrigerator, the condition of the seeds is to be checked weekly so that they are sown after the prescribed stratification period, or planted as germinant (Hilhorst, 2010).

Another form of scarification is naked stratification. Naked scarification involves soaking seed in water to obtain full imbibition, draining off the excess water, and placing the seeds in polyethylene bags in refrigerated storage where the temperature is held slightly above freezing. In most cases, however, running water rinses are preferred to standing soaks because the bubbling water keeps dissolved oxygen levels high, and also cleanses the seed coat of pathogenic organisms (Charlotte, 2017).

2.4 Effects of Salinity on Seeds Germination and Growth Plants are divided depending on their reaction to salinity into halophytes and glycophytes. While the halophytes are the ones that thrive well in saline conditions, the glycophytes are those that thrive well in non-saline habitat (Bahizire, 2007). 10

Salinity varies from extremely very low to extreme salinity. Conditions with electro conductivity values less than 2 dS M-1 being regarded as non-saline. Between 2-4 dS M-1 being slightly saline with little effect in plants except for very sensitive crops. Values between 4-8 dS M-1 and 8-16 dS M-1 are regarded as moderate and severely saline respectively with values above 16 dS M-1 being regarded as extremely severe and only a few grass species can thrive in these conditions (Bahizire, 2007).

The adverse effects of salinity on germination, plant growth and development are complex. These may result from a combination of factors such as nutritional deficiencies, cytotoxicity and osmotic stress which cause ionic imbalances, oxidative and osmotic stress and nutritional deficiencies (Bahizire, 2007).

Salinity affects imbibition, germination and root elongation. Since a solution of sodium chloride is an osmotic solution with low water potential, water can enter the seed slowly allowing gradual seed imbibition, activation of early phases of germination while preventing radicle protrusion. Usually, water potential of such a solution varies from -1.0 down to -2.0, implying that values of water potential together with duration of the treatment should always be adjusted to species, cultivar and sometimes seed lot (Lutts, 2016).

As has been reported by Bahizire (2007), salinity becomes problematic when enough salts accumulate in the root zone to negatively affect plant growth. This is so because it hinders plants roots from withdrawing water from the surrounding soil with devastating effects on agriculture due to reduction in biomass.

While different plant growth stages have variable tolerances to salt stress, the effects on the different parts of the plant may also vary. It should also be noted that salts are usually less damaging during germination. As the plant keeps growing and maturing, it becomes more sensitive in the early seedling growth stages and then more tolerant as it matures. Apart from that, high concentration of salt can also reduce the rate of germination or even inhibit seed germination altogether (Bahizire, 2007). Therefore seeds should only be treated with salt solution and after owing, normal conditions should be applied for instance regular water so as not to increase salinity of the soil (Lutts, 2016). 11

2.5 Effects of Salinity on Soil Properties Salinity problems are more prevalent in irrigated lands. Thus, to keep salinity in irrigated soils from exceeding tolerable levels and to ensure sustainable and profitable production in irrigated agriculture, sufficient drainage to leach excess salts are required (Bahizire, 2007).

Salinity also affects soil physical and chemical properties of which a change in osmotic pressure is the most important. Salinity together with sodicity (salinity caused by sodium) though all have opposite effects on soil dispersion have effects on soil structure. In essence, salinity improves flocculation in soil (which is beneficial in terms of soil aeration), root penetration and root growth (Bahizire, 2007).

Sodicity on the other hand, can reduce the permeability, decrease the infiltration capacity of soil and induce crusting (Bahizire, 2007). In effect, soil salinity affects soil chemical balances, pH and the availability of nutrients such as P, Fe and Mn and in case of boron, sodium and chloride, toxic levels may be reached in the soil (Bahizire, 2007).

CHAPTER THREE: MATERIALS AND METHODS 3.1 Materials The materials used were freshly harvested podocarpus seeds (Kapchorwa provenance). These seeds were extracted from the study site at National Tree Seed Centre (NTSC). Distilled water was used for the making of solutions of sodium chloride of different concentrations. This was preferred because it was free from impurities that would alter the germination of seeds (Chachar, 2008).

Sodium chloride (common salt) is an inorganic salt from which solution of different concentrations were made for the pre-treatment of Podocarpus latifolius seeds (El-Juhany, 2008).

Laboratory scale was used for measuring the amount of sodium chloride to add in distilled water in order to come up with different solution concentrations to be used as independent variable.

Measuring cylinder was also used to measure the volume of distilled water required for the making a particular concentration of solution required for immersing the seeds.

Lastly, seed bed was used for germination of the seeds. The bed was divided according to the different treatment factor combinations of time and solution concentrations in which the seeds were soaked (Hafiz Haider Ali, 2011).

3.2 Methods 3.2.1 Research Design This was an experimental research design with the solution concentrations, rinsing and time of pretreatment or soaking as the independent variable and time for seed germination and germination responses of Podocarpus latifolius seedlings as the dependent variables (Nabanyumya, 2015).

3.2.2 Experimental Setup a) Bed Preparation A nursery bed of dimension (10 by 1m) was first measured and constructed with poles and sides lined with bricks to form a raised ground off the normal ground. Top soil layer was then scrapped off the bed using a hoe and spade. Fine nursery soil mixture of loam soil and sand soil in ratio of 1:1 were mixed after thorough sieving to obtain fine soil (Defoer, 2009). 13

The sieve pabbles or gravel were then first poured into the bed as the first layer before the fine mixture of sand and loam soil was poured to ensure proper aeration and water filtration since a damp soil was required for germination not a wet one. The mixture was then transfered into the bed to form an equally level ground bed so as to ensure no gradient for soil runoff during rainy season or watering (Dharmasena, 2016).

b) Seed Preparation for Different Treatments Eight thousand four hundred (8400) seeds of Podocarpus latifolius were sorted from a seed batch freshly obtained from kapchorwa and weighed (Nabanyumya, 2015). The weight obtained for 8400 seeds was (9.81kg), purity test was (100%), and viability test was (97%). Different aqueous solutions of sodium chloride were prepared by dissolving different amounts of sodium chloride salt in distilled water as follows: control (no sodium chloride), 100mM, 200mM, 300mM, 400mM, 500mM, and 600mM.

For each solution, equal number of seeds (1200 seeds) were soaked in it so that the seeds were fully immersed such that the solution volume was twice the volume of the seeds (Bojović, 2010) (Figure 1).

Figure 1: Treatment illustrations 14

From each of the soaked batches, 400 seeds were withdrawn after time intervals of 6 hours, 12 hours and 24 hours and further divided into 200 seeds before sowing. The 200 seeds of each lot were sown directly and the other 200 seeds were rinsed first with fresh water for 6 hours and then later sown in the bed in replicates of 50 seeds per mini plot and monitored for germination (Bojović, 2010). A seed was considered germinated after the emergence of the plumule and or radicle (Getahun, 2011 ).

3.2.3 Plot layout The seed bed was partitioned in terms of hours of treatment, concentration, rinsed and unrinsed, and then the experimental replicates of 50 seeds per section (Figure 2).

The layout was in Complete Randomized Block Design (Nabanyumya, 2015).

50 seeds Mini plot 1

50 seeds Mini plot 2 1 Sowed without rinsing 50 seeds Mini plot 3

50 seeds Mini plot 4

50 seeds Mini plot 5

50 seeds Mini plot 6 Rinsed before sowing

50 seeds Mini plot 7

50 seeds Mini plot 8

Figure 2: Plot layout

3.2.4 Data Collection Data were collected on the number of seeds germinated (Nabanyumya, 2015), number of first true leaves unfolded, height of true leaf formation, number of days taken for seed germination and number of days to formation of first true leaves for every treatment combination (Cordazzo, 1999).

3.2.5 Data Analysis Parameters such as germination percentage, mean germination time (MGT), mean germination rate (MGR), germination vigor, were calculated according to Labouriau and Agudo (Getahun, 2011 ) as follows:-

푛 a) Germination Percentage = ∗ 100 푁 Where: n= total number of germinated seeds; N= total number of seeds in the sample

∑푛푖푡푖 b) The mean germination time MGT = ∑푛푖 Where: ni= number of seeds germinated between time ti; ti= time (in day) taken since germination experiment started;

1 c) Mean germination rate MGR= 푀퐺푇 Where: MGT = mean germination time in days.

Data were then subjected to analysis of variance (ANOVA) to determine whether the independent factors had significant effects on the dependent factors, taking into account that the treatment structure consists of all possible combinations of all levels of the all factors under investigation. Least significant difference (LSD) was used to show the effect and interaction of salt solution concentration and time of soaking on germination of Podocarpus latifolius seeds at significance level of 5% (Nabanyumya, 2015).

A two sample t-test and confidence interval was computed to ascertain whether there was a significant difference between the number of seeds sown directly without rinsing and seeds sown after rinsing for 6 hours that germinated (Getahun, 2011 ). 16

CHAPTER FOUR: RESULTS

4.1 Determination of Sodium Chloride Concentration for the Shortest Germination Days of Podocarpus latifolius Seeds Unrinsed seeds soaked in 0.3M solution for 6 hours germinated with the shortest time period of 36 days while rinsed seeds soaked for 6 hours in 0.5M solution took 35 days to germinate (Figure 3 a & b).

Unrinsed seeds took 55.76±11.74 days to germinate while rinsed seeds took 59.72±10.31 to germinate within the experimental period (Table 1).

(a)

Days

Figure 3a: Mean germination days by sodium chloride solution concentrations and soaking time of Podocarpus latifolius Rinsed seeds

(b)

Days

Figure 4b: Mean germination days by sodium chloride solution concentrations and soaking time of Podocarpus latifolius Unrinsed seeds

Table 1: Number of days taken for germination of seeds of Podocarpus latifolius

Rinsed Unrinsed Variable Minimum Mean Maximum Minimum Mean Maximum Days to seed 35 59.72±10.31 73 36 55.76±11.74 70 germination

4.2 Examination of the Effects of Sodium Chloride on the Growth Responses of Podocarpus latifolius Seedlings unrinsed seeds indicated better performance in the rate of germination and addition of biomass compared to seeds that were rinsed before sowing. Rinsed seedlings took 70.20±9.66 days to for their leaves to unfold while unrinsed seedlings took 67.01±11.43 days for their leaves to unfold. On average, rinsed seedlings had 6.914±2.524 leaves unfolded while unrinsed seedlings had

6.830±1.988 leaves unfolded at heights of 3.630±0.905cm and of 4.018±0.801 cm respectively (Table 2).

Table 2: Comparison of effects of sodium chloride solution and soaking time on days to seeds germination and germination responses of Podocarpus latifolius seedlings

Rinsed Unrinsed Variable Minimum Mean Maximum Minimum Mean Maximum Number of seeds 01.0 1.1935±0.4774 03.0 01.0 1.250±0.645 04.0 germinated Days to first 45.0 70.20±9.66 82.0 46.0 67.01±11.43 82.0 true leaves Number of 01.0 6.914±2.524 12.0 02.0 6.830±1.988 11.0 true leaves Height of leaves 01.3 3.630±0.905 06.6 02.7 4.018±0.801 05.9 formation (cm)

Both rinsed and unrinsed seeds, Podocarpus latifolius seedlings soaked in 0.3M solution had the best germination responses. However not all treatment combination under 0.3M produced the same results (Figure 3 and 4).

Rinsed seeds soaked for 12 hours in 0.3M solution had the highest mean height of leaves formation (6.6cm) and unrinsed seeds soaked for 6 hours in 0.3M solution had the best height of 5.9±0.801cm (Figure 4).

Seedlings of rinsed seeds soaked in 0.3M solution for 12 hours produced the greatest mean number of leaves (12±2.524 leaves) while seedlings for which seeds were pre-soaked in 0.0 M solution for 12 hours produced the highest number of leaves (11±1.988 leaves) in the unrinsed seeds (Figure 5).

(a)

(b)

Figure 5: Mean heights of leaves formation by sodium chloride solution and soaking time for Podocarpus latifolius seedlings Note: (a) Rinsed seeds and (b) Unrinsed seeds 20

(a)

(b)

Figure 6: Mean number of true leaves by sodium chloride solution and soaking time for Podocarpus latifolius seedlings Note: (a) Rinsed seeds and (b) Unrinsed seeds

4.3 Assessment of the Significant Differences in the Growth Responses of Podocarpus latifolius Seedlings Pre-Treated with the Different Salt Solution Concentrations There was no significant effect of sodium chloride solution alone on days to seed germination (F=0.65, df =6, p<0.690), number of seeds germinated (f=0.55, df =6, p<0.767), days to first true leaves (f=0.62 df=6 p<0.711), number of true leaves (f=0.92, df=6, p<0.484), and height of leaves formation (f=0.43, df=6, p<0.853); soaking time alone on days to seed germination (f=1.29, df =2, p<0.281) number of seeds germinated (f=0.45 df= 2 p<0.640), days to first true leaves (f=1.09 df=2 p<0.341), number of true leaves (f=0.60, df =2, p<0.549), and height of leaves formation (f=0.79, df=2, p<0.460) or the interaction of both treatment factors on days to seed germination (f=1.24, df=12, p<0.279), number of seeds germinated (f=1.08 df =12 p=0.390), days to first true leaves (f=1.24, df =12, p<0.277), number of true leaves (f=1.52, df=12, p<0.139), and height of leaves formation (f=1.33, df=12, p<0.222) among unrinsed seeds of Podocarpus latifolius (Table 3).

Table 3: ANOVA on effect of sodium chloride solution concentration, soaking time and their interaction on germination responses of Podocarpus latifolius seedlings

Source of variation Salt solution Soaking time Salt solution concentration concentration * soaking time Unrinsed Rinsed Unrinsed Rinsed Unrinsed Rinsed Germination rate 1.17ns 1.10ns 0.37ns 0.40ns 1.09ns 1.30ns Days to seed 0.65ns 1.00 ns 1.29 ns 0.11 ns 1.24 ns 1.32 ns germination Number of seeds 0.55 ns 1.02 ns 0.45 ns 0.12 ns 1.08 ns 1.44 ns germinated Days to first true 0.62 ns 1.04 ns 1.09 ns 0.14 ns 1.24 ns 1.27 ns leaves Number of true 0.92 ns 1.08 ns 0.60 ns 0.33 ns 1.52 ns 0.94 ns leaves Height of leaves 0.43 ns 0.86 ns 0.79 ns 0.05 ns 1.33 ns 1.08 ns formation Note: the numbers in the table represent f values. The superscript ns means not significant

There was also no significant effect of sodium chloride solution alone on days to seed germination (f=1.00, df =6, p<0.432), number of seeds germinated (f=1.02, df =6, p<0.421), days to first true leaves (f=1.04 df=6 p<0.409), number of true leaves (f=1.08, df=6, p<0.386), and height of leaves formation (f=0.86, df=6, p<0.526); soaking time alone days to seed germination (f=0.11, df =2, p<0.895), number pf seeds germinated (f=0.12 df= 2 p<0.888), days to first true leaves (f=0.14 df=2 p<0.871), number of true leaves (f=0.33, df =2, p<0.717), and height of leaves formation (f=0.05, df=2, p<0.954) or the interaction of both treatment factors on days to seed germination (f=1.32, df=12, p<0.232), number of seeds germinated (f=1.44 df =12 p=0.174), days to first true leaves (f=1.27, df =12, p<0.258), number of true leaves (f=0.94, df=12, p<0.517), and height of leaves formation (f=1.08, df=12, p<0.389) among rinsed seeds of Podocarpus latifolius (Table 3).

This therefore meant that germination rate, days to seeds germination, number of seeds germinated, days to first true leaves, number of true leaves and height at which leaves unfolded among both rinsed and unrinsed seeds of Podocarpus latifolius were not dependant on the treatment factors and neither did they depend on the interaction of the treatment factors.

From multiple pairwise comparisons of means, days to seeds, number of seeds germinated and germination responses of seedlings differed in the seeds soaked in 0.6M solution and control solution. Seeds soaked in the rest of other solutions showed no significant difference in the number of days taken for germination to the control solution though also number of seeds germinated further differed in solution of 0.3M solution from those in 0.6M solution but the rest were similar.

CHAPTER FIVE: DISCUSSIONS

5.1 Determination of the Sodium Chloride Concentration for the Shortest Germination Days Seed germination is the fundamental basis in forest establishment and management and as it offers a starting point in forest establishment (Nabanyumya, 2015). This is usually influenced by uptake of water. While, uptake of water by seeds during imbibition leads to the activation of metabolic processes as the dormancy of the seed is broken following hydration (Lutts, 2016), elevated salinity slows down water uptake by seeds, thereby inhibiting their germination (Katembe, 1998). This was quite evidenced in seeds of Podocarpus latifolius soaked especially in sodium chloride solution concentrations of 0.6M especially for 24 hours which did not even germinate for both rinsed and unrised seeds (Figure 2).

The first phase of water uptake by the seeds involves movement of water into the free space (apoplast) and does not depend on the osmotic potential of the surrounding solution. The second slower linear phase of water uptake involves the movement of water across cell membranes into the cells of the seeds and is determined by the difference between the osmotic potential of the seed and that of the medium (Bewley, 1994). NaCl readily crosses the cell membrane into the cytoplasm of the cells unless an active metabolic pump prevents accumulation of the ions (Katembe, 1998).

In some cases, NaCl in the cytoplasm can result in toxic accumulation of a particular ion or decreased availability of some essential nutrients. Presence of Na+ and Cl− ions in the cells may also induce changes in protein activity because ions affect the structure of the hydrated water which surrounds the protein molecule. NaCl may also be inhibitory to the activities of some enzymes that may play critical roles in seed germination (Kaymakanova, 2009). Flowers (1972), experimenting with species in the genera Beta, Salicornia and Suaeda, and Cavalieri and Huang (1977) investigating species in the genera Borrichia, Distichlis, Juncus, Salicornia and Spartina, reported that malate and glucose-6-phosphate dehydrogenase were among the enzymes affected. One or a combination of these effects of sodium chloride on the seeds of Podocarpus latifolius may have caused the impeded growth in some of the germinated seeds.

Since there is an upper limit (0.6M) of salt solution concentration beyond which no seed of Podocarpus latifolius germinates, it is important that NaCl salt solution concentration should be considered carefully in establishment of saline germination solutions. While Nabanyumya (2015), reported that Podocarpus latifolius seeds can take up to 70 days to germinate, in this study, the shortest time taken by Podocarpus latifolius seeds to germinate was even half (35 days). This implies that appropriate NaCl solution can shorten germination days hereby enhancing germination capacity of Podocarpus latifolius seeds.

5.2 Effects of Sodium Chloride on the Growth Responses of Podocarpus latifolius Seedlings According to Gayalwa (2012), the effect of salinity in many species is to reduce leaf growth rate, leaf emergence rate, and overall shoot development. The reduction in leaf growth of plants exposed to such different NaCl concentration in this study is attributed to reduced turgor or reduction in extensibility of expanding cell walls. This inhibition of leaf growth in the short-term may be due to water stress, while on long-term scale, leaf growth is affected by ion toxicity when the ions move through the transpiration stream and accumulate in the leaves, which eventually leads to increased leaf mortality and senescence (Gayalwa, 2012). This is so because lack of vasculature to the meristems reduces transport of Na+ and Cl- ions to these cells and the fully expanded leaves that are ion sinks may abscise to allow plants minimize exposure of these cells to the ions in the tissues. The reduced leaf area is an adaptation to reduce ion uptake by roots (Gayalwa, 2012). This attributes to the observed increase or decrease in number of leaves in seedlings whose seeds were treated with 0.5M solutions and above (Figure 3).

Subsequently, treating seeds with NaCl can affect plant development since the reduced leaf area contributes to less photosynthesis, and hence less dry matter accumulation (Gayalwa, 2012). This is seen for the height of Podocarpus latifolius seeds treated with solution of concentration more than 0.4M solution (Figure 3) in deed these Podocarpus latifolius seeds treated with solution whose concentration was more than 0.4M did not even germinate.

The amount of formed biomass and the rate of biomass formation in Podocarpus latifolius seedlings was significantly different in control solution and 0.6M solution with the exception of 0.3M solution. In 0.3M solution, the number of true leaves formed were different compared to 25 seeds soaked in 0.6M solution but similar to the rest of the other seeds soaked in the other solutions (Figure 4). This could be due to a wide salinity tolerance range for Podocarpus latifolius seeds and also the amount of time for which the seeds get exposed to saline conditions. This further justifies why seeds of Podocarpus latifolius should not be soaked in solution concentrations 0.6M and above for more than 12hours. Indeed Podocarpus latifolius seeds soaked in 0.6M for 12 hours and above would take more time to germinate and even further produce less biomass at an additionally slower rate. This is because under salt stress conditions, elongation rate of coleoptiles may decrease by low soil water potential and seedlings may not be established well due to weak coleoptile and root growth (Demir, 2008). This also accounts for the differences in the emergence rate of the leaves in the different Podocarpus latifolius seedlings (Cordazzo, 1999).

Since sustainable production of high quality seedlings is a prerequisite for successful on farm tree planting and plantation establishment, conservation and domestication of wild tree populations (Nabanyumya, 2015), a clear and proper understanding of germination capacity and the effects of sodium chloride on the germination responses of Podocarpus latifolius seedlings is very vital. Ascertaining the effects of NaCl on germination also increases on easy accessibility by tree growers to good quality seedlings since access to good quality seeds has been a major constraint to on-farm planting of Podocarpus latifolius (Nabanyumya, 2015). Similarly, the findings in this study can thus be used to facilitate on farm planting, conservation, domestication and improvement of Podocarpus latifolius which can be exported either as seedlings or high quality softwood timber to other regions with similar ecological characteristics as its area.

5.3 Significant Differences in the Growth Response of Podocarpus latifolius Seedlings Pre-treated with Different Salt Solution Concentrations Since Podocarpus latifolius seeds can germinate in a range of salt solutions, it is an indication that plants with high osmotic tolerance usually maintain high growth rates, particularly over the first few days after exposure to Na+ (Munns, 2002). According to Gayalwa (2012), salt-tolerant plants usually have lower cytoplasmic Na+ concentrations than sensitive ones because of their efficient ability to sequester Na+ into the vacuole. Eventually greater accumulation of Na+ in plants also increases the cell solute potential together with their osmotic adjustment (Gayalwa, 2012). In this study, Podocarpus latifolius thrived well in the range of salt solution concentration of (0.0 to 0.3M). These ranges were not detrimental to germination and growth responses of Podocarpus 26 latifolius seedlings; implying that such salinity range is the non-lethal range within which Podocarpus latifolius is able to adjust without either its germination or germination responses being impeded.

Although salinity varies from extremely very low to extremely very high, Podocarpus latifolius has a range of salinity within which it performs best (0.1M to 0.3M), followed by medium salinity (0.4M to 0.5M) and extreme salinity (0.6M and above). Since proper seedling development is within the low salinity levels, higher salinity levels of 0.5M and above would impede germination of Podocarpus latifolius more especially if the seeds are soaked for more than 12 hours. Germination and addition of biomass would also get impeded if the seeds are soaked for more than 12 hours. This is so because salinity varies for different plants ranging from halophytes to glycophytes which tolerate varying extremities in salinity (Katembe, 1998). Such findings provides for further justification not to soak seeds of Podocarpus latifolius in solution of concentrations more than 0.6 M as the imposed stress conditions can restrict the water to reach the threshold level for germination and thereby retarding all other seedling growth responses (Demir, 2008).

CHAPTER SIX: CONCLUSIONS AND RECOMMENDATIONS 6.1 Conclusions The following conclusions were drawn: i. Soaking Podocarpus latifolius seeds in solution concentrations more than the range within which it can germinate especially for more hours (0.6M for 24hours), will impede its germination. ii. Unrinsed Podocarpus latifolius seeds had better germination rate (67.01 ±11.43 days) for their leaves to unfold compared to soaked and rinsed seeds which took 70.10±9.66 days for their leaves to unfold; an indication that sodium chloride can influence the growth responses of Podocarpus latifolius seedlings. iii. The reduction in the number of leaves unfolded and lesser height at which leaves were formed for seedlings whose seeds were soaked in solutions of concentration 0.4M and above is an indication of the effect of sodium chloride solution on the growth responses of Podocarpus latifolius seedlings. iv. Germination rate in Podocarpus latifolius, amount of biomass formed and the rate of biomass formation are higher and relatively the same within the non-lethal ranges of sodium chloride solution (0.0 to 0.3M) though any increase in NaCl solution conclusion beyond optimum, leads to a reduction in amount of biomass and the rate of biomass production, it implies that sodium chloride concentrations above the optimum concentrations are lethal to germination success of Podocarpus latifolius. v. For Podocarpus latifolius, the optimum NaCl solution concentrations that are non-lethal are 0.0 to 0.3M; moderately high concentrations are 0.4 to 0.5M and extremely lethal concentrations range from 0.6M and above.

6.2 Recommendations The following recommendations were made: a) For the shortest germination days, greater amounts of biomass addition and greater rates of biomass addition, salt solution concentrations within the optimum levels of up to 0.3M solution should be considered. b) For establishment of saline germination solutions, NaCl solution concentration should be carefully considered taking into account the optimal levels, medium levels and lethal levels. 28 c) For best germination results of Podocarpus latifolius seeds should be soaked in NaCl solution of 0.3M solution for 12 hours and for the best germination responses in Podocarpus latifolius seedlings, their seeds should also be soaked in solution of concentration of 0.3M for 12 hours. d) Effects of NaCl solution on dry matter, root length and cellular components should be investigated to find out whether sodium chloride solution has significant effects on these. e) Experiments can also be done to investigate the effects of watering with sodium chloride solution on the Podocarpus latifolius through investigating the effects on germination and germination responses to assess whether there are significant differences between this mode of treatment investigated in this research and this suggested in this paragraph.

REFERENCES

Adie ML. (2010). Podocarps in africa: temperate zone relicts or rainforest survivors? Smithsonian contributions to botany, 80-96. Bahizire, F. B. (2007). Effect of salinity on the germination and seedling growth of canola. Stellenbosch: university of stellenbosch. Bentsinka, M. K. (2008). Seed dormancy and germination. Arabidopsis book., 119. Blake, J. H. (2003). Factors affecting cereal establishment and its prediction. Hereford: home-grown cereals authority. Bojović, G. Đ. (2010). Effects of nacl on seed germination in some species from families brassicaceae and solanaceae. Kragujevac: institute of biology and ecology, faculty of science, university of kragujevac. Moreno C, Seal C.E, Papenbrook J. (2007). Seed priming improves germination in saline conditions for chenopodium quinoa and amaranthus caudatus. Salinity stress, 42. Chachar. (2008). Influence of sodium chloride on seed germination and seedling root growth of cotton (gossypium hirsutum l.). Reading: 1department of plant physiology and biochemistry, faculty of crop production, sindh agriculture university, tando jam-70060-pakistan. 2department of soil science, school of human and environmental sciences, university of reading, whiteknights, po box 233. Charlotte, J. (2017). Seed treatments: soaking, scarification and stratification. Cordazzo C V. (1999). Effects of salinity on seed germination, seedling growth and survival of spart/na c/l/ata brong. Acta boi. Bras., 317-323. Defoer. (2009). Establishing a nursery. Facilitator’s manual, 1-4. Demir, K. M. (2008). Effect of salt and osmotic stresses on the germination of pepper seeds of different maturation stages. Brazilian archives of biology and technology, 898-901. Dharmasena. (2016). Nursery mnaagement: handbook for beginners. Eu support to district support development programme, 1-92. Dhief, M. G.-S. (2012). Effects of some seed-coat dormancy breaking treatments on germination of three calligonum species occurring in southern desert of tunisia. Ecologia mediterranea, 19-25. El-Juhany. (2008). Response of eucalyptus camaldulensis, eucalyptus microtheca and eucalyptus intertexta seedlings to irrigation with saline water. World journal of agricultural sciences 4, 825-834. El-Khalifa, M. A. (2004). Effect of seed scarification methods on germination and seed vigor of poinciana. (delonix regia). Khartoum: department of horticulture,university of khartoum. Erv, F. A. (1999). Overcoming seed dormancy: trees and shrubs. North carolina: north carolina state university. Farjon, A. F. (2013). Podocarpus latifolius. The iucn red list of threatened species, 5-9. Fern, K. (2014). Calopogonium caeruleum. Useful tropical plants database, 256-272.

Gayalwa. (2012, semptember 4th). Nacl salinity affects germination, growth, physiology,and biochemistry of bambara groundnut. Brazilian society of plant physiology, pp. 151-160. Getahun, S. (2011 ). Studies on seed germination physiology, germinant establishment and seedling growth performance of ficus sur forssk. (moraceae). Addis ababa: addis ababa university school of graduate studies plant biology and biodiversity management program unit. Hafiz Haider Ali, A. T. (2011). Methods to break seed dormancy of rhynchosia capitata, a summer annual weed. Chilean journal of agricultural research, 483-487. Hilhorst. (2010). Dormancy in plant seeds. Netherlands: narcis (netherlands). Hongxiang Zhang, L. J. (2010). The effects of salinity and osmotic stress on barley germination rate: sodium as an osmotic regulator. Annals of botany, 1027-1034. Hoyle, H. (2014). Effects of reduced winter duration on seed dormancy and germination in six populations of the alpine herb aciphyllya glacialis (apiaceae). Conservation physiology, 5-15. Hylton, A. (2009). Explaining conifer dominance in afrotemperate forests: shade tolerance favours podocarpus latifolius over angiosperm species. Forest ecology and management, 176-186. Ido, Y. W. (1973). Inter-relationships between halophytes and glycophytes grown on saline and non-saline media. Journal of ecology, 775-786. Isabelle Debeaujon, K. M.-K. (2010). Influence of the testa on seed dormancy, germination, and longevity in arabidopsis. Plant physiology, 403-414. Katembe. (1998). Effect of salinity on germination and seedling growth of two atriplex species (chenopodiaceae). Annals of botany, 172-173. Kaymakanova. (2009). Effect of salinity on germination and seed physiology in bean (phaseolus vulgaris l.). Biotechnology & biotechnological equipment, 326-329. Kaymakanova, M. (2014). Effect of salinity on germination and seed physiology in bean (phaseolus vulgaris l.). Bulgaria: agricultural university plovdiv. Li, E. A. (2011). Seedling salt rolerance in tomato. Euphytica, 403-414. Lutts, P. B. (2016). New challenges in seed biology - basic and translational research driving seed technology. Seed priming: new comprehensive approaches for an old empirical technique, 1-30. Lynn. (2006). What makes a seed breathe faster. Cornell science inquiry partnership, 1-3. Macdonald, B. (1986.). Practical wood plant propagation. Portland: timber press. Manuela, C. R. (2015). Effect of osmopriming on germination and initial growth of physalis angulata l. Under salt stress and on expression of associated genes. Annals of the brazilian academy of sciences, 504-513. Miceli. (2003). Effect of water salinity on awwsa germinationof ocimum basilicum l., eruca sativa l., and petroselinum hortense hoffm. Acta horticulturae, 365-370. Michael Dorman, P. M. (2009). Factors affecting dormancy of oncocyclus iris seeds. Israel journal of plant sciences, 329-333.

Mohammad, M., & Smith, D. (2013). Plant hormones and seed germination. Environmental and experimental botany, 110-121. Munns, R. (2002). Comparative physiology of salt and water stress. Plant, cell and environment, 239-250. Nabanyumya, J. O. (2015). Germination of afrocarpus usambarensis and podocarpus milanjianus seeds in sango bay, uganda. Uganda journal of agricultural sciences, 2015, 240-242. Saira Saeed, B. G. (2011). Comparative effects of nacl and sea salt on seed germination of arthrocnemum indicum. Karachi: institute of sustainable halophyte utilization. Sayed Roholla Mousavi, M. R. (2011). A general overview on seed dormancy and methods of breaking it. Advances in environmental biology ·, 3333-3335. Simon A. Mng’omba, E. S. (2007). Germination characteristics of tree seeds: spotlight on southern african tree species. Tree and forestry science and biotechnology, 3-4. Yeager, D. L. (2010). Propagation of landscape plants. Florida: university of florida.

APPENDICES

(a) Podocarpus latifolius seed carried above soil

(b) Podocarpus latifolius seeds left below the ground

Plate 1: Germination types in Podocarpus latifolius 33

(d) Podocarpus latifolius seeds before and after rapture.

Plate 2: germination characteristics in Podocarpus latifolius