( PD 528/08 Rev.1 (F): Towards Sustainable Indigenous Mahogany

PD 528/08 Rev.1 (

PD 528/08 Rev.1 (F): Towards sustainable indigenous Mahogany production in Ghana: Phase II, refining the silviculture “tool kit” and practical training for industrial-foresters and community farmers

Assessing the effect of different media on the rooting of Khaya ivorensis and Khaya grandifoliola cuttings Sarfo, Y.2, Opuni-Frimpong, E.1 and Abebrese, I. K.2 1) Forestry Research Institute of Ghana 2) Kwame Nkrumah University of Science and Technology

SUMMARY

African Mahoganies are among the most valuable tropical timbers and important export in the international timber market. Currently, the international trade in Mahogany from Africa is limited and this is due in part to the decrease in sourcing natural grown Mahogany. The pressure of over exploitation mounted on Mahogany species has threatened its availability within the natural forest and therefore cited as vulnerable species. The establishment of mahogany plantations have produced enormous successes alternative to natural regeneration; however, the effectiveness of Mahogany plantation is being threatened by a destructive pest- Hypsipyla robusta. Existence of genotypes tolerant to the shoot borer therefore necessitates vegetative propagation in raising seedlings. This study investigated the influence of different rooting media on root formation, elongation and number in simple non-mist propagators using stem cuttings of African mahogany species: Khaya grandifoliola and Khaya ivorensis. It also assessed the survival rates of the two species in the different rooting media. Data on root development callusing, number and length of roots were analyzed using analysis of variance (ANOVA). Khaya grandifoliola exhibited higher rooting ability than Khaya ivorensis. Rooting ability was highest (1.5cm) in the 20v biochar+40:40v mixture (Loam and river sand) medium for Khaya ivorensis while Khaya grandifoliola exhibited higher rooting ability (2.4cm) in the river sand medium. Root elongation was highest in 20v biochar+40:40v mixture (Loam and River sand) for both Khaya grandifoliola and Khaya ivorensis at 12.84cm and 7.17cm respectively. The study further revealed that biochar was the principal catalyst for the high survival rates in both species. This study strongly supports the idea that Khaya ivorensis and Khaya grandifoliola can be propagated vegetatively using stem cuttings which are important for ex-situ conservation and restoration of the mahogany species in Ghana’s forest estate.

1.0 INTRODUCTION

1.1 Background of the study

African Mahoganies (Meliaceae) are among the most valuable tropical timbers and important export in the international timber market (Atuahene, 2001). They are mostly found in Cameroun, Niger, Cote D’Ivoire, Uganda and also common in the dry and wet semi deciduous forests of Ghana (Oteng-Amoako, 2006). Amongst some of the highly valuable Mahogany species in Ghana are Khaya ivorensis and Khaya grandifoliola. The heartwood of Mahogany is dark, red- brown, clearly demarcated from pinkish sapwood, coarse to medium texture with low luster and aromatic odour. This makes Mahogany species durable for making panelings, luxury cabinets and furniture works. The bark yields a brown dye and can also be used for cold and flu treatment as well as widely utilized in managing malaria (Taylor, 1960; Abbiw, 1990). The versatile nature of mahogany has brought about the increase in exportation over the years (FAO, 1993).

Until the 1950’s, Mahogany timber formed up to 70% of the total export from Ghana with an annual volume of approximately 100,000m3 but since then its export has steadily declined (Opuni-Frimpong, 2008). Currently, the international trade in Mahogany from Africa is limited and this is due in part to the decrease in sourcing natural grown Mahogany. The limited nature of Mahogany therefore requires the appropriate technique in maintaining and sustaining the resource to meet both the present and future needs. Consequently, the establishment of mahogany plantations have produced enormous successes alternative to natural regeneration. However, the effectiveness of Mahogany plantation is being threatened by a destructive pest; Hypsipyla robusta (Newton et al. 1993). This threat caused by the shoot borer has raised concerns globally in securing measures to control its occurrence in plantations in order to reduce the attack to economically endurable level. As a result, ways of producing tolerant mahogany genotype to the shoot borer in plantation is the key to the success of the plantation initiative

1.2 The Problem Statement

As international demand for Mahogany wood remains high, it is necessary to ensure a sustainable future supply. Forests in West Africa have undergone a dramatic change during the past one hundred years. As forest area has declined, it is very important to use the remaining natural resources wisely. Again, the pressure of over-exploitation has been mounted on mahogany species to the extent of threatening its availability within the natural forest and therefore cited as vulnerable species (IUCN, 2004). Moreover, natural regeneration of Mahogany species is limited as the seeds lose their viability between 2 and 3 weeks under natural conditions (Taylor, 1960). Also, the survival of the seedlings is poor under the forest canopy since Khaya species are light demanding (Hawthorne, 1990).

Efforts to restore the depleted Mahogany resource base on plantations have been thwarted by persistent attacks of the Mahogany shoot borer; Hypsipyla robusta (Newton et al. 1993a). The Mahogany shoots borer (Hypsipyla robusta) is among the most economically important insect pests in tropical forestry, virtually preventing the cultivation of mahoganies (Swietenia spp., Khaya spp.) in their native areas. Mahogany trees are susceptible to attack when they reach a height of 0.5m (Griffiths 2001). The insect’s most severe damage occurs when a larva bores into and kills the terminal shoot. A lateral branch grows to replace the lost terminal shoot, resulting in

a crooked main stem. Also, the damage to the terminal breaks apical dominance, resulting in excessive lateral branching (Griffiths 2001). Small trees whose terminal shoots are attacked repeatedly in successive years become extremely deformed.

1.3 Justification

The development of vegetative propagation techniques for the Mahoganies has important implications for the commercial regeneration of these species, which are seriously affected by the shoot borer; Hypsipyla robusta. It is known that by cloning, there may be the opportunity to capture and utilize genetic resistance to these pests and domesticate them (Newton 1993a; Newton, et al., 1993b). Hence, a lot of research is advocated for in determining some factors that would promote the effectiveness of the method to be greatly employed on commercial planting. Studies have been done concerning the influence of the leaf area, age of stock plant, applications of IBA (indole-3-butyric acid) in different percentages on most of the Khaya species (Opuni Frimpong et al., 2008b). Currently, a most promising factor which has been known to play a role in higher rooting success of some timber species such as Khaya senegalenses and Khaya ivorensis in the vegetative propagation system is the type of rooting medium used (Tchoundjeu and Leakey 1996; Limpiyaprapant et al. 1996). Unfortunately, there is limited information on the type of rooting medium to facilitate the rooting success of the Mahogany species in the vegetative propagation system. In order to know the appropriate type of rooting medium to enhance successful rooting of Khaya ivorensis and Khaya grandifoliola, this research concentrated on biochar combined with three rooting media: loamy soil, river sand and mixture of river sand and loam. Biochar serves as a catalyst that enhances plant uptake of nutrients and water. Compared to other soil amendments, the high surface area and porosity of biochar enables it to adsorb or retain nutrients and water and also provide a habitat for beneficial microorganisms to flourish (Glaser et al., 2002, Lehmann and Rondon 2006, Warnock et al., 2007).

1.4 Research Objectives

The objectives of this study were:

1. To determine the rooting response of Khaya ivorensis and Khaya grandifoliola in 20v biochar treatment with: 80v loamy soil, 40:40v/v mixtures (river sand and loamy soil) and 80v river sand. 2. To determine the survival rate of Khaya ivorensis and Khaya grandifoliola in the different rooting media. 3. To determine the effect of biochar treatment in propagation of the two species.

2.0 MATERIALS AND METHODS

2.1 Study Site

The experiment was carried out at the trail site of the Forestry Research Institute of Ghana (FORIG). FORIG is located at Fumesua, 15 km from Kumasi on the Kumasi-Accra high way in the moist semi-deciduous forest zone of Ghana with geographical location; 6 44’N, 1 30’W and relief 280 m above sea level. It has an annual precipitation ranging between 1200-1750 mm per annum (Hall and Swaine, 1981). ⁰ ⁰

2.2 Stem Cuttings Preparation and Propagation Setup

Plant material sources for stem cuttings of the two species; Khaya ivorensis and Khaya grandifoliola was collected from Mesewam nursery site, one of FORIG’s nursery and research sites. These materials from actively growing shoot were then dissected into single node cuttings approximately to length of 6cm. Stem cuttings were collected only in the morning hours (between 7-9 am) and then enclosed in a polythene bags to maintain a humid atmosphere (Agbo and Obi, 2007). The stem cuttings were then taken to one of the trial sites of FORIG for propagation. The media for the trial were river sand collected from streamside, loamy soil and 40:40 v/v mixture of river sand and loamy soil. Each media had an equal 20 v of biochar treatment. The media was prepared by pasteurization (Scalabrelli et al., 1983) and then disinfected with Dursban 4E to kill termites in the soils that might temper with the rooting of cuttings. The addition of biochar was to determine the varied volume effect to the rooting media. Rooting hormone was not applied. Each stem cutting was stuck in the media to a depth of 2.5 cm (Kester et al., 1997). The media were then trodden around the base of the cuttings to offer support and watering was carried out every morning for a period of eight weeks. The humidity and temperature in the propagators was kept at 70-80% and 28-30°C respectively (Cheesman and Spencer, 1936; Kester and Hartmann, 1997). Monitoring was done every day to check for dead leaves and cuttings.

2.4 Experimental Design

In the experiment, twenty (20) cuttings for each treatment were replicated four times and arranged in a completely randomized design. The propagators were then filled with equal volume of treatment and the cuttings of each species distributed uniformly.

2.5 Data Collection

Data were taken based on the parameters such as number of roots and length of root. Lengths of roots were measured with a ruler whereas the number of roots was taken by direct counting. Dead shoot and cutting were also recorded. The number of cuttings thriving in each medium was recorded as well as percentage survival of each cutting per species in each medium.

2.6 Data Analysis

Data were analyzed using Microsoft Excel 2010. The mean number of roots as well as the standard error were evaluated. The data were subjected to the Analysis of variance (ANOVA) at (P < 0.05) to test the significance differences between the media based on the measured parameters

3.0 RESULTS

3.1 Root Formation of Khaya grandifoliola per Rooting Media

The highest mean number of roots of Khaya grandifoliola per cuttings was 2.40 in the river sand followed by 2.0 roots in the mixture medium and 1.2 by the loam and 20 v biochar + 80 v Loam. The lowest root formation was observed in the 20 v biochar + 80 v river sand at a value of 0.4.

Fig 3.1 Number of roots of Khaya grandifoliola per treatment

3.2 Root Elongation of Khaya grandifoliola Cuttings per Rooting Medium

From Fig. 4.2, K. grandifoliola growing in the mixture medium recorded the highest mean root length of 12.84cm. 20 v biochar + 80 v river sand recorded the lowest mean root length of 0.75 cm. Loamy soil, river sand and 20 v biochar + 40:40 v mixture (Loam and river sand) recorded mean root lengths of 7.42 cm, 6.76 cm and 5.16 cm respectively. 20 v biochar + 80 v loamy also recorded the mean root length of 2.86 cm.

Root length Root length (cm) Treatment

Fig 3.2 Root length of Khaya grandifoliola per treatment LSD at P<0.05=5.84

3.3 Root formation of Khaya ivorensis per Rooting Medium

From Fig 4.3, in the 20+80 v mixture (river sand and loam), K. ivorensis recorded the highest mean number of roots of 1.50 followed by loamy and the mixture medium recording the same mean root number of 1.00. River sand, 20 v biochar + loamy and 20 v biochar + riversand recorded the lowest mean number of roots of 0.00 respectively.

Number Number roots of

Treatment

Fig 3.3 Number of roots of Khaya ivorensis per treatment

3.4 Root Elongation of Khaya ivorensis Cuttings per Rooting Medium

20 v biochar + 40:40 v mixture recorded the highest mean root length of 7.17cm followed by the 50:50 v mixture which recorded the mean root length of 3.23 cm. Loamy soil also recorded a mean root length of 3.00cm.Riversand, 20 v biochar + loamy and 20 v biochar + riversand recorded mean root lengths of 0.00 cm respectively.

Root length Root length (cm)

Treatment

Fig 3.4 Length of root of Khaya ivorensis per treatment (LSD at P<0.05=0.86)

3.5 Survival Rate of Khaya grandifoliola Cuttings From Fig. 4.5, the highest survival rate for K. grandifoliola (67%) was recorded in the 80 v mixtures + 20 v biochar. The least percentage was recorded in the medium which contained solely river sand at 19.60% and the rest were loamy soil, 50 v:50 v mixtures, 20 v biochar + 80 v loamy and 20 v biochar + 80 v riversand recorded 21.30%, 25.45%, 55% and 52% respectively. Statistically, there were difference at (p < 0.05) between the survival of the cuttings among the various treatments.

) Survival (%

Treatment

Fig 3.5 Survival rate of Khaya grandifoliola per treatment

3.6 Survival Rate of Khaya ivorensis Cuttings

Figure 4.6 shows the survival percentage of K. ivorensis of which the media which contained 20 v biochar + 80 v river sand recorded the highest percentage of 58% followed by 20v biochar + mixtures (57%) and 20 v biochar + 80 v loam with a value of 45%. The least survival percentage was recorded for the media, loamy soil, river sand and mixtures with a value of 31% for each medium.

survival of cuttings

Treatment

Figure 3.6 Survival rates of Khaya ivorensis per treatment

4.0 DISCUSSION

4.1 Effects of species on the rooting ability of the cuttings

This study shows that both Khaya ivorensis and Khaya grandifoliola can be propagated vegetatively using stem cuttings. For the rooting abilities of the two species in the six rooting media, Khaya grandifoliola exhibited higher rooting ability than Khaya ivorensis. Differences in rooting ability between the two species may be attributed to their genetic make-up and their adaptive environments. Khaya ivorensis adapted to areas with high rainfall thus higher humidity as compared to Khaya grandifoliola which is found mostly in the dry semi-deciduous and the transition zones between the high forest and savannah regions (Kemp, 1961). Leafy stems cuttings are easily affected by environmental stress conditions such as light, temperature and humidity. Thus, cuttings taken from plants mostly used to very wet environments may experience more environmental stress which will affect their rooting abilities (Owusu, 2011). Thus, even though the environment within the propagators were controlled to a large extent, minute changes in some of these environmental factors might have contributed to the low rooting abilities observed in Khaya ivorensis. The reasons for variation in rooting ability of stem cuttings from different species of the same family and genus are not well understood even though physiological, stock-plant and environmental factors that may influence the rooting capabilities in stem cuttings have been investigated.

Studies by Alegre et al., (1998) on two species of the same genus (Dorycnium pentaphyllum and D. hirsutum) showed different rooting abilities when the same auxin treatment, temperature of rooting environment and source of cutting, were applied to the two species. D. pentaphyllum softwood cuttings showed a markedly higher rooting ability than those of D. hirsutum even though the rooting factors applied to them were the same for each of the two species. Opuni- Frimpong et al., (2008) investigated the rooting ability and efficiency of two Khaya species (Khaya anthotheca and Khaya ivorensis), and found out that Khaya anthotheca stem cuttings exhibited higher rooting ability than Khaya ivorensis stem cuttings of the same age of stock-plant in the same propagation environment. Quercus bicolor cuttings exhibited higher rooting ability as compared to lower percentage rooting ability in Q. macrocarpa cuttings under the same propagation conditions even though they are from the same genus (Amissah et al., 2008). These differences in the rooting ability of stem cuttings have been attributed to the anatomy, morphology, physiological pre and post-severance states, the stock-plant adaptive environment as well as the propagation environment all of which together influence the rooting abilities of stem cuttings (Leakey, 2004; Husen and Pal, 2006) and varies from one species to the other. 4.2 Effects of rooting media on the rooting ability of the cuttings

According to Hartman et al., (1997), the factors that influence the selection of an appropriate medium are the types of species, cutting types, propagation environment and season. This experiment revealed that the rooting media influenced the rooting ability of Khaya grandifoliola and Khaya ivorensis stem cuttings just as Long (1932) reported for a number of woody species. Rooting ability was highest in the 20 v biochar + 40:40 v mixture (Loam and river sand) medium for Khaya ivorensis while Khaya grandifoliola exhibited higher rooting ability in the 50:50 v mixture (Loam and River sand) medium. Root elongation was also highest in 50v:50 v mixture and 20 v biochar + 40:40 v mixture (Loam and River sand) for Khaya grandifoliola and Khaya ivorensis respectively. It can therefore be said that mixtures of loamy soil and river sand proved to be the most appropriate media for root formation and elongation of both Khaya grandifoliola and Khaya ivorensis. The significant high rooting and elongation in both Khaya grandifoliola and Khaya ivorensis in the mixture of loam and river sand may therefore be attributed to better aeration and water drainage characterized by these soil types. This is because, high aeration and porosity are responsible for promoting root development (Olabunde and Fawusi, 2003; Puri and Thompson, 2003). Olabunde et al., 2003, reported that loamy soils provide better drainage and infiltration of water and air while river sand offer better aeration for root development. A study by Yeboah and Amoah, 2009 also showed that high aeration and porosity in rooting media is responsible for promoting metabolic activities and enhancing root initiation. Similarly, the mixture of river sand and loamy soil when combined with biochar, yielded positive results in terms of rooting ability and elongation in both species. According to Ofori et al., 1996, a balance between water holding capacity and aeration must be achieved to ensure optimal rooting. The good results obtained from the 20v biochar+40:40v mixture (loam and river sand) medium may be as a result of the good water holding capacity of biochar which supplemented the high aeration of river sand and the high porosity of loamy soil. Also, the two Mahogany species are mostly found on well drained soils (loam) and alluvial soils near water courses (river sand), (Taylor, 1960). In addition to being well-drained, the species prefer soils that are moist and have good water holding capacity (Lemmens, 2008; Mujuni, 2008; Tchinda, 2008).

Tchoudjen et al., 2002) also suggested that even though preferences by the various species are not clear, it could be attributed to the adaptation of various species to their environment. Thus, the high rooting ability and root elongation of the two species in the loam and river sand mixture could also be attributed to the adaptation of the species to their native range of occurrence. Their preference for the loam and river sand mixture medium may be due to their adaptation to semi- deciduous forest types and their preference for alluvial soils near water courses as well as well- drained soils. Rooting ability as well as root elongation for Khaya ivorensis was lowest in river sand. Ofori et al., (1996) also reported a lower rooting ability in river sand for Milicia excelsa stem cuttings which he attributed to its relatively low water holding capacity. This might have accounted for the low rooting ability and root elongation in Khaya ivorensis. In Khaya grandifoliola, rooting ability and root elongation was lowest in the 20 v biochar + 80 v river sand medium. As reported by Ofori et al., (1996) this might also have resulted from the low water holding capacity of the river sand in the mixture.

4.3 Effects of rooting media on the survival rate of cuttings From the study, it was observed for both species that even though cuttings raised in the media with no amount of biochar survived, their survival rate was minimal when compared to that of cuttings raised in some amount of biochar. In 20v biochar+40:40v mixture (Loam and river sand) medium, the survival rate of Khaya ivorensis was 57% whiles that of Khaya grandifoliola was 67%. The survival rate of Khaya ivorensis and Khaya grandifoliola in 20 v biochar + 80 v river sand was 58% and 52% respectively whiles in 20v biochar +80v loam, the survival rates of Khaya ivorensis and Khaya grandifoliola were 45% and 55% correspondingly. Various publications report a generally positive effect of biochar soil amendment on field crops and trees grown under greenhouse and commercial conditions. Early studies by Wardle et al., (1998) reported high survival rates in biochar-amended soils for birch and pine. Similarly, five years following the soil application of biochar, survival and growth rates of Sugi trees (Cryptomeria japonica) was substantially increased (Kishimoto and Sugiura, 1985) which they both attributed to the enhanced nutrient retention capacity of biochar-amended soil. Ogawa and Okimori (2010) also observed that biochar-amended soils showed 50-80% survival rate in plants. It can therefore be said that biochar was the principal catalyst for the high survival rates observed in both species. The means by which biochar improves survival rates of plants can be attributed to direct effects via biochar-supplied nutrients (Silber et al., 2010), and to several other indirect effects, including: increased nutrient retention (Chan et al., 2007, 2008; Chan and Xu, 2009); improvements in soil pH (Yamato et al., 2006; Steiner et al., 2007; Novak et al., 2009); increased soil cation exchange capacity (Cheng et al., 2006; Yamato et al., 2006; Novak et al., 2009); neutralization of phytotoxic compounds in the soil (Wardle et al., 1998); improved soil physical properties including water retention (Iswaranet al., 1980; Ballestero and Douglas, 1996; Glaser et al., 2002; Chan et al., 2008; Laird et al., 2009; Novak et al., 2009); promotion of mycorrhizal fungi (Yamato et al., 2006; Rondon et al., 2007; Warnock et al., 2007); and alteration of soil microbial populations and functions (Pietikainen et al., 2000; Steiner et al., 2008a; Graber et al., 2010; Kolton et al., 2011). Many of these effects are interrelated and may act synergistically to improve the survival and performance of plants.

5.0 CONCLUSION AND RECOMMENDATION

5.1 Conclusion

From the study, Khaya grandifoliola exhibited a higher rooting ability as compared to K. ivorensis. The medium which contained river sand had the greatest influence on the root formation of Khaya grandifoliola as it recorded a mean number of 2.4 cm. Concerning the root elongation of Khaya grandifoliola in the various media, 50 v + 50 v mixture (river sand and loam) was also found to be appropriate medium giving 12.84 cm as the mean results. With Khaya ivorensis, 20 v biochar + mixture was the medium which tended out to be the most appropriate with mean root formation of 1.50cm whereas 20v biochar +mixture (river sand and loamy) also had the greatest influence in terms of root elongation recording 7.17cm as the mean result. With the survival rate, Khaya ivorensis (42.16%) exhibited a higher percentage than Khaya grandifoliola (40.05%) and the biochar serve as a principal catalyst for the high survival rate in both species. For Khaya grandifoliola, among the various media, the 20 v biochar + 80 v loamy, 20 v biochar + mixture (river sand and loamy) and 20 v biochar + 80 v river sand recorded a survival percentages of 55%, 67% and52% respectively. For Khaya ivorensis among the various media, the 20v biochar+80v loamy, 20v biochar+mixture (river sand and loamy) and 20 v biochar + 80 v river sand recorded a survival percentages of45%, 57% and 58% respectively.

In conclusion, mixture of river sand and loamy is the medium which is appropriate to be used when looking out for root formation and elongation but then, the influence becomes great when combined with 20 v biochar. However, river sand can also be considered for rooting formation of Khaya grandifoliola whiles loamy soil can be considered when looking out for root formation and elongation of both species.

5.2 Recommendation

Recommendations based on the research results and methods are as follows: 1. 20 v biochar + mixture (river sand and loamy) is recommended for use in the vegetative propagation of Khaya ivorensis on a commercial scale since it gives the best results in terms of root formation and elongation. 2. 50:50 v river sand and loamy could also be used for the vegetative propagation of Khaya grandifoliola and Khaya ivorensis. 3. River sand is also appropriate in the propagation of Khaya grandifoliola or better still these species can be planted along water bodies to help protect the water bodies. 4. Loamy soil is appropriate for root formation and elongation in the propagation of Khaya grandifoliola and Khaya ivorensis. 5. Rooting hormone should be added to the media to enhance effective rooting. 6. Further research studies should be carried out on the other media in the vegetative propagation of Khaya grandifoliola and Khaya ivorensis. 7. This information should be extended to foresters who would want to go into a commercial scale of vegetative propagation of K. grandifoliola and K. ivorensis to establish plantations.

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