Turkish Journal of Agriculture and Forestry Turk J Agric For (2013) 37: 335-343 http://journals.tubitak.gov.tr/agriculture/ © TÜBİTAK Research Article doi:10.3906/tar-1206-53

Performance of edulis mycorrhized layers under different cropping conditions in Makenene,

1 2, 1 Martin MBEUYO , Nehemie DONFAGSITELI TCHINDA *, Emmanuel YOUMBI , 2 3 Hubert Jean Claude MBITA MESSI , Akoa AMOUGOU 1 Laboratory of Biotechnology and Environment, Faculty of Science, University of Yaounde I, 812 Yaounde, Cameroon 2 Medicinal and Traditional Medicine Research Centre, Institute of Medical Research and Medicinal Plants Studies, 6163 Yaounde, Cameroon 3 Laboratory of Ecology, Faculty of Science, University of Yaounde I, 812 Yaounde, Cameroon

Received: 24.06.2012 Accepted: 19.09.2012 Published Online: 15.05.2013 Printed: 05.06.2013

Abstract: , with its potential dietary and medicinal uses, is an aging member of the agroforestry system and is classified among the priority species for domestication in Central . Reliable techniques for producing quality planting materials other than are urgently needed. The aims of this study were to produce D. edulis layers and integrate them into the cropping system. To promote rooting and the survival rates of layers, 4 treatments were used. The layers produced were inoculated with mycorrhiza and introduced into cropping systems for the evaluation of morphobiochemical parameters. The results show that 67.91% of D. edulis are planted in cocoa plantations and 32.09% in other cropping systems in Makenene. In addition, 12% of the plants are produced from technical improvement, and 88% from seeds. The use of honey significantly increased layer survival and rooting rates after 2 months. The mycorrhized layers grow better in fallow fields than among food crops or in cocoa-based agroforests. High levels of chlorophylls a and b, total proteins, total amino acids, and peroxidase activity supported higher growth rates of mycorrhized layers. The results show the potential of producing materials through layering.

Key words: Agroforestry systems, Dacryodes edulis, domestication, layering, mycorrhizal inoculation

1. Introduction In Cameroon, safou covers a geographical area of In developing countries, food security is still a challenge and about two-thirds of the national territory (Isseri and is one of the most pressing needs among rural communities. Temple 2002). The pulp of its (safou) is consumed Initiatives for the adaptation and dissemination of farm and appreciated by people in its area of production product innovations and participatory management of (Obasi and Okorie 1993). Analysis of nutritional value natural resources and integration of trees into farming indicates high levels of fatty acids and amino acids. The systems can enhance food provision, income generation, oil content of its fresh pulp varies between 33% and 65% and services, ensuring both the short- and long-term depending on the origin and degree of ripeness of the sustainability of agriculture production (Sasson 2012). fruit (Bezard et al. 1991). The oil used in pharmaceutical One solution is to identify new sources of phytomedicines and cosmetic products is the oleic palmitostearate type, and food in unexploited or underexploited equatorial with 47.33% and 27.35% . There forests. is also a significant proportion of essential fatty acids, Safou [Dacryodes edulis (G.Don.) H.J.Lam], a including 20.46% and 1.22% linolenic acid , is featured prominently among (Silou et al. 1991; Ajayi and Adesanwo 2009). In terms of nonconventional oilseeds that are underutilized for economic value, safou is ranked third in Cameroon among medicinal, food, or cultural needs (Ajibesin 2011). It is a important , after banana and cola. An evaluation woody species found in the forest region of Central Africa undertaken in 1998 by Isseri and Temple (2002) placed and the Gulf of Guinea. This plant has been classified as the domestic production of safou at 11,000 t. During this a priority species for domestication by the International same period, Cameroon exported approximately 651 t to Centre for Research in Agroforestry (Tchoundjeu et al. , , and Congo Brazzaville (Ndoye and Ruiz- 2002). Perez 1999). In addition to their importance in local and * Correspondence: [email protected] 335 MBEUYO et al. / Turk J Agric For national markets, safou fruits are sold to the countries of heudelotii, Irvingia gabonensis, and Albizia sp. (Letouzey the European Union (Ndoye and Ruiz-Perez 1999; Awono 1985). et al. 2002). Therefore, in ecological and economic terms, 2.2. Utilization of Dacryodes edulis in cropping systems it is important to provide opportunities for farmers to An assessment was done by survey form to collect diversify and increase their income sources by growing information on farming systems and safou utilization. A safou in a sustainable cropping system. total of 150 farmers were interviewed. The questionnaires The safou sector is underexploited, yet the very few focused on techniques for improvement, cultivation orchards and trees found in the agroforestry system are techniques, methods of selection and breeding of plant aging and scattered among food crop fields, coffee or material, and the marketing system. cocoa plantations, and home gardens without any special 2.3. Dacryodes edulis plants maintenance. In addition, there is a lack of quality planting The layering was performed in a peasant field at Kolon materials, reliable propagation techniques, and effective village. Approximately 16-year-old trees 8–12 m in height management methods. In general, D. edulis is planted were used in this study. The safou were very productive and from seeds, resulting in great architectural variability free from symptoms of disease, and they were grown from and diversity among the fruits, which differ in yield . In general, safou trees bloom in December and the and physicochemical composition (Kengue et al. 2002; first fruits ripen in late May. In cocoa-based agroforests, Anegbeh et al. 2005). safou receives no maintenance and no modern cultivation To increase the supply of good plant materials, a simple techniques (pruning, fertilizing, phytosanitary treatment). and efficient vegetative propagation technique is essential. Although producing safou plant materials through 2.4. Preparation of layers cutting and grafting is difficult, layering tests carried The layers were prepared at the beginning of the rainy out by several researchers have shown that it is possible season (March) on orthotropic branches 3–5 cm in to multiply this plant vegetatively (Okorie et al. 2000; diameter. These branches were characterized by an Kengue 2002). Layering has the advantage of producing ascending stream of sap and developed in the normal individuals that conform to the mother plant, and layering sequence of branching (Kengue 2002). The sheath shortens production time. Association with beneficial containing the substrate was then put under the skinned microorganisms, such as vesicular arbuscular mycorrhizae, part of the branch. The substrate used consisted of will facilitate mineral absorption and, consequently, the decomposed male of oil palm. growth of layers (marcots) transplanted in the field. The 2.5. Effect of hormones and honey on the layering objectives of this study were to produce D. edulis plant There were 4 treatments used to promote rooting ability: materials through layering techniques and integrate them indole-3-butyric acid (IBA), pure honey, a mixture of IBA into the cropping system in Makenene, Cameroon. and pure honey (IBA + honey), and a control without IBA or pure honey. Previous results showed that IBA is 2. Materials and methods more reactive for rooting than indole–acetic acid (IAA) 2.1. Study site and naphthalene acetic acid (NAA) (Mialoundama et al. The study was conducted from March to October 2010 in 2002). Honey facilitates the healing of the abraded part of Makenene, Cameroon, which covers an area of 885 km2. shoot, thanks to its antibiotic properties (Kwakman et al. Makenene is a city located at an average altitude of 580 m 2010). The cutaway portion of the shoot was coated with –1 in the Mbam and Inoubou division of the Center Region. pure honey harvested in the savannah at 30 mL layering , It is bordered to the north by the Noun River and to the while IBA was applied to the substrate in dissolved form –1 south by the coastal region forest (between 3°20′N and by syringe at a concentration of 3 mg L . The experiment 6°N) and to the west and east by the rivers Makenene and consisted of 80 layers (10 trees × 4 treatments per tree × Nde (between 9°40′E and 13°E) (Letouzey 1985). 2 replications). The layering substrate was kept moist by The climate of Makenene is humid equatorial with injecting 50 mL of distilled water every 15 days by syringe. bimodal rainfall, which is characterized by a long dry and At the end of 2 months, the layers were weaned, and the rainy season and a short dry and rainy season. The average following parameters were evaluated: survival rate, rate of annual rainfall is 721 mm. Lateritic are predominantly rooted layers, root number per layering, and root length sandy clay in the plains and valleys. These soils are deep, per layer. fertile, and composed of biodegradable laterite in several 2.6. Mycorrhizal strains and inoculation of layers places (Letouzey 1985). Mycorrhizae used for inoculation of layers were provided The plant cover of Makenene is made up of by the Regional Laboratory for Biological Control approximately 60% savannah or shrub and 40% secondary and Applied Microbiology, Institute of Agricultural forest, dominated by useful species such as Ricinodendron Research for Development (IRAD) of Cameroon. Glomus

336 MBEUYO et al. / Turk J Agric For intraradices and Gigaspora margarita were used in this tube was kept at 4 °C in the dark for 3 days, during which study. Onguene (2000) reported these vesicular arbuscular time all of the chlorophyll was dissolved in acetone. The mycorrhizae in association with Burseraceae. absorbance of the solution was measured at 645 and 663 For inoculation, the layers were produced in a new nm by spectrophotometer. The levels of chlorophyll a [chl experiment using the earlier treatment that gave the a = (0.0127 × A 663 – 0.0269 × A 645) × dilution factor greatest number of roots (IBA + honey). These layers were (mg FW/mL)] and chlorophyll b [chl b = (0.0229 × A 645 sown in pots on sterile substrate mixture consisting of black – 0.00468 × A 663) × dilution factor (mg FW/mL)] were soil and sand in equal volumes. There were 2 treatments calculated using the method of Arnon (1949). in this experiment, control and layers inoculated with The total soluble proteins were extracted using the –1 150 g spores 100 g substrate of Glomus intraradices and method of Lecouteux et al. (1993). The leaves (1 g) from Gigaspora margarita. The experiment consisted of 100 each treatment were ground in 3 mL of acetone to remove layers (25 layers × 2 treatments × 2 replicates). A month the chlorophyll. The resulting powder was mixed with 5 later, the analysis of root colonization was performed. The mL of 0.25 M phosphate buffer at pH 7 and centrifuged roots were cut in small pieces and cleaned with tap water; for 25 min at 6000 × g. The supernatant constituted the then they were colored with a mixture of methyl blue soluble protein fraction. Total proteins were measured (0.01%) + lactic acid–glycerol–water (5:3:2) according to by spectrophotometer at 595 nm using the method of the method described by Phillips and Hayman (1970). Bradford (1976). The dosage of peroxidase activity, using 2.7. Performance of layers in cropping system guaiacol as a substrate, was studied by spectrophotometer The layers were planted in 3 different cropping systems (1 at 420 nm, according to Thorpe and Gaspar (1978). ha for each): cocoa-based agroforests, fallow fields, and Total amino acids were extracted according to Booy food crop farms. Several tree species, such as Ricinodendron et al. (1992). The leaves (1 g) from each treatment were heudelotii, Mangifera indica, Persea americana, and ground in 3 mL of acetone to remove the chlorophyll. schweinfurthii, were planted together with The powder obtained was taken up in 5 mL of ethanol cocoa under the cocoa-based farming system. Food crop (90%). After refluxing for 20 min at 25° C, the homogenate fields consisted of crops such as banana, cassava, and was centrifuged for 25 min at 5000 × g. The supernatant beans; fallow land consisted of unproductive upstream constituted the soluble fraction of the total amino acids. areas of shrub land that had been abandoned for 2 to 3 Amino acids were assayed at 570 nm by spectrophotometer years for soil conditioning. The experiment consisted of 90 using ninhydrin as a substrate, according to the method of layers [only 90 layers were planted because the other layers Yemm and Cooking (1955). were destroyed during handing (15 layers × 3 treatments × 2 replicates)]. Morphological and biochemical parameters 2.10. Statistical analysis were evaluated 4 months after the transfer of layers. The different morphological and chemical parameters of layers were subjected to analysis of variance (ANOVA). 2.8. Assessment of morphological parameters Duncan’s test (P < 0.05) was used to determine mean After 4 months the following parameters were determined: differences. Correlation analysis was used to determine survival rate (SR) of layers, number of branches (NB) per plant, number of leaves per branch (NL), total leaf the relationship between layers and dependent variables. area per plant (LA), plant height (H), and basal diameter These data were processed using SPSS 10.1 for Windows. (D). LA was assessed by recording the surface of each leaf on graph paper using a pencil and converting the 3. Results number of tiles per unit area. Using a measuring tape and 3.1. Integration of Dacryodes edulis in cropping systems callipers, H (height of plant, including the cutting) and D The agroforestry system in Makenene is multifaceted. were measured (D was not measured when the planting According to surveys conducted, farmers aim to diversify was done; it was measured at the end). The plants were and optimize agricultural production through the uprooted and root number (RN) was counted. The length ecological and socioeconomic development of effective of roots (LR) and diameter at the base of the root (DR) and sustainable farming systems. Several species and crop were measured. The roots and leaves were then dried in types are integrated: food crops (such as maize, cassava, an oven and their weights (WR and WL) were evaluated and plantain), export crops (cocoa), fruit trees, and using a Sartorius balance with 0.001 precision. These data medicinal plants. Among the fruit trees, D. edulis is grown were used to calculate the vigor index (VI) [VI = DR × H] for its pulp, which is rich in oil. Its culture requires the and morphological index (MI) [MI = (VI × WR) / WL] involvement of several stakeholders (farmers, exporters of based on the work of Colin (1998). fruits, small retailers, and agricultural extension services). 2.9. Evaluation of biochemical parameters Throughout the area, 88% of farmers confirm that they The leaves (0.5 g) from each treatment were placed into plant safou. The majority of safou plants (88%) are planted test tubes containing 3 mL of acetone (80%). This test from seeds derived from adult individuals, while 12% are

337 MBEUYO et al. / Turk J Agric For from conventional breeding techniques (aerial layering). the supply in the cities of Cameroon (such as Yaounde, The seeds used are selected from trees bearing large, Douala, and Kribi), Gabon, and . nonacid fruits that are rich in oils. 3.2. Air layering Air layering is a recent technique that was introduced The layers were made on orthotropic twigs, with a by researchers from IRAD in Cameroon, following the substrate of male inflorescences of oil palm (Figure 2). training of farmers interested in growing this plant. The roots of the layers began to form and were visible Currently, there are safou populations from layering in the through the transparent sheath a month later. At this time different cropping systems (Figure 1). The cultivation of the maximum survival of layers (95%) was obtained with safou is promoted by introducing its edible fruits into the the honey treatment (Table 1). After 2 months the roots daily diet of households. In addition, the leaves and bark were well developed, with a significant maximum rate of are used in traditional medicine. 95% for the honey treatment compared to 45% for control The safou orchards are located in the following (Table 1). The maximum number of roots per layer (19) cropping systems: gardens among food crops, cocoa-based was obtained with IBA + honey. All treated layers had a agroforests, and fallow fields. At Kolon village, Makenene, significantly higher number of roots per layer than the 67.91% of 589 safou plants were found in the cocoa farms; control (Table 1). However, control gave significantly 23.44% and 8.65% were in gardens among food crops longer root length (26.3 cm) than the other treatments and fallows, respectively. The plants do not benefit from (Table 1). phytosanitary treatment or amendment, as the farmers 3.3. Growth of layers under different cropping systems believe that fallen leaves are a potential source of natural The layers that produced the maximum number of roots fertilizer. The commercialization of the best quality fruits (IBA + honey treatment) were inoculated with mycorrhizae (Figure 1) is ensured by small retailers, 62% of whom are and tested in different cropping systems. Mycorrhizae also producers, while wholesalers (6% also produce) ensure had beneficial effects on growth and development of the

a b

c d Figure 1. D. edulis in the agroforestry system in Makenene: a) layered plant in a cocoa field, b) layered plant in a crop field, c) fruits from layered plants on sale in the local market, and d) fruit from layered plants ready for export.

338 MBEUYO et al. / Turk J Agric For

a b

c c d Figure 2. Different stages of air layering in a cocoa plantation: a) placing a layer, b) rooted layers after 3 months of treatment, c) 2-month mycorrhizal layers, and d) 2 month nonmycorrhizal layers. layers (number of leaves formed, their surface, and color) agroforests. There was a positive and significant (P < 0.05) 4 months after transplantation (Figure 2). The highest correlation between NL and NR (r = 0.695), NL and LA (r significant (P < 0.05) survival rates were recorded in food = 0.724), WL and NL (r = 0.691), LR and NL (r = 0.715), crops fields as compared to cocoa-based agroforests and and VI and H (r = 0.756). fallow fields. However, the highest values of NL, LA, H, D, 3.4. Biochemical parameters and WR were found in mycorrhized layers planted in the The highest levels of chlorophyll a and b, proteins and fallow fields. These results are confirmed by the higher MI amino acids, and peroxidase activity were found in for nonmycorrhizal and mycorrhizal layers in the fallow mycorrhized layers established in fallow fields 4 months areas: 29.72 and 28.55, respectively (Table 2). However, after the transplantation of layers (Table 3). However, in the highest VI of layers was recorded in the cocoa-based the fallow areas, the content of chlorophyll a and b was

Table 1. Growth parameters of D. edulis layers (2 months after layering).

Rooting Average length of a root Treatment Survival rates (%) Number of roots per layer rates (%) per layering (cm) Control 85 ± 05a 45 ± 15a 8.1 ± 1.3a 26.3 ± 3.5c IBA 85 ± 05a 80 ± 00b 16 ± 2.4c 20.2 ± 3.1b Honey 95 ± 05c 95 ± 05d 13 ± 1.9b 22.9 ± 2.4b IBA + honey 90 ± 00b 90 ± 00c 19 ± 2.9d 17.2 ± 3.5a

Values having same letters in the same column are not significantly different according to Duncan’s multiple range test (P < 0.05).

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Table 2. Morphological parameters of layers 4 months after transplantation in the field.

Food crops field Cocoa-based agroforest Fallow field Parameters Control Mycorrhizal layer Control Mycorrhizal layer Control Mycorrhizal layer SR (%) 80.0 ± 6.66b 83.3 ± 3.33b 40.0 ± 6.6a 43.3 ± 10.0a 53.3 ± 6c 60.0 ± 6.6d NB 2.5 ± 0.2a 2.6 ± 0.9a 3.0 ± 0.5b 3.0 ± 0.2b 3.0 ± 0.4b 3.2 ± 0.2b NL 41.5 ± 3.2b 84.7 ± 5.3d 36.0 ± 3a 48.0 ± 2.9c 46.0 ± 3c 92.2 ± 6.2e LA (cm2) 581.0 ± 13b 1185.0 ± 23d 504.0 ± 9a 672.0 ± 12c 644.0 ± 10c 1290.0 ± 15e H (cm) 31.0 ± 2a 44.8 ± 4.4c 35.0 ± 2.4ab 40.0 ± 1.9b 37.1 ± 3.b 49.4 ± 4.5d D (cm) 5.2 ± 0.8a 6.1 ± 1.1a 4.6 ± 0.9a 5.0 ± 0.8a 8.0 ± 1.2b 9.0 ± 2.3b NR 13.5 ± 2.1a 18.5 ± 1.8b 20.0 ± 2.3b 27.0 ± 3c 17.0 ± 2.1b 21.0 ± 3.2c LR (cm) 19.0 ± 1.3a 28.0 ± 3.1b 15.0 ± 2.1a 16.0 ± 2.1a 17.0 ± 2.6a 25.0 ± 2.3b DR (cm) 0.5 ± 0.1a 0.5 ± 0.02a 0.6 ± 0.1a 0.7 ± 0.2b 0.5 ± 0.2a 0.6 ± 0.1a WR (g) 3.2 ± 0.9b 4.4 ± 0.5b 1.3 ± 0.3a 2.2 ± 0.4a 9.1 ± 0.9c 12.1 ± 1.0d WL (g) 6.3 ± 1.2a 13.7 ± 1.3b 5.0 ± 1.0a 6.0 ± 1.2a 6.5 ± 1.2a 12.0 ± 1.0b VI 17.8 ± 2.3a 25.5 ± 3.7c 21.0 ± 2.2b 30.0 ± 4.6e 21.2 ± 3b 28.1 ± 3.0d MI 8.9 ± 1.8b 8.3 ± 1.6b 5.4 ± 1.3a 11.0 ± 2.3c 29.7 ± 4.8d 28.5 ± 3.9d

Values having same letters in the same line are not significantly different according to Duncan’s multiple range test (P < 0.05). SR: survival rate, NB: number of branches, NL: number of leaves per branch, LA: leaf area, H: plant height, D: diameter of stem, NR: number of roots, LR and WR: length and weight of the root, DR: diameter of root, WL: weight of leaves, VI: vigor index, MI: morphological index. not significantly different between mycorrhized and such as Terminalia superba and Chlorophora excelsa; exotic nonmycorrhized layers (Table 3). Moreover, the opposite fruit trees such as Persea americana, Mangifera indica, and phenomenon was observed with proteins and amino acids Citrus spp.; and medicinal plants such as Alstonia boonei in food crop fields and cocoa farms where the mycorrhizal (Sonwa et al. 2002). effect was significantly different. There was a significant At Makenene, although plant selection was low and positive correlation between levels of amino acids and random, farmers were still able to obtain individuals that protein (r = 0.92). produced safou fruits of exceptional quality based on size and taste, which is associated with oil content (Youmbi 4. Discussion et al. 2010). This success is also linked to the layering Agroforestry is the practice of combining woody perennial technique of multiplication used by some farmers on and herbaceous plants in the same cropping system, selected individuals that then retain their characteristics. both in time and in space. In the agroforestry system, Only 8.65% and 23.44% of safou were found in fallow and there is ecological interaction of plants. The system food crops fields, respectively, for the simple reason that aims to address the problems of soil infertility and land cocoa-based agroforest is the dominant cropping system in degradation while diversifying and improving agricultural Makenene. Cocoa plantations are able to provide moisture production (Okafor 2002). The integration of D. edulis for the development of safou trees. Another reason given into the agroforestry system in Makenene fulfils these by farmers is that high-moisture environments can reduce environmental and production objectives. This explains the spread of fire, thus promoting the resistance of safou why safou is among the priority plants that have been to this hazard. adopted by most African populations for cultivation The marketing of Makenene safous in local, national, in different distribution areas (Molet et al. 1994). In regional, and international markets generates income. Nigeria, for example, safou trees, hazel (Plukenetia Although precise figures are not available, Tchatat (1999) conophora), and oil bean (Pentaclethra macrophylla) emphasized that the balance of trade in the border markets are the 3 most dominant woody perennial plants in the of Central Africa (such as Amban-Minko and Kyossi) cropping system (Okafor 2002). In the south of Cameroon weighs in favor of Cameroon, which sells huge amounts of farmers introduced the following plant species into the D. edulis from production areas such as Makenene. agroforestry system in addition to D. edulis: Irvingia The development of a proper vegetative propagation gabonensis and Elaeis guineensis; timber trees of high value technique is essential for the production of high quality

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Table 3. Biochemical parameters of layers 4 months after transplantation in the fields.

Food crops field Cocoa-based agroforest Fallow field Parameters Control Mycorrhizal layer Control Mycorrhizal layer Control Mycorrhizal layer

Chlorophyll b 0.21 ± 0.02b 0.10 ± 0.01a 0.08 ± 0.001a 0.04 ± 0.002a 0.33 ± 0.09c 0.39 ± 0.08c (mg FW mL–1) Chlorophyll a 0.45 ± 0.1a 0.54 ± 0.1b 0.56 ± 0.02b 0.76 ± 0.2c 0.84 ± 0.1d 0.89 ± 0.2d (mg FW mL–1) Proteins 0.50 ± 0.03a 0.90 ± 0.1b 0.80 ± 0.09b 0.92 ± 0.2b 0.60 ± 0.08a 1.20 ± 0.3c (µg mg–1 FW–1) Amino acids 13.20 ± 1.6a 16.10 ± 1.8b 17.80 ± 2.5c 18.50 ± 3.1c 18.00 ± 3.1c 23.00 ± 3.2d (µg mg–1 FW–1) Pox 20.20 ± 3.5c 18.60 ± 2.7b 15.20 ± 1.9a 16.40 ± 1.9a 18.50 ± 2.4b 23.00 ± 1.6d (OD g–1 FW–1 5 mn–1)

Values having same letters in the same line are not significantly different according to Duncan’s multiple range test (P < 0.05). FW: fresh weight, Pox: peroxidase. material. Cuttings and graftings of mature safou trees have generally have a beneficial effect on the growth and failed so far (Damesse et al. 2002). However, previous development of plants when compared to the control. studies have shown that it is possible to multiply this plant Because of their abundance in different soils and their by layering (Okorie et al. 2000; Kengue 2002). Our work influence on nutrition and crop protection, mycorrhizae was to optimize conditions for regeneration. Emphasis represent a significant potential for sustainable agriculture was placed on the IBA and honey treatments. In 2 months, that uses fertilizers and pesticides judiciously (Garg and high rates of survival (95%) and rooting (95%) of layers Chandel 2011; Ong et al. 2012). Several studies have shown were obtained (in honey treatments). These results are a mutually beneficial relationship between the roots of superior to those of Okorie et al. (2000), who obtained most plants and some types of fungi-forming mycorrhizae 88% rooting in layers 4 months after cropping. In most (Moora et al. 2004; Tüfenkçi et al. 2012). These mycorrhizal studies the waiting times for layer rooting varies between associations are involved in facilitating mineral absorption, 4 and 6 months, with percentages lower (52%–90%) especially in the poor soils that dominate tropical rain than those obtained in our study (Damesse et al. 2002; forests (Bothe and Hildebrandt 2002; Parniske 2008; Garg Kengue 2002; Mialoundama et al. 2002). Honey may be and Chandel 2011). In our study, this mineral absorption a very positive external factor for the rooting of layers. It resulted in the ability of mycorrhizal layers to develop a plays both physical and biochemical roles. The viscosity number of leaves and roots and a significantly higher leaf of honey protects the cells of the from water stress area than in nonmycorrhized layers. Dacryodes edulis, like or dehydration after skinning by maintaining favorable most Burseraceae, is associated with arbuscular vesicular osmotic potential. It also facilitates healing of the abraded mycorrhizae. Better nourished, the mycorrhizal plants part of the shoot, thanks to its antibiotic properties (Viuda grow more vigorously, fructify abundantly, and ensure et al. 2008). Honey is an organic material rich in sugars, productivity in plantations (Vega-Frutis et al. 2011). In vitamins, minerals, and amino acids. These substances the current study, fallow areas were more favorable for the are likely to be assimilated directly in the process of root growth and development of this species. Higher organic initiation without the need to wait for synthesis to be matter accumulation in the fallow areas than in other initiated by the leaves and buds of the branches. The honey cropping systems may promote the growth of safou. + IBA treatment did not further improve the rooting of Levels of chlorophylls a and b, total protein, total amino layers when compared to honey. However, their combined acids, and peroxidase activity were higher in mycorrhized action resulted in a significantly higher number of roots layers planted in fallow fields than in mycorrhized layers per layer. IBA, which is a synthetic auxin, acts in synergy grown in cocoa-based agroforests or food crop fields. Plants with the honey for induction and proliferation of roots on in fallow areas receive more sunlight compared to those the layers. in cocoa fields. This exposure to sunlight and the richness When the rooted and mycorrhized layers were of the soil influence the accumulation of chlorophyll, transferred to the fields, it was found that mycorrhizae which is indirectly used in the synthesis of organic matter,

341 MBEUYO et al. / Turk J Agric For notably proteins and amino acids. Peroxides as a group in particular for the construction of the photosynthetic are the most abundant proteins in the plant, and they are system. Conditions in the fallow milieu, in the presence of very active during growth phenomena such as root, leaf, favorable sunlight, led to the synthesis of more chlorophyll and bud development. In addition, fallows are generally by the layers, which also had larger leaf surface areas. On very rich in organic and mineral matter (Djoumessi et the basis of morphobiochemical parameter assessment, al. 1997). Nitrogen is an essential element for growth the fallow system is the most suitable for growing layers and development of the plant. It can be found in the of D. edulis. form of amino acid and protein (notably peroxides, the Integrating safou in fallow areas using mycorrhized most abundant category in plants) in plant roots, leaves, layers could significantly improve production time and the buds, and grains (Maurot-Gaudy 1997). Amino acids and quantity and quality of fruit in the agroforestry system in proteins serve to elaborate their enzymatic structures, Makenene.

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