Effect of water stress induced by polyethylene glycol 6000 on the somatic embryos conversion into whole plantlets in cocoa (Theobroma cacao L.)

Rainfall scarcity due to climate change is a major constraint that limits cocoa productivity in Côte d'Ivoire. This work aims to regenerate cocoa plants tolerant to water stress using in vitro methods. Staminode and petal explants of the genotypes C1, C9, C14, C15, C16, C18 and C20 were used to produce somatic embryos through two methods. Firstly, somatic embryos were induced under stressfull conditions on media containing different concentrations of polyethylene glycol (PEG) 6000 (0; 25; 50; 75; 100 and 125 g/l) and secondly; under non-stressed conditions. Somatic embryos were placed on a conversion medium in the same stress condition. The number of regenerants decreased with the increase in the concentration of PEG with all genotypes. Only genotypes C1 and C15 regenerated plantlets under water stress conditions. The sensitive genotypes C9, C14, C16, C18 and C20 have not developed plantlets on media containing PEG. The plantlets produced under water deficit conditions exhibited a reduction in stem length and leaves number and an increase in length or offset of the high number of roots. The survival rate of regenerants during acclimatization was higher on the sandsubstrate. The selected genotypes could be used in an improvement program of cocoa production.Keywords: Climate change; plant regeneration; genotype; tolerance; drought; in vitr

Influence Du Mode De Culture Du Maïs [Zea Mays (L.) (Poaceae)] Et Du Niébé [Vigna Unguiculata (L.) Walp (Fabaceae)] Sur La Masse Et La Qualité Nutritionnelle Des Graines Des Deux Espèces

Cowpea cultivars C1, C2 and C3 were intercropped with maize in intraline pattern (MND); inter-line pattern (1M1C) and strip-intercropping (2M4C) to determine influence of the cultivation method on the mass of 100 seeds and the nutritional quality of the seeds. Pure maize and cowpea crops were used as control plots. One hundred (100) seeds mass and nutrient content of maize and cowpea seed was determined. The results showed that 100 seeds mass (22,59g in 2015 and 21,03g in 2016) and the highest level of protein (9,87g in 2015 and 11,13g in 2016) maize seeds have been obtained with MC1I. Phosphorus levels were higher with maize seeds from sole maize fertilized MV+P (0,27g in 2015 and 0,25g in 2016). However the 2M4C1 intercropping 2M4C1 (0,24g in 2015 and 0,23 in 2016), 2M4N3 (0,24g in 2015 and 0,25g in 2016) and 1M1C3 (0,24g in 2015 and 0,24g in 2016) may be recommended for their phosphorus content in maize seeds. The 2M4C1 intercropping (12,29g in 2015 et 13,05g in 2016) expressed the highest mass of 100 seeds of cowpea. Intercropping using 2M4C3 can be recommended for improved fat content (1,27g in 2015 and 1,38g in 2016) and phosphorus (200,36g in 2015 and 200,33g in 2016) in cowpea seeds

Evaluation de la technique de surgreffage pour le rénouvellement des vieillissants vergers d’anacardier [Anacardium occidentale (L.)] dans la région du Gontougo en Côte d’Ivoire

La Côte d’Ivoire est le premier pays producteur et exportateur mondial de noix de cajou. Toutefois, les rendements en noix des vergers ivoiriens demeurent faibles. Ces faibles rendements sont dus à un parc composé de vergers vieillissants, à l’absence de variétés améliorées et à la forte densité des plantations. L’objectif général de la présente étude est de contribuer au renouvellement du verger anarcardier par la technique de surgreffage. Pour y arriver, les arbres de différents âges et peu productifs ont été recepés à différentes hauteurs, différentes circonférences du tronc et sous différents niveaux d’éclaircie. Trois mois après le recépage, des greffons prélevés sur des arbres élites ont été greffés sur les repousses. Les résultats collectés ont montré que les plus jeunes arbres et les arbres plus âgés ont donné les plus courts délais de repousse (30,52 à 33,38 jours). Le nombre de pousses feuillées, la surface foliaire des feuilles émises et le pourcentage de réussite ont été plus importants lorsque les arbres ont été recépés à une hauteur de 140 cm à partir du sol. L’analyse de variance a permis de faire ressortir la différence entre les individus pour chaque facteur étudié. Les arbres de diamètre supérieur à 50 cm ont produit le plus grand nombre de pousses feuillées (32). Selon le niveau de l’éclaircie, les greffons bien eclairés ont été plus vigoureux. Les poids moyens des arbres surgreffés selon les génotypes ont été compris entre 27,5 et 234 g/arbre contre 493 g/arbre pour les arbres en plantation non surgreffés.Côte d'Ivoire is the world's leading producer and exporter of cashew nuts. However, walnut yields in Ivorian orchards remain low. These low yields are due to a park of aging orchards, lack of improved varieties and high density of plantations. The general objective of this study is to contribute to the renewal of the cashew apple orchard by the technique of over grafting To achieve this, trees of different ages and low productivity were received at different heights, different trunk circumferences and under different levels of thinning. Three months after the grafting, grafts taken from elite trees were grafted on the regrowth. The results collected showed that the youngest trees and older trees gave the shortest regrowth (30.52 to 33.38 days). The number of leafy shoots, the leaf area of the leaves emitted and the percentage of success were greater when the trees were retrieved at a height of 140 cm from the ground. . The analysis of variance made it possible to highlight the difference between the individuals for each factor studied. Trees larger than 50 cm produced the largest number of leafy shoots (32). Depending on the level of thinning, the well-lit gryphon was more vigorous. The average weights of the trees grafted according to the genotypes were between 27.5 and 234 g / tree against 493 g / tree for non-grafted plantation trees

Effect of antioxidants on the callus induction and the development of somatic embryogenesis of cocoa [Theobroma cacao (L.)]

Abstract The browning of plant tissue and organs is a major constraint in tissue culture of cocoa (Theobroma cacao L.). This study aims to evaluate callogenic and embryogenic potentialities of three genotypes cocoa on culture media supplemented with different types and concentrations of antioxidants. Polyvinylpyrrolidone (PVP), ascorbic acid, silver nitrate and cysteine were used as antioxidant agents. The explants staminode and petal were excised from immature buds of the flowers of genotypes cocoa C1, C8 and C14. The results showed that the induction rate of callus derived from the petal and the staminode varied with the genotypes tested. Except 21 mg/l of silver nitrate, the others antioxidants used namely ascorbic acid, PVP and cysteine have enhanced the callus induction of the genotype C8. In comparison with the control, the callus browning of the three genotypes was reduced two to three times when the culture media were supplemented with various concentrations of the silver nitrate. After 72 days of culture, somatic embryos were induced on callus derived from the petal explants with all the studied genotypes. Addition of PVP (300 mg/l) in the induction medium improved the rate of somatic embryos of the genotypes C1 and C14. The improvement of responses to somatic embryogenesis in reducing the rate of browning of cultures will allow a mass production of the high-yield cocoa genotypes