Tissue culture techniques for enhancing cashew production: A biotechnological approach to sustainable agriculture

Cashew (Anacardium occidentale L.) is a valuable crop with significant economic importance in the world. However, conventional propagation methods face challenges such as low germination rates, slow growth, and susceptibility to diseases, limiting the potential yield and quality of cashew plantations. This work will focus on innovative tissue culture techniques to overcome these challenges and enhance cashew production. To achieve this, documentary research, socio-economic surveys in the Communes identified for high production in Benin as well as laboratory experiments using plant biotechnology techniques and statistical analyses were carried out. From the assessment of the impact of climate variability on cashew cultivation and the identification of cashew trees resistant to climate variability, it was found that the producers perceived the manifestations and negative effects of climate variability and linked this variability to the decline in cashew productivity. However, it has been noted that there are efficient cashew trees that are tolerant to climatic variability. Micrografting used for propagation in accordance with the mother plant and its re-juvenation capacity showed that lateral grafting from axillary buds is the best technique for micrografting; and that genotype, time and the genotype*time interaction influence graft growth very significantly (p < 0.001). The evaluation of the conditions for successful micropropagation for the potential use of grafted plants as sources of 'reinvigorated' bud material for rapid clonal micropropagation was carried out. This evaluation showed that cotyledonary nodes compared to nodal explants were the best and also that MS basal medium with BAP 2.2 mg.L^-1 was the optimal medium for axillary proliferation. 80% of the explants responded with numerous (5 to 8) bud proliferations (5.75±0.12) with good shoot length (6.73±0.3 cm) on MS medium containing 150 mL coconut water. These studies optimize culture media and growth conditions to ensure high production of quality planting material. For industrial multiplication in record time, the more suitable somatic embryogenesis technique was studied. The Development of protocols for somatic embryogenesis, allowing for the mass production of uniform cashew plantlets with desirable characteristics such as increased nut yield and drought tolerance was achieved through the evaluation of the effect of growth regulators on the massive production of embryogenic callus and embryos. Nucellus, cotyledons and zygotic embryo were used in order to optimize total plant regeneration. The highest percentage of callus (26.6%) was observed with nucellus on medium containing 0.5 mg.L^-1 BAP and 3% sucrose at 6 weeks. Callus from zygotic embryos did not produce embryos. These studies illustrate the successful implementation of tissue culture in commercial cashew production, demonstrating increased efficiency and economic benefits.