Toward Sustainable Cocoa (Theobroma Cacao L) Production: The Role of Potassium Fertilizer in Cocoa Seedlings Drought Recovery and Survival

Abstract

Cocoa (Theobroma cacao L) is an understorey plant that is highly sensitive to drought, especially at the seedling stage. In Ghana, only 20% cocoa seedlings survive the dry spells within 24 months after transplanting. Potassium (K) is known to enhance the growth of plants root to increase water uptake under drought conditions. This study assessed the effect of different levels of K fertilizer in enhancing the drought recovery and survival of four cocoa genotypes grown in Ghana. A 3 × 3 factorial experiment in Randomized Complete Block Design was carried out at the FRNR farm, Kwame Nkrumah University of Science and Technology, Ghana in 2019/2020 and 2020/2021 cropping seasons. The treatments consisted of 0 g, 4 g and 6 g plant−1 of muriate of potash (60% K2O) and three cocoa varieties: Amaz15-15XEqx78 (V1); CRG8914XPA150 (V2) and PA7/808XPound10 (V3). The result showed that cocoa varieties applied with 4 g or 6 gK plant−1 produced higher (p < .05) belowground and aboveground biomass than the control. The K treated seedlings had about 77% survival rate than the control (43%) seedlings. Among the varieties, V2 had better drought recovery and survival rate (81%), followed by V3 (78%) and V1 (71%). In addition to the morphological characteristics, K enhanced the nitrogen content in cocoa seedlings during drought recovery and this correlated positively (R = 0.863) with survival rate. In conclusion, when farmers grow V2 and apply 4 gK plant−1 during drought, over 80% of the seedling will recovery and survive. This has implications for K fertility management, yield and the livelihood of smallholder (70%) cocoa farmers.

Keywords

• Water stress
• cocoa varieties
• climate change
• biomass