Growth and yield response of cashew (Anacardium occidentale L.) clones to spacing in the Guinea Savanna zone of Ghana

Abstract

The Guinea Savanna zone of many countries constitutes a critical cashew-producing area. Despite its importance, data-driven recommendations on optimal tree spacing remain largely unavailable to farmers in Ghana. This knowledge gap constrains productivity, reduces returns on investment, and affects farmer interest and ultimately the long-term sustainability of cashew (Anacardium occidentale L.) production. To address this challenge, a field experiment was established in 2010 at the Bole Substation of the Cocoa Research Institute of Ghana, located within the Guinea Savanna agroecological zone, to evaluate the effects of plant spacing on the growth and early yield performance of cashew clones. The study was conducted using a randomized complete block design with four replications. Six spacing treatments were assessed: 4 m × 8 m, 8 m × 8 m, 5 m × 10 m, 10 m × 10 m, 6 m × 12 m, and 12 m × 12 m. The growth and yield data collected included stem diameter, plant height, canopy spread, nut yield, and yield components. The data were subjected to analysis of variance using the GenStat software (version 12.1), and treatment means were separated using the least significant difference test at the 5% probability level. The results indicated that plant spacing did not significantly influence stem diameter, height, or canopy spread of cashew clones during the first 5 years after transplanting. Similarly, the number of nuts per tree and mean nut weight were not significantly affected by spacing. In contrast, nut yield per unit land area was consistently higher under closer spacing, particularly at 4 m × 8 m, and declined progressively with wider spacing. These yield differences were statistically significant throughout the 8 years of the yield assessment. The study therefore concludes that cashew clones can be cultivated at a spacing of 4 m × 8 m in the Guinea Savanna agroecology of Ghana for up to 8 years without the need for thinning. This spacing is recommended due to its higher early-stage yield potential, increased farm income prospects, and the avoidance of thinning practices that many farmers find unacceptable. The adoption of this recommendation is expected to enhance national cashew productivity and contribute to the sustainability of cashew production systems in Ghana.