Effect of Silicon and Potassium on growth and yield of East African Highland Banana

Abstract

Soil fertility is a major constraint to East African highland banana (hereafter referred to as highland banana) and a key concern for ongoing research efforts. Among primary nutrients, potassium (K) is by far the most limiting and is known to confer tolerance to drought and pest attack in banana. This study paves way for the inclusion of silicon (Si) in the banana nutrient menu to augment stress tolerance and contribute to the emerging shift toward nutrient-mediated stress management. The study provides critical Si content and reveals Si by K interactive effects on highland banana. The critical Si content was determined from a survey of two banana-growing regions with contrasting levels of abiotic stress. Soil was sampled and analyzed for silicon and fresh bunch weights were determined non-destructively using allometric models. The relationship between banana yield and soil silicon was assessed through boundary line regression thence critical values determined for each region. This was followed by a factorial screen house experiment with three rates of Si (0, 0.25 and 0.5 g/kg) and two rates of K (0 and 0.75 g/kg) to determine the interactive effect of potassium and silicon on above ground biomass (AGB) and leaf area (LA) of banana. Results of the survey suggested better response to silicon in the a more stressed region with a steeper slope (0.049) and a lower critical silicon content of 93.7 ppm. The slope and critical value in the less stressed region were 0.023 and 166.7 respectively. The factorial experiment revealed significant Si by K interactive (p <0.05) effect on LA and AGB. Application of silicon resulted in leaf area reduction by 23 to 39% compared to the control among K deficient plants and LA increase (11 to 23%) for plants that received K. Similarly, at 0.5 g/kg, Si resulted in reduced AGB (by 13%) compared to the control for K deficient plants. However, for plants supplied with K, this reduction was observed at the lower rate of Si