Combined inorganic and organic potassium inputs to mitigate fusarium wilt disease in potted apple bananas

Abstract

Banana is a source of livelihood for smallholder poor rural farming communities in Uganda. Many banana cultivars are grown in Uganda. Apple banana is the most preferred dessert cultivar because of its short sweet compact fingers. However, production and productivity of apple bananas is low due to low soil fertility and high incidences of Fusarium wilt race 1. Traditional methods of control such as use of fungicides have proven expensive and environmentally unfriendly. Use of resistant cultivars is hampered by consumer acceptability issues in Uganda. Regarding soil fertility, potassium has been pointed out by several researchers as the most limiting nutrient to banana production in Uganda. Potassium has been shown to increase resistance to diseases in many plant species, including banana Xanthomonas wilt disease. However, there has been no investigation to determine how potassium nutrition affects Fusarium wilt race 1 in apple bananas. Therefore, this study was set with a general objective to improve the growth and productivity of apple bananas through integrated potassium management using manure (equivalent to 150kgK/ha), inorganic K (MOP) at a rate of 150kgK/ha and potassium solubilising bacteria (KSB) at a rate of 1litre/ha. A pot experiment was set up consisting different K sources (MOP, Manure, KSB and their combination) in a randomised complete design with a full factorial arrangement of K sources. Growth parameters (pseudostem height, girth, leaf length, width) were measured at weekly intervals to monitor growth via allometric functions. At 8 weeks after planting, half of the plants per treatment were inoculated with 25g of Fusarium wilt race 1 grown on inoculated millet seeds. Observations were done to study the effect of Fusarium wilt on stomatal conductance, chlorophyll content and growth of apple bananas. Fusarium wilt internal and external symptoms were scored per inoculated plant per treatment to determine effects of integrated potassium management on the incidence and severity of Fusarium wilt race 1 in apple bananas. Integrated application of potassium significantly (p<0.001) increased height, girth, leaf length, AGB and leaf area of apple bananas. Combined application of MOP, manure and KSB reduced Fusarium wilt incidence by 38% in apple bananas.