Complementary foliar fertilization boosts physiological performance and nut yield in ‘BRS 226’ dwarf cashew

Due to the short rainy season in the cashew producing region in Northeast Brazil, foliar fertilization has been widely adopted for the nutrition of dwarf cashew trees. The objective of this study was to quantify the effects on growth, physiology, nutrition, and productivity of ‘BRS 226’ dwarf cashew. The experiment was conducted for three consecutive years in Pacajus, Ceará, Brazil. The design was randomized blocks with the following treatments: sources of foliar fertilizers (Master®; Mega 10®; FH CaB®; Master® + FH CaB®; Spray Dunger®) and the control (without foliar fertilizer) with eight replicates each. Growth (crown volume and relative growth rate), physiological (gas exchange, photochemical efficiency and relative chlorophyll index - RCI), nutritional (macronutrients and micronutrients), and production (immature cashew nuts number, percentage of ripe fruits and nut yield) variables were evaluated. Plants that received the Master® + FH CaB® foliar fertilizer showed a higher relative growth rate, with increments of 113, 139 and 95% in the first, second, and third cycles, respectively, compared to the control. Gas exchange increased by approximately 40% with foliar fertilizers, while RCI increased by about 20% to 30%, for these variables, the FH CaB® and Master® + FH CaB® treatments stood. Production aspects were also positively influenced by the application of foliar fertilizers, especially by Master® + FH CaB®. Complementary foliar fertilization in ‘BRS 226’ dwarf cashew, especially with the commercial products Master® + FH CaB®, is a recommended complementary practice to favor vegetative development, gas exchange and increase crop yield.