Growing apples in tropical semiarid: N and K fertigation

Apple tree has been experimentally grown Brazilian tropical semiarid. In these new regions, fertilizing management research for N and K is crucial to reach apple high yields. Therefore, an experiment was conducted to evaluate the effect of N and K fertilizing on fruit production, leaf chlorophyll and N and K nutritional status of apple cv. ‘Julieta’ grown in Brazilian tropical semiarid. The experimental design used was randomized blocks with treatments disposed in a factorial arrangement (4 x 4) referring to nitrogen doses (30, 60, 90, and 120 g of N plant-1) and potassium doses (30, 60, 90, and 120 g of K2O plant-1), with three replications and three plants in each parcel. ‘Julieta’ apple trees propagated by grafting (with ‘M9 filter and Maruba rootstock) and transplanted in 2013 were used in this study. The following variables were evaluated: i) fruit production (kg plant-1); ii) number of fruits (in a plant); iii) leaf chlorophyll index (‘a’, ‘b’, and total); and iv) leaf N and K concentrations (g kg-1). N and K doses effects depend on the consecutive production cycles of apple cv. ‘Julieta’ grown in tropical semiarid. An adequate N supply is very important for the subsequent production cycle. K fertilization until 120 g plant-1 of K2O is not enough to supply K demand of apple cv. ‘Julieta’ grown in tropical semiarid. In tropical semiarid, 60-90 g plant-1 of N through fertirrigation is enough for ‘Julieta’ apple production.