DRIS norms for nutritional diagnosis of dwarf cashew

Abstract

Nutritional evaluation of plants through leaf tissue analysis allows diagnosing the balance between nutrients and helps in the eventual recommendation of fertilization. The objective of this study was to apply DRIS norms and establish the appropriate nutrient contents in dwarf cashew leaves. In 248 plots with the dwarf cashew clones ‘CCP 76,’ ‘Embrapa 51,’ ‘BRS 189,’ ‘BRS 226,’ ‘BRS 265’ and ‘BRS 555’ leaves were collected for analysis of macro and micronutrients, in addition to sodium, and the respective nut yields (kg ha−1) were obtained. Of the total number of plots, 128 were considered to be high-yielding, which corresponded to 51.6% of the population. The decreasing order of nutrients (plus Na) with the highest frequency of limitation due to lack in the high-yielding subpopulation was: Na > Cu > S > P > K = Mg > B > N > Mn > Fe = Zn > Ca. Nutrients (plus Na) with the highest frequency of limitation due to excess, in descending order, were: Na > S > Cu > Mn > Ca = Mg > P = Fe > K > N > B = Zn. The appropriate ranges obtained by DRIS were: 13.0-15.5, 0.8-1.1, 7.6-9.3, 1.4-2.1, 1.3-1.7, 0.7-0.9 and 1.1-1.6 g kg−1 for N, P, K, Ca, Mg, S and Na, and 9.7-19.3, 5.4-7.4, 19.3-29.8, 39.6-70.8 and 11.7-17.3 mg kg−1 for B, Cu, Fe, Mn, and Zn, respectively.