Establishment of dris norms for cactus pear grown under organic fertilization in semiarid conditions

Abstract

The objective of this work was to establish DRIS norms for evaluation of nutritional status of cactos pear of the Gigante cultivar grown under organic fertilization in semiarid conditions. Cladode macro and micronutrient contents and dry matter yield of 72 plots were evaluated. The experiment was conducted in a randomized block design with three replicates, using a 4×3×2 factorial arrangement consisted of four bovine manure rates (0, 30, 60, and 90 Mg ha-1 ano-1), three spacings (1.00×0.50, 2.00×0.25, and 3.00×1.00×0.25 m), and two production cycles (600 and 930 days). The data were separated into high-yield population (HYP) and low-yield population (LYP), above and below 19.93 Mg ha-1 cycle-1, respectively. The mean, standard deviation, coefficient of variation, variances, and variance ratios of all bivariate relations between nutrients were calculated for the establishment of DRIS norms, considering the direct (A/B) and reverse (B/A) form. The selection of direct and reverse relations between nutrients to compose the DRIS norms was based on the variance ratio between LYP and HYP (S2b/S2a). The sixty-six relations between cladode nutrient contents that presented the higher ratios between the variances in the LYP and HYP (S2b/S2a) were chosen. The DRIS norms established make viable the use of leaf diagnosis as an evaluation method of nutritional status of cactos pear of the Gigante cultivar grown under organic fertilization in semiarid conditions.