Preliminary compositional nutrient diagnosis norms in Aloe vera L. grown on calcareous soil in an arid environment

This study calculated the compositional nutrient diagnosis norms of Aloe vera L., and also identified significant nutrient interactions of this crop growing in an irrigated calcareous desert soil. The soil showed high heterogeneity within its chemical properties. For statistical analysis, 64 foliar composite samples from healthy plants were used. Preliminary compositional nutrient diagnosis norms were developed using a cumulative variance ratio function and the chi-square distribution function. Means and standard deviations are given of row-centered log ratios VX of five nutrients (N, P, K, Ca, and Mg) and a filling value R  , which included all nutrients not chemically analysed. Preliminary compositional nutrient diagnosis norms are: VN*=−1.033±0.105, VP*=−2.617±0.142, VK*=−0.041±0.201, VCa*=0.692±0.168, VMg*=−0.7±0.128, and VR5*=3.699±0.104. These compositional nutrient diagnosis norms for fresh matter, providing more than 136.67 t ha−1, are associated with the following foliar concentrations: 8.13 g N kg−1, 1.68 g P kg−1, 22.39 g K kg−1, 45.42 g Ca kg−1, and 11.33 g Mg kg−1. Through the principal component analysis of the CND indexes, the positive interactions P–K and Ca–Mg, and the negative interactions P–Ca, P–Mg, K–Ca, K–Mg, and N–R were identified. By using Pearson correlations, the same interactions were identified plus the following: negative P–R and K–R, and positive Ca–R and Mg–R. Estimated t- and F-values and their corresponding probability levels indicated that N/R antagonism, Ca/R and Mg/R synergisms, and nutrients N, Ca and R were the factors discriminating high- from low-yielding subpopulations.