Root-differential modulation enhances nutritional status and leaf anatomy in pigeonpea plants under water deficit

Abstract

Water deficits often lead to deleterious effects on plant metabolism by interfering with anatomical characteristics and nutrient concentrations. Comparative anatomy may explain tolerance mechanisms to water deficiency in higher plants. The aim of this study was to determine whether root anatomical variables affect nutritional status and leaf anatomical variables of pigeonpea plants by quantitative analysis of root and leaf tissues and determining the concentrations of essential elements in two different pigeonpea genotypes exposed to water deficiency. The experiment was randomized with four treatments, consisting of two genotypes (Fava larga and IAPAR 43, described as FL and I43, respectively) and two water conditions (control and water deficit), with plants being maintained under water deficit for six days. In general, water deficit provoked reductions on leaf anatomical variables and nutritional concentrations of both pigeonpea genotypes, being more intense in the FL genotype (sensitive to drought). To roots, FL genotype presented significant decreases of 23 %, 14 %, 61 %, 28 % and 22 % on thickness / diameter of epidermis (RET), endodermis (RDT), cortex (RCD), vascular cylinder (VCD) and metaxylem (RMD), respectively, compared to control treatment. However, I43 genotype showed increases in all variables evaluated, being significant for RMD and not significant for RET, RDT, RCD and VCD. Finally, the mitigation of the deleterious effects on nutritional status and leaf anatomical variables of I43 are related to increments of RET, VCD and RMD, suggesting a tolerance mechanism of the I43 genotype, improving root protection and nutrient uptake during water deficit.