Potassium is accumulated in substantial amount in water stressed plants, contributing to osmotic adjustment. Eight varieties of chickpea were field grown according to randomized block design with three replications during two consecutive crop seasons to explore the role of K uptake in drought tolerance of chickpea under rain-fed conditions. Plant water relation and other physiological parameters were measured at 70 days after planting, while potassium uptake and yield parameters were recorded at harvest. The varieties were divided into high (HKU), medium (MKU) and low (LKU) K uptake groups, using average K uptake across the seasons. All the data were statistically analyzed group-wise. The HKU, followed by MKU and LKU (i.e. HKU>MKU>LKU) gave the highest values for most of the parameters studied including seed yield and crop biomass. The HKU also exhibited the lowest osmotic potential together with maintenance of elevated water content and turgor in plants compared to MKU and LKU. There was significant season-group interaction regarding most parameters including seed yield and crop biomass. However, such an interaction was not significant regarding K uptake, though varietal group pattern of K uptake was similar to that of seed yield and crop biomass (i.e. HKU>MKU>LKU), indicating that promising chickpea varieties might be selected under rain-fed conditions using K uptake.

A two-year field study was conducted to determine the effect of two zinc (Zn) levels [0 and 10 kg zinc sulfate (ZnSO4) ha-1] in respect with four potassium (K) levels (0, 20, 40 and 60 kg K2O ha-1) on growth, yield and quality of forage sorghum. The soil of the experimental field was loamy sand (Inceptisol), carrying 70, 08, 77, and 0.51 mg nitrogen (N), phosphorus (P), K, and Zn kg-1 soil, respectively. Increasing K levels significantly improved most of the growth, yield, and quality attributes gradually irrespective of the Zn levels. Zinc applied at 10 kg ZnSO4 ha-1 proved significantly better than no zinc application at various K application rates. The benefit of zinc application increased progressively with increasing K rates for most of the parameters studied, indicating significant response of the crop to positive K x Zn interaction in plants in respect with K and Zn application to the soil. Accordingly, 60 kg K2O ha-1 applied with10 kg ZnSO4 ha-1 boosted most of the attributes maximally. It resulted in about 20-40% increase in growth attributes, 25% increase in fresh matter yield, 36-38% increase in dry matter yield, and 38% increase in protein yield compared to the comparable K level applied without zinc. It also enhanced N uptake by 38%, P uptake by 5-19%, K uptake by 40-42%, and Zn uptake by 114-144%. Across the K rates, application of 10 kg ZnSO4 surpassed no zinc application by 30-35% in N uptake, by 8-15% in P uptake, by 33-36% in K uptake, by 120-140% in Zn uptake, by 19-21% in fresh matter yield, by 29-31% in dry matter yield, and by 30-34% in protein yield.