Effects of potassium and zinc on grain protein contents and yield of two wheat genotypes under soil and water salinity and alkalinity stresses

Soil salinity may reduce potassium (K) uptake due to strong competition with sodium cations in the root regions. In calcareous soils, zinc (Zn) precipitates in unavailable forms for plants. In this study, the response of two wheat genotypes (C) named Backcrossroshan and salinity tolerant Line No.4 was studied against to K and Zn fertilizers. A factorial experiment with four levels of K (K0=0, K1=60, K2=120 and K3=180 kg ha-1) and three levels of Zn (Zn0=0, Zn1=20 and Zn2=40 kg ha-1) based on a randomized complete block design was employed. Results of analysis of variance showed significant Zn×K×C interactions for all the measured traits except for ear length. Despite of illite clay and enough available potassium in the root growing media, plants responded to K application. Yield components, grain yield and protein content of the two genotypes increased linearly as the levels of K×Zn interaction treatments increased. Considering K2Zn2 and K3Zn2 treatments, Line No.4 produced 1000-grain weight, weight of grains per ear and grain yield higher than Backcrossroshan by 17%, 30%, and 23%, respectively. Results showed significant relationship between grains weight per ear and grain yield. Consequently the higher the grain weight per spike the higher grain yield was obtained. Results achieved highlight the importance of K and Zn nutrition in salt stress conditions.