PHYSIOLOGICAL RESPONSE OF SPRING WHEAT TO SEEDING AND POTASSIUM APPLICATION RATES

Potassium application to most of the crops including wheat is scarce in Pakistan, although it is a major element required by the plants. The present study was carried out during 2009-10 and 2010-11 on wheat variety Zam-04 to investigate the role of six potassium six levels i.e., 30, 60, 90, 120, 150 and 180 kg ha(-1) along with six seeding rates i.e., 50, 75, 100, 125, 150 and 175 kg ha(-1). Various physiological, qualitative and grain yield traits were studied including leaf area index, (LAI), leaf area duration (LAD), crop growth rate (CGR), net assimilation rate (NAR) and grain protein content. Increasing the rate of potassium beyond 120 kg ha(-1) with seed rate of 125 kg ha(-1) showed decreasing trend for crop growth rate and net assimilation rate, and thus reduced the grain yield. The highest level of leaf area index and leaf area duration could not contribute towards grain yield. However, protein content were increased with combination of highest potassium and lowest seeding rates. Application of potassium fertilizer @ 120 kg ha(-1) and seeding @ 125 kg ha(-1) resulted in maximum crop yield.