Effect of Irrigation and Potassium Levels on Sunflower During Summer and its Allelopathic Influence on Succeeding Crops and Weeds

Abstract

The field experiment was conducted during summer and kharif of 2019 and newline2021 at the Main Agricultural Research Station (MARS), University of Agricultural newlineSciences, Dharwad, Karnataka on medium deep black clayey soils to evaluate the effect newlineof irrigation and potassium levels on sunflower during summer and its allelopathic newlineinfluence on succeeding crops and weeds. The experiment was laid out in split plot newlinedesign with three replications and sixteen treatment combinations and two controls. The newlinemain plot consisted of four irrigation regimes (Irrigation at 0.4, 0.6, 0.8 and 1.0 IW/CPE newlineratio), sub plot consisted of four potassium levels (no potassium application and newlineapplication of potassium at 45, 60 and 75 kg ha-1) and two control (C) treatments (C1: newlineScheduling of irrigation at an interval of 15 days with RDF (90-90-60 kg N:P2O5:K2O newlineha-1) and C2: fallow in summer). newlineThe results revealed that, irrigation at 1.0 IW/CPE ratio recorded significantly newlinehigher growth parameters, yield parameters, grain yield (2144 kg ha-1), stalk yield (4096 newlinekg ha-1), harvest index (0.35) and oil yield (830 kg ha-1) as compared to other irrigation newlineregimes and it remained on par with irrigation at 0.8 IW/CPE ratio with respect to grain newlineyield (2067 kg ha-1) and yield parameters. Potassium levels also significantly affected newlinethe growth parameters, yield parameters, grain yield (2031 kg ha-1), stalk yield (3987 kg newlineha-1), harvest index (0.34) and oil yield (787 kg ha-1) as compared to other potassium newlinelevels. However, it remained on par with application of potassium at 60 kg ha-1 with newlinerespect to grain yield (1983 kg ha-1) and yield parameters. Among interaction effects, newlineirrigation at 1.0 IW/CPE ratio with application of potassium at 75 kg ha-1 recorded newlinesignificantly higher growth parameters, yield parameters, grain yield (2278 kg ha-1), newlinestalk yield (4175 kg ha-1), harvest index (0.35) and oil yield (893 kg ha-1) as compared newlineto other treatment combinations. However, relatively higher concentration of p- newlineCoumaric acid (0.094, 0.098 and 0.810 ppm), caffiec a