Effect of tillage and irrigation regimes on root growth, water removal pattern and water production functions of rice fallow sunflower

摘要

Studies on the interaction effects of tillage practicesand irrigation regimes on water use, seed yield andwater use efficiency of sunflower (Helianthus annuusL) in sandy clay loam Alfisol under rice fallowsrevealed that significantly higher initial crop stand(81%), root length and root length density and leafarea index was possible when tillage was done withtractor drawn disc plough or MB plough tillage (deeptillage) treatments + rotavator. Sub soil contributedsignificant proportion for sunflower waterrequirements in deep tillage practices than shallowand zero tillage practices. The soil moisture removedby sunflower gradually declined with soil depth. Underintense irrigation regimes relatively higher proportionof water removed from surface layers, while undermoisture deficit conditions moisture extraction fromsubsoil layers was in appreciable amounts, irrigationregime at IW/ CPE = 0.8 recorded higher WUE than IW/CPE = 0.6,1.0 and 1.2. Water use (ETa) by sunflowerincreased with increase in intensity of tillage andirrigation. WUE was higher in deep tillage practicesand in irrigation regime of IW/CPE =0.8. Deep tillage,besides saving 18 % irrigation water, resulted in about17% higher sunflower WUE compared with shallowtillage. The seasonal water production function, asexpressed by linear model under various tillagepractices and irrigation regimes, performed well forseed yield at more than 94 % variation in the seedyield indicating that seed yield of sunflower isresponding to both intensity of tillage and irrigation.