Yield and yield structures of irrigated sunflower cultivars as influenced by tillage and wheat residue management systems

Abstract

Limited information is available on heavy surface residue tillage systems on yield of irrigated sunflower (Helianthus annuus L.) grown following irrigated wheat (Triticum aestivum L.) as double cropping. A two-year field study was conducted as a split plot arranged in randomized complete block design with four replications to compare the yield and yield structures of three sunflower cultivars (Alzan, Euroflor, and Armavirsky) under conventional tillage (CT) (residue removal or burning followed by moldboard plowing and two times disk harrowing) and reduced tillage (RT) (chisel plow, disk harrow and a row crop planter equipped with row cleaner) system at various residue levels (0, 25, 50, 75 and 100%). Tillage systems and residue levels had a significant influence on yield and yield structures and the highest seed and oil yields were achieved when 25–50% of wheat residues were incorporated into the soil and the seeds were sown with row cleaner in both years and in all cultivars. The lower early crop growth under RT systems did not affect yields in both years, but partial residue incorporation into soil favored yield formation. It is recommended that farmers bale part of the previous residues and till the field with chisel plow, followed by disk harrow and plant with a modified row crop planter and this is the most reliable tillage system for sunflower production as double cropping.