Weed dynamics and productivity of wheat in conventional and conservation rice-based cropping systems

There exist edaphic and time conflicts between rice and following wheat crop in the conventional rice–wheat system. Conservation agriculture offers a pragmatic option to resolve these conflicts in the conventional rice–wheat system in the Indo-Gangetic Plains. In this two-year field study; wheat was raised through zero tillage, deep tillage, conventional tillage and on raised beds after harvesting rice grown in aerobic, alternate wetting and drying (AWD) and flooded systems. Various wheat tillage systems after different rice production systems significantly affected weed dynamics, stand establishment, morphological and yield-related traits of wheat during both year of study. Soil physical environment was better in the field occupied by aerobic rice followed by AWD-sown rice while it was poor after flooded rice. Density of lambsquarters (Chenopodium album L.) was lowest after flooded rice while densities of toothed dock (Rumex dentatus L.) and littleseed canarygrass (Phalaris minor Retz.) were lowest after aerobic rice. Broad leaf weeds like lambsquarters and toothed dock dominated in deep tillage, conventional tillage and bed sowing; whereas narrow leaf weeds like littleseed canarygrass dominated in zero tillage. Better stand establishment, water use efficiency, resource use efficiency and grain yield were recorded from wheat following aerobic rice culture, which was followed by AWD. Amongst the wheat tillage systems, stand establishment, morphological and yield related traits and water use efficiency were better in deep tillage; whereas resource use efficiency was the maximum in zero tillage wheat. Performance of bed-sown wheat was poor in term of yield related traits and grain yield. However, bed-sown wheat completed the phenological stages more rapidly than other wheat tillage systems. Maximum net income was observed in zero tillage wheat following aerobic rice culture. In crux, zero tilled wheat after aerobic rice culture is the best resource conservation technology; whereas deep tillage in rice–wheat cropping system may ameliorate the puddling-induced edaphic problems.