Weed dynamies and control of weeds in relation to management practices under sugarcane (Saccharum species complex hybrid) multi-ratooning system

A field experiment was conducted during 2001–2005 at Lucknow, to assess the effect of cultural, mechanical and chemical weed-control measures on weed control, sugarcane ratoon yield and weed population dynamics in multi-ratooning system under the conditions of north-Indian sub-tropics. Losses caused to weeds in first and second ratoon yields were 32.7 and 45.9%, respectively. Treatments applied in the first ratoon significantly increased yield, and highest ratoon yield (67.1 tonnes/ha) was recorded either with mulching and hoeing in alternate inter-row spaces or with initial cultivation, followed by glyphosate spray @ 1.0 kg/ha 30 days after ratoon initiation. Residual effects of the treatments on weeds and crop yield in second ratoon was also significant. The highest second ratoon yield (48.6 tonnes/ha) was obtained as residual effect of mulching and hoeing in alternate inter-row spaces done in the first ratoon. Effect of treatments on weed population dynamics was evident from reduced abundance of grasses (less than 5) both in first and second ratoons under all the treatments compared to weedy check (abundance index for grasses 5). Adoption of weed-control measures caused occupation of field by grasses, broad-leaf weeds and sedges, whereas in weedy check grasses were most abundant in first as well as second ratoon.