Weed management in spring planted sugarcane (Saccharum spp hybrid)-based intercropping systems

A field experiment was conducted during spring 2000-01 and 2001-02 at the research farm of the Institute, Lucknow on sandy loam soil to evaluate the efficacy of weed control methods in sugarcane (Saccharum spp hybrid) based intercropping systems. Sugarcane + cowpea (Vigna unguicuata L. Walp), effectively suppressed the weed density (81/m 2 ) and reduced the dry weight of weeds significantly (10.1 g/m 2 ) over the sole sugarcane during early growth stages (60 days after planting). Next in order were sugarcane + greengram [Vigna radiata (L.) R. Wilczek] and sugarcane + blackgram [Vigna mungo (L.) Hepper]. After the harvest of intercrops, at peak tillering stage of sugarcane (90 and 120 days after planting), the weed population was at par under different intercropping systems. Weed dry matter accumulation also followed the same trend. The corresponding weed control efficiency worked out to be 40.6, 37.0 and 39.7% respectively. Plots receiving manual hoeing at 20, 40 and 60 days after planting resulted in minimum weed density (58.3/m 2 ) as well as weed dry matter (15.1 g/m 2 ) and thus proved highly effective. The highest weed control efficiency at 60, 90 and 120 days after planting worked out to be 42.6, 58.5 and 67.8% respectively under this treatment. Plots under sugarcane + greengram intercropping system recorded maximum number of millable canes (89.3 thousand/ha), cane length (184.1 cm), cane yield (72.7 tonnes/ha), cane equivalent yield (86.6 tonnes/ha) and sugar yield - commercial cane sugar (8.4 tonnes/ha). This intercropping system was closely followed by sugarcane + cowpea (for green pods) with cane equivalent yield of 83.3 tonnes/ha. Weed free conditions gave highest number of millable canes (95.5 thousand/ha), cane length (183.2 cm), cane diameter (2.70 cm), weight of individual cane (0.93 kg) and ultimately the cane yield (76.2 tonnes/ha) as well as cane equivalent yield (85.8 tonnes/ha). Other weed control methods were found equally effective among them, but proved quite effective over weedy check (CEY: 59.9 tonnes/ha). Weed free conditions also recorded higher brix (20.50%), pol% juice (18.1), purity coefficient (89.3%), commercial cane sugar (11.8%) and sugar yield (9.0 tonnes/ha). Sugarcane + greengram intercropping system applied with pendimethalin fetched highest profit (Rs 52 480/ha) and B: C ratio (2.53).