Weed dynamics and productivity of irrigated winter (rabi) castor (Ricinus communis) under integrated weed-management practices

A field experiment was conducted during the winter (rabi) season of 2012–13 to 2014–15 on Vertisols of Navsari, Gujarat, to study the effect of integrated weed-management practices on weed dynamics and productivity of winter (rabi) castor (Ricinus communis L.) under irrigated condition. The grassy weeds were dominant as compared to broad-leaf ones during the period of experimentation. Maintenance of weed-free condition [3 handweedings (HW) at 20, 40 and 60 days after sowing (DAS)] resulted in significant reduction in population of monocot, dicot and total weeds at 60 DAS. But, it remained at par with pre-emergence application of pendimenthalin 1.0 kg/ha + 2 hand-weedings at 40 and 60 DAS for density of monocots weeds. All the weed-management treatments recorded significantly lower weed dry matter at 120 DAS as compared to unweeded control and application of pendimenthalin 1.0 kg/ha as pre-emergence, followed by quizalofop-p-ethyl@ 0.05 kg/ha at 20 DAS as postemergence. Similarly, significantly more number of branches, spikes and capsules/plant, spike length and seed yield were also recorded with pre-emergence application of pendimenthalin 1 kg/ha, followed by either 2 HW at 40 and 60 DAS or 1 HW at 40 DAS which remained statistically at par with weed-free condition. The weed-free condition (3 hand-weedings at 20, 40 and 60 DAS) accrued higher net returns ( 42.7 × 10³/ha), closely followed by pendimethalin 1 kg/ha (pre-emergence) + HW at 40 and 60 DAS ( 42.2 × 10³/ha) and pendimethalin 1 kg/ha (preemergence) + HW at 40 DAS ( 40.4 10³/ha). However, higher benefit: cost (BCR) was recorded with pendimethalin 1 kg/ha (PE) + HW at 40 DAS (2.41), followed by pendimethalin 1 kg/ha (PE) + HW at 40 and 60 DAS (2.33).