Improving the efficacy of sorgaab in combination with certain crop water extracts and reduced rates of pendimethalin for weed control in mungbean (Vigna radiata)

The experiment was laid out in randomized complete block design (RCBD) with four replications. The net plot size was 5 x 2.4 m2. Mungbean cv. NM-92 was sown as test crop. Various combination of sorgaab with different crop extracts were sprayed at sowing and 15 days after sowing (DAS) while sorgaab combined with lower doses of pendimethalin and full dose of pendimethalin were sprayed only at sowing with the help of knapsack hand sprayer. Sorgaab @ 10 L ha-1 + 2/3 pendimethalin @ 1.0 kg a.i. ha-1 reduced total weed population by 92.57% and was statistically on par with full dose of pendimethalin @ 1.5 kg a.i. ha-1 (93.33%). Sorgaab @ 10 L ha-1 + 1/3 pendimethalin @ 0.5 kg a.i. ha-1 and sorgaab @ 10 L ha-1 + 1/2 pendimethalin @ 0.75 kg a.i. ha-1 reduced total weed density by 74 and 79% respectively which were statistically different from each other. Sorgaab @ 10 L ha-1 + 2/3 pendimethalin @ 1.0 kg a.i. ha-1 reduced total fresh and dry weight by 8 0-96% and was on par with full dose of herbicide. Sorgaab a 10 L ha-1 + 1/2 pendimethalin @ 0.75 kg a.i. ha-1 decreased these parameters by 74-90% which was fairly good, however, sorgaab @ 10 L ha-1 + 1/3 pendimethalin @ 0.5 kg a.i. ha-1 gave only 52-67% reduction. Sorgaab + eucalyptus extracts each @ 10 L ha-1 and sorgaab + sunflower + eucalyptus extracts each 10 L ha-1 increased total weed fresh and dry weights indicating that these interacted with each other to nullify their allelopathic effects. Mungbean plant height, number of pods per plant and 1000-grain weight were also significantly influenced by different treatments while grain number remained unaffected. Maximum grain yield was obtained in T8 i.e. sorgaab @ 10 L ha-1, + 2/3 pendimethalin @ 1.0 kg a.i. ha-1 (23%) followed by sorgaab @ 10 L ha-1 + 1/2 pendimethalin @ 0.75 kg a.i. ha-1 (22%) which were statistically on par while only 14% increase was noted in case of full dose of pendimethalin and it was on par with s orgaab @ 10 L ha-1 + 1/3 pendimethalin @ 0.5 kg a.i. ha-1 which enhanced grain yield by 13% over control. Crop water extracts were statistically on par with weedy check. Sorgaab 10 L ha-1 + 1/2 pendimethalin @ 0.75kg a.i. ha-1 at pre-emergence provided highest net benefits (15731) followed by T8 and T6 i.e. Sorgaab @ 10 L ha-1 + 2/3 pendimethalin @ 1.0 kg a.i. ha-1 at pre- emergence (15643) and sorgaab @ 10 L ha-1 + 1/3 pendimethalin @ 0.5 kg a.i. ha-1 at pre-emergence (14856). Treatment combination T7 i.e. sorgaab @ 10 L ha-1 + 1/2 pendimethalin @ 0.75 kg a.i. ha-1 gave highest marginal rate of return (282%) followed by sorgaab in combination of 1/3rd dose of pendimethalin (122%) while all other treatments dominated owing to less net benefits. It could be suggested that concentrated sorgaab in combination with 1/2 dose of pendimethalin might be used for weed control in mung bean.