Impact of Low-dose Herbicides on Weed Dynamics and Nutrient Removal by weeds in Transplanted Rice

The objective of this study is to find out the effect of low-dose herbicides on growth and yield in transplanted rice. A field experiment was conducted during the Kuruvai season (June – September 2023) at Experimental Farm, Department of Agronomy, Faculty of Agriculture, Annamalai University, Annamalai Nagar, Chidambaram, Tamil Nadu, India. The experiment was laid out in a randomized block design with nine treatments and three replications. The treatments consisted of T1 - unweeded control, T2 - Twice hand weeding @ 20 and 40 DAT, T3 - PE application of Pretilachlor 50% EC @ 0.75 kg ha-1 on 3 DAT alone, T4 - PE application of Pretilachlor 50% EC @ 0.75 kg ha-1 on 3 DAT alone + One hand weeding at 30 DAT, T5 - PE application of Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP @ 20 g ha-1 on 3 DAT alone, T6 - PE application of Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP @ 20 g ha-1 on 3 DAT + One hand weeding at 30 DAT, T7 - PoE application of Fenoxaprop-p-ethyl 6.9% EC @ 60 g ha-1 on 21 DAT alone, T8 - PE application of Pretilachlor 50% EC @ 0.75 kg ha-1 on 3 DAT + PoE application of Fenoxaprop-p-ethyl 6.9% EC @ 60 g ha-1 on 21 DAT, T9 - PE application of Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP @ 20 g ha-1 on 3 DAT + PoE application of Fenoxaprop-p-ethyl 6.9% EC @ 60 g ha-1 on 21 DAT. Among these treatments, it is observed that the pre-emergence application of Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP @ 20 g ha-1 on 3 DAT + Post-emergence application of Fenoxaprop-p-ethyl 6.9% EC @ 60 g ha-1 on 21 DAT (T9) had effectively decreased total weed count, weed dry matter production and nutrient removal by weeds. This led to an improvement in crop development and production.