Control of complex weed flora in direct-seeded and transplanted rice (Oryza sativaL.) with early post-emergence herbicide

A field experiment was conducted during rainy season of 2010–11 at the Research Farm of the Indian Agricultural Research Institute, New Delhi to study the efficiency of new low dose herbicide penoxsulam on growth and development of rice, their associated weeds and micro flora. The results of experiment revealed that penoxsulam 24 SC at 25 g/haapplied at 10 DAS/DAT significantly reduced the weed population, increased growth, yield (4.86 t/ha) and yield attributes of rice crop. Herbicidal treatments provided a yield advantage of 65.98 to 72.63% over weedy check. Herbicides exerted a significant detrimental effect on soil bacteria, fungi and actinomycetes. The counts of bacteria, fungus and actinomycetes recorded at 10 DAS/DAT revealed that soil microbes were more sensitive to penoxsulam 25 g/ha applied at 10 DAS/DAT and pre-emergence application of pretilachlor @ 750 g/ha as evident from significant reduction in their population, eventually microbial density started to recover slowly.