Density and dry matter production of weeds in aromatic rice under organic nutrient management in the rainfed conditions of Assam

Abstract

An experiment was carried out at the Instructional-cum-Research Farm of Assam Agricultural University, Jorhat, Assam, during kharif season of 2018-19 and 2019-20 to study the effects of organic nutrient management practices and aromatic rice varieties on weed density and dry matter production, root growth and yield of rice. Three aromatic rice varieties viz., Kola joha(V1), Ketekijoha (V2) and Chakhao poireiton (V3) and five organic nutrient management practices viz., control (N0), vermicompost @ 40 kg N/ha (N1), vermicompost @ 30 kg N/ha + in situ green manuring with Sesbania aculeata (N2),vermicompost @ 30 kg N/ha+ in situ green manuring with Sesbania aculeata + seedling root dip treatment with Azospirillium and phosphorus solubilising bacteria (PSB) @ 3.5 kg /ha each (N3) and vermicompost @ 20 kg N/ha + in situ green manuring with Sesbania aculeata + seedling root dip treatment with Azospirillium and PSB @ 3.5 kg /ha each (N4) were tested using factorial randomized block design (RBD).Different organic nutrient management practices and aromatic rice varieties significantly affected the density and dry matter production of weeds and root growth of rice during both the years of experimentation. Among the organic nutrient management treatments, application of vermicompost @ 30 kg N/ha followed by in situ green manuring with Sesbania aculeate and seedling root dip treatment with Azospirillium and phosphorus solubilizing bacteria (PSB) @ 3.5 kg /ha each (N3) produced the highest length, volume and weight of roots and the highest grain yield during both the years. The variety chakhao poireiton exhibited better weed suppressing ability compared to the other two varieties. Organic nutrient management practices involving preseason green manuring practices resulted better weed management in rice compared to the practices without green manuring.