Weed dynamics in pulses cultivated in summer-fallows of double cropped lowland rice fields of Northern Kerala

Abstract

A field study was undertaken to find the weed dynamics in different pulse crops in summer-fallows of lowland rice fields under varying nitrogen doses during summer 2018. Among grasses, sedge and broad-leaved weeds Oryza sativa, Cyperus rotundus and Boerhavia diffusa, respectively were dominant in the field where pulses are grown. Absolute density of weeds was lesser in plots where red gram was cultivated with 75% and 50% of the recommended dose of nitrogen (RDN). Blackgram (50% RDN) was effective in smothering weeds. The dry matter production of weeds was the highest in fallows. The N removal by weeds was higher in fallow and that of P and K were at par in all treatments. The leaf area index (LAI) (100 and 50% RDN), crop growth rate (CGR) (50% RDN), yield (50% RDN) were significant for cowpea. Cowpea and red gram performed better among the different pulses in terms of yield. There was no significant difference in yield of pulses under varying levels of N, indicating that the lower level of N (50% RDN) will be sufficient.