Utilization of potassium-rich green-leaf manures for rice (Oryza sativa) nursery and their effect on crop productivity

Abstract

A field trial was conducted on Godavari Vertisols during the wet season of 2000 and 2001 at Maruteru, to evaluate the performance of potassium-rich weeds, viz. Pistia stratiotes L., Salvinia molesta, Gynandropsis gynandra (L.) Brig., Lantana camara L. and Parthenium hysterophorus L. as green leaf manure in rice (Oryza sa- tiva L.) nursery. Fertilization of nursery irrespective of source, improved the seedling parameters like biomass, vigour index and growth rate. Incorporation of Pistia stratiotes and Salvinia molesta green biomass @ 6 tomes1 ha significantly improved the seedling parameters in rice nursery than rest of the treatments, except complete chemical fertilization (80 kg N, 40 kg P20, and 40 K 2 0 kglha). The seedlings were shorter and poorer in vigour and biomass in Gynandropsis gynandra and Parthenium hysterophorus-treated plots. Significantly less pulling time and high seedling output were recorded when K-rich weeds were added and complete chemical fertiliza- tion was done in nursery. The seedling mortality was very high (25.4%) in unfertilized treatment when flash- floods occurred. Highest grain yield (51.9 qlha) was obtained in plots which received F! stratiotes green leaf ma- nure, followed by S. molesta and complete chemical fertilization to nursery.