Response of rice to intercropping of four Azolla species using phosphorus enriched inoculum

摘要

A field experiment was conducted in Orissa, India, during the wet season of 1994 and 1995 to study the response of rice (cv. IR 36) to intercropping with Azolla caroliniana, A. mexicana, A. pinnata and A. rubra using P-enriched inoculum. The unenriched and P-enriched inocula were grown either without any further application of phosphorus or with 10 kg P2O5 ha-1. In both the years, the fresh weight and N-yield of all the Azolla species increased significantly due to P-enrichment. The percentage increase over no-enrichment treatment was the highest in A. rubra (51.9-64.8) and lowest in A. caroliniana and A. pinnata (23.2-40.7). Application of phosphorus during intercropping increased the fresh weight and N-yield of both unenriched and P-enriched Azolla significantly but the increase was more for unenriched Azolla. The use of P-enriched inoculum and application of phosphorus during intercropping also increased the grain and straw yields of rice. The higher grain yield in these treatments resulted from production of more grains panicle-1. There were no significant differences among the Azolla species as regards their growth, N2-fixation and effects on rice crop.