Effect of liquid seaweed sap on yield and economics of summer rice

The experiment was conducted during 2011 and 2012 to study the efficacy of liquid seaweed sap of Kappaphycus alvarezii and Gracilaria edulis on growth and yield performance of summer rice in a lowland field at Gerua, Assam.The treatments consisted of Kappaphycus (K) sap and Gracilaria(G) sap, each in four different doses viz., 2.5%, 5%, 10% and 15% in combination with recommended doses of fertilizer (RDF); and were compared with RDF in combination with water spray, and, also with the 7.5% K sap + 50% RDF. A total of 10 treatments were evaluated and the results indicated that rice grain yield was increased by 13.8% and 10.3% in the treatments 5% K sap + RDF and 5% G sap+ RDF, respectively, as compared to RDF + water spray. The increase in yield was attributed to increase in the number of panicles per unit area, number of filled grains panicle-1 and test weight. Highest net return (` 29751 ha-1) and benefit: cost ratio (1.75) was obtained under 5%K sap + RDF with 20% increase in net return as compared to RDF + water spray. Application of 5% K or G sap in combination with RDF increased grain and straw yield, net income and benefit:cost ratio of summer rice.