Effect of seaweed extract on the growth, yield and nutrient uptake of soybean (Glycine max) under rainfed conditions

A field experiment was conducted during the rainy ( kharif ) season in Indian in 2006 to study the effects of foliar applications of different concentrations of seaweed extract (prepared from Kappaphycus alvarezii ) on nutrient uptake, growth and yield of soybean [ Glycine max (L.) Merr.] grown under rainfed conditions without the application of chemical fertilizers. The foliar spray was applied twice at seven concentrations (0; 2.5; 5; 7.5; 10; 12.5 and 15% v/v) of seaweed extract. Foliar applications of seaweed extract significantly enhanced yield parameters. The highest grain yield was recorded with applications of 15% seaweed extract, followed by 12.5% seaweed extract that resulted in 57% and 46% increases respectively compared to the control. The maximum straw yield was also achieved with 15% seaweed extract application. Improved nutrient uptake (N, P, K and S) was also observed with seaweed extract applications. Thus, under rainfed soybean production, foliar applications of seaweed extracts could be a promising option for yield enhancement.