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.