EFFICACY OF SEAWEED SAP ON PRODUCTIVITY OF SOYBEAN

Soybean [Glycine max (L.) Merril. ] is a leguminous crop rich in high quality protein (40-42%), oil (18-20%) and other nutrients like calcium, iron and glycine. It is a good source of isoflavones and therefore it helps in preventing heart diseases, cancer and HIV’s. Soybean has the highest protein of all field crops and is second only to groundnut in terms of oil content among food legumes. So, it has established its potential as an industrially and economically viable oilseed crop in the world. Because of its high nutritional value and myriad forms of use, it is recognized as “Golden bean”. In spite of high potential of the crop, its production is still inadequate owing to low yields, resulting in a wide gap between current. In Jharkhand,it is grown in small areas as rainfed crop having very low productivity. Thus, there is tremendous scope of soybean cultivation in Jharkhand. Seaweeds are the macroscopic,multi cellular marine algae that commonly inhabit the coastal regions of the world’s ocean. Liquid extracts obtained from seaweeds have recently gained importance as foliar spray for many crops including various cereals, pulses and horticultural crops. Seaweed extracts contains major and minor nutrients, amino acids , vitamins, cytokinins, auxin and abscisic acid like growth promoting substances (Mooney and Van Staden, 1986) and have been reported to stimulate the growth and yield of plants (Rama Rao, 1991) develop tolerance to environmental stress, increase nutrient uptake from soil (Turan and Kose, 2004) and enhances antioxidant properties (Verkleij,1992). The beneficial effects of seaweed extract is as a result of many components that may work synergistically at different concentrations, although the mode of action still remains unknown. In recent years, uses of seaweed extracts have gained popularity due to their potential use in organic and sustainable agriculture, especially in rainfed crops, as a means to avoid excessive fertilizer application and to improve mineral absorption. Hence, a field experiment was conducted on “Efficacy of seaweed sap on productivity of soybean” at Birsa Agricultural University farm during Kharif season of 2012 on sandy loam soil, moderately acidic in nature (pH 5.02) having organic carbon (0.40%), available nitrogen (225.29 kg/ha), phosphorus (13.44 kg/ha), potassium (150.08 kg/ha) and sulphur (17.16kg/ha). The experiment was conducted in randomized block design with 17 treatments replicated thrice. Treatment consists of seaweed sap of Kappaphycus alvarzii and Gracillaria edulis each of which is applied at five concentration level i.e. 2.5, 5.0, 7.5, 10 and 15% with 100% RDF and three concentration level i.e. 7.5, 10 and 15% with 50% RDF along with one control plot with 100% RDF. Soybean variety RKS-18 was selected for the experimental study. Results revealed that there was improvement in growth attributing characters like plant height (71.96 cm) and leaf area index (3.03) with increase in sap concentration upto the highest level of 15% K sap while the dry matter accumulation (780.64 g/m2) at harvest and yield attributing characters i.e. pods per plant (44.03), seeds per pod (2.17), seeds per plant (91.98), 100 seed weight (10.63 g), grain yield (1673.02 kg/ha) and straw yield (2137.09 kg/ha), increased up to 7.5% concentration of K sap with 100% RDF. Increasing concentration beyond 7.5% concentration of K sap leads to suppression in yield attributing characters and yield. Similarly, the gross return (` 37476/ha), net return (` 19929/ha) and B:C ratio (1.14) recorded highest with the application of 7.5% K sap with 100% RDF. Nitrogen uptake by grain (108.39 kg/ha) and straw (37.21 kg/ha), phosphorus uptake by grain (8.28 kg/ha) and straw (3.14 kg/ha), potassium uptake by grain (24.96 kg/ha) and straw (21.16 kg/ha) and sulphur uptake by grain (7.01 kg/ha) and straw (5.01 kg/ha) were also found highest at 7.5% K sap with 100%RDF. On the basis of present investigation, it may be concluded that application of 7.5% K sap along with 100%RDF proved to be more productive and economically viable for soybean cultivation and seaweed sap can be used as a source of fertilizer in rainfed areas of Jharkhand.