S. T. Zodape

SEAWEED SAP AS AN ALTERNATIVE LIQUID FERTILIZER FOR YIELD AND QUALITY IMPROVEMENT OF WHEAT

The experiment was conducted on a farmers field near Bhavnagar (Gujarat, India) during the Rabi season of 2008–2009 to study the effect of foliar applications of Kappaphycus alvarezii and Gracilaria edulis sap on growth and yield response of wheat var. ‘GW 496’. Three foliar sprays of both saps were applied at the rate of 2.5, 5.0, 7.5, and 10.0% (v/v) along with water as a control at different stages of the crop. It was found that yield of grain was increased significantly by 19.74% and 13.16% for plants receiving 7.5% and 5.0% concentrations of K. alvarezii and G. edulis sap, respectively, over control. The increase in yield was attributed to increases in the number of spike, spike weight, spike length and 100 seed weight. Foliar applications of K. alvarezii sap at 7.5% increased nutrient contents in grains from 7.91% (K) – 31.82% (S) whereas G. edulis sap increased nutrient content 5.72% (N) – 37.54% (Mg).

Seaweed extract as organic bio-stimulant improves productivity and quality of rice in eastern Himalayas

Enhancing productivity through integrated nutrient management is pertinent to sustainable intensification of agricultural ecosystems. Field experiments were conducted during 2012 and 2013 in Eastern Himalayas with extracts from Kappaphycus alvarezii (K sap) and Gracilaria edulis (G sap) to assess growth, productivity and quality enhancement of rice (Oryza sativa). A Petri dish experiment was also conducted to assess the efficacy of saps in improving germination percentage and seedling vigour of rice seedlings. Field experiment included foliar spray of K and G saps (2.5, 5, 10 and 15% concentrations) with 100% recommended dose of fertilizers (RDF) along with water spray + 100% RDF (control). The rice seeds soaked with lower concentrations (2.5 and 5%) of K and G saps recorded higher germination percentage, root and shoot length and seedling vigour index as compared to water soaking. Whilst soaking in higher concentrations (7.5% and above) reduced the germination percentage and seedling vigour index. Foliar spray of K or G sap at 5% and above concentrations + 100% RDF significantly increased plant height, dry matter accumulation, chlorophyll index, crop growth rate, yield attributes and yield of rice (5.4 to 18.4% higher) as compared to control. Application of K or G sap at 10% concentrations + 100% RDF also increased micro-nutrient (Fe, Cu, Zn and Mn) and protein concentration in rice grains. Thus, foliar application of 10% K or G sap along with 100% RDF is a recommendable option for improving yield and quality of rice and sustaining soil fertility in eastern Himalayas and similar agroecosystems elsewhere.

Effect of foliar application of seaweed saps on chemical soil quality, growth and yield of black gram

A field experiment was conducted to evaluate impact of seaweed (Kappaphycus sp. and Gracilaria sp.) saps on chemical soil health, growth and yield of Vigna mungo. Foliar application of saps was carried out 35 days after sowing and at flowering with four concentrations (2.5, 5, 10 and 15%) of K-sap and G-sap separately, 7.5% of K-sap + 50% RDF and control. At harvest, highest build up of organic carbon was recorded due to 15% K-sap foliar application while highest available N was observed due to 10 and 15% K-sap. Foliar application of 7.5% K-sap + 50% RDF and 5% G-sap supported the highest available P and K in soil at harvest, respectively. At flowering, highest nodule number of 43 plant−1 was recorded due to 5% G-sap. Foliar application of seaweed saps at various concentrations, except 2.5%, enhanced the grain yield by 27.43% over control. The foliar application of 7.5% K-sap + 50% of RDF also produced the 25.73% higher grain yield over control which was at par with those of other treatments, saving 50% of chemical fertilizers vis-a-vis environmental pollution