Effect of seaweed sap on germination, growth and productivity of maize (Zea mays) in North Eastern Himalayas

The productivity of maize (Zea mays L.) is very low (1.5 t/ha) in North Eastern Region (NER) of India compared to India's national average (2.5 t/ha). Farmers of the NER hardly use any chemical fertilizers and other synthetic agro-chemicals in crop production. Seaweed sap (contains macro and micro nutrients and plant growth hormones) could be a potential and cheap organic bio-stimulant to enhance the growth and productivity of maize. A 2-year study (2012–13) was conducted during the rainy (kharif) seasons at ICAR Research Complex for North Eastern Hill Region, Umiam, Meghalaya, to study the impact of foliar application of seaweed extracts from Kappaphycu salvarezii (Doty) doty ex. P.C. Silva and Gracilaria edulis (S.G. Gmelin) P.C. Silva on germination, physiological parameters and yield of maize. Treatments consisted of 2 types of sap K-sap from Kappaphycus and G-sap from Gracilaria with 2 concentrations (5 and 10%) and 3 spray schedule [at 25 days after sowing (DAS), 25 and 50 DAS and 25, 50 and 75 DAS]. Results revealed that soaking of maize seeds with low concentrations (5%) of K or G sap improved the germination and seedling vigour of maize. However, soaking of seeds in higher concentration (10 and 15% of K or G sap) decreased the germination and root length of maize. Three foliar spray (at 25, 50 and 75 DAS) of K or G sap @ 5 and 10% concentrations resulted in significantly higher plant height, dry-matter accumulation, chlorophyll content and lower leaf temperature as compared to the control (water spray). The yield attributes like length of cobs, grain rows/cob, grains/row and grain yield were significantly higher with foliar application of 10% G or K sap either 3 or 2 times. The net returns were increased significantly only up to 2 time applications of 10% G or K sap (at 25 and 50 DAS) by 4, 746 and 3, 305 over the control (water spray) respectively. Thus, 2 times spray of 10% G or K sap (at 25 and 50 DAS) is recommended to improve growth, yield and profitability of maize for NER of India.