Productivity, quality and profitability enhancement of French bean, okra and tomato with seaweed extract application under North-Eastern Himalayan condition

Abstract

In the North-Eastern Himalayan region (NEHR) of India, use of chemical fertilizer is minimal due to the unavailability of synthetic inputs, remoteness and inaccessibility. Vegetables are very much favored to grow under organic farming practices in these areas due to high market prices and demand. Seaweed extract is organic and is utilized in various vegetable crops across the globe for multifarious benefits. Therefore, there is a huge potential for the application of seaweed extract by virtue of organic areas. Fresh Kappaphycus alvarezii (K sap), Gracilaria edulis (G sap) and GA3 free Ksap were extracted using a pre-standardized methodology and applied on French bean, okra, and tomato for two consecutive years. Except for 10% GA3 free sap treatment [T8, applied with 75% recommended dose of nutrients (RDN)], other sea weed sap treatments supplied with 100% RDN. The growth (plant height in French bean, chlorophyll index in French bean and tomato and primary branch/plant in tomato) and yield attributes (pod length, pod weight/plant and stover yield in French bean; fruits/plant and fruit length in okra; fruits/plant, weight/fruit and average diameter of fruit in tomato) of French bean, okra, and tomato were enhanced significantly (p ≤ 0.05) with the application of seaweed extract along with 100% RDN in general and T3: K sap @ 10%, T5: G sap @ 10% and T7: GA3 free Ksap @10% in particular. However, T8: GA3 free sap @10% + 75% RDN did not gave promising results as compared to other sea weed sap traetments supplied with 100% RDN. Floral and fruit set attributes of all the vegetables were also significantly (p ≤ 0.05) influenced by foliar application of different sea weed saps. Ascorbic acid and lycopene in tomato fruits were significantly (p ≤ 0.05) improved with the application of seaweed extract. Moreover, 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′ -azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay values of French bean okra and tomato were also significantly (p ≤ 0.05) influenced by different concentration of seaweed saps. Among the major nutrients analysed in the fruits of three crops, N was found to be having significant variation (p ≤ 0.05) in all the three crops, while variation in K was significant (p ≤ 0.05) only in tomato. The available N, P, K content and soil organic carbon (SOC) concentrations in soil after two years of experiment of seaweed saps on French bean okra and tomato significantly (p ≤ 0.05) varied across treatments. Higher concentration of G, K and GA3 free sap recorded increased net return and more net benefit per unit investment compared to the control. Overall, it was concluded that application of 10% K sap, G sap and GA3 free Ksap along with 100% RDN can be recommended for increasing growth, yield and quality in French bean, okra, and tomato in NEHR.