Efficiency of bio-foliar fertilizer extracted from seaweed and water hyacinth on lettuce (Lactuca sativa) vegetable in Central Vietnam

Foliar fertilizer is important for lettuce vegetable development and yield. The present investigation studied different types and ratios of bio-foliar fertilizer to water seaweed extract and water hyacinth (0:1, 1:10, 1:20 and 1:30) in comparison to different two commercially available foliar fertilizers on growth, and quality attributes of lettuce. Four pot and field experiments were undertaken in spring seasons of 2020 and 2021 in randomized complete block design using three replications. The findings revealed that lettuce yield and quality were dependent on the type and spraying ratio of bio-foliar fertilizer from seaweed and water hyacinth. Improved yield and quality of lettuce was found when bio-foliar fertilizers from seaweed and water hyacinth were sprayed at ratio 1:10 (increasing compared to control in 68–81% with seaweed; 61–70% with water hyacinth in pot experiment and 19% with seaweed; 14–17% with water hyacinth in field experiment). Nitrate content was within standard range <1000 mg kg-1 and brix content from 2.20-2.65% as compared to commercial foliar fertilizer. A close relationship was found between biomass yield (R2 = 0.46 to 0.66) and economic yield (R2 = 0.50 to 0.64) with type and ratio of bio-fertilizer. In conclusion, a bio-foliar fertilizer extracts from seaweed at a spraying ratio of 1:10 can be used to achieve better yield and quality for lettuce crop.