Effects of bio-extract on growth and quality of Green Oak lettuce (Lactuca sativa var. crispa L.) cultivated in hydroponics system

Abstract

This research aimed to study the effects of bio-fermented solution on the growth and quality of green oak lettuce (Lactuca sativa var. crispa L.) grown in the hydroponics system using NFT (Nutrient Film Technique). A completely randomized controlled trial was conducted using nutrient solution formulas, including fresh milk biofermentation, fresh milk biofermentation, and farmers’ method nutrient solution, and commercial organic nutrient solution, to be used as a comparison for the growth of green oak lettuce grown for 28 days. The results of the study showed that commercial organic nutrient solution mixed with nutrient solution according to the farmers' method at a ratio of 1:1 had the highest growth values ​​in terms of number of leaves, plant height, and fresh weight with an average value of 23.55±1.23 leaves, 27.00±1.3 cm, and 101.61±9.83 g per plant, respectively. In a comparison between the addition of commercial organic nutrient solution (Treatment 3) and the biologically processed fresh milk solution (Treatment 2), it was found that the biologically processed fresh milk solution had better canopy width values ​​on the 7^th, 14^th, and 21^st days after they were transplanted, with mean canopy widths of 14.25±0.88, 24.35±1.50, and 25.20±1.74 cm, respectively. While the control experiment (no nutrient solution added) (Treatment 1), the biological process fresh milk nutrient solution (Treatment 2), and the biological process fresh milk nutrient solution mixed with TPI nutrient solution at a ratio of 1:1 (Treatment 5) had the lowest accumulated nitrate.  However, all the three treatments were not statistically different at P= 0.05. The average accumulated nitrate was 155.00±2.00, 235.63 ±1.23, and 273.30 ±1.50 mg/kg fresh weight, respectively, and the values ​​found were not higher than the specified standard (2,500 mg/kg fresh weight). In summary, the data obtained from this experiment can be used as a suggestion for farmers to reduce use of chemicals in growing vegetables and, instead, use bio-fermented water as an alternative to reduce risk of nitrate residue amounts exceeding the standard.