Different Response of Hydroponically Grown Vegetables to the Addition of Nostoc sp. GIA13a as an alternative nitrogen source

Abstract

Vegetable growth needs nitrogen (N) supply in the form of nitrate and or ammonium. Alternative environmental-friendly nitrogen can be provided by using N2-fixing cyanobacteria, such as Nostoc. This study investigated the effect of Nostoc sp. GIA13a to spinach (Amaranthus sp.) and water spinach (Ipomoea aquatica) grown in modified Nutrient Film Technique (NFT) system provided with Hoagland Solution. The treatments of nitrogen in Hoagland Solution were as follows: nitrate+GIA13a (NGia), nitrate without GIA13a (N), ammonium+nitrate (AN), ammonium+GIA13a (AGia) and ammonium without GIA13a(A). Inoculant of 2 g was added at the 1st and 14th day after planting (dap). Experiment was carried out for 21 days. The result showed that spinach and water spinach had different physiological responses to the occurrence of Nostoc sp. Gia13a in nutrient solution. Total chlorophyll of spinach was increased in treatment with GIA13a inoculation, while it was decreased in water spinach. Ammonium consumption of water spinach was higher than spinach as shown by ammonium concentration on the nutrient solution after 14 days experiment. Inoculation of Nostoc sp. Gia13a also triggered the growth of lateral shoot of water spinach. During experiment, chlorosis symptom was observed in young leaves of both plants. Chlorosis symptom in water spinach occurred in all treatment except NGia, while in spinach the symptom was found only in AGia and A.