Application of Azolla spp. as a Growing Medium Component for Melon Grown in a Soilless Culture System

Azolla spp. is a prominent macrophyte and one of the world's fastest growing plants, making it a highly important resource that has been widely exploited as a biofertilizer, food and feed, and biofuel production. As a result, the uses, promotion, and application of Azolla spp. in sustainable agriculture would be of significant interest. The objectives of this study were (i) to assess the feasibility of using Azolla as a growing media of melons with a reduction in fertigation concentration in a soilless culture system, and (ii) to compare the agronomic and fruit quality traits of melons grown in different Azolla treatments. The experiment was carried out using a completely randomized design with 4 treatments including: (1) control treatment (1:1 combination of chopped coconut mesocarp (CCM) and coconut coir (CC) with recommended fertigation concentration (RFC)), (2) dried Azolla (1:1:2 combination of CCM, CC, and dried Azolla with 75% of RFC), (3) fermented Azolla (1:1:2 combination of CCM, CC, and fermented Azolla with 75% of RFC), and (4) fresh Azolla (1:1:2 combination of CCM, CC, and fresh Azolla with 75% of RFC). Seven melons per treatment were recorded on the agronomic traits (stem length, stem diameter, leaf width, leaf length, and leaf number) and fruit quality (fruit weight, fruit height, fruit perimeter, rind thickness, pulp thickness, fruit cavity, pulp firmness, pulp color (L*, a*, b*, Hue, and c*), total soluble solid, juice electrical conductivity, juice pH, and juice titratable acidity). Statistical analyses revealed the differences among melon agronomic and yield traits under different Azolla treatments. Nutrient analysis results showed that fermented and fresh Azolla had a high nutritional value as compared to dried Azolla. Most fruit traits from fermented and fresh Azolla treatments with a fertilizer reduction were not significantly different as compared to control. Both treatments were recommended for melon production in a soilless culture system, since these treatments can reduce fertigation use by 25% while maintaining growth and fruit quality when compared to conventional practice.