Effects of relative humidity and growing medium moisture on growth and fruit quality of melon (Cucumis melo L.)

Abstract

As moisture or water is a factor limiting the quality of melon fruit, we investigated the effect of relative humidity and growing medium moisture on growth and fruit quality of melon. The experiment was conducted in the nylon net greenhouse of the Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok from March to June 2017. It was laid out in 2×3 factorial in completely randomized design with 10 replications. Factor A was 2 levels of relative humidity (RH) (normal condition and misted). Factor B was 3 levels of field capacity (FC) of the growing medium (100, 130 or 160%). Moisture content of the growing medium was maintained throughout the experiment using a wet sensor. Melons were grown in plastic bags filled with a mixture of coconut coir, rice hull and sand in the ratio of 2:1:1 by volume. Mist treatment had a significant positive influence on plant growth and fruit quality of melon. Plant height, leaf greenness and leaf area of melons grown under mist were (107.41 cm, 30.66 SPAD unit and 112.02 cm2). They were significantly less than those under normal condition (112.54 cm, 40.78 SPAD unit and 119.70 cm2). Fruit weight and total soluble solids of fruit grown under mist (655.02 g and 11.61 °Brix) were significantly less than those from normal condition (709.11 g and 12.61 °Brix). Moisture content of the growing medium did not affect growth and fruit quality of melons. However, there was an interaction between relative humidity and moisture content of growing medium on leaf area. The mist treatment with 130-160% FC moisture of growing medium led to leaf area reduction. Therefore, the optimum conditions for melon production should be normal condition with 100% FC moisture maintained in growing medium.