Response of Greenhouse Melon (Cucumis melo L.) Cultivars to Nutrient Solutions under Soilless Cultivation Conditions

Nowadays, the cultivation of vegetables in greenhouses using soilless beds has become a widely adopted practice for vegetable production worldwide. The inclusion of new greenhouse crops like melons offers the potential to supply consumers with fresh and high-quality produce. Greenhouse melon cultivation is a relatively new practice in Iran, and there is a scarcity of published information regarding its various aspects of production in a greenhouse setting. One crucial factor that significantly influences the quality and quantity of greenhouse crops, such as melons, when employing soilless cultivation techniques, is the selection of appropriate nutrient solutions. Therefore, the current study was conducted to investigate the influence of different nutrient solutions on vegetative growth, seed and fruit characteristics, and biochemical status of three melon cultivars (Ahlam, Polinica, Curie) under greenhouse condition.           

The present study was conducted at the Horticultural Sciences Department of Shahid Chamran University of Ahvaz in southwestern Iran during the 2017-2018. A factorial experiment based on randomized complete blocks design with three replications, was carried out to assess the impact of three nutrient solution treatments (Pars, Shizuoka, Hachmath) and three different cultivars (Ahlam, Polinica, Curie) on key characteristics of greenhouse melon. The melon plants of the three cultivars were cultivated in pots containing 8 L of a growth medium consisting of a 4:1 ratio of cocopeat to perlite. At the end of experiment, four characteristic groups including vegetative growth parameters (dry weight of leaf, root, stem and plant and the ratio of leaf dry weight to root dry weight), seed characteristics (seed dry weight and hundred seeds weight), physical parameters of fruit (length, diameter, weight, wide of seed cavity and flesh thickness) and biochemical traits (ascorbic acid content, carotenoid content, taste index, total soluble solid content and titratable acidity) were measured.

The findings demonstrated that in the Hochmuth and Pars nutrient solutions, the Ahlam cultivar exhibited the highest total dry weight (63.66 g and 37.65 g, respectively). However, the Polinica cultivar showed the highest total dry weight in the Pars nutrient solution. The Hochmuth nutrient solution resulted in the highest leaf dry weight for the Ahlam cultivar (43.77 g). The Ahlam cultivar also displayed the highest fruit weight (1584 g and 1510 g, respectively), dry weight of hundred seeds (4.04 g and 3.56 g, respectively), seed dry weight per fruit (11.56 g and 10.75 g), weight of seed cavity contents (104.10 g and 114 g, respectively), fruit diameter (13.51 cm and 13.58 cm, respectively), and fruit lengths (17.58 cm and 18.28 cm, respectively). The weight of seed cavity content was influenced by both the cultivar and the nutrient solution. The Ahlam cultivar, when fed with the Pars nutrient solution, exhibited the highest total titratable acidity (0.07 %) and seed cavity thickness (6.38 cm). Regarding the Polinica cultivar, the Pars nutrient solution resulted in the highest total soluble solids (11.98 %B) and taste index (337.3), while the Hochmuth nutrient solution led to the highest ascorbic acid content (1.05 mg g-1 FW). The nutrient solution treatments did not have a significant effect on carotenoid content of the melon cultivars. Different amounts of elements in different nutrient solutions cause different growth behaviors of plants. For instance, the melon plants fed with Pars nutrient solution showed higher values of growth parameters comparing to the other plants, and it could be related to high N content of this solution. The similar results have been reported on the other crops such as cucumber and tomato.

The outcomes of the current study, which investigated variations in vegetative growth, yield, and quantitative and qualitative traits of melon cultivars under different nutrient solutions, indicated that the genetic traits of the cultivar, vegetative growth, and quality attributes of melon fruit were influenced in the presence of cocopeat and perlite media. The findings suggest that prior to selecting a melon cultivar for greenhouse cultivation, it is crucial to assess the impact of various nutrients on both vegetative growth and the qualitative characteristics of the fruits. Conducting such experiments can enhance the efficiency of nutrient utilization in greenhouse melon production.