Effects of Irrigation Amount on Fruiting Period and EC Level by Growth Period on Growth and Quality of Melon (Cucumis melo L.) Using Coir Substrate Hydroponics During Autumn Cultivation

This study was performed to identify the effects of changes in irrigation amounts on the ‘fruiting period’ and of irrigation electrical conductivity (EC) level by the growth period on the growth and fruit properties of melon in hydroponics, using coir substrate. The irrigation amount was regulated based on the drainage rate (%), which was 30% after transplanting. The irrigation amount during the ‘fruiting period’ was regulated to the drainage rate of 10% and 30% for the two consecutive treatments of the irrigation level, and after 40 days of fruiting, the drainage rate was maintained at an equal level of 10%. The irrigation EC level was set to three treatments; low level (1.0-1.5-1.8 dS·m -1 ), middle level (1.5-1.8-2.0 dS·m -1 ), and high level (1.8-1.8-2.3 dS·m -1 ), according to the three growth periods: flowering period, fruiting period, and 40 days after fruiting. For the changes in drainage EC, a low irrigation EC level indicated a low drainage EC level, while a lower value was shown by the 30% drainage treatment with a higher irrigation amount than by the 10% drainage treatment. The results show that leaf length, leaf width, and leaf area were the highest at 30% drainage and the irrigation EC level on the fruiting period was high, but the middle level EC showed a similar pattern without a significant difference. Thus, for the EC level, the middle level (1.5-1.8-2.0 dS·m -1 ) appears to be most suitable. The irrigation amount had more influence on fruit weight, fruit height, fruit width, and fruit shape than the EC level. Meanwhile, the 30% drainage rate group showed higher values. An increase in the irrigation EC level by growth period was found to have increased the fresh and dry weights of the plant, although the fruit sugar content showed no significant difference. The findings of this study suggest that for the hydroponics of the net melon ‘PMR Worldstar’ using coir substrate, a 30% drainage rate was more favorable for melon fruit