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Substrate and nutrient level: effects on the growth and yield of melon 'Cucumis melo' in soilless culture

Fukuda, N., Anami, Y.
Acta horticulturae 2002 no.588 pp. 111-117
Cucumis melo, coconuts, crop yield, drainage, drainage systems, growth retardation, hydroponics, ions, nutrient content, nutrient solutions, potassium, sand
The effect of different substrates and nutrient levels on the growth and yield of melon plants in hydroponic culture was studied. Three substrates, coconut fiber (CF), rockwool (RW), and sand (Sa); and three nutrient levels, low, normal, and high were used. The normal nutrient level was set at a drainage ratio of 120%. The low and high nutrient levels, were set at a drainage ratio of 70% and 130%, respectively. Hydroponics was carried out in an open drainage system. Compared to RW, the growth of melon plants in CF was significantly lower at the low nutrient level. However, at normal and high nutrient levels, there were no differences in the growth of melon plants between the substrates. Under low nutrient levels, melon plants grown in CF, the fruit weights were 10% to 20% lower than those grown in RW or Sa, respectively. Analyses of solutions from CF substrate, under the low nutrient level, found higher NO3 and K ions compared to solutions from the other substrates. The low nutrient solution in combination with the CF substrate, produced NO3-, and K+ concentrations of 500 to 600 ppm, and 200 to 250 ppm, respectively at the beginning of growth. These concentrations rapidly decreased in normal and high nutrient levels, but in the low nutrient solution remained high for two weeks. It is proposed that the high EC of CF causes that inhibition of growth and fruit weight, under low nutrient solutions, specifically with CF.