Sara Sarko(1) and Ghiath Ahmad Alloush*(1)
(1). Department of Soil and Water Sciences, Faculty of Agriculture, Tishreen University, Latakia, Syria.
(* Corresponding author: Dr. Ghiath Ahmad Alloush. E-mail: galloush@scs-net.org).
Received: 24/07/2018 Accepted: 12/11/2018
Abstract
A hydroponic experiment was conducted in a greenhouse during the spring-summer seasons of 2015 to investigate the effect of various ratios of Ca:Mg (4:6, 5:5, 7.5:2.5 and 10:0.5 mM/L-1) and potassium (0.5, 3, and 4.5 mM/L-1) on total fruit production, marketable fruits and quality of tomato fruits (cv. Shannon). The experiment consisted of 12 treatments with three replicates. Pots were completely randomized on the experimental plot. The results showed that the highest fruit production reached 4.72 kg/plant (fruit yield of 5 punches) in the treatment Ca:Mg (7.5:2.5) and 3 mM/L-1 K. Physiological disorder symptoms on fruits along with small size (< 47 mm) decreased the percentage of marketable fruit production to 8% of total in treatment Ca:Mg (5:5) and 0.5 mM/L-1, whereas marketable fruit production were 95% in the same Ca:Mg ratio but 4.5 mM/L-1 K. pH dropped in fruits with increasing Ca:Mg ratios at all K concentrations in the nutrient solution. The decrease pH values became significant in Ca:Mg ratio (7.5:2.5) and 10:0.5. The reverse was true with total titratable acidity. TSS increased as Ca increased in the nutrient solution if K supply was adequate (4.5 mM), and reached 65.2 mg/g in the treatment Ca:Mg ratio (10:0.5). Vitamin C concentrations took the same trend as TSS, and values were between 30-45, which were higher than normally reported (15-25 mg/100 g). Nitrate concentrations, while increasing with increasing Ca and K concentrations in the nutrient solutions, were within normal range (less than 400 mg/L-1)
Key words: Tomato, Hydroponic culture, Fruit yield, Vitamin C; Total acidity, TSS, pH, NO3.
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