Evaluation of yield and fruit quality of hydroponically cultured greenhouse tomato (Lycopersicon esculentum L., Cv. Synda) under partial root zone drying (PRD) conditions

Limitation of high quality water made it necessary to find suitable methods of irrigating management. Reduce of water waste, increase of yield and even controlled water stresses are known as factors improving water use efficiency. Irrigation (fertigation) in hydroponic systems is much more important than in soil based cultivation and is highly depended to physical characteristics of medium used. This experiment was carried out to investigate the response of hydroponically cultured greenhouse tomato to deficit irrigation (DI), partial root zone drying (PRD) and incorporating in different media. A split- plot experiment based on randomized complete block design with three replicates and four observations in each experimental unit was used. Irrigation treatments were applied using 5 methods (normal irrigation using 100% of water need, deficit irrigation with 70 and 50% of water need and PRD treatments by 50 and 70% water need). Three types of media (perlite, perlite + 1% w/w hydrogel and perlite + 2% w/w hydrogel) were considered as secondary factor. Results showed that on average, full irrigation resulted in better values of fruit weight, number, diameter and yield than DI and PRD. Media had 2% hydrogel showed better results than the others on measured traits. Fruit dry matter and firmness were higher in deficit irrigation treatments. Other quality traits including juice pH, vitamin C, fruit color, firmness, titrable acidity (TA) and total soluble solids (TSS) were also statistically different among treatments. PRD obtained higher values in most cases. It seems using small amounts of hydrogel (e.g. 1% w/w) in media is not enough effective on perlite characteristics and can not affect fruit quality indices. For this purpose, higher proportions (e.g. 2% w/w) must be incorporated with coarse perlite.