RATIONALIZATION OF WATER CONSUMPTION OF TOMATO PLANTS GROWN UNDER SANDY SOIL CONDITIONS

Abstract

Field experiment was carried out during the two growing seasons of 2012/2013 and 2013/2014, in a private farm at Bani Salama region, El-Giza Governorate, Egypt. The objectives of this study were to investigate the effect of deficit irrigation (DI) treatments (100% (control), 85%, 70% and 55% of ETo (Reference evapotranspiration)), irrigation systems (surface drip irrigation (SDI) and subsurface drip irrigation (SSDI) (with 20cm soil depth)) and glycine betaine concentrations (GB) (0, 5, 10 and 20 mM/l, applied after 2 and 6 weeks from transplanting date as a foliar application), on vegetative growth, fruit yield and fruit quality of tomato plants (Marwa hybrid) grown under sandy soil conditions. The obtained results could be summarized as follows: 1. Vegetative growth: 1. Deficit irrigation water significantly decreased all vegetative growth parameters compered to full irrigation treatment (control) during the both seasons of study. The highest values for plant length, number of leaves per plant, number of branches per plant, total leaves area per plant and fresh and dry weights of tomato leaves per plant were obtained by the full irrigation treatment 100% ETo (control), whereas, the lowest values were obtained by 55% ETo treatment, in the both tested seasons. 2. Subsurface drip irrigation system (SSDI) showed significant superiority upon surface drip irrigation system (SDI) with all vegetative growth characteristics. Where, the highest significant values were showed with SSDI system compared to SDI system in the both tested seasons. 3. The foliar application of glycine betaine (GB) ameliorated the vegetative growth parameters for tomato plants. Where, The highest significant values for plant length, number of leaves per plant, number of branches per plant, total leaves area per plant and fresh and dry weights of tomato leaves per plant were observed with foliar application of GB at 10 mM/l treatment in both tested seasons and the lowest values were noticed with control treatment (0 mM/l GB). 4. Regarding the combination between DI treatments and irrigation systems, plants were irrigated by 100% ETo (control treatment) with SSDI system produced the highest significant values for most of vegetative growth parameters, in the two seasons. 5. The interaction between DI treatments and foliar application of GB, plants were irrigated by 100% ETo (control) with foliar application of GB at 10 mM/l treatment showed the highest significant values for vegetative growth parameters, in the both seasons. 6. The interaction between irrigation systems and foliar application of glycine betaine (GB), tomato plants were grown under SSDI system and foliar application of GB at 10 mM/l produced the highest significant values for the above mentioned vegetative growth parameters, in the both seasons. 7. Concerning the interaction among DI treatments, irrigation systems and foliar application of GB, tomato plants were irrigated by 100% ETo with SSDI system and foliar application of 10 mM/l GB produced the highest significant values for all vegetative growth parameters, in the both tested seasons. 2. Flowering and fruit yield: 1. Respecting the effect of deficit irrigation treatments, results showed that decreasing irrigation water from 100% ETo to 60% ETo significantly reduced flowering parameters (number of flowers, number of clusters per plant, number of elapsed days to the appearance of first flower on tomato plant