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Egypt is one of the countries facing great challenges due to its limited water resources, so it has become necessary to study the best ways to rationalize irrigation water use and maximizing the efficient use of water under those circumstances. Two field experiments were conducted at a private farm at Al-Nubaria region, Behira Governorate, Egypt, during the two successive seasons of 2011 and 2012, to investigate the effect of three irrigation water quantities (2400, 1800 and 1200 m3 fed-1) and some water saving substances, i.e., control, zeolite, super absorbent polymer and K-humate as well as their interactions on growth, chemical composition, yield, water use efficiency and fruit quality of tomato plants (Jacal F1 hybrid) cultivated under drip irrigation system in new reclaimed lands during early summer season. The obtained results indicate that: - Increasing water quantity applied to tomato plants up to the highest used level (2400 m3 fed-1) significantly increased vegetative growth characters, i.e., stem diameter, foliage fresh weight, leaf area and leaf relative water content as well as total N, P and K uptake by tomato plants. On the other hand, total chlorophyll contents enhanced significantly with decreasing irrigation water supply. Tomato yield characters, i.e., number of fruits per plant, average fruit weight and total yield increased with increasing irrigation water quantity up to 2400 m3 fed-1. The medium irrigation water level (1800 m3 fed-1) recorded the highest values of water use efficiency. Under the low level of irrigation water (1200 m3 fed-1) tomato fruit quality characters, i.e., flesh firmness, lycopene, TSS and total soluble sugars recorded the highest significant values. - Soil application of K-humate led to the significant increases in all vegetative growth traits, total NPK uptake, total chlorophyll, yield characters and water use efficiency as well as tomato fruit quality characters compared to soil application of zeolite, super absorbent polymer and control. - Tomato vegetative growth characters were significantly affected by the combination of 2400 m3 fed-1 and K-humate soil application. Applying 2400 or 1800 m3 fed-1 of irrigation water combined with soil application of K-humate resulted in the highest significant NPK uptake as well as all studied tomato yield characters. Soil application of K-humate combined with the low irrigation level (1200 m3 fed-1) showed the highest significant chlorophyll contents in tomato leaves. Water use efficiency showed the highest value using the medium level of irrigation water (1800 m3 fed-1) combined with the soil application of K-humate as compared to the other treatments. Soil application of K-humate combined with the medium irrigation water level (1800 m3 fed-1) or the low level (1200 m3 fed-1) recorded the highest values of tomato fruit quality characters. Using the medium irrigation level (1800 m3 fed-1) combined with the soil application of K-humate obtained the highest net return and returned the highest benefit-cost ratio (3.48) in comparison with other treatments. It could be concluded that irrigation tomato plants with 1800 m3 fed-1 combined with soil application of K-humate (2 kg fed-1 in every addition, 4 times during the season) incorporated with drip irrigation system could be recommended to improve yield and quality of tomato plants as well as maximizing the water use efficiency by tomato plants, saving about 25% of the total used irrigation water quantity commonly used in tomato production. Such treatment is found to be economically and more agronomically feasible and can be recommended under drip irrigation system in sandy soil in new reclaimed lands, giving the highest net return and benefit-cost ratio to the farmers. |
