SIGNIFICANCE OF APPLIED IRRIGATION AND FERTILIZATION SYSTEMS FOR IMPROVING TOMATO PRODUCTIVITY AND ITS FRUIT QUALITY IN A NEWLY RECLAIMED CALCAREOUS SOIL

A field experiment was carried out on a newly reclaimed calcareous soil with sandy loam texture class at a Private Farm adjacent to Alexandria road (km 52), and cultivated with tomato plants (Lycopersicon esculentum) under two irrigation systems (furrow and drip) during growing season of 2005. Fertilization methods were carried out as soil and fertigation applications. The used fertilizers were urea (46% N) and mono-potassium phosphate (15% P205 and 38% K2O), with rates of 100 kg N fed, 40 kg P2O5 fed -1 and 48 kg K2O fed . This work aims to study the effects of irrigation and fertilization methods on tomato yield and fruit quality, with special reference to NPK fertilizers use efficiency. At the elongation stage (60 days after transplanting), some selected plants were taken to determine some vegetative growth parameters, i.e., plant height, dry weight, leaf area index, number of flowers per plant and the chlorophyll concentration (a and b) as well as N, P and K uptake by plants. Soil samples were also taken at different depths (0-15, 15-30, 30-45 and 45-60 cm) to determine available N, P and K. In addition, at harvest (90 days after transplanting) tomato yield and the fruit quality parameters (firmness, total soluble solids, titrable acidity, vitamin C and total sugar) were identified. The obtained results reveal that experimental soil is classified as Typic Haplocalcids, coarse loamy, mixed, thermic. According to a parametric evaluation system, it could be evaluated as moderately suitable (S2s1s3s4), with an intensity degree for each of soil texture, CaCO3 and gypsum, as soil limitations, lies in the range of slightmoderate (rating = 90-75). In addition, the used irrigation water source (underground water) lies in the first category of C1S1, where ECiw and SAR values lay within the range of < 0.75 dS/m and < 6.00, respectively. Moreover, the obtained data show that the abovementioned vegetative growth parameters recorded the highest increases at fertigation system followed by NPK fertilization as soil application under drip and furrow irrigation ones. Also, available N and K contents in soil behaved the same abovementioned trend of irrigation and fertilization systems, with superiority for fertigation NPK one in soil surface (0-15 cm), may be due to their lesser by leaching. As for available phosphorus, it was prone to fix at the point of application (soil surface). The aforementioned trend was positively reflected on NPK uptake by plants and tomato yield, where fertigation NPK exhibited relatively higher N, P and K uptake as compared to NPK fertilization under drip and furrow irrigation systems. The relative increases in tomato fruit yields reached 36.68 and 16.80% for fertigation and drip over the furrow irrigation system, respectively. Fertigation NPK exhibited significantly higher fruit Nader R. Habashy, et al. 217 Fayoum J. Agric. Res. & Dev. , Vol. 20, No. 2, July, 2006 number per plant (as an average of 56.9) followed by drip (50.4) and furrow (43.7) irrigation systems. The NPK fertilizers-use efficiency was reached a maximum value at fertigation NPK (205.9 kg fruit kg NPK), followed by NPK fertilization as soil application under drip (175.9 kg fruit kg NPK) and furrow (150.6 kg fruit kg NPK) irrigation systems. Thus, it could be concluded that applying fertigation NPK system resulted in a pronounced improvement of vegetative growth parameters, and in turn increasing tomato yield and its fruit quality.