EFFECT OF SOME FERTILIZATION TREATMENTS ON GROWTH OF TREES, PRODUCTIVITY AND QUALITY OF GUAVA (Psidium guajava l.) FRUITS CV. "ETMANI". II. UNDER FASTING SYSTEM.

A series of field experiments was carried out in a private orchard at Qalyob region, Qalubia governorate, Egypt during 2011/12, 2012/13 and 2013/14 seasons for winter production of 9-years-old guava (Psidium guajava L.) cv. "Etmani" trees, planted on clay loam soil at a distance of 5 x 5 m and fasted from April, 1 st to July end, beside improving yield and quality of such winter crop by application of organic compost at either full, 3⁄4 or 1⁄2 the recommended dose (40, 30 and 20 kg/tree, respectively) + both feldspar and rock phosphate at either full, 3⁄4, 1⁄2 or 1⁄4 the recommended dose for each + biofertilizer mixture comprising nitropeine + phosphoreine + potasseine at the recommended dose for each, where all previous compost were arranged in 12 combinations plus the control. The gained results have shown that most fertilization treatments employed in this work raised the means of shoot length, number of leaves/m, leaf area and number of flower buds/m over those of control with various significant levels in the 3 seasons. Similarly, were those results of No. of fruits/m, fruit weight, yield, fruit length, diameter and volume, as well as flesh thickness. The prevalence in all aforenamed characters was for the combination of 75 % compost + 100 % feldspar + 100 % rock phosphate + biofertilizers mixture which gave the utmost high means over control and other combinations in most cases of the three seasons. The percent of TSS was significantly increased in the first season only by 100 % compost + 25 % feldspar + 25 % rock phosphate + biofertilizers mixture combined treatment, but in the 2 nd and 3 rd seasons, it was slightly improved by the different used combinations with nonsignificant differences in between or with control. The acidity % exhibited a similar behaviour in the three growing seasons, but the least percent of acidity was found due to the combining between 100 % compost, 25 % feldspar + 25 % rock phosphate and biofertilizer mixture (T4), especially in the 1 st and 2 nd seasons. In the 3 rd season, however, the least acidity % was attained by 75 % compost + 100 % feldspar + 100 % rock phosphate + biofertilizer nixture (T5). So, the best ratio of TSS/acidity was obtained in the first and second seasons by T4, while in the 3 rd one by T5. Vitamin C content and flesh thickness were also improved by the used fertilization combinations, but the highest records of them was obtained by different treatment in every season. The percent of N, P, K, Ca and Mg in the leaves of fertilized plants was, in general improved over that of control in the three seasons by the different used treatments, but no one of them had the superior effect over the others. Hence, it can be advised to fertilize the 9-years-old trees of guava cv. "Etmani" grown on clay loam soil at 5 x 5 m apart under Qalubia governorate conditions and fasted from April, 1 st to end of July with 75 % of recommended compost dose (30 kg/tree) + 100 % of both feldspar (1.2 kg/tree) and rock phosphate dose (1.3 kg/tree) plus biofertilizer mixture used in this study to get the highest and best quality winter crop from point of commercial and economic view. Osman, I.M.S. et al.