EFFECT OF SOME FLOOD IRRIGATION AND POTASSIUM FERTILIZATION TREATMENTS ON VEGETATIVE GROWTH, YIELD AND FRUIT QUALITY OF “DESSERT RED” PEACH TREES GROWN IN CLAY SOIL

This investigation was carried out during 2008 and 2009 seasons to study the effect of three irrigation regimes at 80, 70 and 60% of field capacity (FC) (I1, I2 and I3) and three potassium fertilizer levels at 0.5, 0.75 and 1 kg K2SO4 (48% K2O)/tree (K1, K2 and K3), as well as, their interaction on vegetative growth, nutritional status, water relations, yield and fruit quality in addition to field water use efficiency (FWUE) of “Dessert Red” peach trees budded on Nemaguard rootstock grown in Sedy Salem District, Kafrelsheikh governorate. The obtained data indicated that, deficit irrigation regime was associated with reduced shoot length and diameter, number of leaves/shoot, area per leaf, shoot and leaf dry weights and trunk cross section area–increase. However, increasing K fertilizer level caused a significant increase in previous vegetative growth characeristics. The application of (I1 x K3) and/or (I2 x K3) considered the best combination treatments for enhanced vegetative growth in both seasons of study. In the two experimental seasons, reducing irrigation rate up to 60% FC led to significant reduction in leaf macro and micro-nutrients, total chlorophyll contents, and significant increment in leaf free proline content. Meanwhile, increasing K fertilizer level from 0.5 to 0.75 or 1 kg K2SO4/tree significantly increased leaf K and free proline contents but significantly reduced leaf Ca, Mg and total chlorophyll contents. On the other hand, leaf N, P, Fe, Mn and Zn-contents were not affected by increasing the level of K fertilizer. Either deficit irrigation regime or high K fertilizer level recorded the highest values of bound water and osmotic pressure of cell sap and the lowest total and free water contents in both seasons. Additionally, fruit yield (kg/tree), yield efficiency (kg/cm2 TCSA) and total yield (ton/fed.) as well as average fruit weight, length and diameter were significantly increased by increasing either irrigation or K fertilizer levels, while, fruit firmness was reduced. Moreover, colour%, skin anthocyanin content and SSC were significantly increased under high K fertilizer level but, significantly decreased under higher irrigation level. However, total acidity was not affected with the both tested irrigation and K fertilizer levels and their interaction in both seasons. Greatest yield with heaviest and largest fruit beside highest values of field water use efficiency (FWUE) were produced by applying (I1 x K3) and/or (I2 x K3) combination treatments. Thus, this study recommend “Dessert Red” peach growers in clay soil to irrigate when soil moisture content reached 70% (FC) and to apply 1 kg K2SO4 (48% K2O)/tree in (I2 x K3) combination treatment which is considered the best one in this study. This treatment is not only stimulated vegetative growth and improved nutritional status and water relations but also produced maximum yield with high fruit quality especially fruit weight, size, colour and SSC content beside, saving irrigation water and increasing FWUE kg/m3.