Effect of rootstocks organic matter and n-fertilization on growth yield and fruit quality of le-cont pear trees

This Research was conducted at Horticulture Research Institute ýOrchard Agriculture Research Center Giza Egypt during 2008 and ýý2009 growing seasons. to determine the effect of rootstocks some ýorganic matter and three N levels on the vegetative growth fruit set ýyield and leaf mineral content (N P K Ca Mg Fe Zn and Mn) of Le-ýCont pear P.communis budded on P.betulifolia P.communis and P. ýcalleryana rootstocks. The trees were five years old, planted at 2.5x3 m ýapart in clay soil under drip irrigation system. The trees were subjected ýto three organic matter treatments soil application of Humic acid (HA) ýthrough drip irrigation system (60ml/tree) HA (30ml/tree) + compost ýý(5kg/tree) and compost (l0kg/tree). The N levels were 50% 75% and ýý100% of the recommended N level (400 g N/tree) as ammonium nitrate ýý(33.5% N). The main and interaction effects of rootstocks organic ýmatter and Nitrogen (N) levels were tested using split-split-plot ýexperimental design. Results indicated that growth of Le-cont pear was ýmore vigorous on P.betulifolia and P.calleryana than P.communis ýrootstock. The vegetative growth characteristics of the trees were ýsignificantly affected by the source of organic matter. Since, HA ýtreatment at 60 ml/tree was more effective followed in decreasing order ýby treatment of HA at 30 ml/tree + Compost at 5 kg/tree and compost at ýý10 kg/tree. However, growth rate was not significantly affected as the ýnitrogen levels decreased from 100% to 75% or even to 50% in both ýseasons of study. Fruit set and yield of trees grown on P. betulifolia ýrootstock were higher than those grown on P. communis and P. ýcalleryana. Also, HA treatment gave the highest fruit set and yield ýfollowed by HA+ compost then compost alone. Yield was not greatly ýaffected as N doses decreased from 100% to 75% and 50%. Results of ýthe physical and chemical proprieties of fruits were in the same trend as ýmentioned with organic matter treatments except acidity and TSS as ýthey decreased with HA treatment than with compost treatment. The ýhighest N content was found in the leaves of trees grown on P. ýcommunis and treated with HA alone and 100 % N dose. Whereas the ýhighest P and K content were found in the leaves of trees grown on ýP.betulifolia and treated with HA alone and 100 % N dose. The highest ýCa content was found in the leaves of the trees grown on P.betulifolia ýand treated with HA alone and 50 N dose while the highest Mg content ýwas found in the leaves of the trees grown on P. communis and treated ýwith HA alone and 100 % N dose. However, the highest Fe, Zn and Mn ýcontent was found in the leaves of trees grown on P.betulifolia and ýtreated with HA alone and 50 % N dose.ý