Document Type : Research articles.
Authors
1
Hort. Res. Instit. Agric. Res. Centre, Giza, Egypt
2
Hort. Dept., Fac. of Agric., Fayoum, Univ., Egypt
Abstract
This investigation was carried out during the two successive seasons 2008
and 2009 on 25- years old Washington Navel orange trees grown in an
orchard at El- Nobaria sector, El- Behera governorate to study the effect of
foliar spraying with urea (0.5%), a mixture of Zn (0.4%), Mn (0.3%),
Fe(o.5%) and Cu (0.3%) in sulphate salts form (23% Zn, 28% Mn, 19% Fe
and 30%Cu), respectively and two growth regulators, GA3 at 25 ppm and
NAA at 10ppm. The trees spraying were two ones, the first before flowering
(the third week of Feb.), and the second spraying applied four weeks after
fruit set to study the effect of these treatments on some vegetative growth
characters and leaf mineral contents, Fruiting aspects (set, drop and Preharvest drop) percentage, yield per tree by number and weight, as well as the
average weight of fruits and some fruit physical and chemical properties. The
obtained results showed that the treatments included spraying Urea&
micronutrients (Zn, Mn, Fe and Cu), Urea and NAA achieved the highest
values for average leaf area and shoot diameter. Regarding shoot length,
Urea& micronutrients followed by GA3 had the highest values. Leaf analysis
showed that the highest values of leaf N content obtained by using Urea,
Urea& micronutrients, GA3 and NAA, respectively. The lowered values of
leaf N content recorded when using micronutrients treatment followed by
control. All treatments were significantly effective in increasing fruit set and
reducing fruit drop as compared with control. Application of NAA, Urea &
micronutrients and GA3 significantly increased fruit set percentage and
reduced June and pre-harvest fruit drop, however NAA was more effective in
reducing fruit drop than GA3. Spraying Washington Navel orange trees with
Urea & micronutrients and NAA significantly increased the number of fruit
per tree, yield per tree. However, the treatment included both of Urea &
micronutrients Followed by GA3 were the most effective in increasing fruit
weight and pulp weight. Spraying of Urea and micronutrients slightly reduced
juice acidity and increased T.S.S., total sugars and ascorbic acid contents as
well as T.S.S./ acid ratio. In the contrary, either of GA3 or NAA caused the
same increase in ascorbic acid content in the juice.
Keywords
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