This investigation was carried out during the two successive seasons of 2013 and 2014 in a private orchard located at "New Gamgarah, Benha" district, Qalyubeia Governerate to study the effect of some stimulating substances i.e., (GA 3 , NAA, seaweeds , yeast extract and proplis) at different concentrations on some fruiting parameters and fruit properties as well as leaf nutritional status of Washington navel orange trees budded on sour orange reatstock. Trees under study were 18-year-old, grown in a clay leamy soil and planted at 5 meters apart under flood irrigation system. Obtained results revealed that all investigated stimulating substances treatments under study as foliar spray at various concentrations resulted in a significant increase in fruit set percentage and yield either Kg/tree or ton/feddan as well as the yield increment % in relation to the control, however decreased the percentage of fruit drop in comparison with the control during both seasons of study. Moreover, both fruit physical characters such as (fruit weight, volume, height, diameter and fruit shap index) and fruit chemical properties (TSS %, total acidity and TSS %, /acid ratio) were significantly improved as a result of sprayed trees with the above mentioned stimulating substances treatments. In addition to that, leaf nutrient contents were improved in all studied treatments from the standpoint of statistic as compared to the control during both the first and second seasons of study. Generally, it could be concluded that, most of investigated treatments resulted in a positive and significant effect on most studied properties, since both treatments of active dry yeast at (150 and 100 ml 3 /L)were the most effective treatments for increasing both fruit set % and productivity while decreasing fruit drop % as well as improving both the most studied of fruit properties and leaf nutrient contents of Washington navel orange trees

This investigation was conducted during two successive seasons (2019/2020; 2020/2021) on almost 12year old identical Gold Nugget mandarin trees Citrus reticulata Blanco (Wilking mandarin x Kincy mandarin), grafted on Volkamer Lemon (Citrus volkameriana) (VOL) rootstock cultivated in a private orchard located in Al Qalyubia Governorate, Egypt. The trees were grown at a distance of 2 × 6 m in silt soil under the Immersion irrigation system. To study the effect of hand thinning, chemical thinning using NAA at 400ppm, Potassium nitrate (5gm/L), Spirulina platensis ( algae extract) (2cm/L) and Potassium sulfate (1.25g/L) +Zinc sulfate (2.5g/L) +Salicylic acid (0.11g/L) on vegetative growth, fruit quality and yield of Gold Nugget mandarin trees. The experiment was designed as a randomized complete block design with five replications. Results illustrate that most of the experimental treatments significantly increased tree canopy volume both hand or chemical thinning was the highest value and Chemical thinning treatment significantly increased leaf area. Potassium nitrate foliar spray significantly increased shoot thickness, number of leaves/ shoot. Spirulina platensis treatment enhancing of the spring growth cycle, number of flowers, fruit-set, number of fruits/tree, tree yield efficiency as the number of fruit / M 3 canopy and vitamin C. as for Potassium sulfate + zinc sulfate+ Salicylic acid treatment was superior with statistic differences for tree yield as kg/tree and kg/ M 3 , fruit physical properties (fruit weight, fruit size, Juice volume, Juice weight and fruit Pulp Weight).

The effects of different soil application levels of Natural Elements Compound( NEC) either alone or in combination with EM soil application rates on Washington navel orange trees budded on sour orange rootstock grown under ''KarKashnda'' region, Qalyubeia Governorate condition to study their effects on some fruiting parameters and physical and chemical of fruit characteristics during the two successive seasons of 2013 and 2014. The obtained results revealed that all investigated treatments under study resulted in significantly increased in the most fruiting parameters and fruit characteristics as compared to the control treatment during the first and second seasons of experimental study. Moreover, data indicated that all studied treatments exhibited significantly increased fruit set % , yields either tree yield in kgs or yield expressed as tons per feddan. Furthermore, results displayed clearly that both studied fruit physical properties ( fruit weight, volume, height and diameter ) and fruit chemical characters such as TSS %, total acidity %, total sugers % and fruit juice vitamin C. contents were improved by subjected trees to different investigated treatments as compared with the control in the two experimental seasons of study. Generally, it could be concluded that , all investigated treatments under the study (NEC and EM ) either alone or in combination with them resulted in a significant and positive effects for increasing all fruiting parameters and improving most studied fruit quality. However, the treatment of (NEC 4 x EM 2 ) i.e. (6.0 kgs of NEC x 900 ml 3 /l of EM /tree /year) exhibited statistically the best and the most effect for increasing and improving all investigated fruiting parameters and fruit characteristics of Washington navel orange trees.

The present investigation was carried out during two successive seasons (2018/2019; 2019/2020) on almost 12-year old identical Gold Nugget trees (Citrus reticulate, Blanco) (Wilking mandarin x Kincy mandarin), grafted on three rootstocks cultivated in a private orchard located in Al Qalyubia Governorate, Egypt. The trees were grown at a distance of 2 × 6 m in silt soil under the Immersion irrigation system. This investigation aimed to study the effect of some citrus rootstocks on Gold Nugget mandarin trees Growth and Productivity. Three citrus rootstocks were: Troyer citrange Citrus sinensis 'Washington' x Poncirus trifoliate (Tr.), Sour orange (Citrus aurantium L.) (SO.) and Volkamer Lemon (Citrus volkameriana) (VOL). The experiment was designed as a randomized complete block design with five replications. The obtained results showed that Gold Nugget grafted on Troyer citrange rootstock recorded the highest significant values of chlorophyll a, b, total chlorophylls, total carbohydrates, spring growth cycle, fruit set and yield. Whereas Gold Nugget grafted on Sour orange rootstock recorded the highest significant values of shoot thickness, Leaf surface area, Rate Increasing canopy, vitamin C and TSS/ acid ratio. Regarding Gold Nugget grafted on Volkamer lemon rootstock recorded the highest significant values of dray matter percentage, the number of leaves, tree Canopy, summer growth cycle, flowering, fruit Physical properties and acidity percentage.

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