25 Jan 2024
Washington Navel Orange

Effect of GA3 and Potassium Nitrate in Different Dates on Fruit Set, Yield and Splitting of Washington Navel Orange

Two concentrations of GA3 were used alone or with 0.5% urea i.e. (50 and 100 ppm) and three levels of potassium nitrate (KNO3) 2 ،4 and 6% were tested as foliar sprays at different times i.e. first time application at full bloom stage , the second time application was at fruit diameter from 1.5-2.0 cm and (first and second time of application) for investigation their effects on fruit set, yield, fruit quality and splitting of 40-years-old Washington navel orange (Citrus Sinensis), trees budded on Sour Orange (Citrus aurantium, L.Osbeck) rootstock during 2008 and 2009 seasons. Data indicated that, all treatments increased fruit set, yield and fruit quality and decreased fruit splitting as compared with control treatment. Data also revealed that, foliar sprays of trees by (GA3 at 50 ppm) with or without 0.5% urea were superior for inducing the highest increase of fruit set and yield, in addition KNO3 at 4% comparing with 2% and 6%. Also, KNO3 treatments increased fruit size, peel thickness and juice acidity especially with high concentrations; on the other hand, the use of GA3 at 50 or 100 ppm alone or with 0.5% urea increased fruit T.S.S and reduced nitrite and nitrate contents in fruit juice as compared with KNO3 treatments. Moreover, it is noticed that trees sprayed at first application or first and second time of application gave the best results, while second application was the best for reducing fruit splitting.


25 Aug 2023
Citrus Fruiting

Physiology of citrus fruiting.

Citrus is the main fruit tree crop in the world and therefore has a tremendous economical, social and cultural impact in our society. In recent years, our knowledge on plant reproductive biology has increased considerably mostly because of the work developed in model plants. However, the information generated in these species cannot always be applied to citrus, predominantly because citrus is a perennial tree crop that exhibits a very peculiar and unusual reproductive biology.


25 Mar 2022
Citrus Climate

Climatic effects on flowering, fruit set and quality of citrus – A review

Weather and genetics have the strongest impact on reproductive response of citrus. Flowering is primarily determined by the amount of cool temperatures and/or drought as well as previous crop load and amount of year-old flush. Citrus in many locations in the Americas responds to both cool temperatures and drought in establishing the flowering level for the next season. Some major factors involved in regulation of fruit set are temperatures, evapotranspiration balance against available soil moisture, and competition with growth amongst fruit and vegetative flush.


28 Aug 2019

Girdling increases carbohydrate availability and fruit-set in citrus cultivars irrespective of parthenocarpic ability

F. Rivas, M. Juan, V.Almela, M. Agusti
Departamento de Producción Vegetal, Cátedra de Citricultura, Universidad Politécnica de Valencia.
E. Alos
Departamento de Citricultura, Instituto Valenciano de Investigaciones Agrarias. Valencia, Spain
Y. Erner
Department of Fruit Tree Sciences. Israel

The effects of girdling performed at various dates were evaluated during two consecutive years in high- and lowbearing commercial orchards of ‘Fortune’ mandarin and ‘Clausellina’ Satsuma mandarin. The time-dependent response was evaluated through fruitlet abscission, final fruit-set and yield as related to carbohydrate contents in developing fruitlets. A few days after treatment, girdling increased the soluble sugars content (SSC) in fruitlets, reduced the daily fruit drop, and thereby diminished abscission. Application of girdling to low-bearing ‘Fortune’ mandarin orchards was most effective 15 d before anthesis (DBA) and 35 d after anthesis (DAA). It increased yield by 125%. In high-bearing orchards, the best results were achieved by girdling 35 DAA, which increased yield by 28%.