Investigation of crop regulation probability in kinnow mandarin by foliar nutrition of magnesium and zinc sulfate in Jahrom.

kinnow (Citrus reticulate Blanco) fruit is one of the best mandarins. Although the main disadvantages of it, alternate bearing cause loss of popularity between citrus growers. In this matter, it has main influence on economic and living of farmers therefore, the investment on this type of mandarin as a fine and export type need control and alternate bearing adjustment. In this manner, a pattern or project was carried out to control and adjust alternate bearing by use of production and reinforcement the flower buds in Off year of trees. In this research, Magnesium Sulfate and Zinc Sulfate fertilizers was used as a foliar spray solution on kinnow mandarin. The experiment was done as factorial and in a randomized block design in 3 replications and each treatment on two trees according to time of Magnesium Sulfate(0.3%) foliar sprays (22th of November, 5th of January and 20th February) in on years and the time of Zinc Sulfate solution spraying after complete harvesting was 5th of January and 6th of March of On years and one to two weeks after complete loss of petals in next spring with concentration of (0.2%) plus control .Four years operation reviewing showed no significant difference between treatments in terms of performance in level of 5% was observed but all treatments showed better performance than blank and the highest performance was related to Magnesium Sulfate solution spraying treatments in 22th of November and Zinc Sulfate early in April. The significant difference was observed between performances in On years in both treatments and the performance in 2011 was better than 2009. The study of alternate bearing index in Zinc spraying experiment showed no significant difference between treatments while significant difference was observed in level of 5% in Magnesium Sulfate spraying experiment. Magnesium Sulfate spraying treatments in 20 th of February has the lowest alternate bearing index. The mean of two years (Off year) a single fruit characteristics (length, width, and weight) and quality attributes (percent water, sugar and acid) were not significantly different between treatments. Key words: Citrus, Alternate bearing ,Kinnow,Zinc Sulfate,Magnesium Sulfate, Foliar sprays