A study was conducted on six years old trees of almond, Shahroud cv. (No. 18), in a three-year trial (2002-04) at Mashhad Agricultural Research Station. The experiment was done on the basis of completely randomized desigh with four replications. In the first and second years of the experiment, ethephon was sprayed in 15 and 20 days before the common time of harvesting, respectively. The concentrations of ethephon in 2002 were variable between zero to 600 mg/l; whereas in 2003, they were 0 upto 900 mg/l. Through 2003 and 2004, ethephon spraying (900 mg/l) was carried out in mid fall every year, too. A Khorasanina cultivar (named as No. 1) was also considered for fall treatment. In each year, the percentage of fruits with dehiscent hull increased by higher concentrations of ethephon, significantly. The force (gravitometer figures) over which fruits have been detached from branches decreased significantly by higher concentrations of ethephon. We concluded that, the concentration of ethephon should at least be 500-600 mg/l so that the required results in ripening of almond fruits can be obtained. In order to delay the flowering time, ethephan spraying (900 mg/l) was the most effective treatment, in mid fall, considerably. In the case of summer treatments trees showed gummosis, mostley.


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