effects of ethephon and soybean oil on the time of flowering of two apricot varieties from shahrood, iran

                                          Early flowering in apricot trees is leading to the spring frost. Delay of flowering is one of approaches to prevent spring frost damage. Hence, a factorial experiment on the base of RCBD was conducted in agriculture faculty, Shahrood University at 2014-15 years. The effect of spraying with soybean oil (10 and 15 percent) and ethephon (100 and 200 mg/l) and combination of soybean oil (15 percent) and ethephon (200 mg/l) was evaluated on an early-flowering variety, Rajab Ali, and a late flowering variety, Khiveai. The results showed that soybean oil treatment delay flowering time only one day in compare to the control. Rajab Ali variety showed respectively eight and nine day delaying in beginning of flowering and full bloom when spraying with 15% soybean oil and 200 mg/l ethephon. However, the maximum delay in the beginning of flowering and full bloom in the Khiveai was respectively four and five day at 100 and 200 mg/l of ethephon. The pre-blossom frost damage on untreated trees was significantly higher in compare to trees treated with ethephon. The primary and secondary fruit set was a significant increase in the ethephon and soybean oil application. The result showed that delay of flowering in ethephon treatment in early flowering varity, RjabAli, more than late flowering, Khiveai.