Reducing Damage of Late Cold on Persian Maple (Acer velutinum Boiss.) Seedlings by Delaying Germination and Seedling Protection

In the last decade, frequency of late cold incidence has increased in the upland forest nurseries. The aim of present study was to reduce the damage caused by spring frost and to increase the efficiency of Persian maple seedlings production in mountain nurseries. This study was conducted as split plot design with two main treatments and three replications in two consecutive years (2009-2010) in Farim Wood Company nursery, Mazandaran Province, Iran. Maple seeds were collected from a site located near the nursery. The main treatment was seedlings protection in two levels of covering the seedlings during the cold days and without covering. Sowing date was sub-treated and applied at six levels (2nd week of Dec., mid-Jan., 1st week of Feb., 3rd week of Feb., 3rd week of Mar. and mid-April).The results showed that seedling covered and seed sowing dates had significant (p<0.01) effect on reducing frost damage. Besides, interaction effect of sowing date and seedling cover was significant (p<0.01) in both years. There was no significant (p>0.05) effect between the sowing dates in protected plots. Overall, mortality of seedlings gradually reduced with shifting sowing date to March in uncovered plots. The maximum mortality rate was related to the sowing in 3rd week of February. Losses of seedlings were the same in covered and uncovered plots in mid-April sowing dates. In the unprotected plots, the maximum losses of seedlings were recorded in the sowing dates before March. In fact, if seed sowing of A. velutinum was postponed until early spring, the seedlings mortality rates were not significantly different in both treatments.