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