Document Type : Research Paper
Authors
Abstract
Fall planting of forage legumes normally is not successful in central Zagross mountain region because of possibility of germination after autumn rainfall and mortality of seedling by early frost during fall season. For planting legumes in the spring there are limitations since seed planted after early spring rainfalls cannot be successfully established. During early spring rainfall period high soil moisture does not allow planting operations. Therefore government projects for rehabilitation of abandoned dry farming lands can not use seeds of forage legumes such as Medicago sativa(Me.sa), Onobrychis viciaefolia(On.vi) and Vicia villosa(Vi.vi) with good quality forage and proper yield with high adaptability to soil and environmental conditions of the region. To solve the problem، this research was conducted to evaluate the effect of seed treatments with germination inhibitors and hydrophobic materials as well as seed pelleting in Shahid Fozveh research station in germinators and green house. Caffeine, vanillin and extract of Eucalyptus leaves were used as inhibitors. Poly ethylene glycol 6000(PEG) and Di- manitol(DM) were used as hydrophobic substances. Seed pelleting was achieved by using a coating drum device. Treated seeds were put in germinator with 25ºС constant temperature. Velocity coefficient of germination, percent germination, germination commencement delay and alometric ratio were determined. Data were analyzed as complete random design and Duncan’s test was used to determine significant differences. Results indicated that vanillin caused 18 and 14 days germination delay for Me.sa and Vi.vi respectively. Vanillin and extract of Eucalyptus leaves delayed germination of On.vi unshelled seeds for 21 and 22 days respectively and proved to be best materials for this purpose. Caffeine reduced germination percentage of all seeds. PEG and DM delayed germination only for 3 to 7 days, not long enough to be useful for practical purposes. Pelleted seeds without inhibitors and hydrophobes showed 9 to13 days germination delay. Pelleting along vanillin treatment caused 20 and 16 days delay in germination of Me.sa and Vi.vi respectively. Pelleted unshelled seeds of On.vi treated with vanillin and extract of Eucalyptus leaves had germination delays for 26 and 22 days respectively. With rapid decrease of temperature during fall season in central Zagross region it seems reasonable to consider a delay of more than 15 days to be practically effective to reduce or eliminate mid fall germination of these species and increase success of fall seeding considerably. Further investigations with field planting is recommended.
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