Effects of different levels of treatments GA3,, Prechlling and Priming on seed germination of Kochia prostrata [L.] schrad in relation to seed harvest date and shrubs’ age.

Seed germination and establishment of Kochia prostrata L. as an important plant of rangelands in iran has become problematic and the population of this species is declining in their habitats. In this research, seed harvest date, maternal age of shrubs and different priming techniques as factors affecting germination traits of K.prostrata were studied.

Shrubs devided to three different age classes and their seeds of K. prostrata shrubs were collected separately at two different dates (late November and late December). Five priming treatments consist of Hydropriming 4 hours, Halopriming with potassium nitrate 7.5 mM/L, Gibberellic Acid 750 ppm, wet chilling +5°C and dry chilling -2°C were treatments that were applied on seeds.

results showed all seed traits were significantly different among different age classes at 1% significant level. Also, the effect of seed harvest date on all seed traits except seed germination rate and seed vigor was significant at 1% significant level. Normal seedlings are different between the seeds of different shrubs. It believed that seed dormancy is related to normal seedlings in K.prostrata. Gibberellic Acid of 750 ppm and dry chilling treatments of -2°C had the highest effect on germination, normal seedlings, seedling weight and vigor of seeds of 5-6 year olds and 7 years old class ages and harvest date in late November. The highest rate of germination was in potassium nitrate of 7.5 mM/L. The maximum root length was 4-hour hydropriming treatment on seeds of 5-6 year old class and harvest date in late November.

According to the results, seeds of 5-6 year old shrubs have higher seed quality than other two age classes due to having more 1000- seed weight (more than two times) and higher average seed yield (more than 3 times). It seems that seeds of the mature and old shrubs have dormancy more than the seeds of young shrubs. Collection of seeds of the mature class is recommended for the production of seedlings or for use in rangeland improvement and rehabilitation programs. Due to the variability of the maturity time of seeds, it is recommended that the immature seeds are collected in late November to early December before being dispersed. Seed dormancy (immature embryo) is then removed with dry chilling (-2°C) or Gibberellic Acid (750 ppm) treatments. The 4-hour Hydropriming can be used in order to increase the root length and seedlings length, and potassium nitrate of 7.5 mM / L for improving the germination rate.