چكيده لاتين :
Introduction Water scarcity is one of the main problems in the agricultural land around the world. The climate changes indicate a rise in temperature and a decrease in average rainfall, which that its augments the drought stress effects in future (Farre and Faci, 2006). Tolerance to dehydration plants to grow in arid and salty is very important. Germination and establishment of plants due to low viability is difficult and environmental stresses, especially drought than other factors are reduction of green. Priming one of the ways to increase the germination under stress conditions. The aim of this study is to investigate the effect of seed priming treatments on emergence parameters improve of ajowan (Carum copticum L.) medicinal plant. Material and methods A split plot experiment was conducted in randomized complete block design with three replications at farm of agricultural college, Shahrekord University, 2014. Different levels of irrigation (irrigation after 11, 22, and 33 mm evaporation from pan evaporation class A) were evaluated as the main plot and seed priming treatments consisted of no priming (control), hydropriming (seed soaking in distilled water for 36 hours), KNO3 (seeds were placed on potassium nitrate 4%), ZnSO4 (seeds were placed on potassium nitrate 0.1%), PEG600 (seeds were placed on 12 bar of polyethylene glycol) and GA3 (seeds were placed on 100 ppm of gibberellic acid) as subplot. Treatments were chosen according to a preliminary priming experiment. The amount of potassium nitrate required is calculated using equation Want hoof (Siebert and Richardson, 2002). In this experiment, parameters such as rate of emergence, percentage of emergence, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index were evaluated. data were analyzed by using both one or twoway analysis of variance (ANOVA) and mean comparisons were performed by LSD test if Ftest was significant at (p < 0.05) to determine whether differences among means were significant between treatments drought stress and seed priming. Results and discussion The results showed that emergence percentage, root dry weight, soot dry weight, vigor index were influenced by drought stress (p < 0.05, p < 0.01, and p < 0.01, respectively). The seed priming effect for emergence rate, emergence percentage, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index was significant (p < 0.01, p < 0.01, p < 0.01, p < 0.05, p < 0.01, p < 0.01, p < 0.01, p < 0.01, and p < 0.01, respectively). The drought stress × seed priming interactions for emergence rate, emergence percentage, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index was significant were statistically significant. Means comparison results indicated that in mild stress (irrigation after 22 mm evaporation), the highest rate and percentage of emergence were obtained in PEG treatment. The greatest of root dry weight was observed in GA3, KNO3, and ZnSO4, and PEG treatments. In addition, root length, shoot length, shoot dry weight, allometric coefficient of primed seed not only not improved but also values of these characters declined in compare to nonprimed seed. In severe stress (irrigation after 33 mm evaporation), rate and percentage of emergence and vigor index increased in PEG, GA3, ZnSO4. Also, The maximum root length (6.7 cm) and shoot length (4.4 cm), were observed GA3 and ZnSO4, respectively.Primed seed with ZnSO4 increased shoot dry weight (16.12mg) and the allometric coefficient (0.82), as well as. Conclusions In overall it can be concluded that in drought stress conditions, seed priming of ajowan medicinal plant with gibberellic acid and zinc sulfate improves germination and seedling growth in farming systems. Thus, these pretreatments increases root growth and strengthen and better establishment seedling under drought stress conditions that it would be appropriate for the development of production in such semiarid environments. In addition, by reducing the frequency of irrigation for optimum seedling establishment can make good use of water resources in these areas.
