نوع مقاله : مقاله پژوهشی
چکیده
کلیدواژهها
عنوان مقاله [English]
Seed germination and seedling emergence are two important plant phenologic growth stages. The plant survival, particularly in saline conditions, depends on these phenologic stages. To study the effect of salinity on the germination rate and seedling growth of sorghum (Sorghum bicolor L. Moench) in a natural saline soil and to compare the germination process in natural and artificially made saline water (NaCl + CaCl2 solution), a 3-phase experiment was conducted in randomized complete block design with 13 saline treatments and 3 replications. Germination in the first two phases was carried out in petridishes in an incubator (20 oC) and included a non-saline water treatment (EC = 0.3 dS/m) and 12 saline water treatments of 2 to 24 dS/m from two sources: natural saline water and NaCl + CaCl2 solution as a charge base. Germination in phase 3 was carried out in a greenhouse in pots containing natural saline soil, treated with saline water having the same salinities. The germinated seeds were counted at desired time intervals until full germination or until two continuous countings were identical. The percentage of germinated seeds and germination rates were then calculated and the results statistically analyzed. The calculated means were also compared, using Duncan’s multiple range method. The results indicated that germinated seeds and germination rates decreased with salinity increase. But this decrease was greater in natural saline water than in the NaCl + CaCl2 solution. Comparison of seed germination in soil and in incubator showed that the seeds could germinate at all the salinity treatments tested in incubator (in spite of a decrease in the rate of germination), but seed germination rates in soil continued in salinity levels of up to 4 dS/m and decreased with increasing salinity levels up to 14 dS/m. With time, seedling growth decreased with increasing salinity and sometimes fully stopped. The seeds could not germinate and grow in soil salinities more than 14 dS/m. Although seed germination was observed in all saline treatments in the incubator, it seems that sorghum is tolerant to salinity levels of up to 4 dS/m in the germination stage.