چكيده
To reduce the effects of salinity stress in plants, different methods are used in different stages of plant growth, including germination. Humic acid is a natural substance that has a positive effect on plant growth and is used as a pretreatment in germination research. The purpose of this experiment was to investigate the moderating effect of humic acid on the physiological characteristics and germination of safflower seeds (Carthamus tinctorius L.) under salt stress. This experiment was implemented as a factorial in the form of a completely randomized basic design with three replications. The experimental treatments include salinity stress at four levels (0 (control), 50, 100 and 150 mM sodium chloride) as the first factor and humic acid at three levels (0 (control), 400 and 800 mg/L) as It was the second factor. According to the results of analysis of variance, salinity stress and humic acid had a significant effect on germination percentage, germination speed, root length and root wet weight. But salinity stress was significant on stem length at the 95% level, but it had no significant effect on stem fresh weight. And humic acid treatment had no significant effect on the length of the stem, but it was significant on the fresh weight of the stem at the level of 95%. Also, the effect of salinity stress on all physiological traits was significant except for carotenoids, and humic acid treatment also had a significant effect on all desired traits except for chlorophyll ab. The interaction between salinity stress and humic acid had a significant effect only on chlorophyll b and proline content. Average comparison graphs showed that the lowest percentage of germination (56.85%), germination rate (0.285 per day), root length (3.38 cm) and root fresh weight (0.128 grams) in Salinity stress treatment of 150 mM sodium chloride, the highest percentage of germination (96.28%), germination rate (0.751 per day), root length (4.28 cm) in humic acid treatment with 800 ml per liter), and the lowest content of chlorophyll a related to salt stress treatment (150 mM) in the control (without humic acid) at the rate of 1.1 (mg/g), the lowest content of chlorophyll b related to the treatment (150 mM) molar) at the rate of 1.8 (mg/gram) and the lowest is related to the salt stress treatment (150 mM) at the rate of 2.8 (mg/gram) and finally the highest content of chlorophyll a is related to the control interaction treatment (without salt stress) in the consumption of 800 (mg/liter) humic acid at the rate of 3.3 (mg/gram), the highest content of chlorophyll b is related to the treatment using 800 (mg per liter) of humic acid was obtained at the rate of 4.2 mg/g. Salinity stress caused a further decrease in germination traits and plant growth, but the application of humic acid improved the effects caused by stress to some extent.
