Study of improvements in the biological yield and the physiologic indicators of Ajwan (Carum copticum L.) as affected by application of polyamines under salt stress conditions

This experiment was conducted to study the improvement of biological yield and physiological indicators of Ajwan by application of polyamines under salt stress conditions in 2018. A factorial study was conducted with a randomized complete design with two factors and three replications. The first factor included four levels of water salinity including the control (without salt stress) and salinities of 1000, 2000 and 3000 mg/l. The second factor included five levels of using zero polyamine, 0.5 and 1.5 mmol/l putrescine and 0.5 and 1.5 mmol/l spermidine. The results showed that increasing the salinity levels resulted in a reduction of the height, the biological yield, the lateral branch and the number of umbels in the plant. The lowest amount of chlorophyll a and b and the highest sodium and chloride content in the salt stress of 3000 mg/l was observed. Under salt stress of 2000 mg/l, the spermidine treatment as 1.5 and 0.5 mmol/l led to an increase in the proline content to the amounts of 44.56 and 40.16% as compared with that of the control. Also, the highest peroxidase in the spermidine treatment of 1.5 and 0.5 mmol/l was observed in the amounts of 3.60 and 3.20 micromoles per minute protein. Therefore, the polyamine compounds lead to the reduction of the salt stress effects through improvement in the physiologic characteristics, including increase in the osmotic adjusting compounds and the activity of antioxidant enzymes. Moreover, the polyamine compound of spermidine has a better function than putrescine.