The effect of putrescine foliar application on the induction of drought resistance in Mexican marigold (Tagetes minuta L.)

This study was investigated, the effect of foliar application of different levels of putrescine on physiological, biochemical traits, and essential oil content of Mexican marigold (Tagetes minuta L.) under drought stress.

The experiment was conducted as a factorial experiment in a completely randomized design with three replications in greenhouse conditions. The first factor was drought stress at three levels (75, 50, and 25% of field capacity) and the second factor was putrescine foliar application at four levels (0, 0.5, 1, and 2 mM). Four seedlings were planted in each pot. Stress was applied when the plants reached a height of about 25 cm. Putrescine was sprayed one week before flowering and every 7 days until the 80% flowering stage.

The results showed that 2 mM foliar application of putrescine was more effective than other concentrations and was able to greatly reduce the harmful effects of drought stress on this plant. With the increasing drought, antioxidant activity, total phenol, proline, and electrolyte leakage also increased, and in contrast, the relative content of leaf water, photosynthetic pigments, and soluble protein decreased. Drought also increased the activity of the antioxidant enzymes guaiacol peroxidase (GPX) and polyphenol oxidase (PPO) and the amount of malondialdehyde in this plant. With increasing drought stress up to 50% of field capacity and foliar application of 1 mM putrescine, the essential oil content of Mexican marigold increased, while under severe stress (25% of field capacity) is decreased. Putrescine decreased by inducing drought resistance. The activity of antioxidant enzymes and the amount of malondialdehyde.

The use of putrescine induced resistance to drought stress in Mexican marigold, and the use of a concentration of 2 mM can be effective and recommended.