The effect of foliar spraying with putrescine on some morphological and physiological parameters of basil (Ocimum basilicum L.) under drought stress conditions

Abstract



Background and purpose:

Drought stress, as one of the main abiotic stresses, reduces plant growth and performance by affecting various physiological and biochemical processes, such as membrane integrity, photosynthetic pigments, osmotic regulation, water relations, stomatal closure, and reducing photosynthetic activity. Basil (Ocimum basilicum L.) is one of the species of the Lamiaceae family, which is well known for having a wide range of medicinal properties. This plant is traditionally known for its use for culinary and perfumery purposes. Polyamines are a group of polycationic organic compounds with low molecular weight and having two or more amino groups and are found in almost all living organisms. The general effect of putresin not only participates in the growth and development processes of plants, but also helps to withstand various abiotic stresses such as salt, drought, high temperature and cold.

Materials and methods:

This factorial experiment was carried out in the form of a completely randomized design in pots in the educational and research greenhouse of the Department of Horticultural Sciences, College of Agriculture and Natural Resources, Mohaghegh Ardabili University in 2016. The first factor of drought stress at three levels (complete irrigation and stop irrigation at the beginning of reproductive growth and stop irrigation at 50% of flowering) and the second factor of foliar spraying with putrescine at three concentrations (0, 1 and 2 mM) in the control treatment of leaf spray with Distilled water was used.

Findings:

The obtained results showed that under drought stress, growth parameters such as plant height, stem dry weight, number of leaves, physiological parameters such as photosynthetic pigments, the relative water content of leaves decreased and the amount of ion leakage and proline increased. While, foliar spraying with putrescine improved growth parameters and reduced ion leakage. So that the highest plant height (60.16 cm), shoot fresh weight (17.33), total chlorophyll content (11 mg/g fresh weight) in the treatment without stress and foliar spraying with a concentration of 2 mM putrescine was obtained, and the lowest amount of these traits was observed in the treatment of stopping irrigation at the beginning of reproductive growth and without foliar spraying with putrescine. In addition, the highest amount of proline (2.51 μmol/fwg-1) and ion leakage (37.56%) were obtained in the treatment of stopping irrigation at the beginning of reproductive growth and foliar spraying with a concentration of 2 mM putrescine and without foliar spraying, respectively.

Conclusion:

Based on the obtained results, drought stress, especially at the beginning of reproductive growth, caused a decrease in growth and physiological parameters. On the other hand, using putrescine as a foliar spray improved growth and physiological parameters due to its positive effect on photosynthetic pigment and osmotic regulation.