Strigolactone and Auxin Applications on Cotyledon Senescence in Sunflower Seedlings under Salt Stress.

Objective: Senescence is a programmed cell death process and is important in the growth, development and flowering process of the plant. Delaying senescence has a very important effect on agriculture in terms of product yield. Indole-3-acetic acid (IAA) and strigolactone (GR24) are growth regulators that affect plant development and senescence. Salt stress accelerates the senescence process. The aim of this study is to increase crop yield by delaying senescence by the application of auxin and GR24 under stress conditions, because the delay of senescence causes the prolongation of the vegetative process and the formation of more apical tips. In this case, the seedling produces more fruit. Materials and Methods: In this study, senescent cotyledons of sunflower seedlings were used as experimental material. Half of the developing sunflower seedlings were irrigated with Hoagland solution, and the other half was irrigated with 150 mM sodium chloride (NaCl) solution. IAA and GR24 were applied by spraying on seedlings that are grown both in Hoagland solution and under salt stress. Results: The degree of senescence of the cotyledons of the plants was determined in terms of the percentage of green area. When the green area percentage of cotyledons of seedlings grown in Hoagland solution was 50, all cotyledons were harvested. After that, fresh weight, pigment contents, total protein, malondialdehyde, and proline levels, peroxidase enzyme activities of cotyledons were determined. The application of IAA and GR24 to the cotyledons of seedlings grown in the salt medium significantly delayed the senescence. Conclusion: This study was conducted in the plant growth chamber under controlled conditions. Results showed that the application of IAA and GR24 to leaves can ameliorate the adverse effects of salt stress and delay senescence due to the activation of chlorophyll components and modulation of photosynthesis as well as antioxidant defense capacity. The effect of IAA is more precise when all analyzes are considered. More importantly, showed that all findings (except MDA and Proline) IAA and GR24 promote senescence in Hoagland in this research. Delaying senescence contributes to basic science. It is desired to increase fruit and vegetable yield by delaying senescence. It is suggested that this information can be used practically in the field of agriculture. On the other hand in this study, we can say that IAA and relatively GR24 can play an important role in the protection of plants in agricultural areas in salt stress. [ABSTRACT FROM AUTHOR]