APPLICATION OF PLANT GROWTH REGULATORS IN SUNFLOWER SEEDLINGS UNDER WATER STRESS CONDITIONS DURING EARLY VEGETATIVE GROWTH (V4)

BOERO ALDANA ; RAMÍREZ FEDERICO ; VIGLIOCCO ANA ; ANDRADE, ANDREA MARIELA; ALEMANO, SERGIO

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Physiology RAFV Conference 2023,; 2023

It is widely documented that in sunflower water stress modifies various processes involved in plant growth and development. Plant growth regulators are compounds that play crucial roles during the life cycle of plants and are also involved in responses to abiotic stress. Our aim was to evaluate the action of different plant growth regulators on the growth of sunflower seedlings subjected to water stress. For this, seedlings of two inbred lines (B59 and B71, sensitive and tolerant to water stress respectively) were grown in pots with sterile substrate inside Conviron PR48 Environmental rooms. From the 3rd day after sowing, and every 2 days, saturation irrigations were performed using Hoagland´s solution 50% ionic strength; and 10 days after sowing, the water stress treatment was started using 265 mM mannitol solution. After 17 days, and every 2 days, the plant growth regulators were applied by foliar spray with GR24 (3 µM), BL (0.01 µM) and KAR2 (10 nM) solutions. At 24 days (growth stage V4) the seedlings were harvested, sectioned into aerial and root parts and the determinations were made. In general, the effect of the application of the regulators was observed in seedlings of both lines, both in control and water stress conditions. The application of GR24, BL and KAR2 in stressed seedlings mainly resulted in a greater length of taproot, dry weight of aerial part and dry weight of roots. GR24 and BL increased the leaf area and fresh weight of the aerial part, while KAR2 increased the fresh weight of the roots. Similarly, in control seedlings, GR24 and BL stimulated leaf growth and, together with KAR2, taproot elongation. It is important to highlight that the application of plant growth regulators resulted in an improved relative root biomass in response to water stress for both lines.