Effect of putrescine, 4-PU-30, and abscisic acid on maize plants grown under normal, drought, and rewatering conditions

The experiments were carried out with maize (Zea mays L.) seedlings, hybrid Kneja 530, grown hydroponically in a growth chamber. Twelve-day-old plants were foliar treated with putrescine, N-1-(2-chloro-4-pyridyl)-N-2-phenylur ea (4-PU-30), and abscisic acid (ABA) at concentrations of 10(-5) M. Twenty -four hours later the plants were subjected to a water deficit program, ind uced by 15% polyethylene glycol (PEG; molecular weight, 6,000). Three days after drought stress half of the plants were transferred to nutrient soluti on for the next 3 days. The effects of the water shortage, rewatering, and plant growth regulator (PGR) treatment on the fresh and dry weights, leaf p igment content, proline level, relative water content (RWC), transpiration rate, activities of catalase and guaiacol peroxidase, hydrogen peroxide con tent, and level of the products of lipid peroxidation were studied. It was established that the application of PGRs alleviated to some extent the plan t damage provoked by PEG stress. At the end of the water shortage program t he plants treated with these PGRs possessed higher fresh weight than drough t-subjected control seedlings. It was found also that putrescine increased the dry weight of plants. Under drought, the RWC and transpiration rate of seedlings declined, but PGR treatment reduced these effects. The accumulati on of free proline, malondialdehyde, and hydrogen peroxide was prevented in PGR-treated plants compared with the water stress control. The results pro vided further information about the influence of putrescine, 4-PU-30, and A BA on maize plants grown under normal, drought, and rewatering conditions.