Seed Priming Improves Germination, Yield, and Water Productivity of Cotton Under Drought Stress

The deleterious effects of drought stress on cotton (Gossypium hirsutum L.) could be mitigated through seed priming. The objective of this study was to assess the effects of various seed priming materials on cotton under different soil moisture levels and to compare the effectiveness of these priming materials in mitigating the detrimental effects of water-deficit stress. A polyhouse experiment comprising six seed priming treatments (priming with salicylic acid [SA] at100 mg L–1, silicon [Si] at 1 mM, potassium nitrate [KNO3] at 5 g L–1, proline [PRO] at100 mg L–1, glycine betaine [GB] at 100 mg L–1), hydropriming, and non-primed control) under three soil moisture levels (50, 75, and 100% field capacity [FC]) was carried out. The results revealed a significant decrease in all evaluated parameters with reducing soil moisture levels (44–58% reduction in boll number per plant, 25–50% reduction in seed cotton yield, 18–41% reduction in lint index, 6–21% reduction in leaf relative water content, and 18–53% reduction in net photosynthetic rate at 50% FC in comparison to 100% FC) across seed priming treatments. However, there was up to a 9-fold increase in free proline concentration at 50% FC in comparison to 100% FC across seed priming treatments. Plants raised from KNO3- and GB-primed seeds outperformed all other treatments and caused a significant increase in germination-related traits and other evaluated parameters. There were 54, 36, and 125% higher shoot dry matter, seed cotton yield, and net photosynthetic rate, respectively, of KNO3-primed plants over the control plants (non-primed) at 50% FC, and 31, 11, and 79% higher single boll weight, leaf greenness, and membrane stability index, respectively, of GB-primed plants over the control (non-primed) at 50% FC. Priming cotton seeds with KNO3 at 5 g L–1 or GB at 100 mg L–1 can be recommended as a promising technique for growing cotton under water-scarce environments.