Comparison of different priming methods of pumpkin (Cucurbita pepo) seeds in the early stages of growth in saline and sodic soils under irrigation with different water qualities

Abstract

Salt stress is one of the most important environmental stresses affecting the growth, quantity, and quality of agronomic crops. This study was undertaken to investigate the effect of seed priming on the salt tolerance of pumpkin seedlings. Seeds were primed with eight different treatments including control (pre-soaking), Hydropriming with deionized water, Nanopriming with TiO2, Chemopriming with putrescine, Biopriming with Pantoea agglomerans and Pseudomonas putida bacterias, Hormone priming with salicylic acid, plant extract priming with Moringa (Moringa oleifera), and osmopriming with zinc sulfate. After germination, two groups of sampling were grown in two types of soil: saline (Ssa) and sodic (Sso) and they were investigated separately and irrigated with two types of water: saline-sodic (Wss) and non-saline-non-sodic (Wnss). Results showed that under Wnss/Ssa conditions, hydropriming did not affect the TAC and K+/Na+, as well as TDM and gas exchange parameters, while osmopriming increased all parameters. Likewise, in this soil-water condition, the osmopriming increased respiration and dry matter by 21.8%, while it increased photosynthesis in all four soil-water conditions. Hormone priming in Wss/Ssa conditions caused a 31% increase in dry matter, while it did not affect SOD, Proline, and TAC, moreover, respiration and K+/Na+ also increased. In Wss/Sso, nanopriming was the only superior treatment in terms of dry matter with a 10% increase compared to the control. In mentioned soil water condition, nanopriming was among the treatments with the highest values of SOD, TAC, Proline, and K+/Na+, respiration, and the lowest values of MDA and Na+. In all conditions except Wss/Sso, biopriming increased dry matter. In the mentioned condition, despite having higher SOD, and proline compared to the control, biopriming did not lead to an increase in respiration and K+/Na+. In Wss/Ssa conditions, biopriming led to the highest increase in the dry matter by 34.1%, while it had no effect on proline and TAC and increased K+/Na+ by 3.7 times compared to the control. Priming with plant extract also increased dry matter in all conditions except Wss/Sso. In the condition of Wss/Ssa, even though the priming of the plant extract did not affect TAC and proline, it caused an increase in K+/Na+ compared to the control, in addition, it was one of the superior treatments in terms of respiration. In conclusion, seed priming through ionic regulation was found to be effective in reducing the harmful effects of salinity and sodicity stress in pumpkin seedlings.