| Salt stress is an important constraint of waxy maize (Zea mays L.) production. Seed pruning could improve the seed vigor, and it can enhance the energy of gennination, germination percentage, reduce the mean germination time and increase the seedling dry weight. In present study, after selecting the salt-tolerant and salt-sensitive inbred lines from 10 inbred lines of waxy maize, the effects of seed priming with different concentrations of salicylic acid solutions on seed germination and physiological changes of seedling using No. 44 (salt-tolerant) and No. 28 (salt- sensitive) inbred lines were investegated under high-salt stress. The effects of sand priming on seed germination and physiological changes of waxy maize subjectd to high-salt stress were also researched. Main results were as follows:Three waxy maize inbred lines were germinated under different NaCl concentration (w/v) (0%, 0.5%, 1.0% and 1.5%), 1.0% (w/v) was chosen as a threshold for growth of waxy maize seeds. Then, the sensitive to salt stress in 10 waxy maize inbred lines was identified at 1.0% NaCl solution. The characteristics of germination and seedling qualities of waxy maize were measued under the salt stress, also, the ratios (relative values) of trait values at the salt stress to those at normal condition were used to assess salt tolerance. The results showed that the energy of germination, shoot height, root length and dry weight of root and seedling of salt-tolerant waxy maize inbred lines were higher than thoses of salt-sensitive inbred lines. The cluster analysis was used to solve assessing difficult of salt tolerance due to small differences among relative values in waxy maize inbred lines. Waxy maize inbred lines were clustered into four groups: salt-tolerance, intermediate salt-tolerance (I and II) and salt-sensitivity. The correlation analysis showed that the relative values of shoot height, relative dry weight of seedling and relative dry weight of shoot were significantly correlated each others; these were suitable parameters for evaluating salt tolerance.The effects of seed priming with the four concentration of salicylic acid (SA) (0, 0.25, 0.5 and 0.75mmol/L) on germination and physiological characteristics of waxy maize (salt-tolerant No.44 and salt-sensitive No.28) under 1.0% high-salt stress were investigated. Priming with salicylic acid significantly enhanced the energy of germination and germination percentage, reduced the mean germination time. It also improved the shoot height and root length, and increased the shoot and root dry weight in both inbred lines. The 0.5mmol/L SA had the best priming effects. 0.75mmol/L SA had negative effects to growth of shoot height, root length and the weight of shoot and root in inbred line NO.44. Along with the increase of salicylic acid concentration, the content of chlorophylls was declined firstly, then increased, and there was no significantly changes in the content of carotenoid in both inbred lines. Priming with SA significantly enhanced peroxidase (POD) activity, decreased ascortbate peroxidase (APX) activity. As compared to unprimied control (CK), priming with lower concentration of SA (0～0.5mmol/L) declined the content of malondialdehyde (MDA), however, priming with 0.75 mmol/L SA had significant higher MDA content in No.44 and had no significant difference in No.28. Along with the increase of SA concentration, the content of proline (Pro) was increased firstly, then decreased, the Pro content primed with 0.25mmol/L was significantly higher than that of CK in both inbred lines. Priming with 0.5mmol/L had a lowest Pro content in all treatments and significantly lower than CK in both waxy maize inbred lines.Seeds of three waxy maize cultivars, cv. Suyunuo 1, Huyunuo 1 and Zhenuoyu 1, were used to investigate the effects of sand priming on germination and physiological changes under a high-salt concentration (1.0% NaCl) stress. Waxy maize seeds were mixed with sand containing 4.0% (v/w) water, sealed in plastic box, and then were primed at 15℃for 48 h. While sand priming significantly affected the speed of germination in two cultivars, and contributed to shorten mean germination time for the three cultivars studied. It also significantly enhanced shoot height, seedling fresh and dry weight in the three cultivars compared to unprimed control. Sand priming also increased the content of soluble sugar and the activities of peroxidase (POD) and catalase (CAT). At the same time, the malondialdehyde (MDA) and proline accumulation decreased under a high-salt stress condition. Thus, it indicated that sand priming could improve speed of germination and seedling growth, suggesting beneficial effects on salt tolerance of waxy maize seedlings. |
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