腐植酸浸种对不同耐盐性小麦品种幼苗碳氮代谢的影响

为了解腐植酸对小麦盐胁迫的缓解作用,以春小麦耐盐品种龙麦26和盐敏感品种克旱16为材料,分别用清水和腐植酸浸种,利用水培方式进行幼苗培养,在NaC1胁迫7d后,测定幼苗叶片硝态氮、铵态氮、可溶性蛋白质、蔗糖、可溶性糖含量,以及硝酸还原酶(NR)、谷氨酰胺合成酶(GS)和蔗糖磷酸合成酶(SPS)活性,分析腐植酸与盐胁迫对小麦碳氮代谢的互作效应.结果表明,盐胁迫抑制了春小麦茎叶的生长,降低了幼苗叶片硝态氮、铵态氮、可溶性蛋白质含量,以及NR活性和NR/SPS活性比.盐胁迫后,龙麦26的蔗糖、可溶性糖含量降低,叶片GS活性提高,但克旱16的蔗糖和可溶性糖含量升高.腐植酸浸种降低了盐胁迫下叶片硝态氮含量和NR、GS、SPS活性,提高了铵态氮、蔗糖和总可溶性糖含量,增加了龙麦26的可溶性蛋白质含量和NR/SPS活性比,以及克旱16的SPS活性,而降低了克旱16的可溶性蛋白质含量和NR/SPS活性比及龙麦26的SPS活性.推测腐植酸浸种可能是通过调控SPS活性和降低NR活性来增加蔗糖含量,从而影响小麦在盐胁迫下的碳氮代谢及平衡.

Effect of Seed Soaking with Humic Acid on Carbon and Nitrogen Metabolism in Wheat Cultivars with Different Salt Tolerances under Salt Stress

The seeds of two spring wheat cultivars were soaked by clean water and humic acid of 100 mg·L^-1 , and the seedlings were cultivated by hydroponic nutrient solution in order to explore their response in carbon and nitrogen metabolism to salt stress, and the ameliorating effects of humic acid on salt stress of wheat. The contents of nitrate nitrogen, ammonia nitrogen, soluble protein, sucrose and total soluble sugars, and the activities of nitrate reductase (NR), glutamine synthetase (GS) and sucrose phosphate synthase (SPS) in the seedling leaves were determined at 7 days after salt stress to investigate the response mechanism in carbon nitrogen metabolism to salt stress, and their interrelation. The results showed that salt stress inhibited the growth of the stem and leaves, reduced the contents of nitrate nitrogen, ammonia nitrogen and soluble protein, as the activities of NR and the ratio of NR/SPS as well. The contents of sucrose and total soluble sugars decreased, and the activity of GS improved for salt tolerant variety Longmai 26, while the contents of sucrose and total soluble sugars increased for salt sensitive variety Kehan 16. Soaking seed by humic acid reduced the content of nitrate nitrogen and the activities of NR, GS and SPS, increased the content of ammonia nitrogen, sucrose, total soluble sugars and soluble protein. In addition, soaking seed by humic acid increased the content of soluble sugars, the ratio of NR/SPS of salt tolerant variety Longmai 26 and the activity of SPS of salt sensitive variety Kehan 16. This study suggested that soaking seed by humic acid influenced the carbon nitrogen metabolism and the salt stress might be regulated through the activities of SPS and NR to increase the sucrose content.