氮素形态及其配比对老芒麦生长及生理特性的影响

以采自高寒草甸野生老芒麦(Elymus.sibiricus)种子为材料,单一氮素添加为对照,采用营养液沙培方式研究硝态和铵态氮及其不同配比(NO3^--N∶NH4^+-N分别为0∶10、3∶7、5∶5、7∶3和10∶0)对老芒麦苗期生长特性的影响,旨在探索不同氮素形态对老芒麦的促生效应,以期找到最佳的氮素形态配比。结果表明:混合态氮素较单一氮素施入能够更好促进老芒麦的生长,硝态和铵态氮配比为7∶3时,老芒麦株高、叶片硝酸还原酶活性和可溶性蛋白含量较其他处理高,硝酸还原酶活性较单一NO3^--N和NH4^+-N处理分别提高了48.54%和74.71%,可溶性蛋白含量分别提高了10.16%和7.30%。硝态和铵态氮配比为5∶5时根系活力最高,该处理下老芒麦根系活力较单一NH4^+-N和NO3^--N处理分别提高了31.05%和8.08%,且与对照间差异达到显著水平(P<0.05)。NO3^--N∶NH4^+-N为3∶7时根长和全氮含量达到最大,全氮含量分别比NO3^--N和NH4^+-N为唯一氮源时提高了43.90%和29.76%,且差异达到显著水平(P<0.05)。经隶属函数度进一步综合分析得出,NO3^--N∶NH4^+-N为7∶3时氮素能更好地提高老芒麦生理活性,且促进其生长。

Effects of nitrogen forms and proportions of nitrogen forms on the growth and physiological characteristics of Elymus sibiricus

To clarify the effects of different nitrogen forms and different ratios of nitrate nitrogen(NO3^--N)and ammonia nitrogen(NH4^+-N)on the growth and physiological characteristics of Elymus sibiricus,the seeds of wild E.sibiricus were collected from an alpine meadow and used in an experiment.Different ratios of nitrate nitrogen(NO3^--N)and ammonia nitrogen(NH4^+-N)(0∶10,3∶7,5∶5,7∶3 and 10∶0)were tested using the nutrient solution sand culture method.The results showed that the mixed nitrogen forms promoted the growth of E.sibiricus more than did single nitrogen forms.Plant height,nitrate reductase activity,and the soluble protein content of leaves had the highest values when the ratio of NO3^-N and NH4^+-N was 7∶3,while nitrate reductase activity increased by 48.54% and 74.71%when compared with either effects of nitrate or ammonium,respectively,and the content of soluble protein content increased by 10.16% and 7.30% when compared with effects of nitrate or ammonium alone,respectively.The root vigor was the highest at the ratio of NO3^--N and NH4^+-N of 5∶5,which increased by 31.05%and 8.08%when compared with effects of nitrate or ammonium nitrogen alone,respectively.In addition,when the ratio of NO3^--N and NH4^+-N was 3∶7,the root length and total nitrogen content improved significantly and increased to 43.90%and 29.76%when compared with effects of nitrate and ammonium nitrogen alone,respectively.Through a comprehensive analysis using the membership function method,it was found that the ratio of 7∶3 NO3^--N∶NH4^+-N had the most obvious effects on the growth and physiological characteristics of E.sibiricus.