【摘要】 为揭示氮肥缓解苗期干旱对小麦根系生长的影响,以高产高蛋白品种Spitfire(S)和抗旱品种Drysdale(D)为材料,采用沙培方式研究了不同氮素处理(180和22. 5 kg·hm-2)和水分处理(干旱和正常浇水)对苗期小麦根系形态建成和生理生长的影响。结果表明,苗期干旱下增施氮肥减小了2个品种小麦根系总根长、根系表面积、总根体积、根尖数和分枝数,显著增加了根系直径和根系活力,S品种根系干重减小7. 0%,而D品种根系干重增加12. 0%。施高氮还降低了干旱下2个品种小麦根系可溶性糖含量,并提高了游离氨基酸含量,且耐旱性品种D变化幅度较大,2个品种根系可溶性蛋白含量的变化均不明显。此外,增施氮肥能促进根系对氮素的吸收,提高根系硝酸还原酶(NR)活性和含氮量。综上,在苗期干旱下增施氮肥能够促进小麦根系生长,提高根系活力和NR活性,以增强根系对氮素的吸收同化能力,促进氮代谢水平,从而提高小麦的抗旱性,但不同耐旱品种对干旱下增施氮肥的响应程度存在差异。本研究结果为通过增施氮肥有效缓解干旱进而提高小麦产量提供了理论依据。更多还原

【Abstract】 The purposes of this study were to investigate effects of nitrogen fertilizer on root morphology and physiology of wheat in alleviating drought stress at seedling stage. The spring wheat variety Spitfire(S) with high yield and protein content and another drought-resistant variety Drysdale(D) were planted in sand. Two treatments of different N levels(low N of 22. 5 kg·hm-2 and high N of 180 kg·hm-2) and two water levels(well-watered and drought stress) were conducted. The results showed that the total root length,root surface area,total root volume,root tip number and branch number of two wheat cultivars were decreased by high N during seedling drought,but root diameter and root activity were increased significantly. However,the dry weight of underground part in S cultivar decreased by 7. 0%,while that in D cultivar increased by 12. 0%. Increasing nitrogen fertilizer also reduced the soluble sugar content and increased the free amino acid content in root of two wheat cultivars under drought stress,drought-tolerant cultivar D changed significantly,but there was little change in soluble protein content. In addition,high N promoted root uptake of nitrogen and increased root nitrogen content and NR activity in two wheat cultivars. Therefore,increasing nitrogen fertilizer amendment in seedling drought can improve drought resistance of wheat by promoting root growth,increasing root activity and NR enzyme activity,enhancing root absorption and assimilation ability of nitrogen,and promoting nitrogen metabolism level.However,different drought-tolerant varieties have different responses to increasing nitrogen fertilizer application under drought stress. This study is of great significance to improve wheat yield by nitrogen fertilizer via alleviating drought stress at seedling stage in agricultural production.更多还原