【作者】 曹翠玲；

【导师】 李生秀；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2002， 博士

【摘要】 氮素是植物需求量最大的元素，同时是植物个体乃至自然生态系统和人工生态系统中作物生长的限制因子。本文通过1998年—2001年4年的水培、沙培及大田试验，初步探讨了氮素水平及氮素形态对小麦、玉米、向日葵等作物不同生育时期的生理效应及作物产量的影响，在大田试验条件下探讨了NR活性和不同基因型小麦产量的关系。以期为科学适量施肥提供理论依据。主要结果和结论如下： 1．在水培条件下完成了小麦的生活史，获得了小麦的经济产量。氮素水平影响分蘖期小麦生长的最根本原因是影响了小麦体内的水分含量。氮素水平与小麦生殖生长时期的生理代谢密切相关。 在水培条件下，研究了氮素水平对冬小麦(Triticum aestivum)分蘖期植株含氮化合物及水分含量的影响。在不同氮素水平供给下，植株叶片、根系硝态氮、可溶性蛋白、铵态氮及叶片叶绿素含量有明显的差异。随着氮素水平提高，小麦叶片、根系硝态氮含量及可溶性蛋白含量升高。氮素水平影响了植株含水量。由于氮素水平影响了作物体内含氮化合物及水分含量，最终导致了小麦植株的叶面积、地上和根系鲜重、干重有显著差异。从试验结果全面分析，氮素水平影响生长的最根本原因是影响了小麦体内的水分含量：氮素水平合适时植株体内水分含量最高，生物量最大。 在水培条件下进行了小麦全生育期的培育，获得了小麦的经济产量，完成了小麦的生活史。采用水培条件，研究了氮素水平对小麦生殖生长时期一些生理特性及产量影响。生殖生长时期，外源供氨水平供应增加，叶面积、叶片光合速率及叶绿素含量均随之增加；叶片叶绿素含量和外源供氮水平之间有极显著的正相关。供氮不足，根系、叶片DNA含量及根系RNA含量随供氮水平升高而升高。孕穗期不同氮素水平培养15天，对小麦成熟后生物量及经济产量有明显影响：小麦生物量和经济产量均随氮素水平的升高而升高。 2．氮素胁迫对单子叶植物和双子叶植物的影响有差异。 通过沙培试验研究了氮素胁迫对双子叶植物向日葵(Heliomthus annuus L)和单子叶植物玉米(zay mays L)两种作物幼苗耗水量、吸氮量、细胞膜透性、根系活力、NR活性、游离氨基酸含量的影响。试验结果显示，氮素供应不足，玉米和向日葵的吸水量和吸氮量减小，细胞膜透性增大，根系活力增强；减少供氮量，根系、叶片的NR活性与叶片中游离氨基酸含量也相应降低或减少。减少氮素供给，可提高水分利用率。玉米水分利用率高于油葵。两种作物的生理变化利生物量变化表明，N素胁迫对单子叶植物玉米的影响大于对双子叶植物油葵的影响。 3．作物不同，所利用氮素形态不同。铵、硝态氮比例为50:50是小麦生长最好的氮肥配比比例。供给硝态氮，玉米幼苗生长良好。 氮素形态对小麦营养与生殖并进生长阶段的生理特性及小麦成熟后的产量有显著影响。在氮素形态可控的水培条件下，研究了不同氮素形态对冬小麦营养与生殖并进生长阶段叶片和根系内含氮物质、生理特性及对小麦成熟后生物量的影响。营养液中加入了不同比例的硝态氮、铵态氮第n页 中文摘要及尿素。氮素形态对根系活力、叶绿素含量、根系和叶片的硝态氮、按态氮和酚胺态氮含量均有影响，不但影响了这一时期下的生物量，而且影响了成熟期的生物量及经济产量。按、硝态氮比例为50：50，叶面积最大，叶片叶绿素含量最高，根系活力最强，小麦收获时，地上干重、籽粒产量最大，根冠比最小。 供给硝态氮，玉米生长良好的主要原因是氮素形态影响了玉米幼苗水分状态。采用不同的铰、硝态氮配比，在沙培条件下研究了铰、硝态氮对玉米幼苗根系、叶片水分状态及某些生理特性的影响。结果表明：单供硝态氮，根系膜透性最小，叶片NR活性最高，叶片胞间CO。浓度最大，气孔导度、蒸腾强度最大，光合强度大；根系、叶片自由水与束缚水比值最高。这些生理特性的差异导致了玉米产量最高。 4．轻度水分胁迫和氮素有限胁迫对小麦拔节期的生理特性、养分积累和收获后生物量和经 L济产量有明显影响 在水培条件下，将小麦从分孽期培养至成熟，研究厂轻度水分胁迫、氮索有限胁迫对小麦某些生理特性、养分累积及小麦收获后产量的影响。水分、养分胁迫恢叶绿素含量及叶片NR活性低于对照，根系活力、K。Fe（CN）。还原活性降低，水分胁迫的影响大于氮素胁迫的影响，水分和氮素胁迫之间存在交互作用。水分胁迫下，小麦植株地上部氮、磷、钾含量高于对照水平，但根系含量降低；氮素胁迫下，地上和根系的养分含量均低于对照水平；水分和氮素之间有极显著交互作用。拔节期水分、氮素胁迫使小麦成熟后的产量明显降低。 5．小麦返青拔节期叶片NR活性和小麦籽粒还原态氮素之间有显著的正相关，而与小麦产量无关。 在?更多还原

【Abstract】 Among the elements required by plant, nitrogen is the largest one, and at the same time it is a limited factoring the signal plant ,natural ecosystem and artificial ecosystem. The experiment of water culture and sand culture were carried out with different crop such as wheat, corn and sunflower to study effect of nitrogen and N form on the yield and physiological characteristics, we also devise the field experiment to search the relationship between NR activity of different genotype and its mass, yield and protein content of kernel. The aim is to supply the evidence for optimum and scientific fertilizer. The results as follows:I.We accomplished the water culture of winter wheat from regreen梛oints stage to matured stage, we harvested the wheat. The ultimate reason of N rate affecting the growth of wheat is that it affected the water content of wheat tissue.Water culture experiment was carried out with winter wheat ( Triticum aestivum) at the tillering stage to study the influence of nitrogen rates on some nitrogenous substances and water content . The results showed that with the increase of N rates, the content of endogenous nitrate, the soluble protein were all increased in leaf and root. The content of chlorophyll per plant increased with the increasing of the N rate, there was a biological dilution phenomena about the content of chlorophyll. N rate affected the water content. Because N rate influenced the nitrogenous substances and water content, so it led the remarkable difference in leaf area per plant, fresh weight and dry weight of root and shoot .The conclusion was that supplying the optimum N rate, water content of wheat was higher, biomass was higher, too.We accomplished the life-cycle of winter wheat from regreen-joints stage to matured stage adopting methods of water culture. At the stage of reproduction, supply the different N rate lasting 15 d to study the influence of that one on the some physiological characteristics and biomass. The results showed as follows: with the increasing of exogenous N rates, the leaf area, the photosynthetic rate and the content of chlorophyll were all enhanced: In the condition of supplying deficient nitrogen rate, the content of DNA of root and leaf was increased. It had the remarkable impact on the biomass and yield of wheat when supplying the deficient nitrogen rate at the booting stage.2. Dicotyledon and monocotyledon had different response to the nitrogen stress. Two kind of crop were cultivated at different N concentration (Hoagland solution, l/3NHoagland solution, l/9NHoagland solution) under sand culture. The results showed that: at low N concentration, membrane permeability, activity of root systemincreased while water consumption, amount of N uptake, activity of NR and amount of free ammonia acid decreased; supplying the lower nitrogen, the water consumed decreased, but water use efficiency (WUE) was increased. Compared the crops, nitrogen deficient had grater effect on monocotyledon than on dicotyledon.3. The different crop had the different response to N form. The rate of NH/桸 to N03桸 was 50:50 was the optimum proportion for wheat growth. Nitrate N was the better form for corn seedling growth.Nitrogen form had a remarkable effect on the physiological characteristics and yield when treated wheat with different N form at the stage of vegetation and reproduction growth being conducted together. Solution culture experiment was carried out with winter wheat (Xiaoyan 22) as an indicator crop to study the influence of different form of N on the nitrogenous compounds in leaf and root and on some physiological characteristics at the stage of the vegetative and reproductive growth being conducted together, and different ratios of ammonium N to nitrate N as well as sole urea were adopted in solution for this purpose. The results showed that when the ratio of NO"3-N to NHVN was 50 I 50, the leaf area was largest, and the chlorophyll, root activity was the highest in all treatments. Consequently, this ratio resulted in higher shoot and grain yie更多还原