【作者】 邹铁祥；

【导师】 曹卫星；

【作者基本信息】 南京农业大学 ， 生态学， 2006， 博士

【摘要】 氮、钾素是作物必需的大量矿质元素，土壤氮、钾不足限制了小麦籽粒产量的提高和品质的改善。理解专用小麦籽粒品质形成的生理机制及氮、钾调控原理，对深化小麦品质生理生态研究和指导专用小麦调优栽培具有重要的理论意义和应用前景。本研究于2003～2005小麦生产年度，以蛋白质含量差异的两个冬小麦品种宁麦9号（低蛋白）和扬麦10号（中蛋白）为材料，研究了不同氮、钾素施肥水平下小麦籽粒品质形成、光合特性、物质运转和相关酶活性的变化规律，明确了氮、钾施肥水平对中、弱筋小麦籽粒品质形成的生理调控作用，为深化和拓展小麦籽粒品质生理生态、指导专用小麦调优栽培提供了理论基础和技术途径。1．增施氮、钾明显提高了试验小麦籽粒蛋白质及其组分含量、延长了面团稳定时间，提高了湿面筋含量和沉降值，对醇溶蛋白和谷蛋白的影响大于对清蛋白和球蛋白的影响。施氮还显著提高了籽粒的谷／醇比；而施钾对两小麦品种籽粒蛋白质谷／醇比的影响年度间有所差异。施钾对扬麦10号籽粒蛋白质含量的提高作用大于宁麦9号。氮钾互作极显著提高了籽粒蛋白质含量，降低淀粉含量和对其他品质指标的影响不显著。发现提高开花期叶片含钾量是施钾提高籽粒蛋白质含量的生理原因；提高开花期叶片氮、钾营养并保持适宜的氮／钾比，是提高产量并维持适宜籽粒蛋白质含量等品质指标的营养生理基础。2．施钾显著提高了花前储存物运转和花后同化物的积累，有利于提高籽粒产量。球蛋白和醇溶蛋白是钾素提高籽粒蛋白质含量的主要基础，也是施钾降低谷／醇比的生理原因。增施钾肥提高了开花期叶片含钾量，进而显著促进了两小麦品种花前储存氮素向籽粒的运转和扬麦10号的花后氮素积累，但对宁麦9号花后氮素积累的作用较小。花前储存氮素的运转与花后氮素积累分别是施钾提高宁麦9号和扬麦10号籽粒蛋白质含量的重要生理原因，其不同源自花后氮素积累对开花期叶片含钾量反应的差异。提高光能转化效率是氮、钾施肥提高产量和蛋白质含量的能量基础，中蛋白品种扬麦10号籽粒蛋白质含量的提高不仅依赖储存氮素的运转，还较多地依赖花后氮同化。3．提高开花期叶片氮、钾含量并保持适宜的氮／钾比，是氮、钾施肥提高蛋白质合成关键酶活性进而提高籽粒蛋白质积累的生理原因。适宜的开花期叶片氮／钾比显著提高了旗叶SPS（磷酸蔗糖合成酶）和籽粒SS（蔗糖合成酶）活性——氮钾配施提高“源”同化物供应和“库”转化能力的生理原因，进而显著提高了籽粒淀粉及其组分产量。灌浆中期SS／SPS活性比可以小幅调控小麦成熟期淀粉特性，宁麦9号成熟期籽粒总淀粉含量还受灌浆前期SS／SPS活性比的影响。较高的开花期叶片氮、钾营养并维持适宜的氮／钾比提高了籽粒SSS（可溶性淀粉合成酶）和GBSS（束缚态淀粉合成酶）活性，是氮钾配施提高“库”中直、支链淀粉转化能力和产量的生理保证。调控灌浆初期和后期GBSS／SSS活性比能小幅调控小麦籽粒淀粉特性。弱筋小麦宁麦9号GBSS和SSS显著高于中筋小麦扬麦10号是其淀粉含量较高的生理原因。4．增施钾肥提高了开花期叶片含钾量，进而显著或极显著提高了SOD（超氧化物歧化酶）活性、极显著降低了MDA（丙二醛）含量和灌浆后期叶绿素的分解及净光合速率的下降——延缓衰老，因而极显著增加了花后同化量。说明较高的开花期叶片含钾量是施钾延缓衰老、增加花后同化和增产的生理原因。氮、钾施肥增加了叶面积指数、叶绿素含量、光能捕获效率和净光合速率，说明较高的开花期叶片氮、钾营养和适宜的氮／钾比是协调光反应与暗反应（即促进光合同化）的生理基础，也是氮代谢的能量保证。适当增施氮、钾肥能使叶片保持较高的开花期氮、钾含量和适宜的比例，进而显著提高叶绿素α光化学效率（将光能转化为CO₂还原力的能力）。因此，较高的开花期氮、钾含量并维持适宜的氮／钾比，是光合碳、氮代谢能量保证的生理基础。中蛋白品种扬麦10号的光能转化与利用效率强于低蛋白品种宁麦9号，较高的LAI和F_v／F_m、F_v／F_o、F_v’／F_m’、F_PSⅡ等叶绿素荧光特性是保证扬麦10号较高能量需求的生理基础。综上所述，提高小麦开花期叶片氮、钾营养水平并保持适宜的氮／钾比，是氮、钾施肥显著提高小麦旗叶净光合速率、光合（C、N）产物积累与输入籽粒的生理原因，既是氮、钾营养影响籽粒蛋白质与淀粉产量和含量差异的生理基础，也是氮、钾营养显著提高旗叶SPS、籽粒SS、SSS、GBSS和旗叶GS、籽粒GPT等活性的生理机制，进而是提高籽粒淀粉和蛋白质积累的生理基础。氮肥的作用大于钾肥。因此，氮、钾施肥水平通过造成开花期叶片营养状况的不同来影响小麦物质积累、运转以及淀粉和蛋白质合成关键酶活性的差异，从而调控小麦籽粒品质形成的过程。更多还原

【Abstract】 Nitrogen and potassium, two macro-elements of crop plants, markedly affect formation of grain yield and quality in wheat. Elucidating the physiological mechanism and regulation principles for grain quality formation in wheat is important significance for understanding grain quality physiology and guiding cultural management in wheat. The present investigations were undertaken to elucidate the photosynthetic characters, carbon and nitrogen assimilation and translocation, and regulatory enzyme activities in relation to grain quality formation in specialty winter wheat under different supply levels of nitrogen and potassium. In Nanjing （118°48’ E, 320°5’ N） and Jingxian （117°17’ E, 30°37’ N）, two winter wheat （Triticum aestivum L.） cultivars differing in grain protein contents, ’Yangmai 10’ （medium protein） and ’Ningmai 9’ （low protein）, were grown in the field experiments under varied rates of nitrogen (0, 112.5, 225 kg N hm^-2) and potassium (0, 75, 150 kg K₂O hm^-2) in two seasons of 2003～2005. The main results were as follows:1. Most nitrogen （N） and potassium （K） fertilization significantly increased the content of grain protein, protein component, wet gluten content, dough development time and SDS-sedimentation volume as compared with no N and K treatment. N and K fertilization had greater effects on gliadin and glutenin than on albumin and globulin. N fertilization significantly enhanced the ratio of glutenin to gliadin of both two sides. K fertilization significantly decreased the ratio of glutenin to gliadin of ’Ningmai 9’ in both two growth seasons, while the ratio of ’Yangmai 10’ was oppsite between two growth seasons. The role of potassium fertilization in increasing grain protein content was greater in ’Yangmai 10’ than in ’Ningmai 9’. In addition, the interaction of nitrogen and potassium fertilization significantly increased grain yield and wet gluten content in both sites, and grain protein content of Jingxian, and affect starch content and other quality parameters insignificantly. Higher leaf potassium content at anthesis was the vital physiological basis for determining grain protein formation of wheat with potassium supply, but too high leaf potassium restricted grain. yield. Suitable ratio of leaf N to K at anthesis based on higher leaf N and K nutrition was the key physiological basis for synchronously improving grain yield and quality of winter wheat.2. Potassium significantly increased grain yield through enhancing carbon reserves translocation and post-anthesis accumulation. Globulin and gliadin were the main physiological basis for enhancing grain protein content with potassium. Thus, the ratio of glutenin to gliadin decreased markedly. Higher leaf potassium content at anthesis very significantly increased pre-anthesis nitrogen translocation in two cultivars and post-anthesis nitrogen accumulation in ’Yangmai 10’, only slightly in ’Ningmai 9’. Higher leaf potassium content at anthesis significantly increased post-anthesis nitrogen accumulation, is the vital physiological basis for determining grain protein formation in ’Yangmai 10’, while pre-anthesis stored nitrogen translocation was true for ’Ningmai 9’. Higher chlorophyll a fluorescence (F_v/F_m, F_v/F_o, F_v’/F_m’ and F_PSⅡ) parameter was the energy basis for higher grain yield and protein content. ’Yangrnai10’ （medium protein） enhanced its protein content not only based on pre-anthesis nitrogen translocation, but also on post-anthesis N accumulation, while ’Ningmai 9’ （low protein） just mainly based on pre-anthesis N translocation.3. Suitable ratio of N to K in leaves at anthesis based on higher leaf N and K nutrition was the vital physiological foundation for synchronously improving the activities of key enzymes in source and sink organs for grain protein formation and protein content in wheat. The similar effects of N and K on the activities of key enzymes for starch formation and starch yield were observed, but starch content decreased. The ratio of SS to SPS in flag leaves at middle grain filling stage could affect starch content in two cultivars, with the starch content of ’Ningmai 9’ also affected by the ratio of SS to SPS in flag leaves at early filling stage. Suitable ratio of N to K in leaves at anthesis based on higher leaf N and K nutrition was the vital physiological basis for synchronously improving the activities of SS and GBSS and the yield of amylose and amylopectin in winter wheat. The ratio of SSS to GBSS at early and post anthesis could affect grain starch content slightly. Higher activities of SSS and GBSS of weak gluten wheat ’Ningmai 9’ was favorable for higher starch content than in medium gluten wheat ’Yangmai 10’.4. Potassium fertilizer increased post-anthesis accumulation through enhancing chlorophyll content （SPAD readings）, net photosynthetic rate, SOD activity and MDA content of flag leaves, significantly delayed flag leaf senescence during late grain filling through delaying the sharp decline of chlorophyll content in leaves. The results indicated that higher leaf potassium content at anthesis was associated with higher post-anthesis accumulation and grain yield. Suitable ratio of leaf N to K at anthesis based on higher leaf N and K nutrition enhanced both light reaction （chlorophyll a fluorescence parameter of flag leaves） and dark reaction of photosynthesis. That is the energy basis for specific carbon and nitrogen metabolisms. Higher LAI and chlorophyll a fluorescence (F_v/F_m, F_v/F_o, F_v’/F_m’ and F_PSⅡ) parameter of flag leaves in ’Yangmai10’ could meet its higher energy needs （medium protein） than in ’Ningmai 9’ （low protein）.In summary, suitable ratio of leaf N to K at anthesis based on higher leaf N and K nutrition was the vital physiological basis for enhancing net photosynthesis, carbon and nitrogen accumulation and translocation for grain growth in wheat. The differences in these processes induced the differences in the yield and content of protein and starch in wheat grains. Suitable ratio of leaf N to K at anthesis based on higher leaf N and K nutrition increased the activity of flag leaf SPS and GS, grain SS, SSS, GBSS and GPT, which enhanced the accumulation of starch and protein in grains, with the role greater by nitrogen han by potassium under this experiment. It is concluded that the differential carbon and nitrogen substrates caused the differences in protein and starch contents of wheat grains under different leaf nutrition at anthesis, which is the physiological foundation for regulation of different rates of nitrogen and potassium on grain quality formation in specialty wheat.更多还原