施氮量对小麦氮代谢相关酶活性和子粒蛋白质品质的影响

摘要

To determine the effects of nitrogen rates on activities of nitrogen metabolism related enzymes and grain protein quality of wheat, the field experiment was conducted with a strong gluten wheat cuhivar Jimai 20 in 2003 - 2004 and 2004 -2005 growing seasons. Five nitrogen rates with N 0, 96, 168, 240, 276 kg/ha and four nitrogen rates with N 0, 96, 168, 240 kg/ha were designed respectively. The results of two years show that： In proper range of nitrogen rate, the total protein content in grain, No. of spikes and grains per hectare, grain yield, protein yield increased significantly with the increase of nitrogen rate; Continue to increase nitrogen rate, grain yield decreased significantly. No. of spikes, grains per hectare and protein yield decreased or had no significant differ- ences. In the 2004 -2005 growing season, with the increase nitrogen rates from 0 to 168 kg/ha, glutaminesynthetase （GS） activities in flag leaves after anthesis, endopeptidase （EP） activities in flag leaves at 21 days after the anthesis, free amino acid contents in flag leaves, gliadin content in grain, high molecular weight glutenin subunits （ HMW - GS） and low molecular weight glutenin subunits （ LMW - GS） contents, HMW - GS / LMW - GS ratios, total protein contents in grains, No. of spikes and grains per hectare, grain yields are all increased signifi- cantly, while the dough development time and dough stability time are not extended. However, with 240 kg/ha nitrogen applied, GS activity is not significantly changed, EP activity in flag leaves at 21 days after the anthesis, ω - gliadin, α - gliadin, HMW - GS, LMW - GS and total protein contents in grains are still increased significant- ly, the dough stability time is extended, and the grain yield is decreased significantly. It is indicated that the excessive nitrogen application is useless for nitrogen assimilation and grain yield. There are indirect regulations of GS and EP on synthesis of protein components in grain. Improving GS activity in flag leaves after the anthesis and EP activity in flag leaves at the late filling stage are conducive to the accumulations of HMW - GS and LMW - GS, and the increase of HMW - GS / LMW - GS ratio. The synchronization increases of grain quality and yield are achieved by increasing the number of spikes and grains per hectare and the storage of the nitrogen and photosynthetic products in grain per unit area when appropriate amount of nitrogen applied. Under this experimental conditions, the optimum nitrogen rate for high quality, high yielding and high efficient production is 168 -240 kg/ha. Key words： wheat; nitrogen rate; activity of nitrogen metabolism related enzymes; protein quality; nitrogen agronomic efficiency%在2003～2004年和2004～2005年小麦生长季，以强筋小麦济麦20为材料，分别设置NO、96、168、240、276kg／hm2 5个施氮量处理和0、96、168、240kg／hm24个施氮量处理，研究不同施氮量对小麦氮代谢相关酶活性和子粒蛋白质品质的影响。两年度的试验结果均表明，在一定施氮量范围内，随施氮量增加，公顷穗数、穗粒数、蛋白质含量、子粒产量和蛋白质产量均显著升高；继续增加施氮量子粒产量显著降低，公顷穗数、穗粒数、蛋白质产量降低或无显著差异。其中2004～2005年生长季，在0～168kg／hm2施氮量范围内，随施氮趟增加，旗叶谷氨酰胺合成酶（GS）活性、开花21d后的旗叶内肽酶（EP）活性、旗叶游离氨基酸含量、了粒醇溶蛋白禽量、高分子量谷蛋白哑基（HMW—GS）和低分子量谷蛋白亚基（LMW—GS）含量、HMW—GS／LMW—GS比值、子粒蛋白质含量、公顷穗数和穗粒数、子粒产量均显著升高，面团形成时间和稳定时间延长；继续增加施氮量至240kv／hm2，GS活性无显著变化，但开花21d后的EP活性、ω-醇溶蛋白、α-醇溶蛋白、HMW—GS、LMW—GS和子粒蛋白质含量仍显著提高，面团稳定时间继续延长，子粒产量显著降低。说明施氮过多对小麦氮素同化和产量无益；提高开花后旗叶GS活性和灌浆后期旗叶EP活性，有利于HMW—GS和LMW—GS的积累及HMW—GS／LMW—GS比值的提高。适量施氮不仅提高了子粒灌浆所需氮源的供给能力，而且显著增加公顷穗数和穗粒数，扩大了单位面积库容，增加了单位面积上的氮素和光合产物在子粒中的贮存，这是适量施氮实现子粒品质和产量同步提高的生理原因。本试验条件下高产优质高效的施氮量为168～240kg／hm2。