玉米不同基因型双列杂交后代抽丝后氮素代谢特性

Study on Characteristics of Nitrogen Metabolism in Diallel Cross Generation of Different Maize Genotypes After Silking

【目的】阐明保绿型玉米和非保绿型玉米双列杂交后代抽丝后氮素代谢特征。【方法】选育氮高效品种是实现玉米高产高效生产的根本途径。为明确不同基因型玉米双列杂交后代的氮代谢和利用特征,筛选出保绿型玉米氮高效品种,采用大田试验的方法,选择保绿型(SG,stay-green)玉米自交系Q319、CZ01、VA91和非保绿型(NSG,non-stay-green)玉米自交系BM、B73、MO17,以此组配6×6完全双列杂交,以双列杂交后代为材料,系统研究不同玉米品种主要生育时期叶片、茎鞘、籽粒氮含量和粗蛋白质含量的变化,抽丝前后氮素积累、分配和氮收获指数,叶片氮代谢关键酶硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合成酶(GOGAT)活性等的影响,并对叶片氮代谢酶活性与保绿性的相关性进行了分析。【结果】不同基因型双列杂交后代抽丝后叶片氮含量呈倒"V"型变化特性,高峰期在灌浆期前后。茎鞘和籽粒氮含量均随生育期推进呈逐渐降低的变化趋势。保绿型(SG)玉米叶片、茎鞘、籽粒氮含量均显著高于非保绿型(NSG)玉米。抽丝前保绿型玉米自交后代氮积累、抽丝后氮积累、氮积累总量分别比NSG高20.00%、82.30%和45.23%;其转移量、转移率和氮素收获指数则分别比NSG低51.28%、66.59%和14.32%,抽丝后保绿型玉米的氮积累量约占50%,而非保绿型玉米仅为40%左右。保绿型玉米自交后代叶片和茎鞘粗蛋白质含量分别比非保绿型高108.23%和33.63%。抽丝至成熟期叶片硝酸还原酶活性的变化呈单峰曲线,高峰期在灌浆期前后,不同基因型玉米间变化趋势一致。抽丝后叶片GS活性、GOGAT活性和可溶性蛋白含量变化均呈单峰曲线,高峰期在抽丝后15 d左右。保绿型玉米NR活性、GS活性、GOGAT活性和可溶性蛋白含量在各时期均高于非保绿型。相关分析表明,叶片保绿度与叶片氮含量、可溶性蛋白含量、GOGAT活性呈极显著的正相关,与GS活性呈显著正相关,与NR呈正相关,但不显著。叶片氮含量与可溶性蛋白、GOGAT活性、GS活性呈极显著的正相关。氮素的同化与相关的酶活性关系极为密切。【结论】较高的氮代谢水平是叶片保绿的营养生理基础之一,保绿型玉米有较高的氮代谢酶活性,在后期有较强的氮素吸收和同化能力,保绿性可作为筛选氮高效玉米品种的一个重要农艺性状。

[Objective] This study aimed to explore the characteristic of nitrogen metabolic in diallel cross generation of different maize genotypes after silking.[Method]Selection high nitrogen use efficiency hybrid maize plays an important role in high yield and high efficiency production of maize A full diallel cross was made with three stay-green inbred lines （Q319, CZ01, VA91）and three non-stay-green inbred lines （BM, B73, MO17） in field. The physiological traits of nitrogen metabolic in diallel cross generation were analyzed.[Result]Content of nitrogen in leaf graphed as inverted“V”-shapes after silking stage in different maize genotypes. The peak of nitrogen content in leaf occurred in filling stage. Content of nitrogen in stem-sheaf and sheath reduced with the extension of the growth duration. Content of nitrogen in leaf, stem-sheaf and sheath of stay-green （SG） inbred lines were much higher than those in non-green-stay （NSG） ones. Nitrogen accumulation before silking stage （NABS）, nitrogen accumulation after silking stage （NAAS） and total nitrogen accumulation （TNA） in SG self cross were 20.00%, 82.30% and 45.23%, respectively, higher than those in NSG ones. However nitrogen translocation, nitrogen translocation rate and nitrogen harvest index in SG were 51.28%, 66.59%and 14.32%, which was significantly lower than those in NSG ones. TNA of SG was about 50%and TNA of NSG was only 40%after silking stage. Crude protein content in leaf and stem-sheaf of SG were 108.23%and 33.63%, higher than those in NSG ones. The straws were still higher valuable after harvesting. Some key enzymes to nitrogen metabolic activity such as nitrate reductase （NR） activity, glutamate synthetase （GOGAT） and glutamine synthetase （GS） in leaf of stay-green type were significantly higher than those in non-green-stay types. NR activity in leaf increased firstly and the peak occurred in filling stage after silking stage in different maize genotypes. GS activity, GOGAT activity and soluble protein content in leaf increased firstly, and the peak occurred 15 days after silking. Correlation analysis between stay-green degree, content of nitrogen, soluble protein content, GS activity, GOGAT activity and NR activity indicated that there existed significantly or highly significant positive correlations. Activities of those key enzymes on nitrogen metabolism were significantly important for nitrogen assimilation. [Conclusion] High nitrogen metabolism level is one of the nutrition physiological basis which makes leaves keep green for long time. Compared with the non-stay-green types, stay-green genotypes behave higher activities of key enzymes to nitrogen metabolic and higher nitrogen asorption and assimilation at late growth stage. In conclusion, character of stay-green could be used as an important agronomic trait in selecting high nitrogen efficient genotypes and inbred line.