不同氮效率小麦品种苗期相关指标的杂种优势

为探究不同氮效率小麦品种氮代谢相关指标的遗传差异，选用了5个不同氮效率的小麦品种及其组配的6个杂交F₁，设置低氮（LN，0.4 mmol·L^-1 ）和正常供氮（CK，4.0 mmol·L^-1）两个氮水平，研究不同氮处理下小麦苗期形态、抗氧化酶和氮代谢相关酶活性的差异，并对其杂种优势进行了分析。结果表明，5个品种的根鲜重在低氮水平下明显高于正常氮水平，6个F₁的杂种优势表现为超中亲或偏低亲优势；苗鲜重在低氮水平下低于正常供氮水平，其F₁杂种优势表现为中亲优势。两种氮水平下，氮高效品种的硝酸还原酶（NR）、谷氨酰胺合成酶（GS）、谷氨酸脱氢酶（GDH）、超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性均高于氮低效品种，6个杂交F₁的上述6种酶活性大多表现出正向杂种优势。正常氮水平下，小麦叶片MDA含量低于低氮水平；低氮水平下，6个F₁的MDA含量杂种优势表现为超中亲或偏低亲优势。两种氮水平下，6个F₁叶片可溶性蛋白含量表现为正向杂种优势，其中低氮水平下，表现为超亲优势。综上所述，低氮条件下，氮高效品种较氮低效品种表现出较好的生长潜力；利用氮高效品种作为亲本能提高杂交F₁的氮利用效率，可用于小麦氮高效育种。

Heterosis of Indices Related to Nitrogen Metabolism in Wheat Varieties with Different Nitrogen Efficiency at Seedling Stage

In order to study the heredity and gene expression differences of wheat nitrogen metabolism related indices,five wheat varieties with different nitrogen use efficiency and their six hybrid progenies were used as materials. Samples were grown in Hoagland''s nutrient solution with 2 nitrate levels at seedling stage: low nitrogen(LN) and normal nitrogen(CK) at 0.4 and 4.0 mmol·L^-1,respectively. Heredity of morphology,antioxidant enzymes and nitrogen metabolism related enzymes were explored,which will provide a theoretical basis for selecting wheat cultivars with high nitrogen utilization. The results showed that the root fresh weight under low nitrogen level was significantly higher than that under the normal nitrogen level,and the heterosis showed super middle parent or below mid parent; while the seedling fresh weight was lower than that under the normal nitrogen level at low nitrogen level,and the heterosis showed middle parent. Under two nitrogen levels,the activities of NR,GS and GDH enzymes in N efficient wheat varieties were higher than those in N inefficient wheat varieties,and most of the crosses showed positive heterosis. The content of MDA in wheat leaves under normal N level was lower than that under low N level,and the heterosis under low N level was super middle parent or low parent. The soluble protein content showed positive heterosis at both nitrogen levels,and super parental dominance at low nitrogen levels. These results indicated that nitrogen efficient cultivars showed better growth potential under low nitrogen conditions,and nitrogen efficient cultivars as parents can improve the nitrogen use efficiency of hybrid combinations. Therefore,it is an effective way for nitrogen efficient breeding of wheat by using nitrogen efficient heterosis to configure hybrid combinations.