玉米自交系铁7922苗期耐低氮胁迫原因探讨

Discussion on the Resistance of Maize Inbred Line Tie 7922 to Low Nitrogen Stress in Seedling

以低氮胁迫(NO3--N0.2mmol/L)与正常供氮(NO3--N2mmol/L)条件下的生物量比值作为耐低氮能力指标,从12份玉米自交系中筛选出在低氮胁迫条件下苗期能够正常生长的自交系铁7922。通过不同玉米自交系对低氮胁迫反应差异的比较研究,从根系与氮利用效率对低氮环境的响应以及硝酸盐吸收动力学等3个方面对铁7922耐低氮原因进行了探讨。结果表明,铁7922对低氮环境的适应是多因素共同作用的结果,表现在氮胁迫浓度下根干重的增加、氮利用效率的显著提高以及较小的Km和低的Cmin。单纯的根干重的增加(掖515)或氮利用效率的提高(H21)或较小的Km(4F1、豫8701)并不能保证在低氮环境的正常生长。

According to the biomass ratio of maize inbred line grew in two nitrate levels （0.2mmol/L, low nitrogen stress level; 2 mmol/L, normal nitrogen level） in water culture, the maize inbred line Tie7922 which grew normally in low nitrogen stress solution in seedling was observed. Comparing the responses to low nitrogen stress of 12 maize inbred lines, the resistance mechanism of Tie7922 to low nitrogen stress of was discussed from three aspects： root growth, nitrogen use efficiency（NUE） and nitrate uptake dynamics parameters. The adaptation of Tie7922 to low nitrogen was a joint effect of several factors： the root dry matter was increased and the NUE was improved significantly when the inbred line was cultivated in low nitrogen solution, the smaller Km and the lower Cmin in normal nitrogen supply. But when the root dry matter increased single （the maize inbred line Ye515）, or NUE improved single （the maize inbred line H21）, or a smaller Km single （the maize inbred lines 4F1 and Yu8701）, they can not grow well as in normal nutrition solution.