玉米自交系氮效率基因型差异的比较研究

采用溶液培养的方法。选用经田间，土壤试验对N反应有典型差异的玉米自交系478，H21，Wu312,Zong31,Baici，在4个供氮水平下（0.04,0.4,2和4nmol/L)，研究了不同基因型玉米苗期氮素吸收，利用的差异及其原因，结果表明：极低N胁迫条件下（０.04mmol/L),总干重的基因型差异是由根系，地上部的共同作用的结果，高N下，总干重是由地上部的差异所决定的（表1），极低供N条件下，4578的总干重最大，且有较高的氮效率，Wu312,Zong31相对较低，478相对较高的氮效率主要来源于吸收效率的差异。该基因型在低N下总吸氮量最高，H21居中，Baici,Zong31相对较低，478相对较高的氮效率主要来源于吸收效率的差异。该基因型在低N下总吸氮量最高，H21居中，Baici,Zong31,Wu312相对较低（图1），吸收效率的差异主要是由于根系全N量的不同所致（图3），而根系全N量的差异主要是由于根系大小不同（表1），在极低氮水平下，不同基因型玉米根系全氮量的变幅比地上部高出28.1%，高N下（4mmol/L)，全N量的变幅比地上部高出15.4%(图2，图3），在0.04mmol/L下，478与Wu312,Zong31的利用效率不存在显著差异（表2）。

GENOTYPIC DIFFERENCE IN NITROGEN EFFICIENCY OF FIVE MAIZE INBRED LINES AS AFFECTED BY NITRATE LEVELS

Five maize inbred lines(478,H21,Wu312,Zong31 and Baici ), which showed significantly different response to N in three years field and pot experiment,were used to study the genotypic variation in their uptake and utilization efficiency by four NO - 3 supply (0.04, 0.4, 2, 4 mmol/L)in solution culture. The results showed that the genotypic difference of total dry weight was caused by both shoot and root at low N supply, whereas it mainly depended on shoot at high N supply(Tab 1). The total dry weight was the highest in 478 with high N efficiency among the five genotypes, relatively lower in Wu312 and Zong31 at low N supply, due to its higher N uptake efficiency, followed by H21, Baici, Zong31 and Wu312 (Fig 1).The difference of uptake efficiency of the five lines resulted from the difference in total root N content (Fig 3), which was caused by root size (Tab 1). The contribution in root N to total N content in 478 was larger than that in Wu312 and Zong31.The variation in total root N content among the five genotypes was larger than that in shoot N content (Fig 2,Fig 3) by 28.1% and 15.4%, respectively at both low and high N condition. No significant difference was found in utilization efficiency among 478, Wu312 and Zong31 at low NO - 3 of 0.04 mmol/L (Tab 2). Fig 3, Tab 2, Ref 11