不同磷效率小麦品种对缺磷胁迫反应的比较

在营养液培养条件下，以根据相对产量为指标筛选出的6个不同磷效率的小麦(Triticum aestivum L.)品种为材料，对其苗期在缺磷条件下生长、根冠磷含量及其分配，以及叶片韧皮部汁液中磷浓度等进行了比较研究。结果表明，缺磷抑制植株地上部生长，但刺激根系生长，导致植株根／冠比增加。无论在供磷或缺磷条件下，磷高效品种的根冠生长速率都低于磷低效品种。缺磷导致植株体内的磷含量下降与根系相比，地上部磷含量的下降速率更快。但在缺磷条件下，不同磷效率的小麦品种根冠间的磷分配变化没有差异。研究发现，在正常供磷条件下，磷高效小麦品种的叶片韧皮部汁液中磷浓度较低，而磷低效品种的叶片韧皮部汁液中磷浓度较高。但开始缺磷后，磷高效品种的叶片韧皮部汁液中的磷浓度下降较慢，使其相对磷浓度较高。缺磷后10天，磷低效品种叶片韧皮部汁液中的磷浓度为供磷对照的35．9％，而磷高效品种叶片韧皮部汁液中的磷浓度为供磷对照的59％。

Comparison on Responses of Different Phosphorus-Efficient Wheat Varieties to Phosphorus-Deficiency Stress

Six wheat (Triticum aestivum L.) varieties with different phosphorus (P) efficiency, selected according to their relative yield in P-deficient soil to that in P sufficient soil, were used to compare their responses to P deficiency in growth, root and shoot P content and P concentration in leaf phloem exudates in solution culture. Results showed that P deficiency repressed shoot growth, whereas stimulated root growth. Accordingly, root-shoot dry weight ratio of the P deficient plants was relatively larger than that of the P-sufficient plants. Comparing with P-inefficient varieties, the growth rate of shoot and roots of P-efficient varieties was relatively low both under P-sufficient and -deficient conditions. Phosphorus deficiency also resulted in decrease in shoot and root P content. The rate of decrease in shoot was faster than in root. Difference in P partitioning in shoot and root between P-efficient and -inefficient varieties could not be observed. However, a negative relationship between P concentration in leaf phloem exudates of nine-day-old seedlings of these wheat varieties and their degrees of P efficiency were found under the P-sufficient condition, with higher in P-inefficient varieties but lower in P-efficient varieties. The reduce rate of P concentration in leaf phloem exudates of P-efficient varieties was rather slower than that of P-inefficient varieties, showing higher relative P concentration in leaf phloem exudates. The relative P concentration in leaf phloem exudates under P deficiency ranged from 35.9% of the P-sufficient controls in P-inefficient varieties to 59.0% in P-efficient varieties on the 10th day after the treatments.