油菜生育期氮素的吸收、分配及转运特性

Absorption, Distribution, and Translocation of Nitrogen at Growth Stages in Oilseed Rape Plant

在Hoagland完全营养液的沙培条件下,采用15N示踪方法,研究了两个冬油菜品种不同生育期吸收的氮素在体内的分配、转运及损失情况。结果表明(两个品种平均值),83.5%苗期吸收的氮素和66.3%蕾薹期吸收的氮素分布在叶片中;79.1%开花期吸收的氮素分布在叶片和茎中,其中叶片中分布的氮占42.8%;而角果发育期吸收的氮素有42.4%直接分配到角果中,此时角果已成为氮素直接分配的比例最大的器官。苗期、蕾薹期、开花期和角果发育期吸收的氮素从营养器官向生殖器官的转运比例分别为34.4%、44.3%、41.2%和31.7%,单株转运量分别为203.2、325.8、218.0和82.0mg。在籽粒全氮中转运氮占65.1%,其中蕾薹期吸收后转运的氮素所占比例最大,为25.8%,其次是开花期和苗期,分别为16.9%和15.9%,角果发育期比例最小,为6.4%。以上4个生育期吸收的氮素损失比例分别为24.0%、10.5%、11.7%和7.3%,单株损失量分别为141.6、79.2、43.2和16.2mg。

The differences of concentration and distribution of nitrogen in crop depend on organs and growth stages, and nitrogen redistribution in different organs will be occurred at different stages; these differences are related to the transfer of growth center. Consequently, the high crop yield depends not only on the high amount of nitrogen absorption, but also on the high efficiency of nitrogen redistribution. The objective of this study was to reveal the law of nitrogen absorption, distribution, and translocation in oilseed rape plant at different growth stages using two winter oilseed rape cultivars with the 15N labeling method in sand culture under Hoagland complete nutrient solution conditions. The results （average value from the two cultivars） indicated that 83.5% of nitrogen absorbed at the seedling stage, and 67.3% of nitrogen absorbed at the stem elongation stage, were distributed to leaves; 79.1% of the nitrogen absorbed at flowering stage was contained in leaves and stems, with 42.8% of it in the leaves. However, 42% of the nitrogen absorbed at siliquing stage was distributed to siliquae which is just the organ directly distributed the highest proportion of nitrogen absorbed at this stage. The nitrogen absorbed at four growth stages （seedling, stem elongation, flowering, and siliquing） translocated from the vegetative to the reproductive organs at 34.4%, 44.3%, 41.2%, and 31.7%, i.e. 203.2, 325.8, 218.0, and 82.0 mg plant-1, respectively. The translocated nitrogen from vegetative organs to the total nitrogen in seed accounted for 65.1%; among with 25.8% absorbed at the stem elongation stage, 16.9% absorbed at flowering stage, 15.9% absorbed at seedling stage, and 6.4% absorbed at siliquing stage, respectively. The proportion of nitrogen loss, after being absorbed at the four growth stages, was 24.0%, 10.5%, 11.7%, and 7.3 %, i.e. 141.6, 79.2, 43.2, and 16.2 mg plant-1, respectively. To sum up, nitrogen absorbed by roots at the earlier growth stages in oilseed rape was mainly translocated to leaves first, and then to the reproductive organ at the later growth stages.