磷营养对粳稻根部性状的影响

黑龙江省三江平原已垦和未垦低磷土壤面积在300万hm2左右,筛选耐低磷水稻品种是提高这类土壤的水稻生产潜力的重要途径。研究选用生产上已广泛应用的5个水稻品种,采用不同磷水平砂培法,分不同时期调查水稻根部性状。结果表明,在不同磷营养水平下品种间根部性状有显著差异。品种根部性状值相对较大的材料为耐低磷种质,对磷不敏感的材料为筛选耐低磷种质的首选种质。根部性状中,总根长、根数对磷的最敏感期为分蘖盛期,根重对磷的最敏感期为抽穗期,因此,调查根部性状的适宜时期为水稻分蘖盛期和抽穗期前后;在低磷水平下,根数、根重是筛选耐低磷品种的两个重要指标。水稻植株磷含量在同一磷水平内,不同品种虽有差异,其与生物产量无关。植株吸磷量随磷水平的提高而增加的途径之一是通过根表面积的增大而致。筛选耐低磷种质的适宜磷水平为3mg/kg。研究为筛选大量品种初步筛选出耐低磷种质提供依据和可行的方法。

Effects of the Applied Phosphorus on The Root Characteristics of Japonica Rice

With 3,000,000 hm2 of the low level of phosphorus soils including cultivated and un-reclamation land Sanjiang Platlands of Heilongjiang province, it is an important way to select the rice variety with the tolerance to low-level P to meet the demand of the rice development in this area. Five Japonica rice varieties were used in the pot test in which different levels of applied P were designed. The results showed that the characteristics of the rice roots responded differently to the levels of applied P, the rice variety with the favorite root index was selected as the germplasm to resist the low-level P stress. The sensitive period of the root length and root number to the low-level P stress was in the maximum tiller number stage, while that of the root weight was the heading stage, and hence these two stages were favorable for the root investigation. Under the low-level P applied, both the root number and the root weight were two important indexes and the P-level of 3mg/kg was the reasonable condition in the selection of the rice germplasm. Although existing differences among different rice varieties of Phosphorus contents in the same level-P, there was no correlation to biomass. One of way, which the amount of phosphorus absorption increased as the improvement of the level-P, was owing to the increasing of area of root surface. The results and methods achieved are useful for the selection of the rice variety with the low P-tolerance.