美国水稻品种的遗传基础比较单一。美国农业部现有的16008份水稻种质仅有141份在育种上得到利用。由于育成水稻栽培品种的亲本间高度一致,以致在品种抗病性、品质等方面存在一些问题,这就要求水稻种质的评价着重于下述7种特性种质的筛选。 1.植化相克性(allelopathy) 植化相克性是通过根系分泌诸如醛类、酸类、生物碱类、糖苷类、硫氰酸类、内酯类、香豆素类、苯醌类、类黄酮类、甾类、丹宁类、萜类及一大批其他化学物质和植物生长调节剂而抑制杂草种群的生长。对于水稻的植化 The genetic basis of the US rice varieties is relatively simple. Only 141 of the 1,6008 rice germplasm currently available to the USDA are used for breeding. Due to the high degree of similarity among the parents of the cultivated rice cultivars, there are some problems in the disease resistance and quality of the cultivars. This requires that the evaluation of rice germplasm focuses on the screening of the following seven germplasm of germplasm. 1. Phytosanitary Alzheimer’s disease (allelopathy) Phytochemical gacitivity is the secretion of the root system such as aldehydes, acids, alkaloids, glycosides, thiocyanates, lactones, coumarins, benzoquinones, class Flavonoids, steroids, tannins, terpenoids and a host of other chemicals and plant growth regulators to suppress the growth of weed populations. For the planting of rice