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(一) 杂交水稻在我区推广以来,随着种植年代的延续,在三系世代不断增加的情况下,混杂现象较为普遍,致使杂交一代种优势下降,严重影响了杂交水稻的增产效果。根据南京农业大学调查,目前杂交水稻的混杂率一般在5%以上,高的达10～20%以上。杂交水稻混杂原因有哪些呢?归结起来主要有三个方面: 1.生物学混杂。因为目前水稻杂种优势的利用是采用三系配套法,其中的不育系是人工培育的雌性水稻,最容易与邻近相同花期的各种籼粳糯品种异交结实。江苏省研究资料证实,在4～5级风的情况下,水稻花粉顺风向飘移距离可达700米以上,目前各地的不育系繁殖田和制种田的隔离达不到这个标准。据观察,不育系亲本中杂株主要有保持系、迟不育株和半不育株三类,以保持系居多。保持系混在不育系中,抽穗比不育系早2～3天,花
(A) Since the popularization of hybrid rice in our district, with the continuation of the planting age, with the increasing number of generations of three generations, the phenomenon of hybridization is more common, resulting in a decrease in the advantages of hybrid generation and seriously affecting the yield increase of hybrid rice. According to a survey conducted by Nanjing Agricultural University, the current hybrid rice hybrid rate is generally above 5%, up to 10 to 20% or more. What are the reasons for the hybrid rice hybrid? Summarized in three main areas: 1. Biology mixed. Because the current utilization of rice heterosis is the use of three-line matching method, which is a sterile male-sterile female rice, the easiest and adjacent to the same flowering of indica and japonica waxy varieties outcross. Jiangsu Province, research data confirmed that in the 4 to 5 wind conditions, the rice pollen downwind distance of up to 700 meters or more, at present, around the CMS breeding and farming system of isolation does not meet this standard. It is observed that the main male sterile line of maintainer lines, late infertility and semi-infertile strains of three categories in order to maintain the Department of mostly. Keep the line mixed in sterile lines, heading 2 to 3 days earlier than sterile lines, flowers