进一步提高水稻雄性不育系异交率的育种潜势
POTENTIAL OF BREEDING MALE STERILES AT HIGH LEVELS OF OUTCROSSING
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摘要: 本文主要综述有关以下方面的研究:1.影响水稻雄性不育异交率的重要因素;2.若干重要花器性状的遗传变异和遗传特性;3.花器性状之间以及异交率与花器性状之间的相关;4.选育高异交不育系的途径和展望。与野生稻比较,不育系雄性不育彻底、开颖时间长,有利异交。但其柱头外露性较差、柱头较小,是异交的不利因素。此外,不育系包穗、闭颖、迟花时和开花分散等因素不利异交。影响异交的主要性状都是遗传性状。一般地说,与花器构造有关性状的遗传力较高。而与开花习性有关的性状受环境因素影响较大,遗传力较低。花器性状在稻属内存在显著的遗传差异。理想种质主要存在于野生稻种内。但在栽培稻种内也不乏优良种质。不育系异交率存在显著差异,但原因尚不清楚。花器性状(除柱头外露外)对异交率的遗传效应及其相对重要性还未有过研究报道。柱头外露率与异交率的表型正相关显著。大多数花器性状间的相关也是显著的。文章还讨论了多柱头、颖花不闭合、一天中两次开花高峰、长穗颈(eui)等四种特殊种质的发现、特性和可能利用。根据已有的研究结果,认为通过不育系花器性状,主要是雌蕊性状的改良选育高异交不育系的育种计划是可行的。Abstract: This paper deals mainly with the following:1.the important traits influencing the outcrossing of male steriles(MS) in rice;2.the genetic variability and inheritance of the floral traits; 3.the correlations between the floral traits, and between the floraltraits and the outcrossing of MS; 4.the approach and prospect of breeding MS lines at high levelsof outcrossing.Compared with wild rice, MS lines have some characters favourable to outcrossing, such as complete male sterile, longer duration of spikelet opening; MS lines also have a few unfavourable factors, for instance, lower stigma exsertion, smaller size of stigmas, late flowering,incomplete exsered panicles, cleistogamy.The characters mentioned above are inherited. In general, the traits related to floral structure have greater heritability than those related to flowering behaviour. The latter traits are greatly affected by environmental factors.The genetic differences in the floraltr aits are apparent.The desirable floral plasm exists mainly in wild rice, and also in cultivars.There have not yet been reported the genetic effects of the floral traits on the outcrossing of male steriles and their relative importance. Marked phenotypic correlation has been found between outcrossing and stigma exsertion.The correlation between floral traits are also significant. Discussions have been made on the identification,peculiarity and possible utilization of four special materiales-multi-stigmas, unclosedspikelets after opening,two flowering peaks a day and long panicle necks (eui) .The paper concludes that the program of breeding male steriles at high levels of outerossing by improving the floral traits, especially pistil characters is feasible.
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