以长中胚轴/短中胚轴杂交组合的两个亲本、F1、B1、B2和F2为试验材料，在小型人工气候箱黑暗条件下培养幼苗，对水稻中胚轴伸长特性的遗传规律进行了研究。结果表明，中胚轴伸长特性受两对隐性基因控制。F2群体中长、短中胚轴植株在节间长度、穗长、株高和剑叶长等性状上均存在较明显的差异，而中胚轴伸长特性与节间粗、剑叶宽、单株穗数、每穗总粒数、结实率、千粒重和单株产量等性状关系不明显。还对水稻中胚轴伸长特性的遗传改良以及长中胚轴材料在直播稻育种上的利用进行了探讨。
Rice mesocotyl refers to the structure between radicel and coleoptile of seedlings. The mesocotyl length is related directly to the emerging ability of seedlings from soil in direct sowing rice. The rice direct sowing technique with simple and labor-saving characteristics has increasingly become attractive in recent years in China, but many breeders pay little attention to the rice mesocotyl character, one of the most important agricultural characters for rice direct sowing, in the current rice breeding programs, so there are little direct sowing rice cultivars with elongated mesocotyl in production. The emergence of seedlings is affected by the elongation of mesocotyl. In general, the length of mesocotyl is correlated to the depth of the seeds in soil, but it varies depend upon rice cultivars. Although some cultivars with long mesocotyl have been screened, the inheritance on the rice mesocotyl elongation is little known up to now. In the present study, the combinations between a long mesocotyl cultivar H10 and two short mesocotyl cultivars Xiushui 110 and Chunjiangxiangjing and their parents were used to study the inheritance on mesocotyl elongation of rice under the treatment of darkness during germination, and determine the internodeⅠ length, internodeⅡ length, internodeⅢ length, internodeⅣ length, internodeⅤ length, internodeⅥ length, panicle length, internode thickness, flag leaf length, flag leaf width, panicles per plant, grains per panicle, seed setting rate, 1000-grain weight and yield per plant of F2 plants with long mesocotyl and with short mesocotyl so as to understand the relationship between mesocotyl elongation and the agronomic traits of rice. The results indicated that the mesocotyl elongation of rice was mainly controlled by two recessive genes. The internode length, panicle length, plant height and flag leaf length of F2 plants with long mesocotyl were larger than those with short mesocotyl, but there were no obvious differences in internode thickness, flag leaf width, panicles per plant, grains per panicle, seed setting rate, 1000-grain weight and yield per plant. The improvement for the elongation character of rice mesocotyl and the utilization of long mesocotyl germplasm in direct sowing rice breeding were also discussed.
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