密穗型水稻品种籽粒垩白性状改良研究

采用籽粒长宽比较大、穗部着粒密的散穗型材料(EG23)改良粳稻密穗型品种的籽粒垩白性状.结果表明,经改良后得到的密穗型品系EA6,与原亲本浙粳20比较,其穗部长度缩短,每穗总粒数增加,着粒密度增大,而籽粒垩白特性得到明显的改善,表明在穗部长度和着粒结构未得到改良的情况下,调节籽粒长宽比对改善密穗型品种籽粒垩白性状具有可能性.穗部不同粒位籽粒垩白性状改良的效果不同,穗顶部和穗中部的改良效果明显优于穗基部.设计的4个不同杂交配组方式中,以反回交配组方式(浙粳20/ EG23//浙粳20)选育效果最好.EA6具有较好的农艺性状,既可作为优异种质资源利用,也可直接应用于生产.这一结果从育种实践上较好地协调了密穗型品种高产与优质的矛盾,对于培育既有密穗型的高产株型又有优良籽粒外观品质的水稻品种具有重要意义.

Improvement in Chalkiness Characters of the Compact Panicle Type of Rice

Grain chalkiness characters of the compact panicle type rice (CPR) was improved using the loose panicle type rice line (EG23) with larger length-width ratio of brown rice. The results showed that the improved CPR line EA6 had higher chalkiness quality of rice grain, but shorter panicle, more grain number and larger grain density compared with its parent Zhejing 20. It implied that it is possible to effectively improve grain chalkiness of CPR through adjusting length-width ratio of grain while keeping the panicle length and the grain density. The results also showed different effects for improving grain chalkiness among differently positioned grain within a panicle. The chalkiness improvement was better in the top and the middle grains than the bottom ones within the panicle. In addition, in four different crossing methods, the counter-backcrossing, Zhejing 20/EG23//Zhejing 20, was the most effective for selecting expected materials. EA6 with the improved comprehensive agronomic characters might be used as a good gene resource of rice for improving grain quality in japonica rice breeding, and might be directly applied to the rice production. The results showed that contradiction between yield and quality in CPR was effectively corresponded, and it may be a new way for breeding new rice varieties with both high grain quality and CPR trait.