不同生态条件下稻种耐冷性经济性状的遗传研究

用５个不同耐冷级别品种按１／２Ｐ（Ｐ－１）配制１５个组合及其亲本在籼稻区，籼粳交错区和温凉粳稻区进行云南稻种不同世代主要经济性状的遗传研究，结果表明：（１）不同稻作区亲本品种及其杂交组合主要经济性状及其一般配合力（ＧＣＡ）、特殊配合力（ＳＣＡ）存在明显差异，因基本型和生态条件呈现一定的规律性变化。（２）亲本品种及其组合随海拔升高，株高，穗长，每穗实粒数和颖花数有增大的趋势，但结实率则相反；杂种后代

GENETIC STUDY OF THE MAIN AGRONOMIC CHARACTERS OF 5 COLD TOLERANCE STANDARD VARIETIES OF YUNNAN RICE (ORAYZA SATIVA L.) UNDER DIFFERENT ECOTOPES

Five standard varieties of rice ( Oryza sativa L. ) with different cold tolerance were crossed in 15 combinations and grown in Sanya, Hainan (Alt. 15 m), Kunming, Yunnan (Alt. 1916 m) and Yiliang, Yunnan (alt. 1532 m), and the main agronomic characters were recorded in their P1,P2,F1,F2 and F3. Great differences were observed among various varieties and their cross combinations in the GCA and SCA of their agronomic characters investigated in this study. Plant height, ear length, filled grains per spike and total grains per spike tended to increase with altitude, and seed setting rate showed a reverse trend it dropped with the increase in altitude. The extent of difference in the SCA of the agronomic characters between different rice cultivating regions and between different generatious was shown to be closely associated with the affinity of the parents. It is concluded that in deciding rice breeding targets, the conditions of specific rice - cropping regions should be taken into consideration.