Genetic Analysis of Grain Yield in a 7×7 Diallel Cross F_2 Population of Wheat(T.Aestivum L.)

In order to obtain genetic information for grain yield, seven genetically diverse wheat cultivars were crossed in an incomplete diallel to study the inheritance of grain yield using F_2 progenies for two years. Significant differences were observed among genotype, year and genotype × year interaction for grain yield, and both general combining ability(GCA) and specific combining ability(SCA) were also highly significant for grain yield, suggesting that the trait was controlled by both additive and non-additive effect. The GCA estimates revealed that the best combiners for grain yield were Yangmai 5 and Ningmai 9. Adequacy tests revealed that data of grain yield was fully adequate for genetic interpretation. Over-dominance genetic effects were important for the expression of grain yield. Grain yield exhibited moderately high value of narrow sense heritability(h_N^2=66.98% and h_N^2=72.37%).

合与分:清代乡村土地交易中的典与活卖

学界关于清代土地交易中典与活卖的认识存在着相反的观点,但少有明确的论证分析。从观念演变和实际交易中的产权转移表现可以发现,清代的典与活卖呈现出既“合”又“分”的形态,即在普通百姓日常认知中,典与活卖并无什么不同,但在具体的典与活卖交易过程中,对契税、推收过割和完粮采取不同的实践方式,体现了其谋求利益的选择逻辑,这一逻辑亦形塑了典与活卖的合流。而对于清政府而言,为了保证赋税、减少诉讼,其多次立法澄清二者的区别,尤其在找价回赎问题方面,试图消除因典与活卖的模糊性所带来的弊病,且直接影响了民间交易实践对典与活卖二者内涵认知的调整,但效果甚微。清末典契税的重新征收加剧了这种混乱,并延续至民国,进而影响到民法中的物权问题讨论,而当下学者的认知困境与民国学人又极其相似。