Early generation stability of a japonica rice variety, 84-15, was retested by using the allelic differences of two qualitative traits, i.e., glume tip color and waxy endosperm. Results showed that both glurne tip colo...Early generation stability of a japonica rice variety, 84-15, was retested by using the allelic differences of two qualitative traits, i.e., glume tip color and waxy endosperm. Results showed that both glurne tip color and waxy endosperm segregated in progenies of single F1 plants derived from two crosses of 84-15/Zi 18 （purple color） and 84-15/Dahuaxiangnuo （waxy）. The results denied the conclusion obtained in previous studies that 84-15 had a characteristic of early generation stability. Moreover, it was found that using the coefficient of variation as an indicator of early generation stability was unreasonable by analyzing plant height as an example. Importance of avoiding systematic error in research works was also discussed.展开更多
The development of a core collection could enhance the utilization of germplasm collections in crop improvement programs and simplify their management. Selection of an appropriate sampling strategy is an important pre...The development of a core collection could enhance the utilization of germplasm collections in crop improvement programs and simplify their management. Selection of an appropriate sampling strategy is an important prerequisite to construct a core collection with appropriate size in order to adequately represent the genetic spectrum and maximally capture the genetic diversity in available crop collections. The present study was initiated to construct nested core collections to determine the appropriate sample size to represent the genetic diversity of rice landrace collection based on 15 quantitative traits and 34 qualitative traits of 2 262 rice accessions. The results showed that 50-225 nested core collections, whose sampling rate was 2.2%-9.9%, were sufficient to maintain the maximum genetic diversity of the initial collections. Of these, 150 accessions （6.6%） could capture the maximal genetic diversity of the initial collection. Three data types, i.e. qualitative traits （QT1）, quantitative traits （QT2） and integrated qualitative and quantitative traits （QTT）, were compared for their efficiency in constructing core collections based on the weighted pair-group average method combined with stepwise clustering and preferred sampling on adjusted Euclidean distances. Every combining scheme constructed eight rice core collections （225, 200, 175, 150, 125, 100, 75 and 50）. The results showed that the QTT data was the best in constructing a core collection as indicated by the genetic diversity of core collections. A core collection constructed only on the information of QT1 could not represent the initial collection effectively. QTT should be used together to construct a productive core collection.展开更多
The agronomic and qualitative traits of 17 alfalfa varieties were analyzed in field and lab from 2006 to 2008, and these traits were evaluated by principal component analysis and cluster analysis. A total of 10 main t...The agronomic and qualitative traits of 17 alfalfa varieties were analyzed in field and lab from 2006 to 2008, and these traits were evaluated by principal component analysis and cluster analysis. A total of 10 main traits were classified as five factors： growth factor, quality factor, stem and leaf factors, plant factor and yield factor. These five factors and their correlation were selected for breeding. These 17 varieties can be divided into five clusters. The domestic varieties have better agronomic traits, while the introduced ones have better qualitative traits.展开更多
基金supported by the Program of Introducing Talents of Discipline to University,China(Grant No.B08025)
文摘Early generation stability of a japonica rice variety, 84-15, was retested by using the allelic differences of two qualitative traits, i.e., glume tip color and waxy endosperm. Results showed that both glurne tip color and waxy endosperm segregated in progenies of single F1 plants derived from two crosses of 84-15/Zi 18 （purple color） and 84-15/Dahuaxiangnuo （waxy）. The results denied the conclusion obtained in previous studies that 84-15 had a characteristic of early generation stability. Moreover, it was found that using the coefficient of variation as an indicator of early generation stability was unreasonable by analyzing plant height as an example. Importance of avoiding systematic error in research works was also discussed.
基金supported by the National Natural Science Foundation of China (Grant No. 30700494)the Principal Fund of South China Agricultural University, China (Grant No. 2003K053)
文摘The development of a core collection could enhance the utilization of germplasm collections in crop improvement programs and simplify their management. Selection of an appropriate sampling strategy is an important prerequisite to construct a core collection with appropriate size in order to adequately represent the genetic spectrum and maximally capture the genetic diversity in available crop collections. The present study was initiated to construct nested core collections to determine the appropriate sample size to represent the genetic diversity of rice landrace collection based on 15 quantitative traits and 34 qualitative traits of 2 262 rice accessions. The results showed that 50-225 nested core collections, whose sampling rate was 2.2%-9.9%, were sufficient to maintain the maximum genetic diversity of the initial collections. Of these, 150 accessions （6.6%） could capture the maximal genetic diversity of the initial collection. Three data types, i.e. qualitative traits （QT1）, quantitative traits （QT2） and integrated qualitative and quantitative traits （QTT）, were compared for their efficiency in constructing core collections based on the weighted pair-group average method combined with stepwise clustering and preferred sampling on adjusted Euclidean distances. Every combining scheme constructed eight rice core collections （225, 200, 175, 150, 125, 100, 75 and 50）. The results showed that the QTT data was the best in constructing a core collection as indicated by the genetic diversity of core collections. A core collection constructed only on the information of QT1 could not represent the initial collection effectively. QTT should be used together to construct a productive core collection.
基金Supported by National Basic Research Program of China ( 973 Program) ( 2007CB108906)~~
文摘The agronomic and qualitative traits of 17 alfalfa varieties were analyzed in field and lab from 2006 to 2008, and these traits were evaluated by principal component analysis and cluster analysis. A total of 10 main traits were classified as five factors： growth factor, quality factor, stem and leaf factors, plant factor and yield factor. These five factors and their correlation were selected for breeding. These 17 varieties can be divided into five clusters. The domestic varieties have better agronomic traits, while the introduced ones have better qualitative traits.
