Breeding Of Cytoplasmic Male Sterile Line And Hybrid F1 "Qingfeng NO.1" Of Pakchoi

Pakchoi (Brassica campestris L. ssp. chinensis Makino var. communis Tsen et Lee) is very popular and widely cultivated in our country due to its fresh tastes and abundant nutrition. Now the pakchoi cultivars in practice are still general varieties which exibit less on yield, quality and resistance to disease. On the other hand the imported seeds are expensive. Breeding of new excellent pakchoi variety has much benefit to economy and society. In our research we are focusing on breeding of new pakchoi varieties with high yield, good quality and resistance to disease. The main results were as follows:(1) 107 DNA fragments were amplified from 74 samples under the control of 11 ISSR primers and each primer averagely had 9.72 DNA fragments. 102 fragments were polymorphic with the 93.5% percentage of polymorphology. The value of Nel's genetic similarity (GS) indexes of 74 pakchoi resource based on the ISSR data varied from 0.61 to 0.88. Cluster analysis using UPGMA method showed that 74 pakchoi resources could be divided into six groups. The ISSR analysis is feasible to reveal the genetic diversity and genetic relationships among pakchoi species, and is helpful for parent selection of pakchoi breeding.(2) New cytoplasmic male-sterile lines of pakchoi are synthesized by hybridization, which the male-sterile Chinese cabbage NY8481 is as donor of male-sterile cytoplasm and subsequently backcrossed by pakchoi inbred lines. Their agricultural traits, flowering and seeding characters are observed and selected during crossing and backcrossing generations. It was showed that the cytoplasmic male sterility lines were nearly the same as their maintainer lines in agricultural traits in BC₅. A new excellent cytoplasmic male sterile line "709-311 A" had been synthesized with thorough sterilility.(3) 12 economic traits of pakchoi were investigated by means of correlation and path analysis in 19 pakchoi cultivars. It was showed there were significant positive correlation between plant weight and plant height, plant width, petiole length, petiole width, petiole weight, blade length, blade width, blade weight and leaf number. Meanwhile, the partial correlations between plant weight and head width, petiole width, blade width, leaf number were observed to be positive correlation with significance. The path analysis suggested that head width, blade width, leaf number and petiole width were the main factors for plant weight of pakchoi.(4) A new hybrid named "Qingfeng NO.1" using "709-311A" crossing with "801-112" are developed with good growth vigour and high yield, good quality and resistance to disease. It had been authorized by the Science and Technology Department of Zhejiang Province at Dec. 2005. Meanwhile, the common application technology of "Qingfeng NO.1" were also studied in the paper including high quality seeds cultural technology and new varieties cultural technology.