Studies On The Reasons Of Field Bolting Of Summer Chinese Cabbage

The paper detailedly studied the effect on field bolting of summer Chinese cabbage about varicty,datc of so\ving,sccd storage tcmpcrature,thc number of differentiation leavcs,stress(drought) atmosphere tcmperature,hormone,low temperature vernalization time vie. in the experiments through treats on 10 usually used Chinese cabbage varieties by means of outside and inside invcstigation.The results revealed that:(l)Due to the genetic mechanism of every variety itself,different variety has different condition of flower bud differentiation,alabastron and field bolting.Thercby,the tested varieties can be sorted into three types:(a) heavy bolting endurance ability type,including No.6qiuzhenbai,No.7 qiuzhenbai,No.4 zhengbai,Dongfangxiahui, No.1 xiazhenbai,etc.;(b) moderate bolting endurance ability type,including Yuyuan 50,No.l yuzao,No.3xiayou, etc.,(c) light bolting endurance ability type,hiding Dongfangxiarong,No.1 xiayou, etc..According to concrete condition of different regions,selecting suitable varicties,based on try planting.is the key factor which determines whether summer Chinese cabbage can be successfully planted or not. We should select fast-growing,fast-heading under summer high temperature,heavy bolting endurance summer Chinese cabbage varietics.For example,Dongfangxiahui,No.3 xiuyou, No.1 yuzao,Yuyuan 50, No.1 xiazhenbai,No.6 qiuzhenbai,No.7 qiuzhenbai etc. are the optimal varieties in Zhengzhou,Hcnan.Because of light bolting endurance ability and heavy field bolting,Dongfangxiarong and No.1 xiayou are not suitable to planting in Zhengzhou,Henan.Although No.4 zhengbai has heavy bolting endurance ability,it is not suitable to planting in Zhengzhou,Henan as a result of bad-heading in summer culture, and suitable to fall-winter culture;(2) Dry seed (including about 8% water) storage tcperature has not any effect on differentiation,alabastron and field bolting of summer Chinese cabbage;(3) Determining suitable dates of sowing,on account of different variclics,is a decided factor which ensures successfully planting,e.g. early sowing (early and middle in June) for heavy bolting endurance varieties,and late sowing ( middle and late in July) for moderate and light bolting endurance variciios; (4) High or low air temperature affects diffcrentiation,alabastron and field bolting by affecting growth rate and field heading of summer Chinese cabbage.According to the degree of sensitivity of summer Chinese cabbage varieties differentiation, alabastron,field heading under high temperature and bolting to air tempcratiire, the varieties can be devided into three types: low-temperature vernalization type , high-temperature vernalization type and moderate-temperature nalization type ;(5)In view of the condition of differentiation leaves when the summer Chinese cabbage begindifferentiation and field bolting,the tested varieties can be sorted into two types:(a) difficult-differentiation type ;(b)easy- differentiation type which can be devided into leafy type and thin-leaf type by the number of the differentiation leaves when they emerge differentiation and field bolting;(6) Drought treatment heavily affects summer Chinese cabbage differentiation, alabastron, field bolting and heading,the more deepening drought,the more proportion of differentiation,alabastron and field bolting ,and the worse fielding heading;(7)Spraying GA treatments greatly accelerate differentiation,the higher concentration of GA and the more spraying frequency,the earlier differentiation,the more proportion of alabastron and field bolting,so as to not heading. Spraying 800mgl and 13 times GA has the most evident effect in the experiment.(8) The result of low-temperature vernalization treatment on gc:,,; mating seed showed that the longer treatment timc,the earlier differentiation, the more proportion of alabastron and field bolting. Different types varieties demand for different treatment fitne,thc long time for heavy bolting endurance ability type,and the short time for light bolting endurance ability type.