Effect Of Effective Low Temperature Of Broccoli Flower Bud Differentiation And Accumulation

Broccoli(Brassica oleracea L.var.italica Plenck)which is a green plantvernalization in developmental process,not sensitive to low temperature at the seeds sprout and must accept low temperature,until the plants grows big enough.and then enter the stage of flower bud differentiation,which is the premise to obtain product organs of flowers.At present the production of broccoli,the head stage is inconsistent,head quality is poor,the fundamental reason is the planting date and planting seedling age would affects vernalization,and then affects the yield and quality of curd,thus effectively accumulateds temperature in vernalization and influence of flower bud differentiation of broccoli growth is huge.In this experiment,took different maturing broccoli varieties(early maturing variety“Zhongqing 10”,in the early maturing variety "Zhongqing 9" and "middle maturing varieties“Zhongqing 8”)as materials,used different low accumulation rate and different time in different leaf age of broccoli seedlings were induced by low temperature,to study effective temperature accumulation and low temperature accumulation rate relate to vernalization and theflower bud differentiation,while observed the different treatments influence on the metabolic changeof broccoli vernalization process,the field of growth,yield and quality,obtained the following conclusions:(1)The effective temperature accumulation in vernalization of broccoli was 117±13~198±11℃.In this experiment,the maximum effective accumulation was 198 ± 11 ℃ in vernalizationof broccoli.Which,in thestagein 6,7 leaf of "Zhongqing 9",and stagein 7,8 leaf of "Zhongqing 8",completing vernalization was198 ± 11 ℃,andthe stagein 5 leaf of "Zhongqing10",completing vernalization was 195±13℃.195±13℃,however,had no significant difference with 198±11℃.In thestage7 leaf of "Zhongqing10" completing vernalization of effective temperatureaccumulation was the lowest,was 117 ± 13 ℃.Therefore,we could conclude that the range ofeffective temperatureaccumulation that completed vernalization for early,mid early maturing and mid maturing varieties of broccoli was117±13~198±11℃,and the critical temperaturewas 198℃,The vernalization could be completedreaching the198℃.(2)The key of effective temperatureaccumulation was 363℃ for flower bud differentiation of broccoli.The effectivetemperature accumulation was 351 ± 13 ℃ for completing flower bud differentiation stage in 5 leaves of "Zhongqing10".The effectivetemperature accumulation was 363±11℃ completing flower bud differentiation stage in 6 leaves of "Zhongqing 9".The effectivetemperature accumulation was 363±11℃ completing flower bud differentiation stage in 8 stage of "Zhongqing8".We could concludethat broccolicompletedflower bud differentiation that the effectivetemperatureaccumulation was 363℃ in the suitable leaf age.(3)With the gradual accumulation of the effective temperature in vernalizationof broccoli,The content ofsoluble sugar and reducing sugar and sucrose increased significantly,the content of starch decreased significantly of carbon metabolism.The content of soluble protein increased significantly,the content of total nitrogen decreased significantly of nitrogen metabolism.The content of nucleic acid and DNA increased significantly.Witch showed that the content of the metabolic substances need to reach a certain value of broccoli,the plant wouldcomplete possibly vernalization and flower bud differentiation.The specific value: soluble sugar content washigher than 0.963 mg.g-1,reducing sugar content was more than 0.445 mg.g-1,the sucrose content is higher than 0.141 mg.g-1,the starch content waslower than0.131 mg.g-1,the soluble protein content was higher than 0.203 mg.g-1,the total nitrogen content was lower than 0.832 mg.g-1,the nucleic acid content washigher than 0.090 ug.g-1,the DNA content was higher than 0.071 ug.g-1.(4)Low accumulation rate did not affect the value of related substances content of completedvernalization and flower bud differentiation in the metabolismof broccoli.The accumulation rate of low temperature only affected the time of reaching the value,and did not affect the size of the value.(5)Low accumulation rate did not affect the value of effective temperature accumulation for completing vernalization and flower bud differentiationof broccoli.The higher the accumulation rate was,the shorter the time was completedfor the vernalization and flower bud differentiation,and the effective low temperature accumulation was not significant.(6)Low temperature treatment could advance theeach growth period of broccoli,the bigger the low accumulation rate was,the earlier the time advance.Specific data that the treatments T7,T11,T15 advanced 38.24%、19.12%,11.76% compared with the corresponding control in budding stage for early varieties.The treatments T7,T11,T15 advanced 32%,13.33%,9.33% compared with the corresponding control in budding stage for early maturing varieties.the treatments T7,T11,T15 advanced 19.23%,12.82%,7.69% compared with the corresponding control in budding stage for maturing varieties.other growth period advanced accordingly.(7)The best of vegetative growth in the field of broccoli in the low accumulation rate was 11℃and 15℃,the highest yield of broccoli was 15 ℃,The highest yield was 348.33 g per plant,the best inherent quality and the firmness of the curd were 15℃,The highest soluble protein content was 42.34± 1.09 ug.g-1 fresh weight,The highest soluble solids content was 1.555 ± 0.001%,the highest Vc content was 77.41±1.54 mg.100g-1,the highest soluble sugar content was 1.69±0.03 mg.100g-1,the highest head compactness was 69.97%.We could conclude that the suitable temperature accumulation rate was 15℃.