Resources Of Resistance To Late Planting On Northernwinter Rapeseed (Brassica Campestris) And Observation Of Progress To Flower Bud Differentiation

With the success of the northward movement of Winter Rape cultivation, Winter Rape hadbecome an important winter and spring cover crops and oil crops in northern cold and arid regions,nd its development is conducive to the reform of the northern tradition of a system of three harvestsTwo years or two harvests a year and to improve the multiple cropping index. It had significanteconomic and ecological benefits. Meanwhile it was contradictory to the limited growing seasonbefore winter. It was particularly important that discussing of resistance to late.seeding of northernwinter rape varieties and screening resistant sowing varieties to late.In this study, order to disscussthe in of overwintering rate, rowth and development, roduction, and flower bud, five differentvarieties of cold resistance and4different sowing time of the northern winter rape were used, It wasaiming to provide the basis of screening suitable winter rape varieties during different sowing time.1The tested varieties resistant to late sowing had significantly differential: the resistance tolate sowing of Longyou6and Longyou7was better than other varieties, Longyou8took the secondplace. Longyou9and Longyou4were the poorest.Varieties resistant to late sowing and their coldresistance are closely related.3With the sowing time delay, overwintering ability of Winter Rape had significantly downtrend. Sowing time and overwintering rate had a significantly negative correlation; the changes ofoverwintering rate resulted in the major changes on agronomic characters and lowering the oil rate.Took Longyou6for example: sowing time delayed from8/15to8/29, plant height from105.5cmdown to68.7cm; pod number per plant from157reduced to88; grain number per pod from23down to19; By-grain weight from3.2g down to2.3g; Oil rate dropped from44.15%to43.18%.4With the delay of seeding date, the root cause of over-winter rate,chang of agronomic traitsand Oil Length is the decrease of accumulated amount of dry matter and root to shoot ratiocorrespondingly. For example,the amount of accumulated dry matter of long oil6decreased from10.1g to1.99g and root to shoot ratio of long oil6decreased from2.45to1.67.5Decreasing of the accumulated amount of dry matter and root to shoot ration results ineffective accumulated temperature especially in the stage from seedlings to dry period after theseeding date, for example,the effective accumulated temperature of long oil6in different seedingdate in8/15,8/22,8/29,9/5is842℃d,727℃d,615℃d,478℃d. the effective accumulatedtemperature of winter rape reduced before winter with the delay of seeding date. There was apositive correlation between the accumulated temperature before winter and accumulated amount ofdry matter. The accumulated temperature long oil6for growth is2270℃d and its accumulatedamount of dry matter is10.1g in compared with8/15,accumulated temperature for growth in8/22 reduced208℃and accumulated amount of dry matter decreased5.87g accumulated temperature forgrowth in8/29reduced279℃and accumulated amount of dry matter decreased6.31g. accumulatedtemperature for growth in8/22reduced365℃and accumulated amount of dry matter decreased8.11g. Other varieties are similar6There is a big difference as the sowing of flower bud differentiation revelation,which isFound through the observation of different winter rape flower bud in differentiation process. Withthe postponement of the sowing date, flower bud start date delayed, the first broadcast of flower budin August15differentiation has difference about20days, Compared with the latest sowing inSeptember5. Broadcasting in8/15, the period of flower bud differentiation is about late October,and enter the petal primordial formation stage in late November, while Broadcasting in8/22is inthe calyx primordial growing season and petal primordial bulge is growing, Broadcast in8/29is inthe calyx formed, Broadcasting in9/5is just entering the flower bud primordial formation stage.7The broadcasting of flower bud differentiation accelerated after turning green wheat, butflower bud differentiation process has not changed during the Broadcast. The only difference in thenumber of days has shortened compared with the before of winter, compared with the late sowing,Early sowing has began to re-flower bud differentiation about5-7days in advance; After squaring,the earlier sowing enter the pollen formation, the later sowing is late, the latest is about4-5days.Broadcasting in8/15, re-enter the flower bud differentiation stage in early April, has entered thestamens growing season in mid-April; broadcasting in8/22, has in the stamen formation;Broadcasting in8/29, has in the calyx formed late petal formation early; Broadcasting in9/5has inthe calyx formation; After squaring, Around April22, Broadcasting in8/15has in the pollen mothercells; Broadcasting in8/22has in carpel formation of the late; Broadcasting in8/29has Just enteredthe carpel formation; Broadcasting in9/5has in the stamens growing season.8There is a close relationship between the winter rape flower bud differentiation sooner orlater and the cold resistance. The varieties of flower bud differentiation with Strong cold resistanceare earlier than the weakness. the order of5winter rape flower bud differentiation from early to lateis following: Longyou6,Longyou7,Longyou8,Longyou9,Tianyou4.While the Cold resistancefrom strong to weak is following: Longyou6,Longyou7,Longyou8,Longyou9,Tianyou4. So Itcan be seen that there is a close relationship between the winter rape flower bud differentiationsooner or later and the cold resistance.