Effect Of Different Cultivation Measures On Rapeseed Yield And Lodging Resistance

Lodging is an important factor which restricting yield of rapeseed. Therefore, studying lodging mechanism and finding the better cultivation measure to improve yield and lodging resistance of rapeseed is an important topic. In this study, we set three experiments from 2013 to 2015 in the field of Huazhong agricultural university. Experiment one we use Huayouza 62 as material, three nitrogen fertilizer 120 kg hm-2,240 kg hm-2,360 kg hm-2 and three densities 15 × 104 hm-2, 30 × 104 hm-2, 45 × 104 hm-2 were setted; Experiment two Huayouza 62 and Fengyou 520 were used as materials, we applied Si at two stages(seeding stage and early bolting stage), three different concentrations were 0. 047 g L-1, 0.093 g L-1 and 0.140 g L-1; Experiment three Huayouza 62 and Fengyou 520 were as materials, different cultivation methods including direct seeding and transplanting, four different planting densities were 15 × 104 hm-2,30 × 104 hm-2,45 × 104 hm-2,60 × 104 hm-2.Yield and yield component, dry matter accumulation, photosynthetic index and radiation use efficiency, the main agronomic traits, lodging angle and stem lodging index, lignin and the three key genes were tested to research the effects of different cultivation measures on rapeseed yield and lodging resistance. Aiming to find effects of different cultivation measures on rapeseed yield and lodging resistance. In the end, we hope we can provide a theoretical basis mechanical production in the high yield. The main results were as follows:1.(1) Increasing nitrogen fertilizer, the population of photosynthetic leaf(siliques) area index [LAI(SAI)] and light interception ratio(LIR) increased, especially on the bolting stage. Radiation use efficiency(RUE) increased in every stage. The starting time of dry matter accumulation(t1) advanced, the ending time(t2) delayed, so dry matter accumulation duration(△t) increased. While increasing density, the LAI and LIR on seeding stage increased. t2 delayed, so this caused △t increased, The maximum correlation between yield and LAI(SAI) and LIR appear in bolting stage, while RUE in ending flowering stage to ripening stage. Therefore, more attention should be paid to the increase of LAI and LIR of the pre-flowering stage and the increase of RUE after flowering stage for high yield.(2) When increasing nitrogen, the lodging angle increased, both the lower part(LIL) and the upper part(LIU) lodging index increased, the whole plant lodging risk increased. However, when increasing density, the lodging angle decreased, LIL increased, and LIU decreased. This supports that increasing density can reduce the upper part lodging. Nitrogen application and planting density also affect lodging by influencing the content of upper part stem lignin. When increasing nitrogen, acid insoluble lignin content decreased and the lodging resistance decreased,while increasing density, acid insoluble lignin content increased, the resistance to lodging enhancement. Among the three key genes(PAL,4CL,CCR1)in lignin synthesis, when increasing density, their relative expression increased, while increasing nitrogen, the variation was not significant. In N2 level the expression were higher, indicating that in this experiment N2 treatment is the better nitrogen level for the expression of the three key genes.(3) Considering the results of this experiment, the N2D3 has the same yield level with N1D3, but the stem lodging index was significantly less than N3D1. Therefore, by appropriately reducing the nitrogen fertilizer and increasing density can not only obtain higher yield, but also can reduce the risk of lodging, which can meet the requirements of mechanical harvesting.2.(1) Both in T1(seeding stage) and T2(early bolting stage) using silicon reduced seed number per pod, but increased yield by increasing number of pods per plant and 1000 grain weight, especially the pod number of branches per plant. Huayou 62 increased higher than Fengyou 520. Both the two varieties can obtain maximum yield when 0.093 g L-1silicon applied in T2.(2) In contrast, the lodging resistance and silique shattering resistance of Huayouza 62 was stronger than Fengyou 520. Also, the content of Si O2 and lignin in the main stem and silique was higher than Fengyou 520. After applying silicon, both lodging resistance and silique shattering resistance increased. With the increasing of the applied concentration, the increase of the amplitude becomes larger. Also, the content of Si O2 and lignin of the stem, root crown diameter, root-top ratio and stem lodging resistance increased. Meanwhile, the plant height, lodging index, root and stem lodging angle decreased. Among the agronomic traits, root-top ratio reached the maximum correlation with root and stem lodging angle, the correlation coefficient is-0.962**, This showed that silicon mainly improve lodging resistance by increasing the root-top ratio. At the same time, the application of silicon fertilizer reduced silique shattering index by increasing the length, area, fresh and dry weight and water content of the silique. Among them dry weight of the silique reached maximum correlation with the silique shattering index and the correlation coefficient is-0.909**.This showed that silicon mainly increase silique shattering resistance by increasing silique dry matter accumulation.(3) Under the conditions of this experiment, 0.093 g L-1 of the siliconin T2(when bolting height is about 8~12cm) was the optimum combination to obtion high lodging resistance and silique shattering resistance, also, the yield can reached the higher level, which can meet the needs of mechanized production in rapeseed.3.(1)In both direct seeding and transplanting, the plant density is different which can obtain the high yield. In direct seeding condition, Huayouza 62 got the maximum yield in 45×104 hm-2(D3) density, but Fengyou 520 was in 30×104 hm-2(D2) density. In transplanting condition, Huayouza 62 got the maximum in D2 density while Fengyou 520 appeared in 15 × 104 hm-2. So compared with transplanting, direct seeding was more suitable for higher density.(2) Lodging index of direct seeding was significantly smaller than transplanting among all the densities. After increasing density, agronomic traits such as plant height and above ground dry weight decreased, the risk of lodging becoming lower. When increasing density, the part of the lodging occurred move down, and in direct seeding condition was more obvious, The effect on Huayou 62 lodging part was greater than Fengyou 520. This showed that increasing plant density under direct seeding can reduce lodging risk of the upper part.(3) Considering both of the yield and lodging resistance, direct seeding in high density(D2, D3) can obtain higher yield and less lodging risk, while transplanting in low density(D1, D2) can obtain high yield but can not reduce lodging. Therefore, direct seeding in high density is suitable for high yield and lodging resistance.