Study On The Physiological And Ecological Base Of Quality Formation Of Rapeseed

paper discussed systematically the quality formation of rapeseed and the effect of 8 factors, such as dry matter accumulation, physiological feature, nitrogen, phosphorus and potassium spraying, plant growth regulator application, water supplying at flowering stage, sowing date, and different ecological regions. The characteristic of the paper lies in multiple trials in years employed from different angles and levels by adopting the same materials.1. The main results1.1 Formation process of yield and quality of rapeseed1.1.1 Relationship between yield and qualityThe dry matter accumulated at pod maturating stage is pods > stem > branches > roots > leaves. PPA(mg/ cm2), SNPA (seed number/cm2) and the ratio of seed to pericarp (seed dry weight to pericarp dry weight) were positively related to oil content of the seed, in which SNPA has significant relation to oil content. Harvesting index was significantly positively related to Oil content, but negatively related to protein content.1.1.2 Differences of quality from varietiesNo essential differences existed between superior quality and poor quality varieties in the change of fatty and protein content. However, glucosinolate and erucic acid content varied greatly. Glucosinolate content rose again 39 days after polination(DAP) for 'high glucosinolate content' variety, whereas, the changing tendency did not appear for 'low glucosinolate content' variety. Erucic acid content had little change for 'low erucic acid' content variety, whereas it rose gradually 21 DAP for 'high erucic acid' content variety.1.1.3 Relationship between physiology and qualityThe chlorophyll content of seed was positively correlated to seed dry weight in a certain range; too much chlorophyll resembled the weakness of carbon metabolism. The soluble sugar content of seed and pericarp decreased rapidly 25-30DAP, before seed dry weight and fatty acid content rose. Favorable high content of soluble sugar in pericarp benefited to high seed oil content at the late maturating period. The activities of glutamine syntheses in seed declined as the process of ripening of the seed, but it rose rapidly for Zhongyou 821.Low content of IAA and ABA, and high content of GA and iPAs in buds and flowers at flowering stage was favorable to the numbers of flowers and pods per plant. IAA, ABA,GA, iPAs might take part in the process of both the export and unload of the organic matter from pod. The gradual increase of seed IAA and GA 35 DAP might be related to sink growth and expansion. A good correlation existed between the rapid increase of seed iPAs and the fast increase of seed dry weight and fatty acid content. GA content in buds and flowers of 'double-high' variety was much higher than that of 'double-low' variety. The content of iPAs declined dramatically from the peak at initial flowering stage for 'double-high' variety, but it reached the peak at flourish flowering stage for 'double-low' variety and much higher than that of 'double-high'. GA and iPAs could take part in the synthesis and regulation of glucosinolate and erucic acid.1.2 Influences of nitrogen, phosphorus and potassium on rapeseed yield and qualityNitrogen applying increased the biomass significantly, yield increased and the ratio of vegetative growth increased as well, but varied from varieties. It also augmented chlorophyll content, the ratio of chlorophyll a/b, and nitrogen assimilation, but decreased the content of soluble sugar in pod. In the period of seed weight fast gaining, the viability of glutamine syntheses strengthened significantly, and at last, protein content increased. Nitrogen applying increased the content of iPAs, ABA, GA in pericarp, and IAA peak delayed, and at the same time, decreased the content of IAA, GA and iPAs, and postponed the augment of iPAs. Oil content of seed dropped 0.88-8.72 percentage points if nitrogen applying amount was 7.5~22.5kg/667m2, dropping 0.11-0.42 percentage point per kilo nitrogen. Seed protein content would rise as the increase of nitrogen applying, and the changing degree was greater than that of oil content change caused by nitrogen applying.Phosphorus applying at flowering stage promoted the accumulation of dry matter in pod, and the increase of seed content of chlorophyll and soluble sugar, and IAA, iPAs at the early and middle growing stage of seed and IAA, iPAs, ABA same time, altered the viability of in seed and pod at different growing stages. Phosphorus applying also enhanced the content of IAA, iPAs in seed at its early and middle growing period, and the content of IAA, iPAs, ABA in pod at its late growing period. Applying 0.2%, 0.4% and 0.6% of phosphorus and potassium at flowering stage might increase the pod number per plant, seed yield and harvesting index, in which phosphorus had more significant effect. Phosphorus and potassium applying at flowering stage also had the tendency of increasing oil content and decreasing glucosinolate content, however, phosphorus applying might increase erucici acid content of high erucici acid variety.Lowering the ratio of nitrogen in the fertilizer of applying before sowing could decrease glucosinolate content, but increase oil content. At the condition of applying 22.5kg/667m2 nitrogen, phosphorus and potassium enhancement could make oil content and glucosinolate content stable.1.3 Effect of exogenous hormones on rapeseed qualityApplying 40mg/L of NAA, 20mg/L of GA, 20mg/L of ABA, 200mg/L of MET at flowering stage could prolong chlorophyll content in its peak in seed, and increase soluble sugar content in seed and pericarp, and strengthen carbon metabolism.Spraying 40 mg/L of NAA, 20 mg/L of GA, 20 mg/L of ABA, 200 mg/L of MET at flourishing flowering stage could enhance seed yield per plant. ABA and MET had the effect of increasing the number of effective pods per plant and number of seeds per podand economic coefficient simultaneously.Spraying NAA, ABA, MET and GA at a certain concentration had the tendency of increasing oil content, but lowering protein content. However, it was different from years, soils, varieties and plant growing status. GA and MET had the tendency of decreasing glucosinolate content, and four regulator could increase erucic acid content.1.4 Effect of draught and waterlogging on rapeseed qualityThe plants at flowering stage could bear continuous draught or waterlogging for 7 days, but the plants death rate would be 35%~58% if the draught or waterlogging continued for 17d ~ 22d. The plants survived from 14 days of continuous draught had more branches. Continuous draught for 7d with the soil moisture content lower than 11% would cause 70% loss of yield. Prompt drainage and management soon after 7 days waterlogging would reduce the yield loss with 30%.Waterlogging at flowering stage augmented the dry weight of pericarp greatly. Draught and waterlogging reduced chlorophyll content in seed and pericarp. Chloroplast was more sensitive to draught. Draught reduced the soluble sugar content in seed and pericarp, but waterlogging had an opposite effect. Draught and waterlogging decreased IAA and iPAs content, but increased GA content in seed, however, ABA content in seed and pod increased greatly.Draught and waterlogging at flowering stage reduced oil content, but increased protein content in seed. Whereas, in the process of being submerged, protein content was decreasing. Draught and waterlogging at flowering stage enhanced the content of glucosinolate, but had little effect on fatty acid composition.1.5 Effect of sowing date on rapeseed qualityAll the items such as the number of effective branches and pods per plant, biologic and economic yield declined, but maturing process speeded up as the sowing date being postponed in September to November. The dry matter accumulation of seed and pericarp slowed, soluble sugar content declined, and the accumulation process of fatty acid, protein and glucosinolate shortened. The seed chlorophyll content rose rapidly with a high peak.Sowing date caused 0-3 percentage points difference of oil content and protein content, and 0-7 u mol/g difference of glucosinolate content for low glucosinolate content variety.Oil content was extremely significantly and negatively correlated to accumulated temperature (AT) from budding and elongation stage to maturating stage. Protein content was significantly and positively correlated to AT and the total sunshine hours at seedling stage, budding and elongation stage and maturating stage, but negatively and extremely significantly correlated to daily average precipitation. Glucosinolate content was positively and significantly correlated to daily average temperature and total sunshine hours at flourish flowering stage.1.6 Effect of regional environment on rapeseed qualityThe results of the trials showed that Chenxian County of Gansu, Wuhu City, Hefei City of Anhui fell to the region of high oil content, Hangzhou City of Zhejiang, YichunCity of Jiangxi, Beipei City of Chongqing, Zunyi City of Guizhou fell to the region of low oil content. The regions with a high glucosinolate content were Yichang City of Hubei, Kunming, Guiyang, Beipei City, Wanzhou City of Chongqing, Mianxian of Shan'xi, and the regions with a low glucosinolate content were Wuhan, Zhengzhou, Xiangfan of Hubei.2 Theory innovation spot2.1 The yield formation process was the quality formation process as well. The yield formation factors combined with quality formation factors by harvesting index.2.2 The plant vegetative growing status correlated positively with protein content in seed. Oil content was determined by nitrogen/carbon assimilates equilibrium and the ability of synthesis and export of pericarp.2.3 Chlorophyll a/b value was important for yield and quality formation of rapeseed. Chlorophyll a/b value was high when organs were forming and nitrogen metabolism was flourishing. That chlorophyll a/b value was high at the early stage and low at the late stage would benefit enhancement of oil content.2.4 That pericarp glucosinolate content rose at the late growing stage for high content variety was closely related to the great change of viability of glutamine synthase in pericarp.2.5 IAA, ABAGA, iPAs had a closer relationship to pod formation, seed development and products transportation and download, in which IAA and iPAs might have closer relation to fat synthesis.2.6 The active AT after initial flowering stage was closely related to oil content. Under the condition of equal AT, the difference on oil content for different treatment varied from AT before maturating stage.2.7 The favorite temperature for nutrients transformation and fat accumulation would possibly be 10℃~11℃ at elongation stage, less than 17℃ of the daily average at maturating stage, 1450℃~1500℃ of AT from elongation to maturating stage.3. Proposals for high quality and high yielding cultivationEarly sowing with a density of 7,000-8,000 plants per 6667m2. Apply nitrogen 10~15kg/667m2, in which, 40%~60% applied at seedling stage, accompanied with phosphorus and potassium. Free of draught and waterloggin. Spray ABA, MET on the nourishing plants, or NAA, GAon the weak plants.