| Shanyou 28 is a new Brassica napus variety,which is suitable for mechanized cultivation.The main characteristics of this variety are high yield,medium early maturity,good comprehensive resistance,especially its outstanding lodging resistance.Previous studies have shown that the lodging rate of Shanyou 28 is generally low under the condition of high density(less than 600000 plants/hm~2),so the research on the lodging resistance of Shanyou 28 can provide support for the breeding of lodging resistant rapeseed varieties.In this experiment,four varieties Shanyou 28,Qinyou 28,Qinyou 10 and Qinyou 7 with different lodging resistance were used as experimental varieties.The main area was sowing date(September 24,October 1,October 7),the secondary area was planting density(150000 plants/hm~2,300000plants/hm~2,450000 plants/hm~2,600000 plants/hm~2),and the secondary area was planting variety.The growth process and agronomic characters of four varieties under different sowing dates and densities were investigated.The contents of lignin and cellulose in stems at different development stages were measured,and the microscopic sections of stems were observed.Based on the determination of lignin content in stem,the gene expression levels of key enzymes in cellulose and lignin synthesis pathway were determined1.The lodging grade of the tested varieties in the field showed that Shaanyou 28 was a strong lodging resistant variety,Qinyou 28 and Qinyou 10 were medium lodging resistant varieties,and Qinyou 7 was a weak lodging resistant variety.The lodging index and stem bending resistance of the three types of varieties were significantly different.The stem bending resistance of Shanyou 28 with strong lodging resistance was 1.34-1.49 times of that of Qinyou28 and Qinyou 10 with medium lodging resistance,and 2.35 times of that of Qinyou 7 with weak lodging resistance.2.The increase of density will lead to the decrease of individual plant,the deterioration of agronomic traits,the decrease of stem bending resistance,the increase of lodging index and the aggravation of lodging.The effect of sowing date delay on Agronomic Traits and yield of rape was the same as that of density,but the effect of sowing date delay on Lodging Resistance of four rape varieties was different from that of density.The lodging rate,lodging index and lodging resistance of the four varieties decreased with the delay of sowing date.3.With the increase of density,the pod number per plant,seed number per pod and yield per plant of each variety showed a downward trend,and the oil content showed a gradual upward trend,while the plot yield showed an increase first and then decrease.The optimum density of lodging resistant variety Shaanyou 28 was D3(450000 plants/hm~2),and the yield per mu could reach 236.43kg.The most suitable planting density of middle and low lodging resistance varieties such as Qinyou 28,Qinyou 7 and Qinyou 10 was D2(300000 plants)/hm2,and the yield per mu was 217.56-229.77kg.4.With the delay of sowing date,the degree of individual plant development and yield traits decreased.The number of pods per plant,yield per plant and plot yield of each variety showed a decreasing trend.The oil content increased gradually with the delay of sowing date.The highest yield of four lodging resistant varieties was T1(September 24).5.The contents of lignin and cellulose in four varieties were in the order of final flowering stage>pod stage>mature stage>first flowering stage.Under the density/sowing date combination D1/T1,the contents of lignin and cellulose of Shanyou 28 were higher than those of Qinyou 28,Qinyou 10 and Qinyou 7.With the increase of planting density,the contents of lignin and cellulose in four varieties increased first and then decreased.There was a significant positive correlation between lignin and stem bending resistance(R~2=0.77),and there was a significant positive correlation between cellulose and stem bending resistance(R~2=0.46).6.The stem section of four varieties showed that Shanyou 28 had the largest proportion of stem lignification area(31.18%)and the highest degree of lignification.Qinyou 28 and Qinyou 10 accounted for 28.34%and 27.32%of the lignified area and the degree of lignification was medium,while Qinyou 7 accounted for 23.57%of the lignified area and the degree of lignification was the lowest.7.The expression levels of lignin and cellulose key enzyme genes showed that the expression levels of Bn CCR,Bn PAL,Bn4CL,Bn CESA6 and Bn CESA7 in Shaanyou 28 were higher than those in other varieties at initial flowering stage,final flowering stage and pod stage.The expression levels of medium lodging varieties Qinyou 27 and Qinyou 10 were higher than those of easy lodging varieties Qinyou 7.The expression level of bncesa6 was1.49 times,2.15 times and 2.66 times higher than that of Qinyou 7 at the initial,final and pod stages.The expression of Bn CESA7 gene in Shanyou 28 was 1.37,2.54 and 2.41 times higher than that in Qinyou 7.The expression of Bn CCR gene in Shanyou 28 was 1.48,2.34 and 3.35times higher than that in Qinyou 7.The expression of Bn PAL gene in Shanyou 28 was 1.66,3.88 and 2.79 times higher than that in Qinyou 7.The expression of Bn4CL gene in Shanyou28 was 1.79,2.61 and 2.57 times higher than that in Qinyou 7.In this experiment,the lodging situation,folding resistance,biochemical composition,microsection and gene expression of different lodging ability of Brassica napus.L were studied,and the reason of lodging resistance of Shanyou 28 was explained,so as to provide data support for breeding new lodging resistant varieties of Brassica napus.L in the future. |
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