Effects Of Brassinolide On Grain Filling And Yield Of Tartary Buckwheat

Tartary buckwheat is a miscellaneous crop with the same food and medicine.Its rich functional ingredients such as bioflavonoids can effectively prevent diseases such as hypertension,hyperglycemia,hyperlipidemia and have great market development potential.In terms of production,Tartary buckwheat is quite different from most other crops.The total number of flowers is large,but the effective grain per plant is small,the seed setting rate is low,the yield is low and unstable,and the yield potential needs to be tapped.To this end,this paper sprayed four different plant growth regulators during the flowering period of Tartary buckwheat,and selected the best growth regulator brassinolide（EBR）for improving the fruiting and yielding effects of Tartary buckwheat.Based on this,the most suitable spraying concentration of EBR was studied,and its effects on photosynthesis,grain filling,material accumulation and distribution and transportation of Tartary buckwheat were further explored,and the physiological mechanism of EBR regulating Tartary buckwheat grain filling,increasing fruit setting and increasing yield was revealed.Provide theoretical basis and technical support for the high-yield cultivation technology of Tartary buckwheat.The main results are as follows:1.The effects of brassinolide（EBR）,gibberellin（GA₃）,bijou（B9）and ethephon（ETH）on the fruit setting and yield of Tartary buckwheat were studied by potted and field experiments.The results showed that:four Growth regulators can significantly increase the total number of flowers of Tartary buckwheat,increasing by 21.80%,16.61%,8.96%and 6.12%respectively compared with the control,but the effects on other indicators are obviously different.Among the four growth regulators,only GA₃ and EBR can significantly increase the seed setting rate of Tartary buckwheat by 26.29%and 28.29%,respectively,and increase the yield of Tartary buckwheat（9.84%and15.75%）,and the effect of EBR treatment is better.B9 and ETH had no significant effect on the fruit composition and yield of Tartary buckwheat.2.Appropriate EBR treatment can significantly increase the seed setting rate,grain formation rate,grain number per plant,grain weight per plant,and yield of Tartary buckwheat,and significantly reduce the abortion rate of grains.The high seed setting rate material Chuanqiao 1（CQ1）and The low seed setting rate material Xiqiao 1（XQ1）showed the same trend.Under different concentration treatments,the Tartary buckwheat seed setting rate,grain formation rate,grain number per plant,grain weight per plant,and yield all increased first and then decreased with the increase in concentration,and were significantly higher than those of the control treatment.High27.08%-31.99%,1.24%-6.60%,7.18%-39.47%,15.25%-30.28%and 1.60%-10.00%,while the abortion rate of grains is opposite.At the same concentration,the high seed setting rate material Chuanqiao 1（CQ1）had significantly higher seed setting rate,grain formation rate,grain number per plant,grain weight per plant,and yield than the low seed setting material Xiqiao 1（XQ1）.It is1.87%-4.91%,3.51%-4.74%,2.50%-17.40%,39.50%-51.70%,4.00%-9.20%higher.EBR had no significant effect on the plant height,the number of main stem branches and the number of main stem nodes of Tartary buckwheat,and the performance trends of the two materials were the same.It shows that EBR treatment（0.1mg/L）with G2 concentration has the best effect on improving the seed setting rate and yield of Tartary buckwheat.3.The grain filling process after EBR treatment conforms to the"S"growth curve,which can be fitted by Richards equation,but there are significant differences in grain filling parameters between different treatments.With the increase of EBR concentration,the maximum filling rate and average filling rate of Tartary buckwheat grains both increased first and then decreased,and each treatment was higher than the control treatment,but the time to reach the maximum filling rate was reversed.At the same concentration,the maximum filling rate and average filling rate of the high seed setting rate variety CQ1 were significantly higher than the low seed setting rate variety XQ1,and the time to reach the maximum filling rate was also significantly lower than XQ1,indicating that EBR can significantly increase the grain filling rate of Tartary buckwheat,And varieties with high seed setting rate have stronger grouting ability than varieties with low seed setting rate,and can accumulate more substances per unit time.4.Appropriate EBR（0.1mg/L）treatment can significantly increase the chlorophyll content of Tartary buckwheat during the filling stage.CQ1 and XQ1 increased by 13.3-44.8%and 12.3-50.5%respectively,and the leaf area increased by 11.2-25.0%and 11.6-25.5%,the net photosynthetic rate increased by 17.9-24.4%,19.3-25.0%,the maximum photochemical quantum yield increased by8.1-27.4%,6.6-14.6%,and the effective photochemical quantum yield increased by 11.9-19.8%,17.5-26.5,respectively%,the actual photosynthetic capacity increased by 9.9-22.5%,14.6-26.1%,but the intercellular CO₂ concentration decreased by 5.5-7.5%and 0.8-8.3%,respectively.It shows that EBR can significantly promote the photosynthetic capacity of Tartary buckwheat and increase the photosynthesis efficiency,and the promotion effect of the high seed setting rate variety CQ1 is more obvious.5.EBR treatment can significantly increase the sucrose content,grain sucrose content and starch content of Tartary buckwheat leaves in the early stage of Tartary buckwheat filling,and reduce the sucrose content of leaves and grains in the late stage of Tartary buckwheat filling.At the same concentration,CQ1 increased more than XQ1.EBR can significantly increase the dry matter weight of Tartary buckwheat from flowering stage to mature stage,and increase the material distribution ratio of roots at flowering stage,flowers and leaves at the early stage of filling,and grains at the late stage of filling stage.CQ1 and XQ1 have significant differences in the dry matter distribution ratio.It shows that EBR can significantly promote the accumulation of photosynthetic products in the grains of Tartary buckwheat at the filling stage,and CQ1 has a stronger ability to accumulate and transport photosynthetic products than XQ1.6.EBR treatment can significantly increase the leaf SPS enzyme,grain SS enzyme and AI enzyme activity in the late filling stage of Tartary buckwheat,and significantly reduce the AI enzyme in the early filling stage,SPS enzyme and SS enzyme activity in the late filling stage.CQ1is more active than XQ1 at the same concentration.EBR treatment significantly affected the content of abscisic acid（ABA）,gibberellin（GA₃）and brassinosteroid（BL）in the grain filling stage of Tartary buckwheat,and CQ1 and XQ1 showed different differences.ABA showed a downward-up-down trend with the increase of EBR concentration in CQ1.G1 and G3 were lower than the control group G0,and G2 was significantly higher than G0;it showed an upward trend in XQ1,but the overall content of the treatment group was lower than the control group.GA₃ was at the same level in CQ1,and there was no significant difference;in XQ1,the concentration of EBR showed a low-decreasing and high-increasing trend.The treatment group was lower than the control group.BL showed an upward trend with the increase of EBR concentration in CQ1;in XQ1,it showed a downward-up-downward trend with the increase of EBR concentration.But there is no significant difference between auxin（IAA）and zeatin（TZ）.It shows that EBR can promote the accumulation and transport of sucrose-starch in grains by regulating changes in enzyme activity.In summary,spraying EBR at the initial flowering stage of Tartary buckwheat can increase the leaf area and chlorophyll content of the plant,increase the activity of sucrose-starch metabolic enzymes in the leaves and grains,increase the dry matter weight,and enhance the filling of Tartary buckwheat.During the period of photosynthesis and increase the grain filling rate,so as to promote the Tartary buckwheat seed setting rate and increase the yield,the best treatment effect is 0.1mg/L.