| Mung bean is a traditional edible legume crop in China,which has strong adaptability,rich nutrition and homology of medicine and food.It is an important resource for daily consumption and food processing,and plays an important role in the adjustment of agricultural planting structure.At present,there are few studies on the dynamics of material accumulation and starch physical and chemical properties in the process of mung bean grain formation.In order to explore the rules of mung bean grain development and material accumulation,this study selected four mung bean varieties,Lvfeng 2,Ankang Mung Bean,Ji0816 Mao-3 and Anlv 7,combined with field experiments and laboratory analysis,to explore the main material accumulation dynamics,starch accumulation characteristics and differences of starch properties in the process of mung bean grain formation,as well as the effects of plant growth regulators on nutrient accumulation in the process of grain formation,so as to improve mung bean varieties.The main results are as follows:(1)After flowering,the grains and pods of mung bean gradually developed.The length,width and volume of the grains and pods increased rapidly and then decreased slightly.The fresh weight increased at first and then decreased,and the water content decreased continuously,with the largest decrease at 20 ～ 25 days after flowering,and the water content of the grains was about 10% at mature stage.And the dry weight of grain and pod showed an "S" type growth trend.The grain filling rate showed a single peak,and the peak value appeared around 15 days after anthesis.Correlation analysis showed that the dry weight of mung bean seeds was positively correlated with the length,width,volume and dry weight of pods,as well as the length,width,volume and fresh weight of seeds.There was a positive correlation trend with the fresh weight of pods,but it did not reach a significant level,and it was negatively correlated with the moisture content of pods and seeds.(2)During the filling process of mung bean,the content of amylose in grains increased continuously,the content of amylopectin and total starch increased in an "S" shape,and the content of crude fat,crude protein,total phenol and flavonoids decreased;The SOD activity of seeds showed a "V" type change;The hydroxyl radical scavenging rate was low at the early stage of grain filling,and increased rapidly about 15 days after anthesis.DPPH free radical scavenging increased first and then decreased.There was almost no difference in crude fat,total phenol,flavonoid content and hydroxyl radical scavenging rate of mung bean seeds of four varieties at maturity.Comparatively speaking,the crude starch content of Lvfeng 2 is higher,the crude protein content of Ji 0816 Mao-3 and Anlv 7 is higher,the SOD activity of Anlv 7 is higher,and the DPPH free radical scavenging rate of Ankang mung bean is higher.(3)After flowering,the starch accumulation in mung bean grains followed the Logistic curve,and there were some differences among different varieties.Among the four varieties,Ji 0816 Mao-3 has the fastest starch accumulation rate and shorter starch accumulation duration.The starch accumulation of Lvfeng 2 and Ankang mung bean lasted longer.The starch content in grains of Lvfeng 2 and Ankang mung bean was higher than that of Ji 0816Mao-3 and Anlv 7 at mature stage.The key period of starch accumulation of different varieties of mung bean is slightly different,with Lvfeng 2 starch accumulation in 5 ～ 18 days after anthesis,Ankang mung bean starch accumulation in 8 ～ 21 days after anthesis,Ji 0816Mao-3 starch accumulation in 6 ～ 11 days after anthesis and Anlv 7 starch accumulation in 5～ 15 days after.The enzyme activities related to starch synthesis in mung bean basically showed a trend of increasing at first and then decreasing,and the peak time of AGPase enzyme activity coincided with the peak time of total starch accumulation rate.Correlation analysis showed that AGPase,GBSS and SSS activities were significantly or extremely significantly positively correlated with the accumulation rate of amylose,amylopectin and total starch,while SBE activities were significantly correlated with the accumulation rate of amylose.AGPase,GBSS and SSS jointly regulate the accumulation process of amylose,amylopectin and total starch in mung bean.(4)Different varieties of mung bean starch granules have similar morphology,but their properties are different.Most of mung bean starch granules are smooth ellipsoid or kidney-shaped,and a few are spherical.Lvfeng 2 has high water-holding capacity,solubility and swelling degree,and its hot paste is stable and difficult to gelatinize.Ankang mung bean starch with large grain size has many grains,good transparency,low water holding capacity and freeze-thaw stability,high damage degree and weak pressure resistance.Ji 816 Mao-3and Anlv 7 have low solubility and swelling degree,low final viscosity and retrogradation value,difficult retrogradation and good stability.Anlv 7 has a good freeze-thaw stability.(5)Spraying uniconazole and amiodarone on the leaves of mung bean at the beginning of flowering period can increase the yield of mung bean,except Lvfeng 2,which has no significant effect,and the yield of other treatments is significantly higher than that of the control.Uniconazole treatment effectively reduced the plant height of mung bean plants.Uniconazole and amiodarone reduced the crude protein content in mung bean mature grains.Uniconazole can promote the accumulation of mung bean starch,and its regulatory effect on Lvfeng 2,Ankang mung bean and Anlv 7 starch is better than Ji 0816 Mao-3.Amine ester had no obvious regulating effect on starch accumulation in mung bean grains.Uniconazole and amiodarone had no obvious regulating effect on the change of crude fat content during mung bean seed formation.Comprehensive analysis shows that there are genotypic differences in substance accumulation and starch physical and chemical properties in the process of mung bean seed formation,and the effects of growth regulators on its quality are also different.Therefore,varieties can be bred and popularized according to processing requirements,and cultivation techniques can be optimized according to substance accumulation characteristics in order to achieve high yield and high quality. |
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