| As an important legume crop in China,Vicia faba L.has not only rich nutritional value,but also unique medicinal value.It is used for both food and feed,and has a wide cultivation area.In recent years,it has become the most popular way for people to cultivate fresh and pollution-free vegetables,because it is the most convenient way for people at home and abroad.The content of a large number of beneficial compounds in plants is affected by genetic and environmental factors such as variety type,cultivation conditions and light.Therefore,under the social background of the rapid development of plant natural component extraction technology and the surge in demand for functional food,looking for better broad bean varieties and obtaining high concentration of bioactive substances such as levodopa in combination with the best harvest time of broad bean sprouts and seedlings and the most suitable light environment conditions are the key competitiveness of broad bean as a source of natural medicinal components.At present,there are few reports on the research of broad bean sprouts in China.（1）This subject takes broad bean sprouts as the research object,analyzes the differences and variation rules of quality indexes of different varieties of broad beans at different harvest times from the perspective of correlation,and discusses the relationship between nutritional quality and levodopa content;（2）The differences and changes of growth and nutritional quality indexes of broad bean sprouts under different light intensity and light cycle were explored in order to select the optimum light intensity and light cycle with better growth and higher yield of levodopa;（3）The differences and variation rules of growth and nutritional quality indexes of broad bean sprouts under different single light quality were studied,and the best light quality which has a great influence on the growth indexes of broad bean sprouts and is sensitive to the change of levodopa was selected;（4）The red and blue light ratio which is most suitable for the growth of broad bean sprouts and vegetables and makes the main quality such as levodopa optimal was explored.This research topic provides a theoretical basis for breeding new broad bean varieties with high levodopa content and comprehensive development of broad bean resources,and provides a certain scientific support for the development of intensive and large-scale production of broad bean sprouts and vegetables in facilities and the rational allocation of light environment parameters.The main results are as follows:1.Six tested varieties of’Lincan No.2’,’Qidou No.1’,’Haimen daqingpi’,’Beidou Qixing’,’Black broad bean’and’Hong xiangjiao’were selected for the experiment.Four harvest periods（3rd,6th,9th and 12th days after germination）were set to determine and analyze the growth indicators and nutritional indexes of sprouted vegetables respectively.The results showed that with the extension of harvest time,the seedling height and edible fresh weight of broad bean sprouts increased,reached the maximum at the 12th day,and the yield of levodopa also reached the highest‘The edible fresh weight of’Black broad bean’was the largest at the 12th day of harvest,and the contents of soluble protein,free amino acids and total flavonoids were the best.The yield of levodopa was the highest,which was 1392.48 mg/10 plants.’Haimen daqingpi’and’Qidou No.1’ranked second and third respectively.2.Select’Black broad bean’as the test variety;Taking darkness as the control,four light intensity treatments(20,80,140,200μmol·m-2·s-1)for light intensity test;Set 3photoperiods（8,12,16 h/d）for photoperiod test;The growth and nutritional quality indexes of the harvested broad bean sprouts were measured and analyzed.The results showed that the seedling height of broad bean decreased gradually with the increase of light intensity within 12 days after germination;When the light intensity is 140μmol·m-2·s-1,the content of total flavonoids and total polyphenols in’Black broad bean’was the highest;The light intensity is 200μmol·m-2·s-1The content of soluble protein and levodopa reached the maximum,but the yield and light intensity of levodopa were no significant difference at 140μmol·m-2·s-1.Similarly,within 12 days after germination,the height and moisture content of broad bean seedlings decreased gradually with the extension of photoperiod,but the dry and fresh weight reached the maximum at 12 h/d;The content of total polyphenols,total flavonoids and levodopa was the highest when the photoperiod was 16 h/d,but the yield of levodopa reached the maximum when the photoperiod was 12h/d.3.Taking’Black broad bean’as the test variety,dark treatment and white light treatment were selected as the test control.Three monochromatic light treatments were set as light quality treatment,namely red light（650nm）treatment（R）,blue light（450nm）treatment（B）and green light（550nm）treatment（G）.All light intensities were set to 60μmol·m-2·s-1;The growth and nutritional quality indexes of the harvested broad bean sprouts were measured and analyzed.The results showed that under the dark control,the plant grew in vain,the plant height reached the maximum,and other growth indexes performed poorly,and the content of levodopa was significantly lower than that under the monochromatic light treatment,but the content of free amino acid,soluble sugar and cellulose reached the maximum under the dark treatment.The aboveground fresh weight under blue light and green light treatment was significantly higher than that of other treatments,in which green light reached the maximum aboveground fresh weight of 8.485g,and the content of photosynthetic pigment always ranked first.Under red light treatment,most quality indexes of broad bean sprouts reached the best,including total polyphenols,total flavonoids,soluble protein,vitamin C,anthocyanin and levodopa.The content and yield of levodopa reached 101.992mg/g and 2714.148mg/10 plants respectively.4.Taking’Black broad bean’as the tested variety,white light was selected as the control,and four red and blue ratios were set as the experimental treatments:4R:1B,3R:2B,2R:3B and 1R:4B.The total light intensity of all treatments was set to 60μmol·m-2·s-1.The results showed that all red and blue treatments significantly reduced plant height compared with white light control,but had no effect on stem diameter,and there was no significant difference in total biomass and aboveground dry and fresh weight among all treatments.The higher the proportion of red light,the higher the chlorophyll content.The contents of chlorophyll a and chlorophyll b in 4R1B treatment were the maximum,but carotenoids were on the contrary,significantly lower than the other four treatments.The content of total flavonoids,anthocyanins and levodopa in broad bean sprouts were significantly affected by high red blue ratio,in which 4R1B treatment tended to reach the maximum and was significantly higher than that of white light control.The content of total polyphenols was not sensitive to the proportion of red and blue light,but all red and blue treatments were significantly higher than that of white light control.The treatment with low red blue ratio had an obvious effect on the improvement of soluble protein,in which 2R3B reached the maximum,and 1R4B and 1R4B were significantly higher than other treatments.The content of free amino acids first increased with the gradual increase of the proportion of blue light,and reached the highest value under 2R3B treatment,but continued to increase to 1R4B,and its content decreased significantly.The content of vitamin C was also not sensitive to the change of the proportion of red and blue light,but the content of VC in red and blue treatment was always higher than that in white light control.In conclusion,the best broad bean variety suitable for levodopa extraction is’Black broad bean’,and the optimum harvest time is the 12th day;The optimum light intensity condition suitable for the growth of’Black broad bean’,which is conducive to the improvement of quality index and the accumulation of levodopa,and relatively energy-saving and environmental protection is 140μmol·m-2·s-1,the optimum photoperiod is 12 h/d;Red light is the most important monochromatic light affecting the growth and quality of broad bean sprouts,and green light also has a prominent impact on broad bean sprouts,which can be further studied;When the ratio of red to blue light was 4:1,the growth index and quality index of broad bean sprouts were the best. |
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