Effect Of Farming Environment On Flavanoids Content Of Buckwheat

Buckwheat can be served as edibles and medicaments and its specially nutritional and pharmaceutical value receive more attention. Currently, the application of buckwheat is prevalent especially in the fields of food and medicine and the products made of buckwheat are more popular with the raising standards of living. It is predicted the buckwheat will be in short supply and become one of important foods. Buckwheat is mainly cultivated in the remote and economically backward areas inclding mountainous areas in the west of China and areas where minority ehtic group live.Therefore full utilization of buckwheat is important to adjust the structure of agromonic products and better off the backward areas, meanwhile, it is conducive to the implementation of the strategy of development of the western part of China on a large scale and maintain the stability of minority ethic group. More imporatantly, buckwheat is also famous for the abundant flavonoids, which has a beneficial effect on the rich malaise such as glycuresis, hyperlipemia and hypertension.In this paper, flavonoids was extracted form the buckwheat seeds by employing microwave method in which the effects of these factors including microwave power,alcohol concentration, ratio of solid to solvent and extraction time on the contents of flavonoids were investigated by using single factor and orthogonal mrthods. The content of flovonoids extracted form different organs in different development stage was determined and the effects of sowing time and cultivation environment on the content were investigated. The results showed that:(1) Factors including microwave power,extraction time,ratio of solid to solvent and alcohol concentration all had effects on flavonoids content. The optimal condition was obtained as follows: microwave power was 360W, alcohol concentration 60%, ratio of solid to solvent 1:60, extraction time 4 minutes.The advantages of the microwave method including saving time and energy, high efficiency, easiness to use, low cost, reducing pollution, determined that it was superior to conventional extraction method and should be adopted in the laboratory experiment and production.(2) The flavoniods content of different organs of tartary buckwheat was higher than that of common buckwheat in the whole growth period.The flavoniods content of different organs was in the decreasing order:bud>flower>milky ripening seeds>mature seeds,the same pattern applied to the flavonoids content of common buckwheat.The flavonoids contents of flowers and leaves achieved highest in the budding stage and flowering and seed-setting stage respectively. There was negligible change in the flavonoids contents of stem over the whole growth period and limited difference between flavonoids content of tartary buckwheat and that of common buckwheat was observed. The flavonoids content of tartary buckwheat seeds was 5 times higher than that of common buckwheat seeds.(3) The flavonoids content was significantly affected by sowing time.The flavonoids content of buckwheat planted in Yangling in different phase of time was determined.The results showed that the flavonoids contents of flowers, leaves, seeds of plants with normal sowing time (15th in June) were higher than that of the same organs of plants with advanced or delayed sowing time, contrary to the results of the stem.(4) The flavonoids content of the two cultured species, common buckwheat and tartary buckwheat, was different. Among the investigated materials, the flavonoids content of tartary buckwheat seeds was 2.2647%,higher than that of common buckwheat(0.4051%).Among the tartary buckwheat cultivars, Dahonghua had the highest flavonoids content with an average of 0.5205%, and Beizaosheng had the least with an average of 0.3520%. Among the commom buckwheat cultivars, Jiujiang had the highest with an average of 2.4700%, and Lijiang had the least with an average of 2.0317%.The trial location also had a considerable effect on the flavonoids content. The seeds of tartary buckwheat cultivars cultivated in Yulin of Shannxi had the highest flavonoids content, and that in Dingxi of Gansu had the least, the same pattern applied to that of common buckwheat.(5)Cultivation area was also an influential factor to the flavonoids content. The flavonoids contents of the whole plants above the ground and the seeds of tartary buckwheat cultivated in different ecological environments were determined. The results showed that the flavonoids content rose and then declined with the exception of that of plants cultivated in Zhangbei of Hebei which was highest in the seedling stage and declined gradually in the remaining growing stage. In general, the flavonoids content was highest in the flowering and seed-setting stage. In the whole growth stage, the plants cultivated in Zhaojue had the highest flavonoids content (4.60%), followed by that in Ganzi, and that in Zhangbei had the least (3.24%). Generally, the flavonoids content of plants cultivated in the south of China was higher than that of plants cultivated in the north of China.Therefore, the southern part of China was optimal producing-buckwheat area.