Effects Of Soils And Harvest Seasons On The Bioactive Compounds Of Wolfberry Fruits From Three Producing Areas

The accumulation of secondary metabolites of medicinal plants is regulated by plant genotype and environmental factors. This study selected three cultivars (’Ningqi No.4’,’Ningqi No.7’, and ’Zhongke Lvchuan No.1’) of Ningxia wolfberry (Lycium barbarum L.) to study the soil and climate effects on the bioactive components of wolfberry. The total flavonoids, total carotenoids, total polysaccharide contents of the dried fruits were used as evaluation index of bioactive components. Different cultivars were planted in Zhongning County in Ningxia Province, Shahai County in Inner Mongolia, Dulan County in Qinghai Province. Meanwhile, soil collected from Shahai and Dulan were transported to Zhongning. Together with local soil and artificial soil, four types of soil were used for potting plants in Zhongning. The main results are:(1) Summer fruit quality is better than that of autumn fruits both in Zhongning and Shahai regions. (2) The total polysaccharide contents ranked as Zhongning> Shahai> Dulan. Cultivars in Zhongning have highest level of total carotenoid content. But the total flavonoids contents varies greatly among cultivars and growing regions. (3) ’Ningqi No.4’ had the lowest content of total flavonoids in fruits from Dulan.’Zhongke Lvchuan No.1 ’had the highest level of total carotenoid, but rather lower level of total flavonoid especially in Shahai.’Ningqi No.7’ had higher level of total flavonoid in Shahai. It was suggested that the varieties of wolfberry might be affect differently by geographic environmental factors, and the future development of wolfberry varieties need to adapt to various cultivation climate and environment. (4) Four different soil treatments showed that the polysaccharide and flavonoid levels were similar for the artificial soil and Zhongning soil, while total carotenoid content was significantly reduced in artificial soil. So, artificial soil might lack some factors for the accumulation of carotenoids. Dulan soil treatment exhibited inhibition of total flavonoids content of ’Ningqi No.4’, and Shahai soil treatment exhibited inhibition of total flavonoids of ’Zhongke Lvchuan No.1’. These results were confirmed by the data from plants growing in Shahai and Dulan. Therefore, different cultivars might have various adaptability to different soil or geographic regions. In Shahai soil and Dulan soil, "Ningqi No.4’ had significantly lower level of total polysaccharide content, suggesting that salt resistant ability of ’Ningqi No.4’ is low. The content of total polysaccharide accumulation was increased under saline alkali stress. (5) When compare results of various soil treatments from Zhongning and the original growing conditions, no significant difference was discovered for the content of total flavonoids, suggesting that soil might be the main factor for flavonoid accumulation, but not the climate factors. Fruits from Zhongning regions had higher level of total polysaccharide and total carotenoids than those from Shahai and Dulan, suggesting that Zhongning might have beneficial environmental factors and should be the best growing region for wolfberry.