Analysis of Nutritional Components of Naked Barley Under the Ecological Condition of Tibet Plateau

Tibet naked barley (Hordeum vulgare Linn. var. nudum Hook.f.) is rich in nutrients, such as starch, lysine, β-glucan and protein, which are closely related to the ecological and climatic conditions unique to the plateau region. Forty-seven samples of the native varieties of naked barley were collected from parts of Tibet for this investigation during 2013-2015. Local conditions at the sampling sites were recorded. A quadratic polynomial stepwise regression analysis indicated that the temperature was crucial in affecting the lysine content in the grains. The starch content increased with the increasing sunshine and accumulated temperature. The interaction between the monthly and daily average temperatures, when they were greater than 0℃, and the sun exposure facilitated the formation of β-glucan. On the other hand, when the monthly and daily average temperatures were higher than 10℃ and the annual precipitation was abundant, their interaction became detrimental to β-glucan formation. For the protein content, the monthly mean temperature along with sunshine time was found to be beneficial, but not when the altitude was a factor associated with the monthly average temperature or the accumulated temperature. The canonical correlation analysis showed that the combination of altitude, annual precipitation and the accumulated temperature, when the average daily temperature was more than 10℃, were critical on the protein, lysine and β-glucan contents in the naked barley. Whereas, the combination of the accumulated temperature, when the average daily temperature was more than 0℃ or 10℃, and the annual precipitation affected most greatly on the starch and lysine contents in the naked barley.