A Study On Seasonal Dynamic Of The Phenols In Leaves Of Alpine Plants And The Relation Between It And Cold-resistance

The 14 species of alpine plant including 7 herbage species, 7 shrub species were collected from Tianzhu alpine meadows (altitude ranges from 3000 to 3400m) located in eastern-part of the Qilian Mountains on Qinghai-Tibetan Plateau of China. Their leaves in different seasons (except winter) in one year were used as the material in this research by applying the Folin-Ciocalteu methods and Porter et al methods to testing procedures. The seasonal changes of phenols content, such as total phenol, simple phenol, tannin, condense tannin in the leaves were analyzed, in order to understand the relationship between phenol content of leaves and the temperature during the growth process.　This study measured electrolyte leakage that were exposed to temperature between　?3℃~ ?21℃in plants leaves and median lethal temperature (LT50) were determined using leakage combine with logistic function. The quantitative analyses to the cold resistance of the 6 spices alpine plants including Polygonum viviparum,Salix cupularis,Caragana jubata,Berberos kansuensis,Sibiraea angustata ,Rhododendron anthopogonides was studied in different phenological phase including green up period, middle period of exuberance, late period of exuberance and withering period. The aim is to study the cold resistance of this plants.　The result indicated: 1. The cold resistance of the 6 spices alpine plants varies with air temperature. The change curve of the median lethal temperature is a single peak. The median lethal temperature is low and the cold resistance is strong in green up period, withering period, fist period of exuberance and fist withering period. While the median lethal temperature is high and the cold resistance is poor in late period of exuberance. 2. The cold resistance of Rhododendron anthopogonides is the best, and that of the Polygonum viviparum is the poorest. The cold resistance of the other 4 spices plants follows the turn of Caragana jubata, Sibiraea angustata, Salix cupularis, Berberos kansuensis. 3. There are two change trends of phenols content in the alpine plants leaves. One is shown as Wave-shape, and the other is V-shape. The character of the former is that the phenol content is little lower in green up period than in the fist period of exuberance. From the median lethal temperature to late period of exuberance it became lower in the beginning followed by a dramatic drop to the lowest level with the temperature increasing to the highest point. In withering period the phenols content increase a little. The character of the later is that the phenol content is higher in green up period, withering period, while it decreases to base in the middle and late period of exuberance. There is a slight increase in withering period to different levels based on which kinds of leaves they were. 4. There is an important relationship between the change of phenols content and the cold resistance. The phenols content is high and the median lethal temperature is low, then cold resistance is strong in the green up period, fist period of exuberance and withering period. It is on the contrary in the middle and late period of exuberance. 5. The phenols content will change in order to prevent plants and they can act as a index of the cold resistance.