A Comparative Study On Characteristics Of Drought Resistance, Cold Tolerance And Barren Resistance Of Grasses

Grass is the food of livestock, and is the material foundation of the development of stockbreeding. In order to select a kind of eminent grass which is adaptable to the northern China, the present thesis studies ten kinds of grasses from Gramineae, Bromus biebersteinii,Bromus inermis,Festuca arundinacea ,Festuca rubra,Dactylis glomerata ,Phleum pratense,Agropyron desertorum,Agropyron smithii,Elytrigia elongate and Phalaris arundinacea,and also explores the physiological aspects of their drought resistance, cold tolerance and barren resistance.The drought resistance experiment was conducted to study 10 grasses under water stress during seedling stage by simulating indoor drought environment. After fourteen days of different water stress treatments, leaf water content, leaf relative water content, soluble sugar content, leaf relative electrical conductivity, root/shoot ratio, plant height stress index, dry matter stress index were measured. In the barren resistance experiment, we designed three different levels of nitrogen concentration, and after treating fifty days we measured the plant height, root length, root volume, leaf number, leaf length, leaf width, leaf area, tiller number, fresh and dry weight of above and under grass biomass, plant chlorophyll content, the changes of nitrogen content of solution, nitrogen accumulation, nitrogen use efficiencyⅠand nitrogen use efficiencyⅡ. In the cold tolerance experiment, we measured the winter survival rate of grasses in field, and measured electrical conductivity under low temperature treatment indoors and figured out LT50. By comparing the characteristics of Drought resistance, cold tolerance, barren resistance and production, the results are as follows:1. In the aspect of grass drought resistance, leaf water content and leaf relative water content dropped while soluble sugar content and leaf relative electrical conductivity increased, following the decrease of soil water content. Estimating drought resistance of these ten grasses synthetically, it educed a sequence of strong to weak drought resistance of grasses during seedling stage, as follows: Bromus inermis>Festuca arundinacea>Bromus biebersteinii>Dactylis glomerata > Agropyron desertorum >Elytrigia elongate>Agropyron smithii>Phalaris arundinacea >Phleum pratense >Festuca rubra. Leaf water content and leaf relative water content of Bromus inermis, Festuca arundinacea, Bromus biebersteinii decreased lightly under severe water stress, while leaf relative electrical conductivity increased lightly. Moreover, the leaf soluble sugar increased significantly, plant height stress index and dry matter stress index were higher, root/shoot ratio had the trend of rise.2. In the aspect of grass barren resistance, indices of high barren resistance grasses were higher than the control on low nitrogen concentration level. By the cluster analysis, 10 grasses were classified into three types—of high barren resistance: Bromus inermis,Festuca arundinacea, Dactylis glomerata; of medium barren resistance: Bromus biebersteinii,Phleum pratense,Phalaris arundinacea; of low barren resistance: Festuca rubra, Agropyron desertorum,Agropyron smithii,Elytrigia elongate. Nitrogen use efficiencyⅠandⅡof Bromus inermis,Festuca arundinacea, Dactylis glomerata were higher, and they utilized nitrogen efficiently, and accumulated more nitrogen.3. In the aspect of grass cold tolerance, these ten grasses were classified into three types by the cluster analysis, based on winter survival adaptability and LT50 measured under low temperature treatment. High cold tolerance: Bromus biebersteinii,Bromus inermis,Festuca arundinacea, Agropyron desertorum,Elytrigia elongate, Phleum pretense; medium cold tolerance: Festuca rubra, Agropyron smithii,Dactylis glomerata; low cold tolerance: Phalaris arundinacea.As a result, synthesizing the comparison of the characteristics of drought resistance, cold tolerance, barren resistance and production of these ten grasses, we have found that the resistance of Bromus inermis,Festuca arundinacea was better , and consequently Bromus inermis , Festuca arundinacea were proofed to be favorable grasses for developing pasture in northern China in the future. Whereas, Bromus biebersteinii, Festuca rubra,Dactylis glomerata,Phleum pratense,Agropyron desertorum,Agropyron smithii,Elytrigia elongate and Phalaris arundinacea were worse, and therefore measures to local conditions and prudence in the production practice were advocated.