Different Alfalfa Varieties Resistance Research And Evaluation

In the course of adjusting agricultural structure, alfalfa is considered to be the most important forage because of its versatile functions. The resistance of alfalfa is the crucial factor to select and distribute alfalfa varieties. It is useful for alfalfa industrial development to evaluate drought resistance, heat tolerance, cold resistance and salt tolerance of several representative alfalfa species introduced from homeland and abroad in this paper.1. Study on drought resistance of 21 alfalfa varieties. Cell membrane permeability under simulated drought stress by PEG and 24-hour water holding capability of separated leaves were measured in the chamber . Spread obstruction and transpiration rate of stomata in alfalfa leaves under natural drought were determined .Related analysis on drought resistant indexes of 21 alfalfa varieties showed that the percent of cell injured ,24-hour water holding capability of separated leaves and relative spread obstruction may be selected as reasonable indexes for drought resistant identification of 21 alfalfa varieties .By cluster analysis 21 alfalfa varieties were classified into three types :high drought-resistant varieties , medium drought-resistant varieties and low drought-resistant varieties.2. Study on heat tolerance of 19 alfalfa varieties. This part of paper firstly analyzed cell membrane permeability and the percent of cell injured of different alfalfa leaves under different heat-treated hours. The result showed that 50 minutes was optimum stress time for heat-tolerant identification of different alfalfa varieties. Based on this result , heat-tolerant of 19 varietieswere compared . Strong heat-tolerant varieties were Abilene+Z, ISRsupreme, AmeriGuard302+Z, Apollo Supreme and so on . weak heat-tolerant varieties were Ameristand201+Z,affmity+Zand so on.3. Study on cold resistance of different alfalfa varieties .In this research ,alfalfa fall dormancy index was measured by unifoliate inter-node length (UIL) . Related analysis on fall dormancy traits of different alfalfa varieties indicated that UIL was a reasonable index for alfalfa fall dormancy traits, alfalfa varieties were classified as fall dormancy variety, semi-fall dormancy variety and non-fall dormancy variety. The results on alfalfa fall dormancy showed that fall dormancy alfalfa slow growth in seedling stage, re-growth later and slow re-growth in spring was the coldest resistance variety . Fall dormancy variety was higher cold resistance than semi-fall dormancy variety, also semi-fall-dormancy variety was higher than non-fall dormancy variety. This research also identify fall dormancy of several homeland alfalfa varieties.4. Study on salt tolerance of different alfalfa varieties. This research evaluate salt-tolerant identification results of different alfalfa were not constantly consistent by using different salt-tolerant indexes. By analysis several salt-tolerant indexes, partial indexes were selected .Cluster analysis on them showed that order of salt tolerance degree was : Abilne+Z, Archer, Alfagraze, 13Rsupreme>Arriba,Ameristand201+Z,zhongmu > Agressor , Innovator+Z, Affinity+Z , lobo, Apollo supreme, AmeriGuard302+Z > Avalance+Z ,Total,, AmeriGrazed401+Z , Baofeng.5. Study on comprehensive resistance of different alfalfa varieties . This research based on four parts above analyses comprehensive resistance feature of 17 alfalfa varieties .Fuzzy analysis showed that strong resistance varieties were Abilene+Z, Apollo Supreme , Alfagraze and Agressor . weak resistance varieties were Baofeng ,Total and Arriba.