Research On Drought And Cold Tolerance Of Ananas Comosus (L.) Merrill Germplasm At Seedling Stage

In this research, seedlings of 10 different types of pineapple (Ananas comosus (L.) Merrill) germplasm were used as materials. Some physiological and biochemical properties were investigated respectively under drought and cold stress created by natural drying method and artificial low temperature. Finally, integrated evaluation on drought and cold tolerance of these pineapple germplasm were made through fuzzy comprehensive evaluation method. The main results were as following:1. Along with the lasting time of drought stress, the water content in leaves of all the pineapple germplasm declined, relative electrical conductivity, SOD activity and proline content increased, while chlorophyll content decreased at the beginning of drought stress, but then increased; the changing in MDA content and POD activity were different among these germplasm. After 8 weeks of water stress, in all 10 pineapple germplasm, the water content and POD activity decreased; relative electrical conductivity, SOD activity, MAD and proline content increased; chlorophyll content of'Mutant of Comte de Paris'kept invariant,'MD-2'slightly increased, while that of the others decreased. By using fuzzy comprehensive evaluation method, drought tolerance of these 10 pineapple germplasms was evaluated.The drought tolerance order of 10 pineapple germplasm was'MD-2'> 'Tainong No.17'>'Smooth Cayenne'>'Comte de Paris'>'Tainong No.6'> 'Tainong No.19'>'Mutant of Comte de Paris'>'Tainong No.16'>'Tainong No.13' >'Pearl'.2. Along with the lasting time of cold stress, for all the pineapple germplasm, chlorophyll content decreased, relative electrical conductivity, the contents of MDA and proline increased, while the changing in SOD activity, soluble protein and soluble sugar content showed difference among the 10 pineapple germplasm. After 9 days of low temperature stress, for all 10 pineapple germplasm chlorophyll content decreased; relative electrical conductivity, SOD activity, the contents of MDA, proline and soluble protein increased; while soluble sugar content in the leaves increased except for'Pearl'in which it decreased slightly. By using fuzzy comprehensive evaluation method, cold tolerance of these 10 pineapple germplasm was evaluated. The cold tolerance order of 10 pineapple germplasms was'MD-2'>'Comte de Paris'>'Tainong No.16'>'Mutant of Comte de Paris'>'Tainong No.17'>'Tainong No.19'>'Smooth Cayenne'>'Tainong No.13'> 'Tainong No.6'>'Pearl' 3. Through studying on the drought and cold stress tolerance data from physiological and biochemical properties, the drought and cold tolerance in seedlings of 10 10 different types of pineapple germplasm were estimated. The results indicated that'MD-2'was a promising germplasm in China because of its strong tolerance for drought and cold; while 'Pearl'was unsuitable for directly cultivating in drought and cold prevailing areas because of its weak drought and cold tolerance.