Investigation and analysis on heat tolerance of macadamia germplasm resources
With global warming,under the persistent high temperature and dry weather in summer,leaves yellowing occurred on the new shoots of heat-sensitive macadamia germplasm in the macadamia producing areas of Guangdong and Guangxi in China,which directly or indirectly affected photosynthesis,and consequently yield and quality.In order to screen heat-tolerant germplasm to cope with climate change,145 macadamia germplasm resources in the National Tropical Fruit Germplasm Resource Nursery located in Zhanjiang City,Guangdong Province,were used as materials to investigate the heat tolerance of different germplasm,and to analyze the physiological characteristics of germplasm with different degrees of heat sensitivity.The results showed that six longer time of high temperature and low humidity occurred in the afternoon(12:00-18:00)and the evening(18:00-24:00)from June to July in Zhanjiang City,resulting in leaves yellowing of new shoots of the heat-sensitive germplasm.The degree of leaves yellowing of new shoots varied with different heat-sensitivity of the germplasm.The 145 macadamia germplasm resources could be divided into four catego-ries,including heat-resistant germplasm,slightly heat-sensitive germplasm,moderately heat-sensitive germ-plasm,and severely heat-sensitive germplasm.With the increase of the degree of heat sensitivity of germ-plasm,the contents of chlorophyll(chlorophyll a+chlorophyll b,chlorophyll a,chlorophyll b)in leaves decreased significantly,resulting in leaves yellowing.The large quantity of superoxide anion free radicals(O2•-)was accumula-ted,the activity of lipoxygenase(LOX)and the content of malondialdehyde(MDA)were significantly increased,indicating the intensified cell membrane lipid peroxidation caused by the accumulation of reactive oxygen species.Com-pared with heat-resistant germplasm,the activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)were significantly increased in slightly heat-sensitive germplasm.As the degree of heat sensitivity aggravated,the SOD activity of moderately heat-sensitive germplasm and severely heat-sensitive germplasm was significantly lower than that of heat-resistant germplasm.The POD activity was still significantly enhanced,while there was no signifi-cant difference in CAT activity between moderately heat-sensitive germplasm and severely heat-sensitive germplasm,indicating the dysregulation of cellular antioxidant metabolism.
万方数据
维普
