Abstract: Kales,which are widely cultivated as ornamental plants in wintertime or cold areas,play important roles for urban landscaping.Cold stress which can reduce the ornamental value is one of the most important characters for the improvement and breeding of kales.In order to elucidate the physiological characteristics during low temperature and reveal cold resistance mechanism,several varieties and strains which were bred by our group were used as research materials.The relative electrical conductivity (REC) under different low temperature treatment,semi-lethal temperature (LT₅₀) of different accessions,as well as the osmoregulation substances contents and antioxidant enzymes activities under different temperature treatment were analyzed.It was showed that the REC of kale leaves increased rapidly when temperature under -5℃,and reached maximum values at about -10℃.The TL₅₀ values of kale accessions were -10.3——13.7℃.The TL₅₀s of red types were lower than white types,as well as round and leatherleaf types were lower than wrinkle types.These results were consistent with field cold resistance performances of the varieties.Changing characteristics of the detected osmoregulation substances and antioxidant enzyme activities were different under different temperature treatments.These physiological indexes reached maximum values at -5℃ or -8℃ and decreased at lower temperature,except soluble sugar which reached maximum value at -10℃.The principal component analysis revealed that LT₅₀ value,soluble sugar and free proline contents were main components causing cold resistance variations among different varieties.These results will provide theoretical basis for the establishment of kale cold resistance evaluation system,and lay foundation for the development of new varieties with excellent cold resistance.

Key words: Brassica oleracea var.acephala, Cold resistance ability, Semi-lethal temperature, Osmoregulation substances, Antioxidant enzymes

CLC Number: 

• S635.01