EVALUATION OF COLD HARDINESS OF SEVEN LOQUAT ACCESSIONS

Young fruits of seven loquat cultivars of loquat (Eriobotrya japonica Lindl.) were treated at 0, -3, -6, and 7°C for 12, 24, and 48 h. The physiological and biochemical indices were measured to reveal the cold hardiness of the cultivars and selections. Cold hardiness was assessed using principal component analysis and subordinate function value analysis. The response patterns of physiological and biochemical indices to cold treatments in fruit flesh and embryos were basically the same for the seven accessions. According to logistic equations, the half lethal temperatures of the fruit flesh and embryos of the seven accessions ranged from -3.2° to -6.7°C (fruit flesh) and from -3.5° to -6.8°C (embryos). There was a negative correlation between cold hardiness and electrolyte leakage, the half lethal temperature and malondialdehyde content, while there was a positive correlation between cold hardiness and super oxide dismutase activity and proline content. A close relationship existed between cold hardiness and protective enzymes, cell membrane permeability and lipid peroxidation in the principal component analysis.