Screening Citrus Cultivars for Freezing Tolerance by Reliable Methods

Citrus is among the low temperature (freezing) - susceptible plants. The performance of storage and breeding of horticultural crops is mainly dependent on the correlation among the traits. To determine the relationship between stress tolerance (LT۵۰) and some important physiological traits and finding their direct and indirect effects, four commercial citrus cultivars of Japanese mandarin, Thomson orange, Ruby Star grapefruit and Lisbon lemon in three temperature levels (۴, -۴ and -۸ °C) were studied at the Horticulture laboratory of Guilan University in ۲۰۲۱. Before treating and for adaptation of plant material to temperature decrease, the plants were moved to a temperate greenhouse and then to a +۴ °C cool storage with ۶۵±۵ percent relative humidity. Illustrates the changes in LT۵۰ as affected by changes in citrus lipid peroxidation, ion leakage and total flavonoid at +۴ °C and –۴ °C. According to the regression coefficient, a change of one unit in lipid peroxidation led to a ۱.۹۲۳۸ and ۵.۹۶۱۵ unit decrease in LT۵۰ at +۴ and –۴ °C, for ion leakage led to ۰.۱۶۶۱ and ۰.۳۵۸۷ unit changes in LT۵۰ at +۴ and –۴ °C and for total flavonoid led to a ۰.۰۴۷۱ and ۰.۲۳۶ unit decrease in LT۵۰ at +۴ and –۴ °C, respectively. According to the results of the present study which involved the selection of commercial citrus cultivars of Japanese mandarin, Thomson orange, Ruby Star grapefruit and Lisbon lemon in terms of stress tolerance and other traits, ...

Keywords:

citrus , multivariate statistics , Regression , Low temperature , LT۵۰