Study on Cold Tolerance Identification Indices for Bitter Gourd Germplasms

The selection of cold tolerance identification indices for bitter gourd germplasms is an important basis for the breeding of cold-tolerant bitter gourd varieties. In this study, with six bitter gourd germplasms as experimental materials, the cold injury index of bitter gourd was analyzed under low temperature treatment, the changes in physiological indices were revealed, and the main agronomic traits were measured. The results showed that the cold injury index of bitter gourd was in very significant negative correlation with SOD activity, POD activity and PRO content, in significant negative correlation with CAT activity, in very significant negative correlation with flowering node and commodity rate, but in significant positive correlation with female flower ratio. It was found that that cold injury index, SOD activity, POD activity, CAT activity and PRO content could serve as the cold tolerance identification indices for bitter gourd at seedling stage, and flowering node and commodity rate could be used as the auxiliary indices for field cold tolerance identification.

Identification and Evaluation of Cold Tolerance in Bitter Gourd (Momordica charantia L.) at Bud and Seedling Stages under Different Temperature Conditions

[ Objectives] This study was conducted to screen the temperature index most suitable for identification of cold tolerance in bitter gourd （Momordica charantia L. ） at bud and seedling stages. [ Methods] With six different bitter gourd germplasms as experimental materials, the cold tolerance at bud and seedling stages were identified and evaluated. [ Results] At 18℃ , the largest change range of germination potential among different gernlplasms was 11.3% -96.0%, and the largest change range of germination rate was 13.3% - 100.0% ; and the six germplasms could be divided into three grades of cold tolerance. Therefore, 18 9C is an ideal temperature for the identification of cold tolerance in bitter gourd germplasms at bud stage. At 20℃, the cold tolerance in bitter gourd germplasms at bud stage could also be divided into three grades, and the change ranges of germination potential and germination rate were larger than 50.0%, so 20℃ could serve as the candidate temperature for the identification of cold tolerance in bitter gourd germplasms at bud stage. After 1 d of treatment at 6℃, the six bitter gourd germplasms could be divided into three grades, and the cold injury index had the largest range of 20.31 - 84.38 and could serve as the temperature index for the identification of cold tolerance in bitter gourd at seedling stage. [ Conclusions] This study will provide reference for the identification of cold tolerance in bitter gourd at bud stage and seedling stage.

Comparison of methods for identification of cold tolerance of rice

Under low temperature stress,theplasmamembrane and chloroplast of plant cellsare impaired,resulting in electrolyte leakage and al-teration of chlorophyll fluorescence which can bemeasured with conductometer and fluoremeter.The cold tolerance of excised leaves of several ricevarieties were determined with these two instru-ments at seedling and heading stages to compare