The sensitivity of radish cultivars to high temperatures during germination and seedling growth stages
Abstract
A laboratory experiment was conducted at constant temperatures of 20, 23, 26, 29, 32, 35, 38, and 41℃ to identify the response of six radish cultivars with different root sizes and colors to high-temperature stress during germination, emergence, and early seedling growth stage. Also, the optimal temperature was determined by calculating the relationship between seedling length and temperature via a polynomial regression model. The results showed that no seed germination was detected at 41℃, while emergence and seedling growth were not observed at 38℃ and above. Similar germination percentages, mean germination time, and germination index were obtained between 20℃ and 35℃. The root length reduced at 32℃ and it was more sensitive to high temperatures than shoots because the root/shoot length ratio showed a decreasing trend by increasing temperatures and longer root length was recorded at lower temperatures than 32℃. There were genotypic variations among radish cultivars for temperatures and ‘Kırmızı İnci’, ‘Beyaz İnci’, and ‘Siyah İnci’ produced a better performance than the others under high temperatures. The regression analysis predicted the optimal temperatures as 21.5℃ and 22.6℃ for root and shoot length, respectively. This study indicates that high temperatures inhibited seedling growth rather than seed germination performance of radishes.
Keywords
Raphanus sativus L., germination, seedling growth, high temperature
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