Abstract:

To study the adaptability of different Bougainvillea varieties under low temperature, 7 kinds of healthy and mature Bougainvillea plants ‘Brazil Purple’, ‘Mosaic Red’, ‘Green Cherry’, ‘Yunnan Purple’, ‘Pearl White’, ‘Lemon Yellow’ and ‘Chinese Red’ of two-year-old were used as the experimental materials to determine the content of malondialdehyde (MDA), proline, soluble protein and hydrogen peroxide (H₂O₂) and the generation rate of superoxide radicals (O₂ ^·-) and the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) during the natural overwintering process. The results showed that the content of MDA, proline, soluble protein and H₂O₂ of different Bougainvillea varieties had significantly different variation trends during the natural overwintering period. The proline content of ‘Lemon Yellow’ showed a gradual decrease with the decrease of temperature; that of ‘Green Cherry’ and ‘Brazil Purple’ decreased first and then increased with the decline of natural temperature. The H₂O₂ content of ‘Brazil Purple’, ‘Mosaic Red’, ‘Green Cherry’ and ‘Yunnan Purple’ all had an increase-decrease-increase-decrease trend as the temperature decreased during the winter. The POD activity of ‘Yunnan Purple’ first increased and then decreased; while the POD activity of ‘Chinese Red’ showed a gradual decrease as the temperature decreased. Therefore, the low temperature adaptability of different Bougainvillea varieties is indeed very different, ‘Chinese Red’, ‘Brazil Purple’ and ‘Lemon Yellow’ show a strong low temperature adaptability; ‘Green Cherry’ and ‘Yunnan Purple’ have a weak low-temperature resistance, but they could survive safely overwintering, while ‘Mosaic Red’ and ‘Pearl White’ need to have leaf fall to adapt to the low temperature environment during the winter.

Key words: Bougainvillea, overwintering, low temperature, soluble protein, antioxidant enzymes