Studies On The Physiological And Biochemistry Of Freesias During Senescence Process

Freesia×hybrida, which belongs to Iridaceae family, is one of the famous perennial corm plants, being used as a popular cut flower and an important potted plant around the world. Freesias were valued for their wide color range, flower scent, long vase-life, and beautiful posture. But their tepals were easily wilted and the tepals'color deteriorated, afftecting their ornamental value. Therefore, how to lengthen the vase life of the Freesias is becoming one of the limits for its further development.The works in this thesis were focused on the respiration changes and several physiological and biochemical factors in two Freesia cultivars, Freesia×hybrida'Shangnong Jinhuanghou'and Freesia×hybrida'Shangnong Hongtaige', during the flower developmental process. The aim of this study is to know the physiological metabolisms of Freesias.The main results showed as follows:1. The mean vase life of flowers from'Shangnong Jinhuanghou'were longer than that from'Shangnong Hongtaige'.2. The respiratory climacteric was existed in the both cultivars during the flower senescence, and some differences on the change trend of respiration rate were observed in two Freesias. The tepal and the whole flower displayed the same respiratory rate rules, but the pistil's respiratory rate change was different by the varieties. The results of correlation analysis of the whole flower and the organs showed that the whole respiratory was mainly decided by the tepal's respiratory rate.3. During the flower senescence, the soluble protein and sugar contents peaked at the early development stage then decreased dramatically and reached the bottom at the last stage. Meanwhile, a significant different on protein content was also observed between two cultivars. The correlation analysis showed that, the change of the soluble sugar and the soluble protein content were consistent, explained that between them had no or very little transforms.4. The electrolytic leakage and MDA content increased as the progress was developing in tepal tissues of both cultivars. However, MDA content in'Shangnong Hongtaige'was much higher than that in'Shangnong Jinghuanghou'at the same stage. The correlation analysis showed that, the electrolytic leakage and MDA content were strongly related. 5. SOD activity in two cultivars showed an early increasing and later decreasing trend during the senescing process. Meanwhile, SOD activity in cultivar'Shangnong Jinghuanghou'was significant higher than that in'Shangnong Hongtaige'. The activity of POD showed a gradual increasing before tepal wilting and decrease at wilted tepal for both cultivars. The time of initial decreasing point of POD activity appeared later than that of SOD. A higher POD activity also appeared in cultivar'Shangnong Jinghuanghou'. SOD activity higher in the earlier period, and the absolute value of correlation coefficient of SOD is greater than that of POD.6. The anthocyanidin content in the tepal of'Shangnong Hongtaige'presented a quick-slow-quick growth pattern as the senescence.