Preventive mechanisms of gibberellin4+7 and light on low-temperature-induced leaf senescence in Lilium cv. Stargazer
Anil P. Ranwala and William B. Miller
Postharvest Biology and Technology Vol: 19 Issue: 1 Pages: 85-92.
2000
บทคัดย่อ
Lilium cv. Stargazer plants were held for 2 weeks at 4°C,
either in darkness or in light (40 mol
m-2 s-1). Another series of plants was held in darkness after
pre-treatment with 100 mg l-1 GA4+7. Changes in major
senescence parameters were determined during storage at 4°C
and during 6 days after transferring the plants to 22°C. Foliar
sprays of GA4+7 or supplemental light prevented rapid leaf
senescence induced by dark low-temperature storage. During storage at 4°C,
basal leaves showed no significant changes in concentrations of chlorophyll,
soluble proteins, lipid peroxidation, and activity of catalase. However,
shifting from 4 to 22°C induced a series of changes in basal leaves of
dark-held plants including rapid loss of chlorophyll, proteolysis, increased
lipid peroxidation and loss of catalase activity. Both light and GA4+7
treatments prevented these changes. Total soluble carbohydrates decreased
gradually during 4°C dark storage and after transferring to 22°C.
GA4+7 treatments did not prevent the decline in carbohydrate levels
at 4°C,
but prevented it upon transferring to 22°C. Supplemental light during
4°C
storage significantly increased soluble carbohydrate concentration. The abrupt
increases in metabolic activities by shifting from 4 to 22°C
accompanied by oxidative stress in leaves already depleted in reserves during 4°C
storage seem to induce leaf senescence in dark-held plants.