Abstract
Two experiments were conducted to study the effect of temperature during developmental stages of inflorescence on flower bud abortion in Gymnaster savatieri Kitamura.
Plants were grown for 4 weeks from Feb. 2 to Mar. 9 in natural light phytotrons in which day temperature was set at 25, 30 or 35°C, while night temperature was kept constant at 5°C. Temperatures above 30°C markedly induced flower bud abortion of blindness type (characterized by necrotic disk and ray florets), entire necrosis of disk florets type (characterized by necrotic disk florets and undeveloped ray florets) and partial necrosis of disk florets type (characterized by central disk floret necrosis and well-developed ray florets) .
Plants were placed in a natural light phytotron at 33/28°C (day/night) from inflorescence developmental stages until flowering. The type of abortion induced was dependent on the developmental stage of high temperature treatment. Blindness type occurred from the involucre stage to the late stage of petal formation. The percentage of blindness type was high from the involucre stage to the middle stage of petal formation. Entire necrosis of disk florets type occurred from the late stage of petal formation to the complete stage of petal formation. Partial necrosis of disk florets type occurred from the late stage of petal formation to the budding stage. The percentage of partial necrosis of disk florets type was high when the petal formation stage was complete.
