溫度對鳥梨幼年植株針狀枝形成數量之影響

Effect of Temperature on Number of Thorns of Bird Pear (Pyrus sp.)

將採自大湖系與卓蘭系兩地開放授粉的鳥梨種子播種後產生之實生苗盆栽各20盆，置於30/25℃、25/20℃、20/15℃、15/13℃下，並以自然生長環境為對照，以瞭解溫度對鳥梨實生苗針狀枝發生及其他性狀之關係。卓蘭與大湖二系之對照植株的針狀枝數均少於15/13℃及20/15℃處理者，在大湖系中，15/13℃及20/15℃處理的植株，針狀枝的量顯著高於其他三處理。卓蘭系植株的針狀枝，以15/13℃處理者顯著高於其他處理；20/15℃下的針狀枝略低於15/13℃處理者，與對照組差異不顯著，但顯著高於其它處理。由於其他植株性狀在處理間均達到顯著差異水準，將單位植株生長量產生的針狀枝數比較，其結果在處理間仍達顯著差異水準。由此可看出鳥梨實生苗在低溫狀態下，有利於針狀枝的形成，少針狀枝的系統尤其明顯。將植株的性狀與針狀枝間進行相關分析，顯示少針狀枝系統在自然狀況下針狀枝與株高及其他性狀呈顯著正相關，多針狀枝的系統則相關性不佳。在低溫條件下，針狀枝與其他植株性狀多呈顯著正相關。因此，在低溫下，鳥梨實生苗具有較多的針狀枝，且此性狀與株高相關性良好，足以作為株高的判別依據。

Treated two different populations of the bird pear seedlings of Taiwan, which were collected from Da-hu and Chuo-lan, under the temperature (day/night) of 30/25℃, 25/20℃, 20/15℃, and 15/13℃, and the natural grown plant as a control in order to compare the number of thorns from each plant and the relationship between the plant characters and the thorns. The results showed that the number of thorns increased as the temperature decreased. The control had the amount of thorns equivalent to plants grown between 20/15℃, 25/20℃. For Da-hu line, the number of thorns was significantly higher under the temperatures of 15/13℃, and 20/15℃ than under the other three conditions. For Chuo-lan line, the thorns were significantly higher under the temperature of 15/13℃, as compared to plants grown under natural environments as well as the other three conditions (with the exception of 20/15℃ to which 15/13℃ had only slightly larger number of thorns). Although there was a significant difference among the plant height, number of nodes, internode length, and trunk diameter could be found between the five different conditions under which these plants were grown. But when compared the number of thorns along with the other factors, i.e., thorn/plant eight, thorn/number of nodes, thorn/internode length, thorn/trunk diameter, results showed that the comparisons of thorns were comparatively closer to each other. This showed that the cooler the temperature was, the more advantageous it was to the growth of the thorns of bird pears. A regressive analysis of thorns and other factor showed that there was a good correlation between them, especially the plant height, but in thornily treatment, the fewer the thorns, the worse the correlation. From this, it could be concluded that temperature had a great influence on the growth of thorns of spears of the bird pears, especially under lower temperature. In such conditions, the number of thorns per plant showed a good correlation to plant heights. Thorns will be a good selection index of bird pears for plant height.