臺灣數種果樹生理特性之研究第一報：柑橘及荔枝之氣孔開閉習性吸水作用及蒸散作用之研究

Studies on the Physiological Characteristics of Several Fruit Trees in Taiwan-- A Study of the Stomatal Behaviour, Water Absorption and Transpiration in Citrus and Litchi

為瞭解本省果樹之氣孔開閉習性，吸水特性及蒸散作用，曾以2、3年植株為材料，進行比較研討，茲摘要所得結果如下：1.在自然光下，椪柑及桶柑之氣孔開度均有明顯的日變化。在陰、雨天，氣孔開度均減少，但以椪柑較著。又椪柑氣孔有明顯的日間閉孔（midday closure），而桶柑氣孔此現象極輕微。2.在人工控制生長室內之固定光度、溫度及濕度下，氣孔仍有明顯的日變化。3.椪柑被移進人工控制生長室經一段時間後，其氣孔之開啟運動得以人工光源控制。4.椪柑之氣孔開啟運動受土壤含水量及氣溫之顯著影響外，其開啟能力亦有葉令間之差異。5.經斷水後，椪柑之氣孔開度顯示有最適宜土壤水分域存在。且開度減半點出現於水分當量與凋萎係數之中央附近，而在凋萎係數時氣孔尚未完全失去開啟機能。6.蒸散作用與氣孔開度在一日間之變化情形極相似，惟在陰雨天時，蒸散所受影響較氣孔之場合為顯著。7.椪柑、桶柑及荔枝之吸水日變化均有果樹間之差異，其在陰雨天之減少程度，以椪柑最著，而荔枝最小。8.吸水在一年中之變化情形亦有果樹間之差異，即不僅吸水開始增加時期不同，最大吸水期之出現時期亦不同，如椪柑及桶柑之最大吸水期為九月，而荔枝為七月。9.吸水與葉數及蒸發量之相關係數為：椪柑之吸水與葉數之r=0.96；椪柑之吸水與蒸發量之r=0.39；桶柑之吸水與葉數之r=0.92；桶柑之吸水與蒸發量之r=0.67；荔枝之吸水與葉數之r =0.89荔枝之吸水與蒸發量之r=0.37。顯示地上部之大小對吸水具較大作用。此數值又因土壤含水量不同而發生明顯差異。

In order to understand the stomatal behaviour, the characteristics of water absorption and transpiration of several fruit trees in Taiwan were observed. Three years old of Ponkan, Tonkan and Litchi trees were prepared for a comparative observation. The results obtained are summarized as follows: 1. Under the natural conditions, the daily varietions of stomatal aperture in Ponkan and Tankan were apparently. In rainy days the stomatal aperture of both fruit trees decreased. It was rather significant in Ponkan than that in Tankan. In addition, a midday closure occured obviously in Ponkan's stomata andthis phenomenon appeared slightly in the case of Tankan. 2. In the growth chamber, under the given light intensity, temperature and humidity, the stomatal behaviour was still found to appear obvious daily varietion. 3. After the Ponkan plant was moved into gro wth chamber for a period of time, the stomatal opening could be controlled be the artificial light supplied. 4. The opening movement of stomata in Ponkan was significantly affected by the soil moisture as well as the temperature. And the opening capacity also varied with leaf age. 5. The stomatal aperture of Ponkan under water shortage showed the existence of a optimal soil moisture range. And the point of half of the stomatal opening appeared near the middle portion between the moisture equivalent and the wilting coefficient. However, the stomata had not lost their opening function yet as the soil moisture reached the wilting coefficient. 6. The dailv varietions of transpiration occurred was similar to that of the stomatal aperture, but as the weather became cloudy or rainy, its influence on transpiration was more significant than that of stomatal aperture. 7. The daily varietions of water absorption in Ponkan and Litchi evenly appeared the differences among them. The magnititude of decrement of water absorption on cloudy-rainy days was most significant in Ponkan and least in Litchi. 8. The varietions of water absorption durina the year were also different among the fruit trees mentioned above, i. e. the differences occurred not only in the stage at which the water absorption begins to increase but also in the stage at which a maximum water absorptioin period appers. It showed that, forexample, the maximum water absorpton period of Ponkan and Tankan appeared in September but that of Litchi in July. 9. The correlation coefficient (r) between the water absorption and leaf number, and between the water absorption and atmometer evaporation among the fruit trees tested are listed as follows: In Ponkan, the r was 0.96 between the water absorption and leaf number, was 0.39 between the water absorption and atmometer evaporation. In Tankan, the r was 0.92 between the water absorption and leaf number and was 0.67 between the water absorption and atmometer evaporation. In Litchi, the r was 0.89 between the water absorption and leaf number and was 0.37 between the water absorption and atmometer evaporation. But, all the r values would proceed to change and appeared the apparent differences due to the different soil moisture (Table 5).