SOME PHYSIOLOGICAL-RESPONSES OF THEOBROMA-CACAO VAR CATONGO SEEDLINGS TO AIR HUMIDITY
SOME PHYSIOLOGICAL-RESPONSES OF THEOBROMA-CACAO VAR CATONGO SEEDLINGS TO AIR HUMIDITY
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DOI：
10.1111/j.1469-8137.1987.tb02929.x
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发表时间：
1987-11-01
期刊：
影响因子：
9.4
通讯作者：
REICH, PB
中科院分区：
文献类型：
--
作者：
GOMES, ARS;KOZLOWSKI, TT;REICH, PB
摘要三个月大的可可树幼苗的气孔。 var.Catongowe 在高相对湿度 (RH)（76 至 89%）下比在低相对湿度（39 至 62%）下更开放。在这两种情况下，气孔在白天逐渐关闭，下午晚些时候关闭速度加快。蒸腾率（TR）在当天早些时候相应地较高，而在当天晚些时候则较低。在高相对湿度下，平均叶片扩散阻力 (r1) 降低 26%。尽管如此，低相对湿度下的植物的 TR 通常较高，因为叶子和空气之间的蒸气压梯度要大得多。中午突然降低相对湿度迅速增加（r1），增加相对湿度则降低r1。在恒定高或低相对湿度条件下进行的另一项实验中，在高相对湿度条件下，r1较低，净光合作用速率（Pn）较高，叶水势（Φ）较低（更负），TR较低。高相对湿度下的水分利用效率（WUE）高于低相对湿度下的水分利用效率（WUE）。在高相对湿度和低相对湿度下，Pn 和 r1 之间的关系相同。因此，高与低相对湿度下 TR 和 WUE 的差异是两种湿度状态之间蒸气压赤字 (VPD) 变化的直接结果。气孔的打开和关闭反映了湿度对保卫细胞的直接影响，而不是对大叶 Φ 变化的反应。此外，根至叶的水力传导率在低相对湿度下明显大于在高相对湿度下。
SummaryThe stomata of three‐month‐old seedlings ofTheobroma cacaoL. var.Catongowere more open in high relative humidity (RH) (76 to 89%) than in low relative humidity (39 to 62 %). In both regimes, stomata closed gradually during the day, with the rate of closure accelerating in the late afternoon. Transpiration rate (TR) was correspondingly high early in the day and low late in the day. Average leaf diffusive resistance (r1) was 26% lower at the high RH. Nonetheless, TR was generally higher for plants in the low RH, because of the much greater vapour pressure gradient between the leaf and air. Abruptly lowering the RH at noon rapidly increased (r1) and increasing RH decreased r1, In another experiment conducted in constant high or low RH regimes, r1was lower, the rate of net photosynthesis (Pn) was higher, leaf water potential (Φ) was lower (more negative), and TR was lower in the high RH regime. Water‐use efficiency (WUE) was higher in high than in low RH. The relationships betweenPnand r1were identical at high and low RH. Thus, differences in TR and WUE at highvslow RH were a direct result of variations in vapour pressure deficit (VPD) between the two humidity regimes. Stomatal opening and closing reflected direct effects of humidity on guard cells rather than responses to changes in bulk leaf Φ. In addition, root to leaf hydraulic conductivity apparently was greater at low than at high RH.