Wiebel J, Eamus D, Chacko E K, Downton W J, Lüdders P
CSIRO, Division of Horticulture, Private Mail Bag 44, Winnellie, NT 0821, Australia.
Tree Physiol. 1993 Jul;13(1):55-69. doi: 10.1093/treephys/13.1.55.
Gas exchange responses of mangosteen (Garcinia mangostana L.) leaves to photosynthetic photon flux density (PPFD), internal CO(2) concentration (C(i)), leaf-air vapor pressure deficit (VPD), leaf temperature (T(l)) and time of day were investigated in plants grown in three shade treatments. Maximal photosynthetic rate (P(n(max))) per unit leaf area at light saturation did not differ significantly among plants grown in the different shade treatments despite significant morphological differences. Light compensation point (9-15 micro mol m(-2) s(-1)) and quantum yield (0.022-0.023) did not differ significantly among treatments, whereas light saturation point was significantly higher for leaves grown in 20% shade than for leaves grown in 50 or 80% shade (951, 645 and 555 micro mol m(-2) s(-1), respectively). Shade treatments significantly affected assimilation responses to varying CO(2) concentrations. At CO(2) concentrations between 600 and 1000 micro mol mol(-1), leaves from the 20% shade treatment recorded higher P(n) (6.44 micro mol m(-2) s(-1)) than leaves from the 80% shade treatment (4.57 micro mol m(-2) s(-1)). Stomatal conductance (g(s)) decreased with increasing CO(2) concentrations. Vapor pressure deficits higher than 2.5 kPa significantly decreased P(n) and g(s), whereas P(n) remained steady over a 24-33 degrees C temperature range in leaves in 80% shade and over a 27-36 degrees C range in leaves in 20 and 50% shade. Highest carbon gain during a 12-hour photoperiod was observed for leaves grown in 50% shade. The results imply that mangosteen is a shade-tolerant, lower canopy tree adapted to humid tropical lowlands. Providing low VPD in the nursery may result in maximal growth. However leaves of seedlings grown in 50 or 20% shade tolerated high VPD and temperatures better than leaves of seedlings grown in 80% shade, indicating some adaptability to the seasonally wet and dry tropics of northern Australia.
在三种遮荫处理下生长的山竹（Garcinia mangostana L.）植株中，研究了其叶片对光合光子通量密度（PPFD）、胞间二氧化碳浓度（C(i)）、叶-气蒸气压亏缺（VPD）、叶片温度（T(l)）和一天中不同时间的气体交换响应。尽管形态上存在显著差异，但在不同遮荫处理下生长的植株，其在光饱和时单位叶面积的最大光合速率（P(n(max))）并无显著差异。各处理间的光补偿点（9 - 15微摩尔·米⁻²·秒⁻¹）和量子产额（0.022 - 0.023）无显著差异，然而，生长在20%遮荫条件下的叶片的光饱和点显著高于生长在50%或80%遮荫条件下的叶片（分别为951、645和555微摩尔·米⁻²·秒⁻¹）。遮荫处理显著影响了对不同二氧化碳浓度的同化响应。在二氧化碳浓度为600至1000微摩尔·摩尔⁻¹之间时，20%遮荫处理的叶片的净光合速率（P(n)）（6.44微摩尔·米⁻²·秒⁻¹）高于80%遮荫处理的叶片（4.57微摩尔·米⁻²·秒⁻¹）。气孔导度（g(s)）随二氧化碳浓度升高而降低。蒸气压亏缺高于2.5千帕时，显著降低P(n)和g(s)，而在80%遮荫的叶片中，P(n)在24 - 33摄氏度温度范围内保持稳定，在20%和50%遮荫的叶片中，P(n)在27 - 36摄氏度范围内保持稳定。在12小时光周期内，50%遮荫条件下生长的叶片碳积累最高。结果表明，山竹是一种耐荫的下层冠层树种，适应潮湿的热带低地。在苗圃中提供低VPD可能会使生长最大化。然而，50%或20%遮荫条件下生长的幼苗叶片比80%遮荫条件下生长的幼苗叶片更能耐受高VPD和高温，这表明其对澳大利亚北部季节性干湿热带地区具有一定的适应性。
