Tropical Research and Education Center, University of Florida, 18905 S.W. 280 St., 33031, Homestead, FL, U.S.A..
Photosynth Res. 1987 Jan;11(3):245-51. doi: 10.1007/BF00055064.
Taro and cocoyam were grown outdoors in either full sun or under 40% shade. Leaves were tagged as they emerged and the effect of leaf age on net CO2 assimilation rate (A) was determined. The effects of shading on A, transpiration (E), stomatal conductance for CO2 (gc) and H2O (gs), and water use efficiency (WUE) were also determined for leaves of a single age for each species. The effect of leaf age on A was similar for both species. Net CO2 assimilation rates increased as leaf age increased up to 28 days with the exception of a sharp decline in A for 21 day-old leaves which corresponded to unusually low temperatures during the period of leaf expansion. A generally decreased as leaves aged beyond 28 days. Cocoyam had higher A rates than taro. Leaves of shade-grown plants had higher rates of A and E for both species at photosynthetic photon flux densities (PPFD) up to 1600 μmol s(-1) m(-2). Shade-grown leaves of cocoyam had greater leaf dry weights per area (LW/A) and a trend toward higher gc and gs than sun-grown leaves. Shade leaves of taro had greater gc and g3 rates than sun-grown leaves. The data suggest that taro and cocoyam are highly adapted to moderate shade conditions.
芋和魔芋在全日照或 40%遮荫下室外种植。叶子长出后贴上标签，确定叶片年龄对净 CO2 同化率 (A) 的影响。还确定了单叶龄的遮荫对 A、蒸腾 (E)、CO2 的气孔导度 (gc) 和 H2O (gs) 以及水分利用效率 (WUE) 的影响。两种植物的 A 随叶片年龄的变化规律相似。净 CO2 同化率随叶片年龄的增加而增加，直到 28 天，但 21 天龄叶片的 A 急剧下降，这与叶片扩展期间异常低的温度相对应。A 通常在 28 天之后随叶片老化而降低。魔芋的 A 率高于芋头。在光合光子通量密度 (PPFD) 高达 1600 μmol s(-1) m(-2)时，遮荫和阳光种植的两种植物的叶片 A 和 E 速率均较高。与阳光种植的叶片相比，遮荫种植的魔芋叶片每单位面积的干重 (LW/A) 更高，gc 和 gs 也有升高的趋势。与阳光种植的叶片相比，遮荫种植的芋头叶片的 gc 和 gs 更高。数据表明，芋头和魔芋高度适应中度遮荫条件。
