The Response of Aboveground Growth, Leaf Gas Exchange, and Water Use Efficiency of the Common Fig (Ficus carica L.) to Salinity Stress

無花果地上部生長、葉片氣體交換及水分利用效率對鹽害逆境之反應

The cultivation of figs (Ficus carica L.) in Taiwan has been exclusively for fresh markets and completely relied on protected cultivation to avoid the undesirable high precipitation. However, high evapotranspiration, over-fertilization and the lack of nature flushing cause salt accumulation in the soil, thus hindering growth and production. In this study, three concentrations [0%, 0.1% and 0.7% (wt/medium wt.) NaCl] were applied to container-grown '' Noire de Caromb fig. Aboveground growth and leaf gas exchange were measured after salinity treatments. Data from net assimilation rate (A) against intercellular CO2 concentration (Ci) were fitted to FvCB biochemical model. The salinity treatment with 0.1% NaCl slightly reduced the length of shoots and the number of leaves but 0.7% NaCl treatment significantly suppressed the length of shoots and number of leaves, new leaf size, and total leaf area. No difference in photosynthesis among treatments was detected through the 95-day salinity stress period. Significant reduction in stomatal conductance (gs) and transpiration rate (E), and consequent improving intrinsic water use efficiency (WUEi) were detected at 10 days after treatment (DAT) in plants subjected to 0.7% NaCl. However, the regulation of gs and the positive response of WUEi appeared temporarily and diminished thereafter. FvCB model fitting outputs showed that photosynthesis efficiency was reduced at 95 days in 0.7% NaCl treatment, due to suppressed maximum rate of rubisco regeneration (Vcmax) and maximum rate of electron transport (Jmax).

臺灣生產無花果為鮮食市場導向，為避免高降雨量影響生長發育及果實品質，全數於設施中栽培。 設施內高蒸散作用、過度施肥，以及缺乏天然雨水淋洗，常導致土壤鹽份累積，影響植株生長及產量。 本試驗以 0%, 0.1%, 或 0.7% （介質重量百分比）之氯化鈉（NaCl）水溶液，澆灌盆植‘Noire de Caromb’無花 果植株，測量處理後地上部生長及氣體交換指標，並將光合作用量測數據以 FvCB 生化模式進行擬合， 探討鹽逆境對無花果生長及葉片氣孔及光合生化調控能力之影響。0.1% NaCl 之鹽逆境對枝條及葉片發 育影響輕微，但 0.7% NaCl 之鹽逆境對植株地上部之生長造成顯著且持續性的抑制。在 95 天的試驗期 間，處理間淨光合作用速率並無顯著差異，但植株於 0.7% NaCl 之鹽逆境處理 10 天後，氣孔導度及蒸散 作用速率顯著下降，因而實質水分利用效率（WUEi）顯著提高，惟此一因應鹽逆境之氣孔調控及 WUEi 上 升乃暫時性,之後即消失。FvCB 模式擬合顯示，植株於 0.7% NaCl 之鹽逆境處理 95 天後，淨光合作用效 率降低，光合生化作用中之最大羧化速率（Vcmax）及最高電子傳遞速率（Jmax）皆受到抑制。