不同氮营养水平下草莓叶片光合作用对高CO2浓度的适应

研究了不同氮素水平（12mmol／L，4mmol／L，0、4mmol／L）下生长的‘丰香’草莓在富C02（700μL/L）和大气CO（390μL/L）下的光合作用。结果表明，高氮（12mmol／L）下，在富CO2环境中生长的‘丰香’草莓叶片未出现光合作用下调，富CO2下草莓叶片的净光合速率、最大羧化速率（Vc.max）、最大电子传递速率（Jmax）、碳同化的电子传递速率（Jc）和光化学猝灭系数（qp）等均显著提高；而在中氮（4mmol／L）、低氮（0．4mmol／L）下，富CO2下生长的草莓叶片的上述参数均出现不同程度的下降。富CO2下，无论氮素水平如何，草莓叶片的光呼吸电子传递速率（Jo）均降低高氮草莓叶片的非光化学猝灭系数（qN或NPQ）降低，光抑制降低，而低氮则相反。上述结果说明，氮素供应不足时草莓叶片在富CO2下光合作用出现下调，因此生产上进行CO2施肥时应适度增加氮素的供应。

Photosynthetic Acclimation to Elevated CO2 in Strawberry Leaves Grown at Different Levels of Nitrogen Nutrition

Photosynthetic characteristics of strawberry (Fragaria ananassa Duch cv. 'Toyonoka') leaves grown in either elevated CO(2) (700 microL/L) or ambient CO(2) (390 microL/L), and at three levels of nitrogen nutrition (12 mmol/L, 4 mmol/L, 0.4 mmol/L) were studied. The results showed that for strawberry grown in 12 mmol/L nitrogen, P(n), maximal carboxylation rate (V(c, max)), maximal linear electron flow through photosystem II (J(max)), electron flow to the photosynthetic carbon reduction cycle (J(c)) and q(P) were all significantly higher in plants grown and measured at elevated CO(2) than for plants grown and measured at ambient CO(2) (Table 1 and 2, Fig. 2), which were due to a significant increase in J(c) exceeding any suppression of electron flow to the photorespiratory carbon oxidation cycle (J(o)). This increase in photochemistrical quenching with decreased non-photochemistrical quenching (q(N) or NPQ) at elevated CO(2) alleviated photoinhibition by high light (Table 2, Fig. 3). For plants grown at 4 mmol/L and 0.4 mmol/L nitrogen, P(n), V(c, max), J(c) and q(P) were all significantly lower in plants grown and measured at elevated CO(2) than for plants grown and measured at ambient CO(2) (Table 1 and 2, Fig. 2). Consistent with decreased photochemistrical quenching and increased non-photochemistrical quenching (q(N) or NPQ), for leaves grown at 4 mmol/L and 0.4 mmol/L nitrogen, the photoinhibition was aggravated by elevated CO(2) (Table 2, Fig. 3). Elevated CO(2) suppressed J(o) in leaves of plants grown at 12 mmol/L, 4 mmol/L and 0.4 mmol/L nitrogen (Fig. 2). The results above suggested that deficient nitrogen (4 mmol/L and 0.4 mmol/L nitrogen) and elevated CO(2) result in an acclimatory decrease of photosynthesis in leaves of plant grown in elevated CO(2).