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    光强对雪茄叶片光合及叶绿素荧光特性的影响

    Effect of Light Intensity on Photosynthetic and Chlorophyll Fluorescence Characteristics of Cigar Leaves

    • 摘要: 为阐明光照强度对雪茄叶片光合及叶绿素荧光特性的影响,以雪茄品种古引4号为试验材料,设置高光强(T300)和低光强(T100)两个处理,分别于第10叶位可见12、20、28 d测定其光合和叶绿素荧光特性,并测定叶片定长时生物量。结果表明:叶片可见12 d,T300净光合速率、气孔导度、蒸腾速率显著高于T100(p<0.05),增幅86.3%、69.3%、60.2%;T300叶绿素a、叶绿素b、叶绿素总含量、叶绿素a/b显著高于T100,增幅为29.8%、16.8%、25.3%、15.7%;T300叶片净光合速率在光合有效辐射200~1800 µmol/(m2·s)时显著大于T100,最大净光合速率、光饱和点分别显著高于T100 87.7%和20.3%( p<0.05),PSII实际光量子产量显著高于T100 51.3%(p<0.05),非光化学猝灭系数显著低于T100 55.8%,T300总体光合能力高于T100处理。叶片可见20 d,随叶片生长,T100净光合速率、叶绿素含量、最大净光合速率、PSII实际光量子产量等均有较大增长,与T300差距缩小,二者差异不明显;但T300光饱和点显著高24.2%(p<0.05),光补偿点显著低28.6%(p<0.05)。叶片可见28 d,T300净光合速率、最大净光合速率和叶绿素含量与T100无显著差异,但非光化学淬灭系数和光化学淬灭系数较T100显著高13.4%、23.8%(p<0.05);光合-光响应曲线也显示,T300净光合速率在光合有效辐射1500~1800 µmol/(m2·s)范围内显著低于T100。定长后,T300叶片鲜质量、干质量显著高于T100,36.4%和115.4%。可见,在雪茄叶片发育前期强光处理下叶片光合能力显著更高,在叶片发育中期强光与弱光的差异减小,后期T300对强光的利用能力较T100减弱,但综合而言,T300净光合速率更高,更有利于烟叶干物质积累。

       

      Abstract: To elucidate the effects of light intensity on photosynthetic and chlorophyll fluorescence characteristics of cigar leaves, a study was conducted using the cigar variety “Guyin No.4” as the experimental material. Two treatments were applied: high light intensity (T300) and low light intensity (T100) . Measurements of photosynthetic and chlorophyll fluorescence characteristics were measured at 12, 20, and 28 days after the 10th leaf position became visible, and the biomass was determined when the leaves reached full length. At 12 days post-leaf emergence, T300 exhibited significantly higher net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) compared toT100 (p<0.05), with increases of 86.3%, 69.3%, and 60.2%, respectively. T300 showed significantly higher chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll content, and Chl a/b ratio than T100, with increases of 29.8%, 16.8%, 25.3%, and 15.7%, respectively. Under photosynthetic active radiation (PAR) of 200-1800 µmol/(m2·s), the Pn of T300 was significantly higher than T100. The maximum net photosynthetic rate (Pnmax) and light saturation point (LSP) of T300 were 87.7% and 20.3% higher than T100 (p<0.05). The actual photochemical quantum yield of PSII (ΦPSII) in T300 was 51.3% higher than T100 (p<0.05), while the non-photochemical quenching coefficient (NPQ) was 55.8% lower, indicating superior overall photosynthetic capacity in T300. At 20 days post-leaf emergence, with leaf maturation, T100 showed substantial increases in Pn, chlorophyll content, Pnmax, and ΦPSII, narrowing the gap with T300, with no significant differences between treatments. However, T300 maintained a 24.2% higher LSP and 28.6% lower light compensation point (LCP) than T100 (p<0.05). At 28 days post-leaf emergence, no significant differences were observed between T300 and T100 in Pn, Pnmax, and chlorophyll content. T300 displayed 13.4% higher NPQ and 23.8% higher photochemical quenching coefficient (qP) than T100 (p<0.05). The photosynthetic light-response curve revealed that Pn of T300 was significantly lower than T100 under PAR of 1500-1800 µmol/(m2·s). T300 had 36.4% higher fresh weight and 115.4% higher dry weight than T100 (p<0.05) at full leaf length. High light intensity (T300) significantly enhanced photosynthetic capacity at early growth stage (12 days), but the difference was diminished at mid-growth stage (20 days), and T300 exhibited reduced efficiency under extreme high light intensity at late growth stag e(28 days). but overall, T300 maintained higher net photosynthetic rates, favoring dry matter accumulation in cigar tobacco leaves.

       

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