CO<sub>2</sub>加富对甜瓜叶片全生命周期光合作用的影响

李甜; 张志鹏; 侯雷平; 孙胜; 邢国明

doi:10.19303/j.issn.1008-0384.2020.11.004

摘要:

目的揭示甜瓜叶片整个生命周期光合作用的变化过程，确定CO₂施肥的最适浓度，初步揭示CO₂施肥对甜瓜叶片净光合效率提高的原理，为甜瓜CO₂精准施肥以及对吊蔓生长的甜瓜整枝打叶提供理论依据。

方法以芝麻蜜甜瓜品种浪潮为研究对象，设置4个CO₂浓度梯度：CK（400±12）、T1（800±24）、T2（1200±36）、T3（1600±48）μmol·mol⁻¹。测定施肥后甜瓜叶片整个生育期（5、15、25、35、45 d叶龄）的叶绿素含量、光合作用相关参数、叶绿素荧光相关参数的变化。

结果在25 d叶龄时，甜瓜叶片的光合作用达到最大值，T2、T3净光合速率比CK提高51.3%、45.7%，水分利用效率提高58.0%、114.0%，调节性能量耗散的量子产额Y（NPQ）减小 7.1%、11.0%，降低非光化学淬灭系数qN 5.8%、6.2%；T3增加光化学淬灭系数qP 3.9%。在叶片衰老之后（即45 d叶龄），CK浓度下叶片净光合速率只有最高点的19.2%，但CO₂加富处理的叶片仍然有较高的净光合速率。相对于CK，T3净光合速率增加469.2%，叶绿素a含量显著提高20.6%，Y（II）增加16.3%，qP增加 25.1%，Y（NO）降低13.3%；T1、T3气孔导度降低35.1%、31.9%，蒸腾速率降低52.8%、37.7%，Y（NPQ）降低9.1%、6.6%；T1、T2、T3 的qN 分别降低8.3%、14.6%、1.1%。

结论 25 d叶龄的甜瓜叶片光合能力达到最大值，T2处理即CO₂浓度为1200 μmol·mol⁻¹是最适浓度，CO₂加富处理可以提高甜瓜的水分利用速率，增加光化学淬灭，降低非光化学淬灭。在叶片衰老时光合效率的提升依赖于叶绿素含量的提高以及光化学淬灭系数qP的提升。

Abstract:

Objective Changes on photosynthesis of leaves of muskmelon vines grown by hanging in a greenhouse enriched with CO₂ were studied to understand the effect on the plants in a life cycle and application for optimum trellis cultivation.

Method Four CO₂ enrichment treatments were implemented in the experimentation. They included CK at 400±12 mol·mol⁻¹, T1 at 800±24 mol·mol⁻¹, T2 at 1 200±36 mol·mol⁻¹, and T3 at 1 600±48 mol·mol⁻¹. Changes on the chlorophyll content, photosynthetic indicators, and chlorophyll fluorescence indices of the leaves on the hanging melon vines during the entire growth period were determined in 5, 15, 25, 35, and 45d after the treatments.

Result Compared with CK, T2 and T3 increased the net photosynthetic rate by 51.3% and 45.7% and WUE by 58.0% and 114.0%, respectively; while reduced the regulatory energy dissipation quantum yield Y (NPQ) by 7.1% and 11.0%, and the non-photochemical quenching coefficient qN by 5.8% and 6.2%, respectively. For T3, the increase on photochemical quenching coefficient qP was 3.9%. As the leaves aged (i.e., 45-d-old at end of treatment), the net photosynthetic rate under CK was only 19.2% at peak, whereas, that under treatments remained at a higher level. T3 had its net photosynthetic rate increased by 469.2%, chlorophyll A content significantly increased by 20.6%, Y(II) increased by 16.3%, qP increased by 25.1%, and Y(NO) decreased by 13.3% over CK. T1 and T3 showed their stomatal conductance reduced by 35.1% and 31.9%, transpiration rate by 52.8% and 37.7%, and Y(NPQ) by 9.1% and 6.6%, respectively. And, on qN, T1, T2, and T3 decreased by 8.3%, 14.6%, and 1.1%, respectively.

Conclusion The photosynthetic capacity of 25-d-old muskmelon leaves reached the maximum with the optimal CO₂ enrichment at 1 200 mol·mol⁻¹ under T2. The enrichment in the atmosphere also increased WUE and the photochemical quenching with a reduction on the non-photochemical quenching of the plants. The combined effect would improve the efficiency of leaf photosynthesis during plant senescence when the biochemical process depends on the increased chlorophyll content and qP to function well.

CO₂加富对甜瓜叶片全生命周期光合作用的影响

Effect of CO₂ Enrichment on Photosynthesis of Melon Leaves in a Life Cycle

CO2加富对甜瓜叶片全生命周期光合作用的影响

Effect of CO2 Enrichment on Photosynthesis of Melon Leaves in a Life Cycle

CO₂加富对甜瓜叶片全生命周期光合作用的影响

Effect of CO₂ Enrichment on Photosynthesis of Melon Leaves in a Life Cycle