寡照条件下补光频率对番茄幼苗叶片光合特性的影响

Effect of Light Supplementation Frequency on Photosynthetic Characteristics of Tomato Seedling Leaves under Weak Light

以番茄“粉冠”为试材,于2019年12月−2020年4月在南京信息工程大学试验温室内开展控制试验。设计持续补光300min为对照(CK),每日补光两次每次150min、间隔120min为处理1(L1);每日补光3次每次100min、间隔两次每次60min为处理2(L2);每日补光4次每次75min、间隔3次每次40min为处理3(L3);每日补光5次每次60min、间隔4次每次30min为处理4(L4),光通量密度为600μmol·m^(−2)·s^(−1),测定不同间隔频率的补光下番茄幼苗叶片叶绿素含量、光合参数、快速荧光诱导动力学参数和光谱特征。结果表明:(1)补光间隔频率的增加可以促进番茄幼苗叶片部分色素的合成,处理36d时,L4处理的叶绿素a比CK高出16.3%,类胡萝卜素含量比CK多出19.6%。(2)间歇补光下的番茄叶片3个红边参数λ_(red)、S_(red)和D_(red)随间隔频率的增加呈现出典型的“红移”现象,但在补光初期(9d),叶片叶绿素变化与光谱规律有所差异。(3)长时间(36d)间歇补光下的番茄幼苗叶片光饱和点(LSP)、表观量子效率(AQE)和光补偿点(LCP)均高于连续光处理,且间隔频率越高,净光合速率越高,光合能力越强。但番茄叶片气孔会对光照波动产生延迟效应,而气孔延迟改变了叶片光合作用的光捕获过程,同时限制了气孔运动的蒸腾和碳交换过程。(4)间歇补光对PSII反应中心能量分配的影响表现为短期内降低叶片最大光化学效率,当处理天数增加时,反应中心捕获的量子产额(φ_(Po))和用于电子传递的量子产额(φ_(Eo))增加,用于热耗散的量子比率(φ_(Ro))减少,其中L4变化幅度更大,L4的φ_(Po)相较于CK在9d时降低3.8%,36d时增加11.6%,φ_(Ro)在L4处理下相较于CK在9d时增加4.8%,36d时降低6.9%。

The tomato variety "Fenguan" was used in a control experiment in a Nanjing University of Information Science and Technology experimental greenhouse from December 2019 to April 2020. Continuous light supplementation for 300min was used as the control treatment (CK). Treatment 1 (L1) was supplemented with light twice a day for 150min each time at an interval of 120min. Treatment 2 (L2) was supplemented with light 3 times a day for 100min each time and 2 times at 60min intervals. Treatment 3 (L3) was supplemented with light 4 times a day for 75min each time and 3 times at 40min intervals. Treatment 4 (L2) was supplemented with light 5 times a day for 60min each time and 4 times at 30min intervals. Photosynthetically active radiation was 600μmol·m^(-2)·s^(-1). The chlorophyll content, photosynthetic parameters, kinetic parameters of rapid fluorescence induction, and spectral characteristics of tomato seedling leaves were measured under supplementary light at different intervals. The results showed that (1) the increase in the frequency of light supplementation interval could promote the synthesis of some pigments in the leaves of tomato seedlings. At 36 days of treatment, chlorophyll-a content was 16.3% higher and carotenoid content was 19.6% more in the L4 treatment than in CK. (2) The three red-edge parameters λ, S, and Dof tomato leaves under intermittent light supplementation showed a typical "redshift" phenomenon with increasing interval frequency, but the chlorophyll changes of leaves differed from the spectral pattern at the early stage of light supplementation. (3) The light saturation point (LSP), apparent quantum efficiency (AQE), and light compensation point (LCP) of tomato seedling leaves under prolonged intermittent light supplementation were higher than those of the continuous light treatment, and the higher interval frequency, the higher the net photosynthetic rate and the greater the photosynthetic capacity. However, tomato leaf stomata exert a delayed effect on light fluctuations,and stomatal delay alters the light capture process of leaf photosynthesis while limiting the transpiration and carbon exchange processes of stomatal movement. (4) The effect of intermittent light supplementation on the energy partitioning of PSII reaction centers showed a short-term reduction in the maximum photochemical efficiency of leaves, with an increase in the quantum yield captured by the reaction center (φ_(Po)) and for electron transfer (φ_(Eo)) and a decrease in the quantum ratio for heat dissipation (φ_(Ro)) when the number of treatment days increased, with a greater change at L4, where φdecreased at L4 compared to CK at treatment day decreased by 3.8% at day 9 and increased by 11.6% at day 36, and φ_(Ro) increased by 4.8% at L4 treatment and decreased by 6.9% at day 36 compared to CK at day 9 of the treatment.