Hoffmann Anna M, Noga Georg, Hunsche Mauricio
Institute of Crop Science and Resource Conservation - Horticultural Science, University of Bonn, Auf dem Huegel 6, 53121, Bonn, Germany,
J Plant Res. 2015 Mar;128(2):295-306. doi: 10.1007/s10265-014-0698-z. Epub 2015 Jan 28.
We investigated the influence of light quality on the vulnerability of pepper plants to water deficit. For this purpose plants were cultivated either under compact fluorescence lamps (CFL) or light-emitting diodes (LED) providing similar photon fluence rates (95 µmol m(-2) s(-1)) but distinct light quality. CFL emit a wide-band spectrum with dominant peaks in the green and red spectral region, whereas LEDs offer narrow band spectra with dominant peaks at blue (445 nm) and red (665 nm) regions. After one-week acclimation to light conditions plants were exposed to water deficit by withholding irrigation; this period was followed by a one-week regeneration period and a second water deficit cycle. In general, plants grown under CFL suffered more from water deficit than plants grown under LED modules, as indicated by the impairment of the photosynthetic efficiency of PSII, resulting in less biomass accumulation compared to respective control plants. As affected by water shortage, plants grown under CFL had a stronger decrease in the electron transport rate (ETR) and more pronounced increase in heat dissipation (NPQ). The higher amount of blue light suppressed plant growth and biomass formation, and consequently reduced the water demand of plants grown under LEDs. Moreover, pepper plants exposed to high blue light underwent adjustments at chloroplast level (e.g., higher Chl a/Chl b ratio), increasing the photosynthetic performance under the LED spectrum. Differently than expected, stomatal conductance was comparable for water-deficit and control plants in both light conditions during the stress and recovery phases, indicating only minor adjustments at the stomatal level. Our results highlight the potential of the target-use of light quality to induce structural and functional acclimations improving plant performance under stress situations.
我们研究了光质对辣椒植株水分亏缺脆弱性的影响。为此，将植株种植在紧凑型荧光灯（CFL）或发光二极管（LED）下，二者提供相似的光子通量率（95 μmol m⁻² s⁻¹）但光质不同。CFL发出宽带光谱，在绿色和红色光谱区域有主峰，而LED提供窄带光谱，主峰位于蓝色（445 nm）和红色（665 nm）区域。在对光照条件适应一周后，通过停止灌溉使植株遭受水分亏缺；此阶段之后是一周的恢复期和第二个水分亏缺周期。总体而言，与各自的对照植株相比，生长在CFL下的植株比生长在LED模块下的植株受水分亏缺的影响更大，这表现为PSII光合效率受损，生物量积累更少。受缺水影响，生长在CFL下的植株电子传递速率（ETR）下降更强烈，热耗散（NPQ）增加更显著。较高量的蓝光抑制了植株生长和生物量形成，从而降低了生长在LED下的植株的需水量。此外，暴露在高蓝光下的辣椒植株在叶绿体水平进行了调整（例如，叶绿素a/叶绿素b比值更高），提高了在LED光谱下的光合性能。与预期不同的是，在胁迫和恢复阶段，两种光照条件下水分亏缺植株和对照植株的气孔导度相当，表明在气孔水平仅进行了微小调整。我们的结果突出了光质靶向利用在诱导结构和功能适应以改善胁迫条件下植株性能方面的潜力。
