Methuselah, a bristlecone pine growing on the slope of a mountain in southeastern California, has almost certainly been growing at the exact location of that same mountain slope where it emerged from a seed over 4700 years ago. As a consequence of their sessile nature, plants like Methuselah are strictly dependent on their ability to sense and react to their surroundings in order to optimize their chances of survival and reproduction. In nature, rapid and permanent changes to a plant's light environment are relatively rare. Plants grown for horticulture or agriculture, like lettuce or tomatoes, may often be grown under low‐light conditions as seedlings before being transferred to high‐light environments like greenhouses or fields.

The ability of plants to acclimate from low light to high light has been well‐documented, but a thorough understanding of how the spectral quality of light affects this process is still relatively unknown. Given the proliferation of monochromatic LEDs as low‐energy and low‐cost options for growing plants in small spaces like greenhouses, it is important that the effects of these light sources on plant physiology are understood.

In one of the articles in this issue of Physiologia Plantarum, Zheng et al. (2020) have examined the adaptive responses of two ornamental plants under different light regimes: the sun species Chrysanthemum morifolium ‘Bolero’ and the shade species Spathiphyllum wallisii ‘Alfetta’. The plants were grown under low‐light conditions as young plants and transferred to a high‐light greenhouse. Specifically, they grew the young plants under the exact same intensity of either red, blue, red + blue or white light before transferring them to the greenhouse. Immediately after the transfer, and for the next 30 days, they measured the photosynthetic and photoprotective capacities of the plants.

The authors found that Chrysanthemum and Spathiphyllum grown under red light were the worst equipped to deal with the initial transfer to the high‐light greenhouse conditions. Both red light‐grown species exhibited lower electron transport rates and lower levels of CO₂‐fixation at the higher light intensities in their first days in the greenhouse. They also had reduced rates of photosystem II (PSII) electron transport after the transfer, leading the authors to hypothesize that these plants might be more prone to photodamage from excess light. To test this, they measured the plants capacity for photoprotection, which involves the dissipation of excess absorbed light energy. Red‐light grown plants had lower levels of regulated photoprotection (ΦNPQ) and higher levels of unregulated energy dissipation (ΦNO), a telltale sign of photodamage. These negative effects, which the authors speculate might be due to changes in leaf or chloroplast architecture, were still detected up to 8 days after the transfer. At the end of the 30‐day experiment, red light‐grown Chrysanthemums were found to have lower dry weights than those grown under different light conditions.

Blue light‐grown plants also experienced some difficulties on their first days in the greenhouse. They showed a reduced capacity for photoprotection under high light and struggled with the initial transfer like their red light‐grown counterparts, but they were able to recover with no observed long‐term damage. What these observations tell us is that the colors of light that a plant perceives are important for helping it acclimate to future high light intensity. This could have implications in understanding the regulation of photoprotection in plants, a process whose manipulation has been shown to have positive effects in crop yield (Kromdijk et al. 2016).

The observations that growth in monochromatic light may have negative consequences for young plants when they are shifted to high‐light conditions are especially relevant for plant cultivation. Despite the fact that the two plant species in this study appeared to suffer no negative long‐term effects when grown under blue and red light together, dichromatic illumination may not be the solution, as it has been reported to result in suboptimal plant growth. Lettuce grown under red and blue light together, for example, were found to have reduced photosynthesis and increased photodamage unless also supplemented with green LEDs (Bian et al. 2018). Horticulturalists and farmers looking to minimize resource usage while maximizing plant productivity, for example, would be wise to consider the potential long‐term effects of such monochromatic and dichromatic growth regimes for the plants they grow. Further studies are clearly required on the effects of different combinations of LEDs on the growth of plants and on crop yields. While these studies may not result in plants that produce tomatoes or lettuce over a Methuselah‐length lifetime, they will certainly give us a better understanding of how plants adapt to and cope with changes to their light environment.

Methuselah是一种在加州东南部的山坡上生长的刚毛松木，几乎可以肯定，它生长在4700年前从种子萌发的那个山坡的确切位置。由于它们固执的本质，像玛土撒拉这样的植物严格依赖于它们对周围环境的感知和反应的能力，以优化其生存和繁殖的机会。在自然界中，对植物的光照环境进行快速而持久的改变是相对罕见的。用于园艺或农业的植物（如生菜或西红柿）通常在低光照条件下作为幼苗生长，然后转移到温室或田地等高光照环境中。

植物从弱光适应高光的能力已得到充分证明，但是对光的光谱质量如何影响该过程的透彻了解仍然相对未知。鉴于单色LED的普及是在温室等小空间中生长植物的低能耗和低成本选择，因此，了解这些光源对植物生理的影响非常重要。

Zheng等在本期《植物志》中的一篇文章中。（2020）研究了两种观赏植物在不同光照条件下的适应性响应：太阳物种菊花Morifolium'Bolero '和树荫物种Spathiphyllum wallisii'Alfetta '。这些植物在弱光条件下作为幼苗生长，然后转移到高光温室中。具体而言，在将它们转移到温室之前，它们在完全相同的红色，蓝色，红色+蓝色或白色光强度下生长这些幼小植物。转移后立即和接下来的30天内，他们测量了植物的光合作用和光保护能力。

作者发现，在红光下生长的菊花和西番莲是处理最初转移到强光温室条件下最差的装备。两种红色生长的物种均显示出较低的电子传输速率和较低的CO ₂水平在温室的头几天固定在较高的光照强度下。转移后，它们还降低了光系统II（PSII）电子传输的速率，这使作者假设这些植物可能更容易受到过量光的光害。为了测试这一点，他们测量了植物的光保护能力，这涉及到多余吸收光能的耗散。红光生长的植物具有较低水平的受调节光保护（ΦNPQ）和较高水平的不受调节的能量耗散（ΦNO），这是光损伤的明显标志。作者推测，这些负面影响可能是由于叶片或叶绿体结构的变化所致，但在转移后最多8天仍可检测到。在30天的实验结束时，

蓝光生长的植物在温室的第一天也遇到了一些困难。它们显示出在强光下的光保护能力降低，并且像红光生长的对应物一样在初始转移过程中挣扎，但是它们能够恢复而没有观察到长期损害。这些观察结果告诉我们，植物感知到的光的颜色对于帮助其适应未来的高光强度非常重要。这可能对理解植物中光保护的调控有影响，该过程的操纵已显示对作物产量具有积极影响（Kromdijk等，2016）。

单色光的生长可能会对幼小的植物转移到强光条件下产生负面影响，这一发现与植物栽培特别相关。尽管本研究中的两种植物在蓝光和红光下共同生长时似乎没有遭受负面的长期影响，但据报道双色照明可能不是解决方案，因为据报道这导致植物生长欠佳。例如，发现在红色和蓝色光下共同生长的生菜除非具有绿色LED补充，否则其光合作用降低且光害增加（Bian等人2018）。）。例如，园艺学家和农民希望最大程度地减少资源使用量，同时最大程度地提高植物的生产力，考虑这种单色和双色生长方式对他们生长的植物可能产生的长期影响是明智的。显然需要对LED的不同组合对植物生长和作物产量的影响进行进一步研究。尽管这些研究可能不会导致植物在Methuselah的整个生命周期内生产出西红柿或生菜，但它们无疑会使我们更好地了解植物如何适应并应对其光照环境的变化。