Monochromatic red light during plant growth decreases the size and improves the functionality of stomata in chrysanthemum

Abstract

Light emitting diodes (LEDs) now enable precise light quality control. Prior to commercialisation however, the plant response to the resultant light quality regime ought to be addressed. The response was examined here in chrysanthemum by evaluating growth, chlorophyll fluorescence (before and following water deficit), as well as stomatal anatomy (density, size, pore dimensions and aperture heterogeneity) and closing ability. Plants were grown under blue (B), red (R), a mixture of R (70%) and B (RB), or white (W; 41% B, 39% intermediate spectrum, 20% R) light LEDs. Although R light promoted growth, it also caused leaf deformation (epinasty) and disturbed the photosynthetic electron transport system. The largest stomatal size was noted following growth under B light, whereas the smallest under R light. The largest stomatal density was observed under W light. Monochromatic R light stimulated both the rate and the degree of stomatal closure in response to desiccation compared with the other light regimes. We conclude that stomatal size is mainly controlled by the B spectrum, whereas a broader spectral range is important for determining stomatal density. Monochromatic R light enhanced stomatal ability to regulate water loss upon desiccation.

Blue Light Improves Photosynthetic Performance during Healing and Acclimatization of Grafted Watermelon Seedlings

“…A high proportion of B in the growth spectrum (i.e., B and W) led to increased scion length as compared to the other light treatments, while scion stem diameter remained unaffected. These findings are in accordance with previous studies showing that B light generally promotes stem elongation as compared to monochromatic R light in the seedling stage [ 29 , 30 , 31 ], though in subsequent growth stages the opposite trend is often apparent [ 32 ]. In the seedling stage, the B-induced enhancement of stem elongation has been associated with increased accumulation of bioactive gibberellins, as compared to monochromatic R light [ 33 ].…”

Leaf Age-Dependent Effects of Boron Toxicity in Two Cucumis melo Varieties

“…It is suggested by previous studies on other species that the decreased biomass accumulation under these conditions is mediated through impaired leaf functionality [4,36]. Our results indicate that the B-induced reduction in biomass accumulation is mediated by both reduced leaf area development (thus reduced light interception; [37]) and decreased photosynthetic activity (see RCA1 transcription; Figure 2). B is a highly reactive element, and when present in excess inside plant cells can react with molecules critical for both photosynthesis and cellular metabolism [38].…”

Blue Light Improves Photosynthetic Performance and Biomass Partitioning toward Harvestable Organs in Saffron (Crocus sativus L.)

“…Attached, young, fully developed leaves of saffron plants were used for measuring the polyphasic Chl a fluorescence (OJIP) transients 60 days after flowering, using a Fluorpen FP 100-MAX (Photon Systems Instruments, Drasov, Czech Republic) following 20 min of dark adaptation. The parameters obtained from the OJIP protocol were calculated according to previous studies [19][20][21][22]. Basic and calculated parameters and their formula are shown in Table 1.…”

“…Red (R) and Blue (B) lights are more effective for electron excitation in the photosynthetic system since the chlorophyll (Chl) pigments have their highest absorption in those light waveband ranges. Effects of R and B lights, either monochromic or combined, have been widely studied on the growth and physiology of diverse plant species [18][19][20][21]. However, there is still a lack of knowledge on biomass and carbohydrate partitioning toward different organs in bulbous plants such as saffron.…”