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Article

Below-Plant Mirrors Improve Serianthes Seedling Survival and Growth in Shade

by
Thomas E. Marler
Philippine Native Plants Conservation Society Inc., Ninoy Aquino Parks and Wildlife Center, Quezon City 1101, Philippines
Agronomy 2024, 14(8), 1854; https://doi.org/10.3390/agronomy14081854
Submission received: 9 July 2024 / Revised: 13 August 2024 / Accepted: 19 August 2024 / Published: 21 August 2024
(This article belongs to the Section Horticultural and Floricultural Crops)
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Abstract

:
Recruitment failures of Serianthes nelsonii are among the threats to this species’ recovery, yet adaptive management research to understand the causes of seedling mortality is lacking. Insufficient available light in the in situ forest floor is one factor that may be involved, and below-plant reflection of incident light may improve seedling survival. Mirrors were placed beneath S. nelsonii, Serianthes grandiflora, and Serianthes kanehirae seedlings in container nursery conditions and S. grandiflora seedlings in a closed-canopy forest to determine the influence of the additional reflected light on seedling survival and growth. Below-plant mirrors increased nursery seedling survival for S. nelsonii and S. kanehirae, with 75% combined survival without mirrors and 88% combined survival with mirrors. Below-plant mirrors increased stem height by 51% for the three species, with greater stem diameter and ending leaf number also occurring for plants with mirrors. Below-plant mirrors increased S. grandiflora seedling survival to 161% and longevity to 236% compared to plants without mirrors under forest cover. The plants receiving mirrors also increased by 175% in height, 60% in stem diameter, and 117% in leaf number compared to the plants without mirrors. These findings indicate that passive solar engineering by exploiting below-plant light reflection may be used as a Serianthes conservation protocol to improve seedling survival and growth under shaded conditions.

1. Introduction

The native range of Serianthes nelsonii Merr. is restricted to the Mariana Islands of Rota and Guam. This attractive legume tree is currently listed as endangered under the United States Endangered Species Act (ESA) [1] and critically endangered under the International Union for Conservation of Nature Red List of Threatened Species [2]. A national species recovery plan was published in 1994, which called for more research to determine the threats to species recovery [3].
Small-scale, short-term in situ studies have been conducted in Guam in attempts to understand regeneration and recruitment limitations. Hundreds of seedlings emerged each year beneath a single S. nelsonii tree, indicating considerable regeneration potential; however, most of them died in less than one month, illuminating recruitment failure as one of the threats to species recovery [4,5]. In addition to in situ seedling mortality, decades of attempts to grow S. nelsonii nursery transplants have ended in post-transplant mortality [6]. Unfortunately, no research has been conducted to identify the factors that cause the death of nursery plants shortly after transplantation to forest habitats. Clearly, more adaptive management research is needed to determine which factors may be more effectively managed to improve young S. nelsonii plant survival and growth.
Light availability is one of the most important environmental factors determining plant growth and longevity. A few studies concerning the influence of light on plant behavior have been published. Under managed nursery conditions, light was not needed for S. nelsonii seed germination [7]. Moreover, full sunlight reduced seedling emergence and increased seedling mortality compared to shade [8]. Moreover, 75% shade improved long-term seedling growth compared with full sunlight [8]. Under in situ conditions, supplemental light supplied by solar-powered Light-Emitting Diode lamps during midday increased S. nelsonii seedling lifespan 70% [9], indicating limited available incident light may be one of the influential factors causing recruitment failures.
Evaluation of methods for the continuation of light management research to inform S. nelsonii conservation indicates that solar-powered lamp installation is too costly to upscale as a protocol for reducing the mortality of newly emerged in situ seedlings or out-planted nursery plants. The possibility of positioning reflective materials around the plants to passively increase available light has been pioneered in some production systems within horticulture and agronomy industries, which historically employed black plastic mulching. Several studies have evaluated alternative plastic mulch colors as a means of managing light to influence plant growth and behavior [10,11,12,13]. For example, silver or aluminum mulch altered microclimate and reduced insect herbivory to improve the performance of some vegetable crops [14]. Application of this approach, whereby below-plant reflective surfaces increase light availability to Serianthes seedlings, may reduce mortality and increase growth.
The objective of the present study was to determine if under-plant mirrors may improve Serianthes seedling survival and growth under shaded conditions. Serianthes grandiflora (Benth.) F. Müller and Serianthes kanehirae Fosberg have been used in previous adaptive management studies as surrogates for S. nelsonii [6], as these other species are not endangered. All three species were included in this study. The new knowledge may reveal a protocol for passively increasing available light to Serianthes seedlings that can be upscaled in an affordable manner.

2. Materials and Methods

2.1. Guam Nursery Studies

Seeds of three Serianthes species were scarified, imbibed in municipal water for 1 h, and sown in 60:40 peat–perlite medium on 12 April 2015. The conservation nursery was located at the University of Guam. The open-air nursery was covered with commercial shade cloth. The S. nelsonii seeds were collected in northern Guam, the S. kanehirae seeds were collected in Yap, Federated States of Micronesia, and the S. grandiflora seeds were collected in Bohol, Philippines. The 2.6 L containers were placed under several layers of shade cloth such that the midday photon flux density (PFD) was about 63–68 µmol·m−2·s−1 (Skye SKP200 quantum sensor, Skye Instruments, Llandrindod Wells, Powys, UK) on cloudless days. This level of shade was selected to fall within the range of PFD underneath the only surviving mature S. nelsonii tree in Guam [9].
Emerging seedlings were allowed to finish the initial growth stage of hypocotyl extension, to exhibit two cotyledons, to undergo simultaneous epicotyl extension, and to reveal a pair of opposite pinnately compound leaves (described in [15]). Following this emergence process, a short quiescence period occurred, during which the seedlings were 4.5–5.5 cm in height. These plants were sorted so the study could begin with 16 healthy, robust seedlings for each species.
The two treatments consisted of below-plant mirrors versus below-plant mulch, with eight replications per treatment per species. A mosaic tile comprising hexagonal mirrors was placed beneath each of the 48 seedlings. Each mirror was 7.5 cm in diameter. The commercial mosaic wall tile consisted of six mirrors surrounding a central mirror. The central mirror was removed to create a hole through which each seedling was allowed to grow. Each seedling, therefore, received reflected ambient light from 360° around the plant. For the 24 plants under the control treatment for each species, plant litter was placed on top of the mirrors to block the mirror surfaces from all incoming light. The litter was collected from the forest floor in the habitat containing Guam’s sole surviving mature S. nelsonii tree at that time. This ensured the leaf litter was characteristic of in situ habitat.
These three species exhibit differences in nursery growth rates [15] and were, therefore, arranged in individual experiments for each species. The plants were arranged in completely randomized design layouts, with plants on a 50 cm grid in a conservation nursery located on the University of Guam campus. Irrigation was applied by hand through the central hole of each tile mosaic, with the frequency determined according to previous methods [15], using tensiometers mounted in one representative container for each species and treatment. The frequency was every 13–18 days initially and remained so for the duration of the study of the mulch treatment plants. The frequency was weekly for the mirror plants at the end of the study due to greater transpiration losses. Fertilization occurred every two weeks and consisted of 500 mL per plant of a stock solution (2.6 mL·L−1 Vigoro (10N-4.3P-8.3K + micronutrients; Spectrum Group, St. Louis, MO, USA). Arthropod herbivore protection was provided by shade cloth materials, which excluded insect movement to the experimental plants. The plant material was maintained until 28 June 2015, after 11 weeks of growth, when the S. kanehirae plants receiving the mirror treatment reached 30 cm in height. Many of the remaining mulched plants were unhealthy, so the entire study was terminated on this date.
The number of surviving seedlings was recorded, and then stem height, basal stem diameter, and leaf number were measured for each surviving seedling. The S. nelsonii data did not conform to parametric prerequisites, so the data were subjected to the Mann–Whitney U test. The S. grandiflora and S. kanehirae data were subjected to a paired t-test. Statistical tests were conducted with SAS (SAS Institute, Cary, NC, USA) and figures were created with Excel Version 2407 software.

2.2. Philippine Forest Study

A closed-canopy forest in Barangay Sapang Bato, Angeles City, Philippines was used to determine the influence of below-plant mirrors on understory S. grandiflora seedling survival and growth. Viable seeds were not available for the other two species. This species has been used in previous studies as a surrogate for the other species [6]. The canopy cover was primarily Pterocarpus indicus Willd., and secondary trees were Swietenia macrophylla King, Pouteria campechiana (Kunth) Baehni, and Leucaena leucocephala (Lam.) de Wit. The PFD at the forest floor was 5–10% of the incident PFD. Serianthes grandiflora seeds were scarified, imbibed for 1 hr, then germinated in wet paper towels, as previously described [7]. Germinated seeds with radicles at least 2 mm in length were transferred to the forest on 20 December 2023 and planted at a depth of 0.5 cm. The mulch layer was minimal in some of the experimental microsites, so a standard mulch depth of 2 cm was constructed at each plant’s location by removing all competing seedlings from a radius of about 1 m then maintaining the mulch layer manually over this area.
The experimental layout was a randomized complete block with n = 4 and each block consisting of eight seedlings, for a total of 32 plants. The plants were 2 m or more apart and 3 m or more away from the bole of the canopy trees. The four plants which received the mirror treatments within each block were randomly selected, and one mosaic wall tile mirror (described in Section 2.1) was placed on top of the mulch, surrounding the emerging seedling with six reflective mirrors. The same tile mosaic was placed around each of the control seedlings, and then the mulch layer was placed on top of the tile to block incoming light from the mirrors. This procedure ensured the hydrology of each seedling in the study was homogeneous.
Irrigation of 1 L per plant per week was supplied by hand during periods of limited rainfall. Fertilization occurred every two weeks and consisted of 500 mL per plant of a stock solution (2.1 mL·L−1 Miracle-Gro (8N-3.5P-13.3K + micronutrients; Scotts, Marysville, OH, USA). Herbivory was managed by scouting and there were no signs of herbivory for the duration of the study. The quantity of reflected light coming from beneath each plant was measured on numerous clear days and cloudy days. At midday, the PFD experienced by the abaxial surfaces of seedling leaves ranged from 55% to 74% of the ambient PFD for the mirror treatment and ranged from 2% to 3% for the mulch treatment.
The date of abscission of each cotyledon was determined by daily monitoring until all 64 cotyledons had abscised. The date of mortality was recorded for each seedling that died during the study. At least one seedling per treatment per block remained alive at the end of the study. The height, basal stem diameter, and leaf number of the surviving seedlings were measured on 21 June 2024, following 26 weeks of growth. For each treatment–block combination, the percentage survival was calculated, and then mean cotyledon longevity, seedling longevity, and plant size traits were determined. A mean seedling longevity of 26 weeks was assigned to each surviving seedling. The data were subjected to a paired t-test, with n = 4 for each response variable.

3. Results

3.1. Guam Nursery Studies

3.1.1. Serianthes nelsonii

Survival of S. nelsonii seedlings under containerized nursery growth conditions was influenced by the below-plant mirror treatments. Three of the below-plant mulch treatment plants died and two of the below-plant mirror treatment plants died. The height of the survivors with mirrors was 41% higher than that of survivors with mulch (Figure 1a,b). The basal stem diameter of the plants with mirrors was 60% greater than that of the plants with mulch (Figure 1c). The number of leaves per plant was also increased by the mirror treatment (Figure 1d).

3.1.2. Serianthes kanehirae

Survival of S. kanehirae seedlings under containerized nursery growth conditions was greater than that of S. nelsonii and was influenced by the below-plant mirror treatments. All of the mirror-treatment plants survived, but one of the below-plant mulch treatment plants died during the 11-week study. The height of the survivors was influenced by the treatments, with the plants receiving mirrors exhibiting a mean height that was 52% greater than the plants receiving mulch (Figure 2a,b). The mirrors had a greater impact on basal stem diameter than on height, with the diameter of plants receiving mirrors being 67% greater than the diameter of plants receiving mulch (Figure 2c). The number of leaves and the influence of below-plant mirrors was similar to that of S. nelsonii (Figure 2d).

3.1.3. Serianthes grandiflora

Survival of S. grandiflora seedlings under containerized nursery growth conditions was not influenced by the below-plant mirror treatments, and two seedlings died in each of the treatments. The height of the survivors was increased 61% by the mirror treatment (Figure 3a,b), and the basal stem diameter was increased 41% by the mirror treatment (Figure 3c). The ending leaf number of the mirror plants was 50% greater than the leaf number of mulch plants (Figure 3d).

3.2. Philippine Forest Study

The goal of the study beneath a closed-canopy forest was to grow S. grandiflora plants with or without below-plant mirrors until one of the treatments reached about 30 cm in mean height. Based on personal observations, a Serianthes plant this robust in size is less vulnerable to recruitment failure. This height was achieved by the S. grandiflora survivors receiving the mirror treatment after 26 weeks of growth. At this stage, the surviving plants that experienced below-plant mulch remained small and weak in appearance (Figure 4).
The S. grandiflora seedlings receiving below-plant mirrors exhibited survival that was 2.6-fold greater than the mulched plants (Table 1). Moreover, the plants that died with the mirror treatment lived much longer prior to dying, as indicated by a mean longevity that was 3.4-fold greater than that of the plants that received the mulch treatment. The difference in the height of the survivors receiving the mirror treatment relative to the survivors receiving the mulch treatment was much greater than that of the Guam nursery study, with a 143% increase in height for the mirror plants above that of the mulch plants. The basal stem diameter of the mirror plants was 2.75-fold greater than that of the mulch plants, and the leaf number of the mirror plants was 1.6-fold greater than that of the mulch plants. Cotyledon longevity was also influenced by the treatments, with the mirror treatment more than doubling cotyledon longevity compared to the mulch treatment.

4. Discussion

Adaptive management is a core component of endangered species recovery efforts. The national recovery plan for S. nelsonii acknowledged this fact and outlined research to generate new knowledge regarding the core components of managing this endangered tree species [3]. Several recent nursery and in situ studies revealed that management of light availability is of importance when it comes to understanding the ecology and horticulture of the species, with germination, seedlings, and saplings exhibiting significant responses to light manipulations (reviewed in [6]). I have added to this literature on light management, demonstrating that passively engineering sunlight by reflecting ambient light toward seedlings with below-plant mirrors can be exploited to improve survival and growth.
The improved plant performance due to below-plant reflection of incoming light may be a consequence of the direct increase in the PFD under extremely limited available light. Indeed, under the Philippine forest-site conditions, the upward light from the mulch treatment was less than 3% of the ambient incident PFD, but upward light from the mirror treatment was up to 74% of the ambient incident PFD. Light response curves for all plant species reveal a linear increase in photosynthesis for each unit increase in light at the lowest end of the response curve [16]. The quantum efficiency of carbon dioxide assimilation is defined by the initial slope of this light response curve where light is limited, and is a measure of the increase in photosynthetic performance for each increased mole of photons [17,18]. Any incremental increase in available light within this light-limiting part of the response curve has the potential to greatly increase availability of photosynthates for growth and metabolism.
A second explanation for the improved survival and growth when mirrors were placed beneath the plants is the addition of abaxial illumination of the laminae to augment adaxial illumination. This facet of resource availability is independent of the addition of more light energy per se. Supplemental lighting from beneath the leaf surfaces can increase plant performance in a range of crops to a greater degree than adding the same amount of light to the adaxial surfaces [19,20,21,22,23].
In addition to an increase in available light per se and a directional change in the incoming energy resource, below-plant reflective surfaces may also greatly influence the spectral quality of available light in a manner that alters photomorphogenesis [10,11]. Some photomorphogenesis traits that spectral quality may influence are relative allometric relations among organs or the direction of organ growth. Indeed, the availability of red light in relation to far-red light and the amount of incident ultraviolet light are two light-quality factors that can exert a strong influence on how plants respond to available light. The limited root system of container-grown S. nelsonii transplants is one of the proposed reasons for the post-transplant mortality that has plagued Guam’s S. nelsonii recovery efforts for decades [6]. Since root growth relative to stem growth is one of the plant responses that light quality controls, the use of various colors of reflective surfaces beneath transplanted S. nelsonii saplings to improve root growth relative to stem growth offers an exciting prospect for improved conservation of the imperiled species.
Previous Serianthes studies that are directly comparable are few in number, but the results herein differ from previous reports in several respects. The survival percentage reported here was greater than the survival percentage for in situ plants receiving supplemental lighting [9]. This may have resulted from stressors defined by Janzen-Connell as in situ issues [24], as the experimental sites in the present study were not in close proximity to pre-existing Serianthes trees and were at least 2 m apart in the experimental layout. This hypothesis indicates that seedlings growing in close proximity to the parent tree and in competition with high-density siblings may be at a disadvantage compared to seedlings growing in an environment that is distant to any conspecifics. For example, the application of fungicides to newly emerged in situ S. nelsonii seedlings increased longevity, indicating a buildup of soil-borne pathogens beneath the parent tree was partly causal of recruitment failures [9]. The time required to reach 30 cm in height here was greater than during nursery production of S. nelsonii or S. grandiflora [7,15]. This was likely a result of the luxurious horticultural inputs and benign microclimates of container nursery conditions as compared to the closed-canopy forest cover.
This pioneering study illuminates the utility of below-plant light reflection, and should be expanded upon with further research to refine applicable outcomes. First, numerous colors of plastic mulch have been used in horticulture and agronomy production systems, with some colors uniquely influencing many plant responses (reviewed in [10,11,12,13]). For example, red plastic mulch increased tomato (Lycopersicon esculentum Mill.) yields more so than black, silver, or white mulch [25]. White plastic mulch passively reduced leaf herbivory of poinsettia (Euphorbia pulcherrima Wild.) more so than black or red plastic mulch [26]. Contrarily, yellow plastic mulch has been shown to preferentially attract insect herbivores to crop plants [11]. Blue or white plastic mulch elicited greater plant photosynthesis in young cucumber (Cucumis sativus L.) seedlings than brown, black, silver, or red plastic mulch [27]. Red and blue plastic mulch reduced the total aroma content of basil (Ocimum basilicum L.) leaves compared to black, green, yellow, or white plastic mulch [28]. Silver or aluminum mulch altered microclimate and reduced insect herbivory of several vegetable crops [14]. And silver plastic mulch reflected greater quantities of light than black or white plastic mulch [29]. The literature indicates that the use of other highly reflective mulches such as silver plastic mulch or aluminum foil may be a more affordable approach for effectively reflecting light beneath Serianthes seedlings with growth responses comparable to that of mirrors. Comparative trials to determine the utility of these and other less expensive reflective surfaces would be simple to implement. Second, larger mirrors that are strategically positioned with an angle to reflect morning and afternoon light into the Serianthes seedling canopy may improve survival and growth to a greater degree than the small, horizontal mirrors used in the present study. Third, these methods may also improve post-transplant survival of container-grown nursery plants, a likelihood that deserves further research as a means of reducing post-transplant mortality.
Adaptive management based on carefully planned conservation experimental protocols is recognized as a critical component of plant conservation. Some United States agencies have been criticized for avoiding the rigorous experimental approach to conservation that is the fundamental core of adaptive management [30]. This Guam case study has emerged as a key example, as no research was funded or implemented for almost two decades after the recovery plan was published. Recovery efforts of the critically endangered, charismatic tree have been recognized as inadequate during the 30 years since the national recovery plan was published [3]. The 1994 goal was the addition of 2000 S. nelsonii reproductive trees within a 16-year period. To date, no trees produced in conservation nurseries have survived long enough to exhibit successful regeneration [6], and the 122 trees in existence at the time the plan was published have declined to fewer than 40 [31]. Most of the practitioners who have been funded throughout the years have not included carefully planned research in their management efforts, so the new knowledge that could have been added to better inform species recovery efforts is lacking. As a result, progress reports on how species recovery is progressing have relied heavily on practitioner anecdotes and the gray literature [6]. Relying on this form of information is known to elicit conservation failures [32]. The practice of funding capable scientists to execute rigorous experimental approaches while implementing funded S. nelsonii conservation projects is urgently needed.

5. Conclusions

A greater appreciation of the need for more research on managing light quantity and quality may improve S. nelsonii recovery efforts. The present study has shown that the use of below-plant mirrors to passively engineer solar radiation to increase light-energy availability to Serianthes seedlings may greatly improve plant survival, with a 161% increase in survival and 236% increase in longevity in an understory environment. The surviving seedlings also exhibited up to 175% increases in plant height when receiving the extra below-plant reflected light. The placement of reflective surfaces of various colors to control spectral quality offers an exciting prospect that may greatly improve conservation protocols. The results indicate that using below-plant reflective surfaces could be easily adopted as an inexpensive component of managing out-planted stock produced in conservation nurseries and increasing the likelihood of improved in situ recruitment.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.

Acknowledgments

Serianthes grandiflora seeds were provided by the Soil & Water Conservation Foundation Inc., Bohol Island. Serianthes nelsonii seeds were collected under the U.S. Endangered Species Act Recovery Permit TE-84876A-0.

Conflicts of Interest

Author Thomas E. Marler was employed by the company Philippine Native Plants Conservation Society Inc. The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. United States Fish and Wildlife Service. Determination of endangered status for Serianthes nelsonii Merr. (Hayun lagu or Tronkon Guafi). Fed. Regist. 1987, 52, 4907–4910. [Google Scholar]
  2. Wiles, G.; Williams, E. Serianthes nelsonii. In IUCN Red List Threatened Species; International Union for Conservation of Nature (IUCN): Gland, Switzerland, 2017. [Google Scholar] [CrossRef]
  3. United States Fish and Wildlife Service. Recovery Plan for Serianthes nelsonii; USFWS: Portland, OR, USA, 1994. [Google Scholar]
  4. Marler, T.E.; Cascasan, A.N. Number of emerged seedlings and seedling longevity of the non-recruiting, critically endangered Håyun lågu tree Serianthes nelsonii Merr. (Fabales: Leguminosae) are influenced by month of emergence. J. Threat. Taxa 2015, 7, 8221–8225. [Google Scholar]
  5. Marler, T.E.; Cruz, G.N. Extreme wind events influence seed rain and seedling dynamics of Guam’s Serianthes nelsonii Merr. Trop. Conserv. Sci. 2019, 12, 1940082919853764. [Google Scholar] [CrossRef]
  6. Marler, T.E.; Musser, C.; Cascasan, A.N.J.; Cruz, G.N.; Deloso, B.E. Adaptive management lessons for Serianthes nelsonii conservation. Horticulturae 2021, 7, 43. [Google Scholar] [CrossRef]
  7. Marler, T.E. Serianthes nelsonii seed germination and seedling behavior are minimally influenced by chemical and light treatment. Horticulturae 2019, 5, 31. [Google Scholar] [CrossRef]
  8. Marler, T.E.; Cascasan, A.N.; Lawrence, J.H. Threatened native trees in Guam: Short-term seed storage and shade conditions influence emergence and growth of seedlings. HortScience 2015, 50, 1049–1054. [Google Scholar]
  9. Marler, T.; Musser, C. Potential stressors leading to seedling mortality in the endemic Håyun lågu tree (Serianthes nelsonii Merr.) in the island of Guam. Trop. Conserv. Sci. 2015, 8, 738–744. [Google Scholar] [CrossRef]
  10. Decoteau, D.R. The emergence and early development of colored reflective plastic mulch technology in agriculture. In Recent Advances in Agriculture; Stevens, C., Khan, V.A., Eds.; Research Signpost: Trivandrum, India, 2008; pp. 1–17. [Google Scholar]
  11. Amare, G.; Desta, B. Coloured plastic mulches: Impact on soil properties and crop productivity. Chem. Biol. Technol. Agric. 2021, 8, 4. [Google Scholar] [CrossRef]
  12. Manzoor, N.; Shahnaz, M.; Rakshanda, A. Vegetable production under colored plastic mulches: A review. J. Community Mobilization Sustain. Dev. 2023, 18, 365–373. [Google Scholar]
  13. Yadav, D.; Rama Rao, K.V.; Trivedi, A.; Rajwade, Y.; Verma, N. Reflective mulch films a boon for enhancing crop production: A review. Environ. Conserv. J. 2023, 24, 281–287. [Google Scholar] [CrossRef]
  14. Schalk, J.M.; Creighton, C.S.; Fery, R.L.; Sitterly, W.R.; Davis, B.W.; McFadden, T.L.; Day, A. Reflective film mulches influences insect control and yield in vegetables. J. Amer. Soc. Hortic. Sci. 1979, 104, 759–762. [Google Scholar] [CrossRef]
  15. Marler, T.E. Asexual reproduction to propel recovery efforts of the critically endangered Håyun Lågu tree (Serianthes nelsonii Merr.). Trop. Conserv. Sci. 2017, 10, 1940082917697707. [Google Scholar] [CrossRef]
  16. Coe, R.A.; Lin, H.C. Light Response Curves in Land Plants. In Photosynthesis. Methods in Molecular Biology; Covshoff, S., Ed.; Humana: New York, NY, USA, 2024; Volume 2790, pp. 27–39. [Google Scholar] [CrossRef]
  17. Busch, F.A.; Ainsworth, E.A.; Amtmann, A.; Cavanagh, A.P.; Driever, S.M.; Ferguson, J.N.; Kromdijk, J.; Lawson, T.; Leakey, A.D.B.; Matthews, J.S.A.; et al. A guide to photosynthetic gas exchange measurements: Fundamental principles, best practice and potential pitfalls. Plant Cell Environ. 2024, 47, 3344–3364. [Google Scholar] [CrossRef] [PubMed]
  18. Song, Q.; Zhu, X.-G. Techniques for photosynthesis phenomics: Gas exchange, fluorescence, and reflectance spectrums. Crop Environ. 2024, 3, 147–158. [Google Scholar] [CrossRef]
  19. Zhang, G.; Shen, S.; Takagaki, M.; Kozai, T.; Yamori, W. Supplemental upward lighting from underneath to obtain higher marketable lettuce (Lactuca sativa) leaf fresh weight by retarding senescence of outer leaves. Front. Plant Sci. 2015, 6, 1110. [Google Scholar] [CrossRef]
  20. Zhang, Z.S.; Li, Y.T.; Gao, H.Y.; Yang, C.; Meng, Q.W. Characterization of photosynthetic gas exchange in leaves under simulated adaxial and abaxial surfaces alternant irradiation. Sci. Rep. 2016, 6, 26963. [Google Scholar] [CrossRef]
  21. Li, C.X.; Chang, S.X.; Khalil-Ur-Rehman, M.; Xu, Z.G.; Tao, J.M. Effect of irradiating the leaf abaxial surface with supplemental light-emitting diode lights on grape photosynthesis. Aust. J. Grape Wine Res. 2017, 23, 58–65. [Google Scholar] [CrossRef]
  22. Jiang, C.; Rao, J.; Rong, S.; Ding, G.; Liu, J.; Li, Y.; Song, Y. Fruit quality response to different abaxial leafy supplemental lighting of greenhouse-produced cherry tomato (Solanum lycopersicum var. cerasiforme). Horticulturae 2022, 8, 423. [Google Scholar] [CrossRef]
  23. Jiang, C.; Wu, H.; Zhang, X.; Liu, J.; Li, Y.; Song, Y.; Wang, J.; Zheng, Y. Integrating omics reveals insights into tomato abaxial/adaxial leafy supplemental lighting. Front. Plant Sci. 2023, 14, 1118895. [Google Scholar] [CrossRef]
  24. Janzen, D.H. Herbivores and the number of tree species in tropical forests. Am. Nat. 1970, 104, 501–529. [Google Scholar]
  25. Decoteau, D.R.; Kasperbauer, M.J.; Hunt, P.G. Mulch surface color affects yield of fresh market tomatoes. J. Amer. Soc. Hort. Sci. 1989, 114, 216–219. [Google Scholar]
  26. Kelly, J.W.; Adler, P.H.; Decoteau, D.R.; Lawrence, S. Colored reflective surfaces to control whitefly on poinsettia. HortScience 1989, 24, 1045. [Google Scholar] [CrossRef]
  27. Ibarra-Jiménez, L.; Zermeño-González, A.; Munguía-López, J.; Quezada-Martín, M.A.R.; De La Rosa-Ibarra, M. Photosynthesis, soil temperature and yield of cucumber as affected by colored plastic mulch. Acta Agric. Scand. Sect. B-Soil Plant Sci. 2008, 58, 372–378. [Google Scholar] [CrossRef]
  28. Loughrin, J.H.; Kasperbauer, M.J. Aroma content of fresh basil (Ocimum basilicum L.) leaves is affected by light reflected from colored mulches. J. Agric Food Chem. 2003, 51, 2272–2276. [Google Scholar] [CrossRef] [PubMed]
  29. Díaz-Pérez, J.C. Bell Pepper (Capsicum annum L.) grown on plastic film mulches: Effects on crop microenvironment, physiological attributes, and fruit yield. HortScience 2010, 45, 1196–1204. [Google Scholar] [CrossRef]
  30. Fischman, R.L.; Ruhl, J.B. Judging adaptive management practices of U.S. agencies. Conserv. Biol. 2016, 30, 268–275. [Google Scholar] [CrossRef]
  31. Demeulenaere, E.; Ickert-Bond, S.M. Guam’s last håyun lågu tree (Ser. Nelsonii) Peril. Conserv. Sci. Pract. 2023, 5, e13019. [Google Scholar] [CrossRef]
  32. Sutherland, W.J.; Pullin, A.S.; Dolman, P.M.; Knight, T.M. The need for evidence-based conservation. Trends Ecol. Evol. 2004, 19, 305–308. [Google Scholar]
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Figure 1. Serianthes nelsonii seedling size traits after 11 weeks of growth under shaded conditions as influenced by below-plant mirror placement: (a) General plant appearance; (b) height; (c) base stem diameter; (d) leaf number per plant. Open bars depict mirror treatment; shaded bars depict mulch treatment. Mean ± SE, n = 5 for mulch, n = 6 for mirror.
Figure 1. Serianthes nelsonii seedling size traits after 11 weeks of growth under shaded conditions as influenced by below-plant mirror placement: (a) General plant appearance; (b) height; (c) base stem diameter; (d) leaf number per plant. Open bars depict mirror treatment; shaded bars depict mulch treatment. Mean ± SE, n = 5 for mulch, n = 6 for mirror.
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Figure 2. Serianthes kanehirae seedling size traits after 11 weeks of growth under shaded conditions as influenced by below-plant mirror placement: (a) General plant appearance; (b) height; (c) base stem diameter; (d) leaf number per plant. Open bars depict mirror treatment; shaded bars depict mulch treatment. Mean ± SE, n = 7 for mulch, n = 8 for mirror.
Figure 2. Serianthes kanehirae seedling size traits after 11 weeks of growth under shaded conditions as influenced by below-plant mirror placement: (a) General plant appearance; (b) height; (c) base stem diameter; (d) leaf number per plant. Open bars depict mirror treatment; shaded bars depict mulch treatment. Mean ± SE, n = 7 for mulch, n = 8 for mirror.
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Figure 3. Serianthes grandiflora seedling size traits after 11 weeks of growth under shaded conditions as influenced by below-plant mirror placement: (a) General plant appearance; (b) height; (c) base stem diameter; (d) leaf number per plant. Open bars depict mirror treatment; shaded bars depict mulch treatment. Mean ± SE, n = 6.
Figure 3. Serianthes grandiflora seedling size traits after 11 weeks of growth under shaded conditions as influenced by below-plant mirror placement: (a) General plant appearance; (b) height; (c) base stem diameter; (d) leaf number per plant. Open bars depict mirror treatment; shaded bars depict mulch treatment. Mean ± SE, n = 6.
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Figure 4. Twenty-six-week-old Serianthes grandiflora seedlings grown under deep shade: (a) Grown with below-plant mirror; (b) grown with a layer of mulch covering the below-plant mirror.
Figure 4. Twenty-six-week-old Serianthes grandiflora seedlings grown under deep shade: (a) Grown with below-plant mirror; (b) grown with a layer of mulch covering the below-plant mirror.
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Table 1. Traits of 26-week-old Serianthes grandiflora seedlings grown with or without below-plant mirrors under deep shaded conditions. Mean ± SE, n = 4.
Table 1. Traits of 26-week-old Serianthes grandiflora seedlings grown with or without below-plant mirrors under deep shaded conditions. Mean ± SE, n = 4.
Plant TraitWith MirrorWithout Mirrortp
Survival (%)81 ± 631 ±65.657<0.001
Longevity (week)24.5 ± 1.47.3 ± 1.312.262<0.001
Height (cm)30.4 ± 1.112.5 ± 0.912.641<0.001
Base stem diameter (mm)4.4 ± 0.11.6 ± 0.117.282<0.001
Leaf number8 ± 15 ± 13.4340.007
Cotyledon longevity (day)13 ± 16 ± 17.488<0.001
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Marler, T.E. Below-Plant Mirrors Improve Serianthes Seedling Survival and Growth in Shade. Agronomy 2024, 14, 1854. https://doi.org/10.3390/agronomy14081854

AMA Style

Marler TE. Below-Plant Mirrors Improve Serianthes Seedling Survival and Growth in Shade. Agronomy. 2024; 14(8):1854. https://doi.org/10.3390/agronomy14081854

Chicago/Turabian Style

Marler, Thomas E. 2024. "Below-Plant Mirrors Improve Serianthes Seedling Survival and Growth in Shade" Agronomy 14, no. 8: 1854. https://doi.org/10.3390/agronomy14081854

APA Style

Marler, T. E. (2024). Below-Plant Mirrors Improve Serianthes Seedling Survival and Growth in Shade. Agronomy, 14(8), 1854. https://doi.org/10.3390/agronomy14081854

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