Effects of shading on seagrass morphology and thermal optimal of productivity

2020 ◽  
Vol 71 (8) ◽  
pp. 913 ◽  
Author(s):  
Eunice Kong ◽  
Yan Xiang Ow ◽  
Samantha Lai ◽  
Siti Maryam Yaakub ◽  
Peter Todd
Keyword(s):  
Synergistic Effects ◽  
Light Availability ◽  
Temperature Response ◽  
Leaf Size ◽  
Net Photosynthesis ◽  
Shoot Density ◽  
Net Productivity ◽  
Halophila Ovalis ◽  
Light Levels ◽  
Reduced Light

Light and temperature are important factors affecting seagrass primary productivity. Acclimatisation to reduced light availability may affect the optimal temperature at which seagrasses photosynthesise, potentially causing synergistic effects between increasing water temperatures and decreasing light levels on coastal productivity. This study investigated the effects of reduced light availability on the morphology (leaf size, shoot density) and thermal optimal of net productivity in Halophila ovalis (R.Br.) Hook. A 12-week in situ shading experiment was conducted at Chek Jawa Wetlands, Singapore, testing high (68% shading), low (49%) and control (0%) shadings. Every 4 weeks, photosynthetic and respiration rates of H. ovalis leaves and the root–rhizome complex were measured in closed incubation chambers at temperatures from 22 to 42°C (at 4°C intervals). A fitted temperature-response model of net photosynthesis was used to estimate the thermal optimal for each shading treatment. High shading reduced shoot density (mean±s.e.) 87.06±7.86% and leaf surface area 31.72±24.74%. Net productivity (6mg O2 g–1 DW h–1) and its thermal optimal (28–30°C) were not significantly different among shading treatments throughout the experiment. Light levels appeared to have minimal influence on the thermal dependency of H. ovalis net productivity.

scholarly journals HOREHOUND (Marrubium vulgaris L.) PRODUCTION IN NORTHERN AMERICA: RESPONSES TO MULCH, SHADING, AND NITROGEN TREATMENT

HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1162b-1162
Author(s):  
Z.Y. Mao ◽  
Lyle E. Craker
Keyword(s):  
Nitrogen Fertilization ◽  
Leaf Size ◽  
Light Level ◽  
High Nitrogen ◽  
Light Levels ◽  
Leaf Chlorophyll ◽  
Nitrogen Treatment ◽  
Reduced Light ◽  
Field Production ◽  
Number Of Branches

Mulch, light level, and nitrogen fertilization were tested for their effects on productivity of horehound (Marrubium vulgaris L.). Yield of this plant increased under mulched conditions and with the addition of nitrogen fertilizer. Yield decreased with reduced light levels. Productivity of individual plants correlated with the number of branches per plant, leaf size, and leaf chlorophyll content. The number of branches per plant decreased with increased shading, but increased with increased nitrogen fertilization. The influence of mulch and shading on productivity could be due to the changes in soil temperature and in soil water potentials. Full-sun, high nitrogen, and mulch are suggested for optimum field production of horehound.

Assimilate Movement in Lolium and Sorghum Leaves. I. Irradiance Effects on Photosynthesis, Export and the Distribution of Assimilates

1976 ◽  
Vol 3 (3) ◽  
pp. 377 ◽  
Author(s):  
IF Wardlaw
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Vascular System ◽  
Net Photosynthesis ◽  
Low Light ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Light Levels ◽  
C4 Grass ◽  
Reduced Light

At low light levels (20 W m-2 PAR), little difference was detectable in net photosynthetic rates between leaves of the C3 grass Lolium temulentum and the C4 grass Sorghum sudanense. At low light, both species also had similar rates of export of photosynthate per unit leaf area, although the rate of export of 14C, following the assimilation of 14CO2 by the uppermost fully expanded leaf, was much greater in Sorghum. As light levels were increased to 96 W m-2 PAR or greater, net photosynthesis rose more in Sorghum than in Lolium and a greater proportion of the assimilate was exported from the Sorghum leaf, while Lolium with the thicker leaf showed a much greater capacity for storage of photosynthate. High and low light pretreatments, which altered the amount of both soluble and insoluble dry matter in the leaf, had little effect on the percentage rate of export of 14C following the uptake of 14CO2, which suggests that the bulk of the stored material may be effectively separated from the pathway of transfer from the chloroplast to the vascular system within the leaf. The pattern of distribution of 14C-labelled assimilates to other parts of the plant was only slightly affected by reduced light during the 4-h translocation period' however, a 3-day pretreatment at low light significantly reduced the proportion of the assimilates moving to the roots.

scholarly journals Physiological and ecological consequences of the water optical properties degradation on reef corals

Coral Reefs ◽  
2021 ◽  
Author(s):  
Tomás López-Londoño ◽  
Claudia T. Galindo-Martínez ◽  
Kelly Gómez-Campo ◽  
Luis A. González-Guerrero ◽  
Sofia Roitman ◽  
...  
Keyword(s):  
Optical Properties ◽  
Population Decline ◽  
Light Availability ◽  
Potential Effect ◽  
Optical Quality ◽  
Light Penetration ◽  
Reef Corals ◽  
Orbicella Faveolata ◽  
Light Quantity ◽  
Reduced Light

AbstractDegradation of water optical properties due to anthropogenic disturbances is a common phenomenon in coastal waters globally. Although this condition is associated with multiple drivers that affect corals health in multiple ways, its effect on light availability and photosynthetic energy acquisition has been largely neglected. Here, we describe how declining the water optical quality in a coastal reef exposed to a turbid plume of water originating from a man-made channel compromises the functionality of the keystone coral species Orbicella faveolata. We found highly variable water optical conditions with significant effects on the light quantity and quality available for corals. Low-light phenotypes close to theoretical limits of photoacclimation were found at shallow depths as a result of reduced light penetration. The estimated photosynthetically fixed energy depletion with increasing depth was associated with patterns of colony mortality and vertical habitat compression. A numerical model illustrates the potential effect of the progressive water quality degradation on coral mortality and population decline along the depth gradient. Collectively, our findings suggest that preserving the water properties seeking to maximize light penetration through the water column is essential for maintaining the coral reef structure and associated ecosystem services.

scholarly journals Mesophotic.org: a repository for scientific information on mesophotic ecosystems

Database ◽  
2019 ◽  
Vol 2019 ◽  
Author(s):  
Pim Bongaerts ◽  
Gonzalo Perez-Rosales ◽  
Veronica Z Radice ◽  
Gal Eyal ◽  
Andrea Gori ◽  
...  
Keyword(s):  
Large Scale ◽  
Scientific Information ◽  
Temporal Trends ◽  
Light Availability ◽  
Research Community ◽  
Future Research ◽  
Photosynthetic Organisms ◽  
Future Research Directions ◽  
Available Information ◽  
Reduced Light

Abstract Mesophotic coral ecosystems (MCEs) and temperate mesophotic ecosystems (TMEs) occur at depths of roughly 30–150 m depth and are characterized by the presence of photosynthetic organisms despite reduced light availability. Exploration of these ecosystems dates back several decades, but our knowledge remained extremely limited until about a decade ago, when a renewed interest resulted in the establishment of a rapidly growing research community. Here, we present the ‘mesophotic.org’ database, a comprehensive and curated repository of scientific literature on mesophotic ecosystems. Through both manually curated and automatically extracted metadata, the repository facilitates rapid retrieval of available information about particular topics (e.g. taxa or geographic regions), exploration of spatial/temporal trends in research and identification of knowledge gaps. The repository can be queried to comprehensively obtain available data to address large-scale questions and guide future research directions. Overall, the ‘mesophotic.org’ repository provides an independent and open-source platform for the ever-growing research community working on MCEs and TMEs to collate and expedite our understanding of the occurrence, composition and functioning of these ecosystems. Database URL: http://mesophotic.org/

Light availability and soil compaction influence the growth of underplanted Nothofagus following partial shelterwood harvest and soil scarification

2015 ◽  
Vol 45 (8) ◽  
pp. 998-1005 ◽  
Author(s):  
Daniel P. Soto ◽  
Pablo J. Donoso ◽  
Christian Salas ◽  
Klaus J. Puettmann
Keyword(s):  
Soil Fertility ◽  
Soil Compaction ◽  
Light Availability ◽  
Penetration Resistance ◽  
Basal Diameter ◽  
Heavy Machinery ◽  
Light Levels ◽  
Soil Scarification ◽  
Total Light ◽  
Nothofagus Dombeyi

We evaluated effects of topsoil scarification by heavy machinery on growth of two valuable, shade-intolerant tree species — Nothofagus dombeyi (Mirb.) Oerst. (evergreen and considered to be very plastic to different soil fertility levels) and Nothofagus alpina (Poepp. & Endl.) Oerst. (deciduous and considered to be sensitive to soil fertility) — seedlings that were underplanted in Nothofagus old-growth forests, which were subjected to shelterwood cuttings without the final cut in the Chilean Andes. We compared tree basal diameter growth as it responds to light availability and soil compaction (as measured by resistance to penetration) by fitting a growth model based on the Michaelis–Menten equation. Predicted growth of N. dombeyi was greater than N. alpina in high and low light levels; however, there were no significant differences between the species. Both species showed significant differences at high levels of penetration resistance (>2000 kPa). Differences for N. dombeyi occurred above ∼40% in total light, and differences occurred for N. alpina above ∼20% in total light. However, they were not different when compared at low and intermediate levels of penetration resistance. The results suggest that partial shelterwood cuts may provide adequate light levels to achieve appropriate growth of underplanted Nothofagus seedlings. However, if regeneration of N. alpina is desired, scarification of topsoil needs to be implemented with more caution in canopy openings, as traffic and soil removal by heavy machinery can have detrimental effects on growth of this species and other species that are more sensitive to soil compaction.

The influence of fire on Spartina pectinata wetland communities in a northeastern Kansas tallgrass prairie

1995 ◽  
Vol 73 (1) ◽  
pp. 84-90 ◽  
Author(s):  
Stephen R. Johnson ◽  
Alan K. Knapp
Keyword(s):  
Tallgrass Prairie ◽  
Light Availability ◽  
Fire Frequency ◽  
Plant Species Composition ◽  
Prairie Wetlands ◽  
Asclepias Syriaca ◽  
Spartina Pectinata ◽  
Galium Aparine ◽  
Reduced Light ◽  
Diverse Plant

Wetlands dominated by the C4 grass Spartina pectinata were investigated to quantify differences in plant species composition and diversity in response to fire frequency. The study site was a tallgrass prairie in northeastern Kansas that included Spartina wetlands subjected to spring fires at 1-, 2-, 4-, 10-, and 20-year intervals. Because C3 forbs in these wetlands responded strongly to different fire frequencies, the light environment and gas exchange responses of the ubiquitous forb Asclepias syriaca were also assessed. In general, species diversity was lower in annually burned wetlands because of lower forb diversity. Maximum H′ in annually burned sites was 1.64 versus 2.77 in 10- and 20-year burned sites. However, individual forb responses varied. Asclepias increased and Solidago canadensis and Galium aparine decreased in importance with increasing fire frequency. Canopy sunlight interception was greater in annually burned wetlands than in wetlands with lower burn frequencies. Despite reduced light availability, midseason photosynthetic rates of Asclepias were higher in annually burned sites. The results suggest that frequent fire in tallgrass prairie wetlands results in less diverse plant communities, similar to responses of upland prairie, and that the timing of fire, relative to life history and phenology of the subordinate species, strongly influences responses of individual forbs. Key words: wetlands, tallgrass prairie, Spartina pectinata communities, fire.

scholarly journals Current status and variation trend of seagrass beds in coastal water of Son Tra peninsula, Da Nang city

2021 ◽  
Vol 21 (2) ◽  
pp. 183-189
Author(s):  
Hoa Nguyen Xuan ◽  
Nhu Thuy Nguyen Nhat ◽  
Hieu Nguyen Trung
Keyword(s):  
Species Composition ◽  
Coastal Water ◽  
Shoot Density ◽  
Current Status ◽  
Seagrass Beds ◽  
Variation Trend ◽  
Halophila Ovalis ◽  
Density And Biomass ◽  
Size And Structure

Species composition of seagrasses in coastal water of Son Tra peninsula was less diverse, with three species identified. Halophila ovalis was dominant. The seagrass beds are mainly distributed in Bai Nom and Bai But, with a total area of about 1 ha. The seagrass beds had been seriously degraded in both size and structure. Approximately 9 ha of seagrass beds (90% of total area) disappeared compared with data of 2005. Halophila ovalis had only been distributed at a depth of 2–3 m. Coverage, shoot density, and biomass of seagrass beds had also decreased.

scholarly journals Leaf Characteristics and Yield Performance of Mungbean (Vigna radiata L.) Varieties under Different Levels of Shading

2018 ◽  
Vol 15 (2) ◽  
pp. 40-51
Author(s):  
M A Hossain ◽  
M A Hasan ◽  
S Sikder ◽  
A K M M B Chowdhury
Keyword(s):  
Light Intensity ◽  
Grain Yield ◽  
Vigna Radiata ◽  
Dry Weight ◽  
Light Levels ◽  
Spongy Layer ◽  
Partial Shade ◽  
Shade Condition ◽  
Reduced Light ◽  
Leaf Dry Weight

An experiment was carried out to evaluate the leaf characteristics and yield performances of mungbean (Vigna radiata L.) under different light levels at the Crop Physiology and Ecology Research Field of Hajee Mohammad Danesh Science and Technology University, Dinajpur during March to June 2016. The experiment was laid out in a split plot design with three replications. Three light levels (L100 - 100 % light intensity, L75- 75 % light intensity and L50- 50% light intensity) were assigned in the main plots and four varieties (BARl Mung-6, BINA Mung-8, BINA Mung-5 and BU Mug-4) were assigned in subplots. Mosquito nets of different pore size were used for maintaining 75 and 50 percent light intensity. Leaf area was increased due to reduced light levels in all mugbean varieties but the increment was significant in BINA Mung-5 and BINA Mung-8 only at 75% light intensity at 40 days after sowing and only in BARI Mung-6 with L50 and BU Mug-4 with L75 and L50at 50 days after sowing. Due to reduced light levels, leaf dry weight was affected more in BINA Mung-5 and BU Mug- 4 than BARI Mung-6 and BINA Mung-8. Leaf thickness was reduced under shade in all the mungbean varieties, except in BU Mug-4 at 75% light intensity, and the reduction in leaf thickness was mainly due to the reduction in thickness of spongy layer. The palisade layer thickness was influenced insignificantly but spongy layer thickness was increased in BINA Mung-5 at 100% light intensity. The grain yields (t ha-1) of BARI Mung-6 and BINA Mung-8 remained stable under partial shade condition but the grain yield of BINA Mung-5 and BU Mug-4 was reduced drastically under partial shade condition. Higher leaf dry weight, number of pods plant-1, seeds pod-1, and heavier grains in BARI Mung-6 and BINA Mung-8 contributed to the higher grain yield plant-1 under partial shade condition than in BINA Mung-5 and BU Mug-4.The Agriculturists 2017; 15(2) 40-51

Photosynthesis and physiological traits of evergreen broadleafed saplings during winter under different light environments in a temperate forest

2006 ◽  
Vol 84 (1) ◽  
pp. 60-69 ◽  
Author(s):  
Yoshiyuki Miyazawa ◽  
Kihachiro Kikuzawa
Keyword(s):  
Temperate Forest ◽  
Light Availability ◽  
Net Photosynthesis ◽  
Carbon Gain ◽  
Leaf Mass Per Area ◽  
Camellia Japonica ◽  
Leaf Mass ◽  
Unit Leaf ◽  
Canopy Trees ◽  
Photosynthetic Traits

Photosynthetic traits of the evergreen broadleafed species Camellia japonica L. and Quercus glauca Thunb. were continuously investigated during autumn and winter using saplings that grew in different light environments (gap, deciduous canopy understory, and evergreen canopy understory) in a temperate forest. Light-saturated rates of net photosynthesis in midwinter and spring were lower than those in autumn. Photosynthetic capacity, scaled to a common leaf temperature of 25 °C, increased or remained stable after autumn and then decreased in spring in most leaves. Photosynthetic traits per unit leaf area were different among leaves in different light environments of both Camellia and Quercus during most periods. However, photosynthetic traits per unit leaf mass did not differ among leaves in different light environments, suggesting that differences in photosynthetic traits were mainly due to different leaf mass per area among leaves. Photosynthetic rates under light availability typical in the environment were lower in winter than in autumn in leaves in the sun in a gap but were not different in leaves in the shade under evergreen canopy trees. Thus, the importance of winter carbon gain for annual carbon gain is small in leaves in a gap but is large in leaves under evergreen canopy trees.

Sign in / Sign up

Export Citation Format

Share Document