scholarly journals Leaf Gas Exchange Performance of Ten Quinoa Genotypes under a Simulated Heat Wave

Plants ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 81 ◽  
Author(s):  
Ashley Eustis ◽  
Kevin M. Murphy ◽  
Felipe H. Barrios-Masias
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Gas Exchange ◽  
High Temperatures ◽  
Heat Waves ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Reproductive Capacity ◽  
Plant Water ◽  
Assimilation Capacity

Quinoa (Chenopodium quinoa Willd.) is a highly nutritious crop that is resilient to a wide range of abiotic stresses; however, sensitivity to high temperatures is regarded as an impediment to adoption in regions prone to heat waves. Heat stress is usually associated with a decrease in crop reproductive capacity (e.g., pollen viability), yet little is known about how leaf physiological performance of quinoa is affected by high temperatures. Several trials were conducted to understand the effect of high temperatures, without confounding stressors such as drought, on ten selected quinoa genotypes considered to encompass heat sensitive and heat tolerant plant material. Plants were grown under favorable temperatures and exposed to two temperature treatments over four consecutive days. The heat treatment simulated heat waves with maximum and minimum temperatures higher during the day and night, while the control treatment was maintained under favorable temperatures (maximum and minimum temperatures for ‘Heat’: 45/30 °C and ‘Control’: 20/14 °C). Leaf gas exchange (day), chlorophyll fluorescence (predawn and day) and dark respiration (night) were measured. Results show that most quinoa genotypes under the heat treatment increased their photosynthetic rates and stomatal conductance, resulting in a lower intrinsic water use efficiency. This was partly corroborated by an increase in the maximum quantum yield of photosystem II (Fv/Fm). Dark respiration decreased under the heat treatment in most genotypes, and temperature treatment did not affect aboveground biomass by harvest (shoot and seeds). These results suggest that heat stress alone favors increases in leaf carbon assimilation capacity although the tradeoff is higher plant water demand, which may lead to plant water stress and lower yields under non-irrigated field conditions.

Late Season Water Stress in Cotton: II. Leaf Gas Exchange and Assimilation Capacity

Crop Science ◽  
1996 ◽  
Vol 36 (4) ◽  
pp. 922-928 ◽  
Author(s):  
K. L. Faver ◽  
T. J. Gerik ◽  
P. M. Thaxton ◽  
K. M. El‐Zik
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Late Season ◽  
Assimilation Capacity

scholarly journals Beyond the extreme: recovery of carbon and water relations in woody plants following heat and drought stress

2019 ◽  
Vol 39 (8) ◽  
pp. 1285-1299 ◽  
Author(s):  
Nadine K Ruehr ◽  
Rüdiger Grote ◽  
Stefan Mayr ◽  
Almut Arneth
Keyword(s):  
Heat Stress ◽  
Gas Exchange ◽  
Water Relations ◽  
Woody Plants ◽  
Leaf Gas Exchange ◽  
Experimental Studies ◽  
Drought Severity ◽  
Stress Recovery ◽  
Mild Stress ◽  
Post Stress

Abstract Plant responses to drought and heat stress have been extensively studied, whereas post-stress recovery, which is fundamental to understanding stress resilience, has received much less attention. Here, we present a conceptual stress-recovery framework with respect to hydraulic and metabolic functioning in woody plants. We further synthesize results from controlled experimental studies following heat or drought events and highlight underlying mechanisms that drive post-stress recovery. We find that the pace of recovery differs among physiological processes. Leaf water potential and abscisic acid concentration typically recover within few days upon rewetting, while leaf gas exchange-related variables lag behind. Under increased drought severity as indicated by a loss in xylem hydraulic conductance, the time for stomatal conductance recovery increases markedly. Following heat stress release, a similar delay in leaf gas exchange recovery has been observed, but the reasons are most likely a slow reversal of photosynthetic impairment and other temperature-related leaf damages, which typically manifest at temperatures above 40 °C. Based thereon, we suggest that recovery of gas exchange is fast following mild stress, while recovery is slow and reliant on the efficiency of repair and regrowth when stress results in functional impairment and damage to critical plant processes. We further propose that increasing stress severity, particular after critical stress levels have been reached, increases the carbon cost involved in reestablishing functionality. This concept can guide future experimental research and provides a base for modeling post-stress recovery of carbon and water relations in trees.

scholarly journals Salinity Influences Photosynthetic Characteristics, Water Relations, and Foliar Mineral Composition of Annona squamosa L.

1996 ◽  
Vol 121 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Thomas E. Marler ◽  
Yasmina Zozor
Keyword(s):  
Gas Exchange ◽  
Water Relations ◽  
Salinity Stress ◽  
Root Zone ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Chloride Concentration ◽  
Sand Culture ◽  
Mineral Nutrient ◽  
Annona Squamosa

Leaf gas exchange, chlorophyll fluorescence, water relations, and mineral nutrient relations responses of Annona squamosa seedlings to mild salinity were studied in sand culture in five experiments during 1990, 1991, and 1993. Trees were irrigated with a complete nutrient solution (control) or with this solution amended to 3 or 6 dS·m-1 with sea salt. Inhibition of net CO2 assimilation, stomatal conductance of CO2, and transpiration was apparent within 2 weeks of initiating salinity treatments, and gas exchange continued to decline until day 30 to 35. The diurnal pattern of leaf gas exchange was not altered by increased salinity. Salinity reduced CO2, light energy, and water-use efficiencies. Salinity sometimes reduced the ratio of variable to maximum fluorescence below that of the control, and this response was highly dependent on the ambient light conditions that preceded the measurements. Dark respiration was unaffected by salinity stress. Root zone salinity of 3 dS·m-1 administered for 52 days did not influence foliar sodium concentration or the ratio of sodium to potassium, but increased chloride concentration and decreased nitrogen concentration. The sodium response indicated that some form of exclusion or compartmentation occurred. Salinity reduced osmotic potential of root tissue but did not influence foliar osmotic or predawn xylem potential. These results indicate that A. squamosa is sensitive to salinity stress, and that the responses to salinity are consistent with other salt-sensitive woody perennial species.

Late Season Water Stress in Cotton: II. Leaf Gas Exchange and Assimilation Capacity

Crop Science ◽  
1996 ◽  
Vol 36 (4) ◽  
Author(s):  
K. L. Faver ◽  
T. J. Gerik ◽  
P. M. Thaxton ◽  
K. M. El‐Zik
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Late Season ◽  
Assimilation Capacity

The effects of environmental conditions on the inhibition of leaf gas exchange by NO2

1975 ◽  
Vol 53 (5) ◽  
pp. 475-482 ◽  
Author(s):  
H. S. Srivastava ◽  
P. A. Jolliffe ◽  
V. C. Runeckles
Keyword(s):  
Gas Exchange ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Absolute Magnitude ◽  
High Irradiance ◽  
Diffusion Resistance ◽  
Inhibitory Effects ◽  
Natural Ecosystems ◽  
Photosynthetic Inhibition ◽  
Free Air

An open flow system was used to examine the uptake and effects of NO2 on gas exchange by primary leaves of bean (Phaseolus vulgaris L.) under a variety of conditions of irradiance, temperature, humidity, and atmospheric CO2 and O2 concentrations. At 3.0 ppm, NO2 inhibited apparent photosynthesis and dark respiration in all the conditions tested. Both 3.0 ppm and 7.0 ppm NO2 inhibited the evolution of CO2 into CO2-free air. The absolute magnitude of photosynthetic inhibition by NO2 was greatest at high irradiance, at the optimum temperature for apparent photosynthesis, and at high humidities. Changes in CO2 concentration from 100 to 600 ppm and in O2 concentration from 0 to 21% did not affect the percentage inhibition of apparent photosynthesis by NO2. High temperatures increased the inhibitory effects of NO2 on dark respiration.The effects of NO2 on apparent photosynthesis, dark respiration, and CO2 evolution into CO2-free air were based on inhibitory effects exerted within the leaves and not on CO2 diffusion into the leaf. Transpiration rate and stomatal diffusion resistance were only slightly affected by NO2. The uptake of NO2 was enhanced by high temperature, low CO2 concentration, and high humidity. The results of these studies support the view that NO2 uptake is subject to internal limitations ("mesophyll resistance") under many environmental conditions.The range and prevalence of NO2 effects suggest that NO2 may cause general detrimental changes in the physiology of leaf cells. Furthermore, the circumstances under which NO2 effects were found to occur indicate that such effects may be significant in natural ecosystems.

Relationship of plant water status and leaf gas exchange with fruit cracking of pomegranate

2019 ◽  
Vol 76 (2) ◽  
pp. 289
Author(s):  
Akath Singh ◽  
U. Burman ◽  
P. Santra ◽  
Anurag Saxena ◽  
P.R. Meghwal
Keyword(s):  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Plant Water Status ◽  
Plant Water ◽  
Fruit Cracking ◽  
Relationship Of

Inhibition of gas exchange in bean leaves by NO2

1975 ◽  
Vol 53 (5) ◽  
pp. 466-474 ◽  
Author(s):  
H. S. Srivastava ◽  
P. A. Jolliffe ◽  
V. C. Runeckles
Keyword(s):  
Gas Exchange ◽  
Exposure Time ◽  
Gas Flow ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Leaf Growth ◽  
Stomatal Resistance ◽  
Air Pollutant ◽  
Phaseolus Vulgaris L ◽  
Rate Of Absorption

An open gas-flow system was used to examine the effects of the air pollutant NO2 on gas exchange by primary leaves of bean (Phaseolus vulgaris L.). Apparent photosynthesis and dark respiration were both inhibited by NO2 concentrations between 1.0 and 7.0 ppm. The degree of inhibition was increased by increasing NO2 concentration and increasing exposure time. Leaf susceptibility to NO2 varied during leaf growth. NO2 was most inhibitory at the ages when maximum rates of apparent photosynthesis or respiration were observed in the NO2-free controls (11 or 12, or 8 days after sowing, respectively). The rate of absorption of NO2 by leaves increased in direct proportion with the NO2 concentration and declined with increasing exposure time. The NO2 uptake rate in the dark was about half of its rate during illumination because of greater stomatal resistance to NO2 absorption in the dark. Transpiration rate was less affected by NO2 than was photosynthesis or respiration. Accordingly, it is suggested that the principal effects of NO2 on leaf gas exchange are exerted in the leaf mesophyll and are not on the stomata.

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