Despite a parallel decline in stomatal conductance and net photosynthesis, exposure to a hard freeze caused a decrease in the stomatal limitation to gas exchange

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尽管气孔导度和净光合作用同时下降，但遭受严寒冻害后，气孔对气体交换的限制程度降低了。

Apesar de uma diminuição paralela na condutância estomática e na fotossíntese líquida, a exposição a uma forte geada causou uma diminuição na limitação estomática para a troca de gases.

A pesar de una disminución paralela en la conductancia estomática y la fotosíntesis neta, la exposición a una helada intensa provocó una disminución en la limitación estomática para el intercambio de gases.

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The effect of freezing nights on photosynthesis,
stornatal conductance, and internal CO, concentration in seedlings of Engelmann spruce (Picea engelrnannii Parry)

Delucia E. H. (1987)

Plant Cell Environ. 10: 333-338 – https://doi.org/10.1111/j.1365-3040.1987.tb01614.x –

https://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.1987.tb01614.x

Abstract 

The effect of freezing night temperatures on net photosynthesis, stomatal conductance, and internal CO₂ concentration was investigated in unhardened seedlings of Engelmann spruce. Exposure to – 2.5°C in the dark for 10 h caused a slight and reversible reduction in gas-exchange parameters on the following days. Substantial and irreversible inhibition of photosynthesis occurred after exposure to -4°C or –5°C. Despite a parallel decline in stomatal conductance and net photosynthesis, exposure to a hard freeze caused a decrease in the stomatal limitation to gas exchange. Hard-freeze conditions (less than – 4°C) also caused a decrease in carboxylation efficiency and apparent quantum yield, indicating a freeze-induced failure of the dark reactions and electron transport. There was no significant difference in the photosynthetic response to freezing temperatures in different elevational populations of spruce, although acclimatory adjustments were observed. Gas exchange in seedlings grown under cool conditions (14°C day/9°C night) was less affected and recovered more rapidly after exposure to a hard freeze than in seedlings grown under warm conditions (24°C day/19°C night).

Stomatal conductance of seedlings subjected to nitrogen fertilization and drought treatments

Stomatal conductance of seedlings of three oak species subjected to nitrogen fertilization and drought treatments

Hechler W. D., Dawson J. O., DeLucia E. H. (1991)

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In: McCormick, Larry H.; Gottschalk, Kurt W., eds. Proceedings, 8th Central Hardwood Forest Conference; 1991 March 4-6; University Park, PA. Gen. Tech. Rep. NE-148. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 188-193 –

https://www.nrs.fs.fed.us/pubs/3498

Abstract

Both nitrogen-fertilized and unfertilized white oak, bur oak, and red oak seedlings were subjected to progressive drought in a greenhouse study.

Effect of low root temperature on stomatal conductance

 

 

Effect of low root temperature on net photosynthesis, stomatal conductance and carbohydrate concentration in Engelmann spruce (Picea engelmannii Parry ex Engelm.) seedlings

by Delucia E. H. (1986)

Phytotron, Department of Botany, Duke University, Durham, NC 27706, USA.

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in Tree Physiol., 2: 143–154 – PMID: 14975849 –

https://www.ncbi.nlm.nih.gov/pubmed/14975849?dopt=Abstract

Abstract

The effect of low root temperature on net photosynthesis, stomatal conductance and carbohydrate concentration in potted Engelmann spruce (Picea engelmannii Parry ex Engelm.) seedlings was examined under controlled growth-chamber conditions.

Root temperature had no effect on net photosynthesis between 10 and 20 degrees C, however, conductance and photosynthesis declined sharply below 8 degrees C. Net photosynthesis and stomatal conductance decreased to 50 and 34% of the initial values after 7 days at a root temperature of 0.7 degrees C.

Low root temperature also caused a decrease in photosynthetic utilization of internal CO(2), carboxylation efficiency and apparent quantum yield, and it was concluded that the decrease in photosynthetic rate was caused primarily by nonstomatal limitations.

Root chilling caused a small increase in starch content in needles and stems and induced the hydrolysis of starch to glucose in roots. The increase in glucose concentration may enable continued root growth at low temperatures.

Induction of adaxial stomata in Vitis

 Photo credit: PNAS

Epidermal leaf peels show Vitis leaves are hypostomatal, having no stomata on the adaxial side (A), but gall formation generates stomata in increasing density at closer proximity to the gall (out of picture Lower Right; B). Abaxial tissue without or adjacent to galls have similar stomata patterning (Table 1).

Leaf-galling Phylloxera on grapes reprograms host metabolism and morphology

by Nabity P. D., Haus M. J., Berenbaum M. R., DeLucia E. H. (2013)

in PNAS – vol. 110 no. 41, 16663–16668

Epidermal leaf peels show Vitis leaves are hypostomatal, having no stomata on the adaxial side (A) – http://www.pnas.org/content/110/41/16663/F1.medium.gif

Significance

Some herbivorous insects induce galls, abnormal structures, in their host plants, benefiting the gall-forming parasite by providing nutritive tissue. The gall-forming insect Phylloxera induces stomata, openings through which plants regulate water and CO₂, on the upper surface of grape leaves where they typically do not occur. Carbon uptake and transpiration by induced stomata facilitate nutrient acquisition by gall tissue and phylloxera. Moreover, gall formation reprograms the host-leaf transcriptome to increase transcripts associated with sucrose mobilization and glycolysis and decrease defense-related transcripts. Thus, stomata induction by phylloxera reconfigures leaves to increase carbon gain, to partially offset negative impacts of gall formation.