Irrigated Shiraz vines (Vitis vinifera) upregulate gas exchange and maintain berry growth in response to short spells of high maximum temperature in the field

2009 ◽  
Vol 36 (9) ◽  
pp. 801 ◽  
Author(s):  
Chris J. Soar ◽  
Marisa J. Collins ◽  
Victor O. Sadras

We tested the hypotheses that (i) a short period of high maximum temperature disrupts gas exchange and arrests berry growth and sugar accumulation in irrigated Shiraz vines (Vitis vinifera L.), and (ii) the magnitude of these effects depend on the phenological window when stress occur. Using a system combining passive heating (greenhouse effect) and active cooling (fans) to control daytime temperature, we compared vines heated to a nominal maximum of 40°C for three consecutive days and untreated controls. Maximum air temperature in heated treatments was 7.3°C (2006–07) and 6.5°C (2007–08) above ambient. Heat episodes were aligned with the beginning of a weekly irrigation cycle and applied in one of four phenological windows, namely post-fruit set, pre-veraison, veraison and pre-harvest. Heating systems did not affect relative humidity, hence vapour pressure deficit (VPD) was increased in the heated treatments and tracked the daily cycle of temperature. Heat did not affect the dynamics of berry growth and sugar accumulation, except for a 16% reduction in berry size and sugar content in vines heated shortly after fruit set in 2006–07. Vines upregulated stomatal conductance and gas exchange in response to heat. Stomatal conductance, photosynthesis and transpiration at a common VPD were consistently higher in heated vines than in controls. We suggest that stomatal behaviour previously described as part of Shiraz anisohydric syndrome may be adaptive in terms of heat tolerance at the expense of short-term transpiration efficiency.

2010 ◽  
Vol 37 (3) ◽  
pp. 206 ◽  
Author(s):  
Dennis H. Greer ◽  
Chris Weston

High temperatures during the growing season characterise many grape growing regions in Australia and elsewhere in the world, and impact on many processes including growth and berry development. To quantify the impact of heat on the Vitis vinifera L. cv. Semillon, potted vines were grown in controlled environments and exposed to a temperature regime of 40/25°C at flowering, fruit set, veraison and mid-ripening stages. Vegetative and reproductive development was measured throughout and leaf photosynthesis and stomatal conductance tracked during heat exposures. Accumulation of soluble solids was determined during ripening. Leaf growth and stem extension were unaffected by heat whereas flowers completely abscised. Berries treated at fruit set developed normally and those treated at veraison and mid-ripening stopped expanding and sugar content stopped increasing. Photosynthesis was also affected on each occasion, with rates declining by 35% and taking 12 days to recover. Up to 10 mg carbon g (berry dry weight)–1 day–1 was required for ripening after veraison. For vines heat treated at veraison and mid-ripening, net carbon acquisition rates fell to below 4 mg carbon g (leaf dry weight)–1 day–1, which is inadequate to supply berry carbon requirements. This suggests that the impacts of heat on the ripening process can be traced back to the supply of carbon.


2003 ◽  
Vol 30 (6) ◽  
pp. 673 ◽  
Author(s):  
Hans R. Schultz

Measurements of gas exchange and stomatal conductance were made on potted and field-grown grapevines (Vitis vinifera L.) on leaves from different light environments (sun and shade) at different phenological stages during the season to parameterise the Farquhar model. The model parameters for Rubisco activity (Vcmax), maximum electron transport rate (Jmax), and triose-phosphate utilisation (TPU) were estimated on the basis of a large data set (n = 105) of CO2 assimilation (A) versus internal CO2 pressure (Ci) curves. Leaf age was described with the leaf plastochron index (LPI). Stomatal coupling to photosynthesis was modelled with the Ball–Woodrow–Berry empirical model of stomatal conductance. Mature shade leaves had 35–40% lower values of Vcmax, Jmax and TPU than sun leaves. The difference between leaf types decreased at the end of the season. The ratio Jmax / Vcmax and values of day respiration (Rd) and CO2 compensation point in the absence of mitochondrial respiration (Γ*) varied little during the season and were independent of LPI. Validation of the model with independent diurnal data sets of measurements of gas exchange and stomatal conductance at ambient CO2 concentrations for three days between June and October, covering a large range of environmental conditions, showed good agreement between measured and simulated values.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 497e-497
Author(s):  
Lili Zhou ◽  
David Christopher ◽  
Robert E. Paull

The source size and sink strength were modified by continual defoliation and fruit removal in `Sunset' papaya. Flower and fruit set, mature fruit mass, and TSS was recorded weekly. Fruit at four different stages of development were harvested at the end of the experiment. Fruit mass, respiration, sugar content, and sucrose phosphate synthase (SPS), sucrose synthase (SS), and invertase enzyme activities were compared. Continual defoliation resulted in lower new fruit set (25% of control), smaller fruit size (77% of control), and lower TSS (85% of control) in the 24-week experimental period. In contrast, there were 52% and 100% more new fruit when fruit were removed than in the control within the first 8 weeks and 24 weeks, respectively. Larger fruit size, earlier fruit development, lower respiration, and higher sugar contents were observed when fruit were removed at 140, 154, and 175 days from anthesis. No significant difference was found in TSS level in the mature fruit compared to the control. Fruit removal plus defoliation gave the same number and mass of new fruit as the control and slightly lower TSS in mature fruit than in the control. Fruit sugar was higher with increased fruit invertase activity and fruit age. Data confirmed that source–sink balance was critical for fruit set, development, and sugar accumulation in papaya.


Forests ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 46
Author(s):  
Elena Paoletti ◽  
Nancy E. Grulke ◽  
Rainer Matyssek

We measured whole-tree transpiration of mature Fagus sylvatica and Picea abies trees exposed to ambient and twice-ambient O3 regimes (1xO3 and 2xO3 free-air fumigation). After eight years, mean daily total transpiration did not vary with the O3 regime over the 31 days of our study, even though individual daily values increased with increasing daily O3 peaks in both species. Although the environmental parameters were similar at 1xO3 and 2xO3, the main factors affecting daily transpiration were vapour pressure deficit in 2xO3 spruce and O3 peaks in beech. For a mechanistic explanation, we measured O3-induced sluggish stomatal responses to variable light (sunflecks) by means of leaf-level gas exchange measurements only in the species where O3 was a significant factor for transpiration, i.e., beech. Stomata were always slower in closing than in opening. The 2xO3 stomata were slower in opening and mostly in closing than 1xO3 stomata, so that O3 uptake and water loss were amplified before a steady state was reached. Such delay in the stomatal reaction suggests caution when assessing stomatal conductance under O3 pollution, because recording gas exchange at the time photosynthesis reached an equilibrium resulted in a significant overestimation of stomatal conductance when stomata were closing (ab. 90% at 1xO3 and 250% at 2xO3). Sun and shade leaves showed similar sluggish responses, thus suggesting that sluggishness may occur within the entire crown. The fact that total transpiration was similar at 1xO3 and 2xO3, however, suggests that the higher water loss due to stomatal sluggishness was offset by lower steady-state stomatal conductance at 2xO3. In conclusion, O3 exposure amplified short-term water loss from mature beech trees by slowing stomatal dynamics, while decreased long-term water loss because of lower steady-state stomatal conductance. Over the short term of this experiment, the two responses offset each other and no effect on total transpiration was observed.


2020 ◽  
Author(s):  
Wei Li ◽  
Cicheng Zhang

<p>Desert environments are characterized by limited and highly variable rainfall, which is an intermittent source of water critical to the evolution of the structure and functioning of desert ecosystems. The present study was to assess the effects of different amounts of rainfall received through discrete rainfall events and of the ecophysiological responses for Reaumurica soongorica along multiple average precipitation (MAP) gradient. A field experiment was performed under seven simulated rainfall amounts (0 - 40 mm) with Reaumurica soongorica at respective High-P (120 mm), Middle-P (67 mm), and Low-P (35 mm) sites along middle and lower reach of Heihe River Basin in July, 2015. Pre-dawn plant water potential (ψ<sub>pd</sub>), the rates of photosynthesis and stomatal conductance were measured synchronously. Results showed that: photosynthetic response of R.soongorica to rainfall pulse was significant different. The mean daily leaf gas exchange and maximum photosynthesis rate (P<sub>n-max</sub>) of R.soongorica were decreased obviously with decreasing MAP. Vapour pressure deficit (VPD) was the predominant factor for gas exchange limiting. Under the control of VPD, stomatal conductance was pregressively reduced with decreasing ψ<sub>pd</sub>, which was functioned as limiting P<sub>n-max</sub> and further increasing water use efficiency (WUE). However, when MAP was declined below 35 mm, the response of stomatal conductance to ψ<sub>pd</sub> was weakened, from which P<sub>n-max</sub> began to increase again. 2 to 4 days hystereric response of R.soongorica ψ<sub>pd</sub> to various rainfall events was found in High-P. Stomatal conductance was then increased linearly with increasing ψ<sub>pd</sub>, from which P<sub>n-max </sub>was also enhanced linearly. While weakly response of ψ<sub>pd</sub> to similar rainfall events was observed in Low-P, where stomatal conductance and P<sub>n-max</sub> was maintained stable after rain. Mentioned above, the effective rainfall pluse, induced by obvious physiological response of R. soongorica, was 3.63-6.73 mm and 6.73-10.09 mm for Linze and Ejina, respective. Our results provided comprehensively understanding in the consequences of long-term variability in rainfall for the physiology of desert plants and species dynamics in desert ecosystems.</p>


2017 ◽  
Author(s):  
Víctor Resco de Dios ◽  
Arthur Gessler ◽  
Juan Pedro Ferrio ◽  
Josu G Alday ◽  
Michael Bahn ◽  
...  

SummaryOptimal stomatal theory is an evolutionary model proposing that leaves trade-off Carbon (C) for water to maximise C assimilation (A) and minimise transpiration (E), thereby generating a marginal water cost of carbon gain (λ) that remains constant over short temporal scales. The circadian clock is a molecular timer of metabolism that controls A and stomatal conductance (gs), amongst other processes, in a broad array of plant species. Here, we test whether circadian regulation contributes towards achieving optimal stomatal behaviour. We subjected bean (Phaseolus vulgaris) and cotton (Gossypium hirsutum) canopies to fixed, continuous environmental conditions of photosynthetically active radiation, temperature and vapour pressure deficit over 48 hours. We observed a significant and self-sustained circadian oscillation in A and in stomatal conductance (gs) which also led to a circadian oscillation in λ. The lack of constant marginal water cost indicates that circadian regulation does not directly lead to optimal stomatal behaviour. However, the temporal pattern in gas exchange, indicative of either maximizing A or of minimizing E, depending upon time of day, indicates that circadian regulation could contribute towards optimizing stomatal responses. More broadly, our results add to the emerging field of plant circadian ecology and show that molecular controls may partially explain leaf-level patterns observed in the field.


HortScience ◽  
2000 ◽  
Vol 35 (5) ◽  
pp. 868-870 ◽  
Author(s):  
Y. Hayata ◽  
Y. Niimi ◽  
K. Inoue ◽  
S. Kondo

Solutions of CPPU and BA were applied to ovaries of melon (Cucumis melo) flowers with or without pollination, and the effects on fruit set, growth, and sugar content were investigated. Treatment with CPPU increased fruit set in both seeded and seedless melons. Even at low concentrations, CPPU had a strong effect on fruit set in the seeded melons. In seedless melons, CPPU induced 100% parthenocarpic fruit set when applied with 10 mg·L–1; lower concentrations were much less effective. Treatment with BA increased fruit set in seeded melons, but was not particularly effective in the absence of pollination. During the first 10 days after anthesis, CPPU promoted fruit growth, but between 8 and 13 days after anthesis, the growth rate was lower than in the controls. Treatment with CPPU had little effect upon soluble solids (SS) levels in seeded fruit. SS content was significantly lower in seedless than in seeded fruit; this difference was larger in the placenta than in the mesocarp. Sucrose levels of both seeded and seedless fruits were consistently higher than glucose and fructose levels. High concentrations of CPPU reduced sucrose levels in the placenta of seedless fruit. These results indicate that seeds play an important role in sugar accumulation and melon fruit growth during later stages of development. Chemical names used: [1-(2-chloro-4-pyridyl)-3-phenylurea] (CPPU); 6-benzylaminopurine (BA).


2016 ◽  
pp. 625-632 ◽  
Author(s):  
Christa Hoffmann ◽  
Katharina Schnepel

Good storability of sugar beet is of increasing importance, not only to reduce sugar losses, but also with regard to maintaining the processing quality. Genotypic differences are found in storage losses. However, it is not clear to which extent damage may contribute to the genotypic response. The aim of the study was to quantify the effect of root tip breakage on storage losses of different genotypes. For that purpose, in 2012 and 2013, six sugar beet genotypes were grown in field trials at two locations. After lifting roots were damaged with a cleaning device. They were stored for 8 and 12 weeks, either under controlled conditions in a climate container at constant 8°C, or under ambient temperature in an outdoor clamp. The close correlation underlines that storage losses under controlled conditions (constant temperature) can well be transferred to conditions in practice with fluctuating temperature. The strongest impact on invert sugar accumulation and sugar loss after storage resulted from storage time, followed by damage and growing environment (year × growing site). Cleaning reduced soil tare but increased root tip breakage, in particular for genotypes with low marc content. During storage, pathogen infestation and invert sugar content of the genotypes increased with root tip breakage, but the level differed between growing environments. Sugar loss was closely related to invert sugar accumulation for all treatments, genotypes and environments. Hence, it can be concluded that root tip breakage contributes considerably to storage losses of sugar beet genotypes, and evidently genotypes show a different susceptibility to root tip breakage which is related to their marc content. For long-term storage it is therefore of particular importance to avoid damage during the harvest operations and furthermore, to have genotypes with high storability and low susceptibility to damage.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 501c-501
Author(s):  
Andrés A. Estrada-Luna ◽  
Jonathan N. Egilla ◽  
Fred T. Davies

The effect of mycorrhizal fungi on gas exchange of micropropagated guava plantlets (Psidium guajava L.) during acclimatization and plant establishment was determined. Guava plantlets (Psidium guajava L. cv. `Media China') were asexually propagated through tissue culture and acclimatized in a glasshouse for eighteen weeks. Half of the plantlets were inoculated with ZAC-19, which is a mixed isolate containing Glomus etunicatum and an unknown Glomus spp. Plantlets were fertilized with modified Long Ashton nutrient solution containing 11 (g P/ml. Gas exchange measurements included photosynthetic rate (A), stomatal conductance (gs), internal CO2 concentration (Ci), transpiration rate (E), water use efficiency (WUE), and vapor pressure deficit (VPD). Measurements were taken at 2, 4, 8 and 18 weeks after inoculation using a LI-6200 portable photosynthesis system (LI-COR Inc. Lincoln, Neb., USA). Two weeks after inoculation, noninoculated plantlets had greater A compared to mycorrhizal plantlets. However, 4 and 8 weeks after inoculation, mycorrhizal plantlets had greater A, gs, Ci and WUE. At the end of the experiment gas exchange was comparable between noninoculated and mycorrhizal plantlets.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 540a-540
Author(s):  
K.J. Prevete ◽  
R.T. Fernandez

Three species of herbaceous perennials were tested on their ability to withstand and recover from drought stress periods of 2, 4, and 6 days. Eupatorium rugosum and Boltonia asteroides `Snowbank' were chosen because of their reported drought intolerance, while Rudbeckia triloba was chosen based on its reported drought tolerance. Drought stress began on 19 Sept. 1997. Plants were transplanted into the field the day following the end of each stress period. The effects of drought on transpiration rate, stomatal conductance, and net photosynthetic rate were measured during the stress and throughout recovery using an infrared gas analysis system. Leaf gas exchange measurements were taken through recovery until there were no differences between the stressed plants and the control plants. Transpiration, stomatal conductance, and photosynthesis of Rudbeckia and Boltonia were not affected until 4 days after the start of stress. Transpiration of Eupatorium decreased after 3 days of stress. After rewatering, leaf gas exchange of Boltonia and Rudbeckia returned to non-stressed levels quicker than Eupatorium. Growth measurements were taken every other day during stress, and then weekly following transplanting. Measurements were taken until a killing frost that occurred on 3 Nov. There were no differences in the growth between the stressed and non-stressed plants in any of the species. Plants will be monitored throughout the winter, spring, and summer to determine the effects of drought on overwintering capability and regrowth.


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