scholarly journals Interacting Effects of Photoperiod and Photosynthetic Photon Flux on Net Carbon Assimilation and Starch Accumulation in Potato Leaves

1996 ◽  
Vol 121 (2) ◽  
pp. 264-268 ◽  
Author(s):  
Gary W. Stutte ◽  
Neil C. Yorio ◽  
Raymond M. Wheeler
Keyword(s):  
Carbon Assimilation ◽  
Feedback Mechanism ◽  
Starch Accumulation ◽  
Photon Flux ◽  
Assimilation Rate ◽  
Photosynthetic Photon Flux ◽  
Saturation Point ◽  
Starch Concentration ◽  
Carbon Assimilation Rate ◽  
Physiological Limit

The effect of photoperiod (PP) on net carbon assimilation rate (Anet) and starch accumulation in newly mature canopy leaves of `Norland' potato (Solanum tuberosum L.) was determined under high (412 ∝mol·m-2·s-1) and low (263 ∝mol·m-2·s-1) photosynthetic photon flux (PPF) conditions. The Anet decreased from 13.9 to 11.6 and 9.3 μmol·m-2·s-1, and leaf starch increased from 70 to 129 and 118 mg·g-1 drymass (DM) as photoperiod (PP) was increased from 12/12 to 18/6, and 24/0, respectively. Longer PP had a greater effect with high PPF conditions than with low PPF treatments, with high PPF showing greater decline in Anet. Photoperiod did not affect either the CO2 compensation point (50 μmol·mol-1) or CO2 saturation point (1100-1200 μmol·mol-1) for Anet. These results show an apparent limit to the amount of starch that can be stored (≈15% DM) in potato leaves. An apparent feedback mechanism exists for regulating Anet under high PPF, high CO2, and long PP, but there was no correlation between Anet and starch concentration in individual leaves. This suggests that maximum Anet cannot be sustained with elevated CO2 conditions under long PP (≥12 hours) and high PPF conditions. If a physiological limit exists for the fixation and transport of carbon, then increasing photoperiod and light intensity under high CO2 conditions is not the most appropriate means to maximize the yield of potatoes.

The impacts of leaf shape and arrangement on light interception and potential photosynthesis in southern beech (Nothofagus cunninghamii)

2004 ◽  
Vol 31 (5) ◽  
pp. 471 ◽  
Author(s):  
Stephen O. Kern ◽  
Mark J. Hovenden ◽  
Gregory J. Jordan
Keyword(s):  
Flux Density ◽  
Response Curve ◽  
Leaf Shape ◽  
Carbon Assimilation ◽  
Light Response ◽  
Light Interception ◽  
Photon Flux ◽  
Assimilation Rate ◽  
Light Response Curve ◽  
Carbon Assimilation Rate

The impact of differences in leaf shape, size and arrangement on the efficiency of light interception, and in particular the avoidance of photoinhibition, are poorly understood. We therefore estimated light exposure of branches in the cool temperate rainforest tree, Nothofagus cunninghamii (Hook.) Oerst., in which leaf shape, size and arrangement vary systematically with altitude and geographic origin. Measurements of incident photosynthetic photon flux density (PPFD) were made in the laboratory at solar angles corresponding to noon at summer solstice, winter solstice and equinox on branches collected from a common garden experiment. Tasmanian plants showed more self-shading than Victorian plants in summer and equinox. This was related to branch angle, leaf arrangement and leaf shape. Using a modelled light response-curve, we estimated the carbon assimilation rate and the flux density of excess photons at different incident PPFD. Victorian plants had higher predicted assimilation rates than Tasmanian plants in summer and equinox, but were exposed to substantially greater levels of excess photons. Because of the shape of the light-response curve, self-shading appears to reduce the plant's exposure to excess photons, thus providing photoprotection, without substantially reducing the carbon assimilation rate. This is dependent on both regional origin and season.

Altitude of origin influences stomatal conductance and therefore maximum assimilation rate in Southern Beech, Nothofagus cunninghamii

2000 ◽  
Vol 27 (5) ◽  
pp. 451 ◽  
Author(s):  
Mark J. Hovenden ◽  
Tim Brodribb
Keyword(s):  
Stomatal Conductance ◽  
Stomatal Density ◽  
Carbon Assimilation ◽  
Co2 Concentration ◽  
Carboxylation Efficiency ◽  
Assimilation Rate ◽  
Carbon Assimilation Rate ◽  
Southern Beech ◽  
Maximum Stomatal Conductance ◽  
Leaf Biochemistry

Gas exchange measurements were made on saplings of Southern Beech, Nothofagus cunninghamii (Hook.) Oerst. collected from three altitudes (350, 780 and 1100 m above sea level) and grown in a common glasshouse trial. Plants were grown from cuttings taken 2 years earlier from a number of plants at each altitude in Mt Field National Park, Tasmania. Stomatal density increased with increasing altitude of origin, and stomatal con-ductance and carbon assimilation rate were linearly related across all samples. The altitude of origin influenced thestomatal conductance and therefore carbon assimilation rate, with plants from 780 m having a greater photosynthetic rate than those from 350 m. The intercellular concentration of CO2 as a ratio of external CO2 concentration (ci/ca) was similar in all plants despite the large variation in maximum stomatal conductance. Carboxylation efficiency was greater in plants from 780 m than in plants from 350 m. Altitude of origin has a strong influence on the photo-synthetic performance of N. cunninghamii plants even when grown under controlled conditions, and this influence is expressed in both leaf biochemistry (carboxylation efficiency) and leaf morphology (stomatal density).

scholarly journals Modification of Petunia Seedling Carbohydrate Partitioning by Irradiance

1992 ◽  
Vol 117 (3) ◽  
pp. 477-480
Author(s):  
David F. Graper ◽  
Will Healy
Keyword(s):  
Petunia Hybrida ◽  
Soluble Sugars ◽  
Dry Weight ◽  
Invertase Activity ◽  
Acid Invertase ◽  
Starch Accumulation ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Total Carbohydrate ◽  
Relative Growth

Petunia × hybrida Villm. `Red Flash' plants received either 10 or 20 mol·day-1 photosynthetic photon flux (PPF) in growth chambers at: 175 μmol·m-2·s-1 for 16 hours, 350 μmol·m-2·s-1 for 8 or 16 hours, or 350 μmol·m-2 s-1 for 8 hours plus 8 hours of incandescent photoperiod extension (5 μmol·m-2·s-1 PPF). The irradiation components of peak, total, and duration were examined. Doubling total PPF increased total carbohydrate (CHO) production by 60%, seedling dry weight (DW) by 30%, rate of seedling growth by 25%, and acid invertase activity by 50% compared to the other treatments, once the seedlings had reached the two-leaf stage. Seedlings receiving 20 mol·day-1 PPF partitioned 14% more CHO into ethanol soluble sugars rather than starch, which may explain the increase in relative growth rate observed with supplemental irradiance treatments. Extending the photoperiod for 8 hours with 5 μmol·m-2·s-1 PPF reduced total CHO production by 50% compared to the same treatment without photoperiodic lighting. Treatment with 350 μmol·m-2·s-1 for 8 hours resulted in the highest O2 evolution (8.8 μmol O2/min per dm2). Increasing the photoperiod from 8 to 16 hours gave the lowest rate of O2 evolution (4.5 μmol O2/min per dm2). Previous reports of the importance of photosynthetic period in controlling partitioning between starch and sugars may have simply observed a decreasing rate of starch accumulation due to increased total PPF.

scholarly journals Does Spraying of Atrazine on Triazine-Resistant Canola Hybrid Impair Photosynthetic Processes?

2019 ◽  
Vol 37 ◽  
Author(s):  
M.R. DURIGON ◽  
A.S. CAMERA ◽  
J. CECHIN ◽  
L. VARGAS ◽  
G. CHAVARRIA
Keyword(s):  
Electron Transport ◽  
Block Design ◽  
Winter Season ◽  
Carbon Assimilation ◽  
Photochemical Quenching ◽  
Assimilation Rate ◽  
Biochemical Processes ◽  
Randomized Block Design ◽  
Carbon Assimilation Rate ◽  
Rotation Crop

ABSTRACT: Canola is an important rotation crop for the winter season and the use of atrazine-resistant hybrids can lead to an increase in yield. This work was aimed at evaluating the effect of atrazine on photochemical and biochemical processes of photosynthesis in triazine-resistant canola. The experiment was conducted in a greenhouse, with triazine-resistant hybrid Hyola® 555TT, in a randomized block design with three replications. The treatments consisted of application or no application of atrazine on canola plants. The plants were assessed at one, three, five, and eight days after application (DAA) for chlorophyll indexes, modulated chlorophyll a fluorescence and gas exchange. Chlorophyll indexes were higher in canola plants treated with atrazine. Application of atrazine caused an increase in fluorescence at steady state and a reduction in quantum efficiency of photosystem II and electron transport rate, at 1 DAA, and a reduction in photochemical quenching, at 1 and 3 DAA. Lower stomatal conductance, at 1 DAA, and higher net carbon assimilation rate, at 8 DAA, were found in plants treated with atrazine. The application of atrazine temporarily reduces electron transport between photosystems and increases chlorophyll indexes in resistant canola plants, raising the net carbon assimilation rate at eight days after application.

scholarly journals Characterization of Carbon Assimilation Rate, Stomatal Conductance and Transpiration Rate for Eight Proteaceae Species.

2000 ◽  
Vol 69 (5) ◽  
pp. 576-583 ◽  
Author(s):  
Genaro A. Reynoso ◽  
Masahiro Morokuma ◽  
Yoshie Miura ◽  
Atsushi Hasegawa ◽  
Masanori Goi
Keyword(s):  
Stomatal Conductance ◽  
Transpiration Rate ◽  
Carbon Assimilation ◽  
Assimilation Rate ◽  
Carbon Assimilation Rate

scholarly journals Modeling whole-tree carbon assimilation rate using observed transpiration rates and needle sugar carbon isotope ratios

2010 ◽  
Vol 185 (4) ◽  
pp. 1000-1015 ◽  
Author(s):  
Jia Hu ◽  
David J. P. Moore ◽  
Diego A. Riveros-Iregui ◽  
Sean P. Burns ◽  
Russell K. Monson
Keyword(s):  
Carbon Isotope ◽  
Carbon Assimilation ◽  
Isotope Ratios ◽  
Assimilation Rate ◽  
Carbon Isotope Ratios ◽  
Carbon Assimilation Rate ◽  
Whole Tree

Effects of low temperature and light treatment, following winter cold storage, on starch accumulation in Scots pine seedlings

1984 ◽  
Vol 14 (1) ◽  
pp. 114-118 ◽  
Author(s):  
Anders Ericsson
Keyword(s):  
Low Temperature ◽  
Cold Storage ◽  
Dry Weight ◽  
Experimental Period ◽  
Light Treatment ◽  
Starch Accumulation ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Starch Concentration ◽  
Summer Climate

To increase the amount of starch reserves, 1-year-old Pinussylvestris L. seedlings were conditioned in a climate chamber at +5 °C with irradiance of different levels, following thawing from cold storage at −5 °C. Exposure to the conditioning climate was for 0, 1, or 2 weeks, after which the seedlings were transferred to an artificial "summer" climate (25/15 °C, day/night, respectively). The variations in starch concentration of roots and needles were followed during the experimental period. During the conditioning period, starch concentration increased in roots as well as in needles. The result indicated that starch accumulated only in presence of light. Two weeks of treatment with a photon flux density of about 140 μE•m−2•s−1 resulted in starch concentrations comparable with those found in trees during a normal spring in nature. After removal of the seedlings to artificial "summer" climate, the starch reserves of the roots decreased quickly, while the levels of the needles continued to increase to a final maximum value. When seedlings without low temperature and light treatment were placed in "summer" conditions, the starch level increased in the needles but decreased in the roots. The dry-weight determinations showed that growth was not affected by the conditioning in low temperature and light.

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