scholarly journals GAS EXCHANGE CHARACTERISTICS OF FIELD-GROWN `SHAWNEE' BLACKBERRY

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 687G-688
Author(s):  
Curt R. Rom ◽  
John R. Clark
Keyword(s):  
Gas Exchange ◽  
Dark Respiration ◽  
Temperature Response ◽  
Quadratic Function ◽  
Respiration Rates ◽  
Leaf Chamber ◽  
Portable System ◽  
Use Efficiency ◽  
Gas Exchange Characteristics ◽  
Chamber Gas

Gas exchange (assimilation, transpiration, water use efficiency, and conductance) of `Shawnee' blackberry were measured under field conditions with a portable system (ADC-IRGA with Parkinson Leaf Chamber). Gas exchange primocane pentifoliate leaflets were similar. Gas exchange rates of leaves along a cane exhibited a quadratic function of leaf position with leaves in lower-mid sections (relative position 0.3 - 0.5) having higher A, TR, WUE, gs than either basal or apical leaves. Leaves subtending fruiting laterals on fruiticanes had higher assimilation than similar age leaves on primocanes but did not differ in Tr, WUE, or gs. Primocanes had estimated dark respiration rates of 0.33mg·dm-1.hr-1, estimated light compensation at 14-20 mol.m-2.s-1, estimated light saturation at 1000-1100 mol.m-2.s-1 with maximum A rates ranging from 24-30 mg CO2.dm-1.hr-1. Measurements were made at field temperatures ranging from 24-35 C. Although temperature response was not measured, correlation indicated that Tr, WUE, and gs were more closely related to temperature than A. Similarly, Tr and WUE were more closely related to gs than A (r = 0.6 to 0.8).

scholarly journals Leaf Gas-exchange Characteristics of Sixteen Cycad Species

1997 ◽  
Vol 122 (1) ◽  
pp. 38-42 ◽  
Author(s):  
Thomas E. Marler ◽  
Leah E. Willis
Keyword(s):  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
Growth Form ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
African Species ◽  
Use Efficiency ◽  
Gas Exchange Characteristics ◽  
The Difference

Leaf gas exchange characteristics for 16 species of cycad were determined under field conditions in Miami, Fla. Net CO2 assimilation (ACO2) ranged from 4.9 μmol·m-2·s-1 for Lepidozamia peroffskyana Regel to 10.1 μmol·m-2·s-1 for Zamia furfuracea L. fil. in Aiton. Stomatal conductance to H2O (gs) was more variable, ranging from 85 mmol·m-2·s-1 for Cycas seemannii A. Br. to 335 mmol·m-2·s-1 for Encephalartos hildebrandtii A. Br. & Bouche. Transpiration (E) ranged from 1.7 mmol·m-2·s-1 for Cycas chamberlainii W.H. Brown & Keinholz to 4.8 mmol·m-2·s-1 for Encephalartos hildebrandtii. Highly variable E was more controlling of water-use efficiency than the less-variable ACO2. The difference between air and pinnae temperature ranged from 0.3 to 1.6 °C and was inversely related to mean gs among the species. The values within geographic regions representative of the native habitats of the species were highly variable. For example, two of the African species exhibited the highest and lowest values of water-use efficiency in the survey. Leaf gas exchange for the four largest species with arborescent growth form was less than that for the three small species with subterranean or short bulbous growth form. The diurnal variation in leaf gas exchange for Zamia furfuracea exhibited a two-peaked pattern with a distinct midday depression in ACO2 and gs. The ratio of dark respiration to maximum ACO2 for Zamia furfuracea was 0.04. As a group, the values for ACO2 and gs for these cycads ranked at the lower end of the range for all plants species.

Temperature relations of gas exchange in altitudinal populations of Taraxacum officinale

1977 ◽  
Vol 55 (19) ◽  
pp. 2496-2502 ◽  
Author(s):  
Paul R. Kemp ◽  
George J. Williams III ◽  
David S. May
Keyword(s):  
Gas Exchange ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Taraxacum Officinale ◽  
Verbascum Thapsus ◽  
Respiration Rates ◽  
Hill Activity ◽  
Population Origin ◽  
Weedy Species ◽  
Temperature Responses

Taraxacum officinale plants representative of three altitudinally diverse populations were grown under uniform conditions. Temperature responses of net photosynthesis, photorespiration, and transpiration were obtained from four plants of each population over the range of 10 to 40 °C at saturating irradiances(1000 μE ∙ m−2 ∙ s−1). Dark respiration rates were obtained from the same plants over the range of 10 to 30 °C. All plants exhibited similar gas exchange responses to temperature regardless of population origin. Maximum rates of net photosynthesis occurred near 20 °C in all plants and averaged 20.8 mg CO2 ∙ dm−2 ∙ h−1 (mean of 12 plants). Dark respiration and photorespiration rates increased nearly linearly with temperature in all plants. These results are in contrast with previous studies of the same populations in which differences in Hill activity and succinate dehydrogenase activity were reported. However, the photosynthetic patterns and lack of genetic differentiation of photosynthesis are similar to the results obtained for another weedy species, Verbascum thapsus, along the same altitudinal transect.

scholarly journals Canopy Position Affects Light Response Curves for Gas Exchange Characteristics of Apple Spur Leaves

1992 ◽  
Vol 117 (3) ◽  
pp. 467-472 ◽  
Author(s):  
Richard J. Campbell ◽  
Richard P. Marini ◽  
Jeffrey B. Birch
Keyword(s):  
Gas Exchange ◽  
Dark Respiration ◽  
Incident Light ◽  
Light Response ◽  
Net Photosynthesis ◽  
Response Curves ◽  
Light Response Curves ◽  
Light Levels ◽  
Canopy Position ◽  
Gas Exchange Characteristics

Light response curves for gas exchange characteristics were developed for spur leaves of `Stayman' and `Delicious' apple (Malus domestica Borkh.) from interior, intermediate, and exterior canopy positions throughout the season. At full bloom (FB), before full leaf expansion, exterior leaves had higher maximum rates of net photosynthesis (Pn), and a statistically different Pn light response curve than the interior leaves. Intermediate leaves had intermediate Pn rates and light response curves. Pn light response curves for all three `Delicious' canopy positions differed from each other from FB + 6 weeks until the end of the season. Interior leaves had maximum Pn rates of only 50% to 60% of those for the exterior leaves from FB + 10 weeks until the end of the season. Light saturation levels were higher for the exterior leaves than for interior or intermediate leaves. Exterior leaves had a tendency throughout the season for higher quantum efficiency of Pn at subsaturating light levels than interior or intermediate leaves. Stomatal conductance was higher for the exterior than the interior or intermediate leaves of `Delicious' on all dates. Water-use efficiency was equivalent among all leaves. Exterior leaves had higher specific leaf weight, dark respiration rates, and incident light levels on all dates than interior or intermediate leaves.

scholarly journals Gas Exchange Characteristics of Fragaria chiloensis Genotypes

HortScience ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 327-329 ◽  
Author(s):  
J. Scott Cameron ◽  
Carol A. Hartley
Keyword(s):  
Gas Exchange ◽  
Leaf Area ◽  
Carbon Assimilation ◽  
Dry Weight ◽  
Area Basis ◽  
Fragaria Chiloensis ◽  
Use Efficiency ◽  
Gas Exchange Characteristics ◽  
Leaf Dry Weight ◽  
Residual Conductance

Twenty-five female clones of Fragaria chiloensis (L.) Duchesene collected from the California and Oregon coasts were surveyed for gas exchange rates under field conditions. Carbon assimilation (A) rates of native clones were 25% to 69% higher than for `Totem' (Fragaria × ananassa Duchesne) on a leaf-area basis (μmol of CO2 per sec/m2) and 7% to 77% higher when expressed on a leaf dry-weight basis (μmol of CO2 per kg dry wt/sec). Higher rates of stomatal conductance (gs) were observed in 16 of 25 F. chiloensis clones than in `Totem', with nine of 25 clones also having higher rates of transpiration (E). All clones had higher rates of residual conductance (gr) and greater water use efficiency (WUE) than the cultivated standard. The gas exchange characteristics of four strawberry cultivars (F. × ananassa) and four F. chiloensis genotypes were compared under standard greenhouse conditions. F. chiloensis genotypes had higher rates of A than cultivars when expressed on per leaf-area and dry-weight bases. Native clones also had higher rates of gs, gr, E, and WUE and greater quantum yield. Differences in chlorophyll content were observed among genotypes, but not between species.

Gas Exchange and Growth in Wheat and Barley Grown in Salt

1986 ◽  
Vol 13 (4) ◽  
pp. 475 ◽  
Author(s):  
HM Rawson
Keyword(s):  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
Screening Program ◽  
Dark Respiration ◽  
Initial Slope ◽  
Specific Leaf Weight ◽  
Response Curves ◽  
Leaf Weight ◽  
Use Efficiency

By measuring a range of gas exchange and growth variables, attempts were made to select key indicators of response to salinity in a wheat (Q61) and a barley (Beecher). A second wheat (WW15, Anza) was included in the growth measurements. Plants were grown to anthesis in gravel culture flushed with 0, 75 or 150 mol m-3 NaCl, and under the high radiation and evaporative conditions of summer. Salinity increased leaf chloride contents and reduced peak photosynthesis, the initial slope of the light response curves, and dark respiration of young leaves at ligule emergence, but dark respiration of slightly older leaves was increased by salinity as were the CO2 compensation points. Short-duration changes in salinity could modify photosynthesis rates by no more than 15% though dark respiration rates moved quickly towards those of plants held continuously at the new salinity level. While Q61 wheat appeared superior to Beecher barley at moderate salinity using these gas exchange indicators, it died at 150 mol m-3 NaCl; Beecher and WW15 survived. Carbon and water budgets are used to propose that the demise of Q61 could have been partially due to its marginally poorer water-use efficiency and its higher specific leaf weight, i.e. its higher requirement for carbon and water to produce each unit area of leaf. It is suggested that measurements of relative leaf expansion rate, specific leaf weight, and water use efficiency would be basic requirements in a salinity screening program. Measurements of ion contents and gas exchange variables are of little benefit when used alone.

GENOTYPIC VARIATION IN CANOPY PHOTOSYNTHESIS, LEAF GAS EXCHANGE CHARACTERISTICS AND THEIR RESPONSE TO TAPPING IN RUBBER (HEVEA BRASILIENSIS)

2007 ◽  
Vol 43 (2) ◽  
pp. 223-239 ◽  
Author(s):  
H. K. L. K. GUNASEKARA ◽  
W. A. J. M. DE COSTA ◽  
E. A. NUGAWELA
Keyword(s):  
Gas Exchange ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Genotypic Variation ◽  
Canopy Photosynthesis ◽  
Rubber Content ◽  
Gas Exchange Parameters ◽  
Area Index ◽  
Gas Exchange Characteristics ◽  
Exchange Parameters

The main objective of this study was to quantify the genotypic variation of photosynthetic and gas exchange parameters of Hevea and to examine their relationships to dry rubber yield and its components. Canopy photosynthesis (Pc) of the genotype RRISL 211 was 20 % greater than that of RRIC 121. This was primarily due to RRISL 211's greater light-saturated leaf photosynthetic rates and a greater leaf area index in the top canopy stratum. Tapping significantly increased Pc in RRISL 211, but not in RRIC 121. The genotypic variation in photosynthetic capacity was not reflected in the overall dry rubber yield, which did not differ between the two genotypes. However, analysis of yield components showed that while RRISL 211 may have preferentially partitioned a greater proportion of its additional assimilates to increasing the latex volume and extending the root system, RRIC 121 partitioned more assimilates to increasing its dry rubber content through greater biosynthesis of rubber. The higher plugging index and the greater post-tapping girth increment of RRIC 121 were probably responsible for observed increases in its dark respiration following tapping. Although RRISL 211 had a greater transpiration efficiency, this did not provide a yield advantage as the trees were growing in an environment with adequate rainfall throughout the year.

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