COMPARATIVE DATA ON THE RATE OF PHOTOSYNTHESIS, RESPIRATION, AND TRANSPIRATION OF DIFFERENT ORGANS IN AWNED AND AWNLESS ISOGENIC LINES OF WHEAT

1972 ◽  
Vol 52 (6) ◽  
pp. 965-971 ◽  
Author(s):  
I. D. TEARE ◽  
J. W. SIJ ◽  
R. P. WALDREN ◽  
S. M. GOLTZ
Keyword(s):  
Flag Leaf ◽  
Wheat Yield ◽  
Net Photosynthesis ◽  
Triticum Aestivum L ◽  
Isogenic Line ◽  
Photosynthetic Rates ◽  
Flag Leaves ◽  
Isogenic Lines ◽  
Respiration Rates ◽  
The Difference

Net photosynthesis, respiration, and transpiration were determined on heads and flag leaves of two isogenic lines of wheat (Triticum aestivum L. em Thell) by measuring the difference in CO2 and water-vapor concentrations between the incoming and outgoing air streams of an open cuvette system. Net photosynthetic rates (mg CO2 dm−2 hr−1) of the awnless, awned, and awned-clipped heads were not significantly different, but the amount of photosynthesis (mg CO2 hr−1) per head was greater for the awned than for the awnless isogenic line. Net photosynthetic rates of the heads were 20–26% of the net photosynthetic rates of the flag leaves. Respiration rates were nearly two times greater for the awnless and awn-clipped heads than for the awned head. Respiration rates of the heads were 1.7 and 3.0 times greater than the respiration rates of the flag leaves of the awned and awnless isogenics, respectively. Transpiration per head was 34 and 43% of the transpiration per flag leaf for awnless and awned isogenics, respectively. Comparing P/T ratios showed that the awnless isogenic head had a 20% greater water-use efficiency than the awned. This study not only confirmed the work of others, by associating awnedness with increased wheat yield, but also showed how the chlorophyll-containing area of the head is related to photosynthesis, respiration, and transpiration.

POTENTIAL NET PHOTOSYNTHESIS IN FLAG LEAVES OF SEVERELY DROUGHT-STRESSED WHEAT CULTIVARS AND ITS RELATIONSHIP TO GRAIN YIELD

1974 ◽  
Vol 54 (4) ◽  
pp. 811-815 ◽  
Author(s):  
R. KAUL
Keyword(s):  
Desiccation Tolerance ◽  
Flag Leaf ◽  
Assimilation Efficiency ◽  
Relative Yield ◽  
Net Photosynthesis ◽  
Grain Filling ◽  
Triticum Aestivum L ◽  
Wheat Cultivars ◽  
Water Deficits ◽  
Flag Leaves

Six wheat cultivars grown in the field in 1973 showed continuously increasing water deficits which attained severe levels by the end of the season. The relative yield performance of five Triticum aestivum L. cultivars was predictable from the integrated net photosynthetic potential of their flag leaves. Grain productivity of a T. durum L. cultivar, Pelissier, was uniformly underestimated, likely because of poor desiccation tolerance of its flag leaf. It is suggested that Pelissier depended on the longevity of its heavily awned spike for additional grain filling. Results show that photosynthetic desiccation tolerance in severely stressed flag leaves of Pitic 62 ranks above that of Manitou, Cypress, and particularly Selkirk and Pelissier. Glenlea was comparable to Manitou and Cypress in flag leaf assimilation efficiency when subjected to early drought hardening, but exhibited less efficiency when subjected to water deficits late in development.

scholarly journals SUNFLOWER COMPETITION IN WHEAT

1984 ◽  
Vol 64 (1) ◽  
pp. 105-111 ◽  
Author(s):  
GREG R. GILLESPIE ◽  
STEPHEN D. MILLER
Keyword(s):  
Triticum Aestivum ◽  
Helianthus Annuus ◽  
Flag Leaf ◽  
Wheat Yield ◽  
Triticum Aestivum L ◽  
Wheat Crop ◽  
Upper Midwest ◽  
Leaf Stage ◽  
Seeding Date ◽  
Field Season

Sunflower (Helianthus annuus L.) is grown in rotation with wheat (Triticum aestivum L.) in the upper midwest of the U.S.A. However, volunteer sunflower is often a problem in wheat planted the year following sunflower. Wheat yields as influenced by wheat seeding date and sunflower density, duration of sunflower competition and rate of sunflower control were determined in the field. Season-long sunflower competition at densities of 3, 9, and 23 plants per square metre reduced yield of the following wheat crop by an average of 11, 19, and 33%, respectively, averaged over seeding date and location. Sunflower was more competitive with wheat seeded in late than in early May, particularly at the lower sunflower densities. Wheat yield was reduced 22% when 24 sunflower plants/m2 were allowed to compete until the wheat flag-leaf stage. Wheat yields obtained were similar when volunteer sunflower was controlled by postemergence MCPA [[(4-chloro-o-tolyl)oxy] acetic acid], bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), or bromoxynil plus MCPA despite the slower rate of control with MCPA compared to bromoxynil or bromoxynil plus MCPA. This research indicates that wheat following sunflower should be planted early and sunflower densities of nine plants per square metre or higher should be removed before the flag-leaf stage to prevent yield reductions.Key words: Density, duration, bromoxynil, MCPA, Helianthus annuus, Triticum aestivum

The ecology of Ramalina menziesii. VI. Laboratory responses of net CO2 exchange to moisture, temperature, and light

1987 ◽  
Vol 65 (1) ◽  
pp. 182-191 ◽  
Author(s):  
U. Matthes-Sears ◽  
T. H. Nash III ◽  
D. W. Larson
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Response Curves ◽  
Central California ◽  
Photosynthetic Rates ◽  
Chlorophyll Contents ◽  
The Mean ◽  
The Difference ◽  
Thallus Water Content

The response of net CO2 exchange to thallus water content, thallus temperature, and photosynthetically active radiation was measured in the laboratory for two morphologically different forms of Ramalina menziesii collected from a coastal and an inland habitat in central California. Equations describing the response curves are fitted to the data and compared statistically for the two sites during two seasons. Significant differences were present for all responses both in summer and winter but were more pronounced for net photosynthesis than for dark respiration. The main differences between the two forms were in the absolute rates of net photosynthesis; a maximum of 6.2 was measured for the inland form but only 3.6 mg∙g−1∙h−1 for the coastal form. Chlorophyll contents were also different between the two forms, indicating that chlorophyll is the likely cause for the difference in net photosynthetic rates. Net photosynthetic rates were higher at low temperatures during winter than during summer, but otherwise seasonal variations in the gas exchange responses were relatively minor. Both forms of the lichen are light saturated at quantum fluxes greater than 200 μE∙m−2∙s−1. Both show an optimum temperature for maximum CO2 exchange at 25 °C, well above the mean operating temperature of R. menziesii in the field.

Modelling photosynthesis in flag leaves of winter wheat (Triticum aestivum) considering the variation in photosynthesis parameters during development

2015 ◽  
Vol 42 (11) ◽  
pp. 1036 ◽  
Author(s):  
Jingsong Sun ◽  
Jindong Sun ◽  
Zhaozhong Feng
Keyword(s):  
Triticum Aestivum ◽  
Winter Wheat ◽  
Leaf Development ◽  
Flag Leaf ◽  
Seasonal Fluctuation ◽  
Triticum Aestivum L ◽  
Growth Conditions ◽  
Seasonal Patterns ◽  
Flag Leaves ◽  
Parameter Values

The Farquhar–von Caemmerer–Berry (FvCB) model of photosynthesis has been widely used to estimate the photosynthetic C flux of plants under different growth conditions. However, the seasonal fluctuation of some photosynthesis parameters (e.g. the maximum carboxylation rate of Rubisco (Vcmax), the maximum electron transport rate (Jmax) and internal mesophyll conductance to CO2 transport (gm)) is not considered in the FvCB model. In this study, we investigated the patterns of the FvCB parameters during flag leaf development based on measured photosynthesis–intercellular CO2 curves in two cultivars of winter wheat (Triticum aestivum L.). Parameterised seasonal patterns of photosynthesis parameters in the FvCB model have subsequently been applied in order to predict the photosynthesis of flag leaves. The results indicate that the Gaussian curve characterises the dynamic patterns of Vcmax, Jmax and gm well. Compared with the model with fixed photosynthesis parameter values, updating the FvCB model by considering seasonal changes in Vcmax and Jmax during flag leaf development slightly improved predictions of photosynthesis. However, if the updated FvCB model incorporated the seasonal patterns of Vcmax and Jmax, and also of gm, predictions of photosynthesis was improved a lot, matching well with the measurements (R2 = 0.87, P < 0.0001). This suggests that the dynamics of photosynthesis parameters, particularly gm, play an important role in estimating the photosynthesis rate of winter wheat.

scholarly journals Differential Flag Leaf and Ear Photosynthetic Performance Under Elevated (CO2) Conditions During Grain Filling Period in Durum Wheat

2020 ◽  
Vol 11 ◽  
Author(s):  
Angie L. Gámez ◽  
Rubén Vicente ◽  
Rut Sanchez-Bragado ◽  
Iván Jauregui ◽  
Rosa Morcuende ◽  
...  
Keyword(s):  
Triticum Turgidum ◽  
Tricarboxylic Acid Cycle ◽  
Flag Leaf ◽  
Grain Filling ◽  
Good Evidence ◽  
Sugar Accumulation ◽  
Flag Leaves ◽  
Gross Photosynthesis ◽  
Respiration Rates ◽  
The Impact

Elevated concentrations of CO2 (CO2) in plants with C3 photosynthesis metabolism, such as wheat, stimulate photosynthetic rates. However, photosynthesis tends to decrease as a function of exposure to high (CO2) due to down-regulation of the photosynthetic machinery, and this phenomenon is defined as photosynthetic acclimation. Considerable efforts are currently done to determine the effect of photosynthetic tissues, such us spike, in grain filling. There is good evidence that the contribution of ears to grain filling may be important not only under good agronomic conditions but also under high (CO2). The main objective of this study was to compare photoassimilate production and energy metabolism between flag leaves and glumes as part of ears of wheat (Triticum turgidum L. subsp. durum cv. Amilcar) plants exposed to ambient [a(CO2)] and elevated [e(CO2)] (CO2) (400 and 700 μmol mol–1, respectively). Elevated CO2 had a differential effect on the responses of flag leaves and ears. The ears showed higher gross photosynthesis and respiration rates compared to the flag leaves. The higher ear carbohydrate content and respiration rates contribute to increase the grain dry mass. Our results support the concept that acclimation of photosynthesis to e(CO2) is driven by sugar accumulation, reduction in N concentrations and repression of genes related to photosynthesis, glycolysis and the tricarboxylic acid cycle, and that these were more marked in glumes than leaves. Further, important differences are described on responsiveness of flag leaves and ears to e(CO2) on genes linked with carbon and nitrogen metabolism. These findings provide information about the impact of e(CO2) on ear development during the grain filling stage and are significant for understanding the effects of increasing (CO2) on crop yield.

scholarly journals Leaf Anatomical Characteristics in Relation to Grain Yield of Wheat (Triticum aestivum L.) Cultivars

1970 ◽  
Vol 15 ◽  
pp. 153-158 ◽  
Author(s):  
SK Adhikary ◽  
MZ Alam ◽  
SA Haider ◽  
NK Paul
Keyword(s):  
Triticum Aestivum ◽  
Grain Yield ◽  
Flag Leaf ◽  
Wheat Yield ◽  
Correlation Coefficients ◽  
Triticum Aestivum L ◽  
Cultivar Differences ◽  
Radial Dimension ◽  
Anatomical Characters ◽  
Leaf Anatomical Characteristics

An experiment was carried out to study the variability of leaf anatomical characters of wheat (Triticum aestivum L.) cultivars and their association with grain yields. Results indicated that in most of the cases cultivar differences were significant. In respect of 6th leaf anatomical characters, simple correlation coefficients indicated that most of the leaf anatomical traits had significant negative relation with grain yield whereas in respect of flag leaf anatomical traits, only the association between radial dimension of big xylem vessel and grain yield was significantly negative and the correlation between number of veins and grain yield was significantly positive. Key words: Leaf anatomy, wheat, yield, correlation   doi: 10.3329/jbs.v15i0.2156   J. bio-sci. 15: 153-158, 2007

Oxygen isotope ratio of leaf and grain material correlates with stomatal conductance and grain yield in irrigated wheat

2000 ◽  
Vol 27 (7) ◽  
pp. 625 ◽  
Author(s):  
Margaret M. Barbour ◽  
R. Anthony Fischer ◽  
Ken D. Sayre ◽  
Graham D. Farquhar
Keyword(s):  
Stomatal Conductance ◽  
Grain Yield ◽  
Oxygen Isotope ◽  
Isotope Ratio ◽  
Leaf Tissue ◽  
Triticum Aestivum L ◽  
Oxygen Isotope Ratio ◽  
Flag Leaves ◽  
The Difference ◽  
Fractionation Factors

Theory (Craig and Gordon 1965; Dongmann et al. 1974; Sternberg et al. 1986; Farquhar and Lloyd 1993) suggests that the oxygen isotope ratio (d 18 O) of plant material should reflect the evaporative conditions under which the material was formed, so that differences in stomatal conductance should show up in plant d 18 O. To test this theory we measured the oxygen isotope ratio of organic matter from flag leaves at anthesis and grain at harvest from eight cultivars of spring wheat (Triticum aestivum L.) grown under irrigation in each of three seasons in Mexico. The cultivars ranged widely in stomatal conductance and in average grain yield, with which conductance was positively correlated. Supporting theory, the oxygen isotope ratio of flag leaves (d 18 Ol) was found to correlate negatively with stomatal conductance for two of the three seasons. The significant correlations are consistent with high conductance cultivars having lower leaf temperatures and kinetic fractionation factors, and higher vapour pressure fractionation factors and Péclet numbers, all of which combine to result in less enriched d 18 Ol. Yield (grain weight per square meter) was also found to be significantly negatively correlated with d 18Ol in two of the three seasons. d 18 Ol was as good a predictor of yield as stomatal conductance, and significantly better than carbon isotope discrimination. Correlations between grain d 18 O (d 18 Og) and physiological parameters were less clear. Significant negative correlations between d 18 Og and stomatal conductance, leaf temperature and yield were found only during the first season. By measuring the oxygen isotope ratio of cellulose extracted from leaf samples, the difference in fractionation factors (ecp) for cellulose and whole leaf tissue was assessed. ecp was found to be variable, and more negative when d 18 Oc and d 18 Ol were lower. Cultivar means for d 13 C and d 18 O of whole leaf material were found to be significantly positively related, and the factors required to produce such a relationship are discussed.

Studies of grain production in Sorghum bicolor (L. Moench). VII.* Contribution of plant parts to canopy photosynthesis and grain yield in field stations

1976 ◽  
Vol 27 (2) ◽  
pp. 235 ◽  
Author(s):  
KS Fischer ◽  
GL Wilson ◽  
I Duthie
Keyword(s):  
Grain Yield ◽  
Flag Leaf ◽  
Net Photosynthesis ◽  
Grain Filling ◽  
Carbon Dioxide Exchange ◽  
Relative Importance ◽  
Leaf Position ◽  
Canopy Photosynthesis ◽  
Photosynthetic Rates ◽  
Plant Parts

A method based on 14CO2 uptake and carbon dioxide exchange in sorghum canopies at medium and high density populations allowed the estimation of photosynthesis by plant parts (heads, and leaves at each level of insertion) after anthesis. The relative importance of corresponding parts did not differ between populations, nor did photosynthetic rates per unit leaf area. The latter did decline with successive leaf position down the canopy but were generally compensated by increasing area of these leaves. Averaged over the two populations, which differed little, the heads provided 14% of canopy photosynthesis, and the flag leaf and leaves 2, 3 and 4 were responsible for 21, 24, 21 and 13% respectively. Greater leaf areas per unit land area in the higher population, for each leaf position, resulted in higher total canopy photosynthesis. Previous studies having shown that net photosynthesis after heading corresponds closely to grain yield, the relative importance of plant parts to overall net photosynthesis may be regarded as their relative contribution to grain filling. A direct estimate of their importance in this regard, based on another method, showed the head to contribute 17%, and the next four leaves 17, 25, 20 and 17%. Factors controlling photosynthetic rates of parts are discussed, and the estimates of the importance of photosynthetic sites to grain filling are compared with those reported in previous work. _____________________ *Part VI, Aust. J. Agric. Res., 27: 35 (1976).

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