Net assimilation rate of wheat as affected by light intensity and temperature

1969 ◽  
Vol 47 (11) ◽  
pp. 1781-1787 ◽  
Author(s):  
D. J. C. Friend
Keyword(s):  
Light Intensity ◽  
Environmental Conditions ◽  
Relative Proportion ◽  
Net Assimilation Rate ◽  
Continuous Illumination ◽  
Assimilation Rate ◽  
Direct Effects ◽  
Optimal Temperature ◽  
Area Basis ◽  
Net Assimilation

The net assimilation rate of wheat, on a leaf area basis, declined with time under constant environmental conditions. With continuous illumination at temperatures of 20, 25, and 30 °C, the net assimilation rate increased linearly with increases in the light intensity over the range 200 to 5000 ft-c. The optimal temperature was 15 to 20 °C, and the net assimilation rate declined with increases in temperature over the range 20 to 30 °C. These responses are related to direct effects of light intensity on apparent rates of leaf photosynthesis and to changes in the relative proportion of photosynthetic and primarily respiratory organs under different environmental conditions.

Effects of Temperature and CO2Concentration on the Growth of Cotton (Gossypium hirsutum), Spurred Anoda (Anoda cristata), and Velvetleaf (Abutilon theophrasti)

Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 751-757 ◽  
Author(s):  
David T. Patterson ◽  
Maxine T. Highsmith ◽  
Elizabeth P. Flint
Keyword(s):  
Dry Matter ◽  
Dry Weight ◽  
Net Assimilation Rate ◽  
Assimilation Rate ◽  
Short Term ◽  
Leaf Weight ◽  
Matter Production ◽  
Total Plant ◽  
Net Assimilation ◽  
Total Dry Weight

Cotton, spurred anoda, and velvetleaf were grown in controlled-environment chambers at day/night temperatures of 32/23 or 26/17 C and CO2concentrations of 350 or 700 ppm. After 5 weeks, CO2enrichment to 700 ppm increased dry matter accumulation by 38, 26, and 29% in cotton, spurred anoda, and velvetleaf, respectively, at 26/17 C and by 61, 41, and 29% at 32/23 C. Increases in leaf weight accounted for over 80% of the increase in total plant weight in cotton and spurred anoda in both temperature regimes. Leaf area was not increased by CO2enrichment. The observed increases in dry matter production with CO2enrichment were caused by increased net assimilation rate. In a second experiment, plants were grown at 350 ppm CO2and 29/23 C day/night for 17 days before exposure to 700 ppm CO2at 26/17 C for 1 week. Short-term exposure to high CO2significantly increased net assimilation rate, dry matter production, total dry weight, leaf dry weight, and specific leaf weight in comparison with plants maintained at 350 ppm CO2at 26/17 C. Increases in leaf weight in response to short-term CO2enrichment accounted for 100, 87, and 68% of the observed increase in total plant dry weight of cotton, spurred anoda, and velvetleaf, respectively. Comparisons among the species showed that CO2enrichment decreased the weed/crop ratio for total dry weight, possibly indicating a potential competitive advantage for cotton under elevated CO2, even at suboptimum temperatures.

Varietal differences in growth characteristics in sugar cane

1987 ◽  
Vol 108 (1) ◽  
pp. 245-247 ◽  
Author(s):  
S. Singh ◽  
P. N. Gururaja Rao
Keyword(s):  
Growth Rate ◽  
Sugar Cane ◽  
Growth Characteristics ◽  
Net Assimilation Rate ◽  
Assimilation Rate ◽  
Area Index ◽  
Relative Growth ◽  
Varietal Differences ◽  
Net Assimilation ◽  
High Yielding Varieties

In sugar cane, investigations made earlier (Singh & Gururaja Rao, 1985) have shown that high-yielding varieties have higher net assimilation rate than low-yielding types. Similarly, differences in progeny means for relative growth rate and net assimilation rate have been reported by George (1965). In other crops also, varietal differences in leaf area index and net assimilation rate have been reported (Watson, 1947). It appears that in this crop, limited attempts have been made to study all the growth characteristics. This paper describes the differences in most of the growth characteristics in six sugar-cane varieties.

scholarly journals Wplyw stopnia krzewienia się roślin na akumulacje biomasy organicznej u niektórych odmian zwyczajnej pszenicy ozimej [Influence of tillering degree on the accumulation of dry matter of some winter wheat varieties]

2015 ◽  
Vol 28 (2) ◽  
pp. 155-175
Author(s):  
Witold Drezner
Keyword(s):  
Winter Wheat ◽  
Dry Matter ◽  
Net Assimilation Rate ◽  
Assimilation Rate ◽  
Wheat Varieties ◽  
H Index ◽  
Net Assimilation ◽  
Winter Wheat Varieties

The correlation between the net assimilation rate and the degree of plant tillering are investigated for several varieties of simple winter wheat. The net assimilation rate (E, NAR, An) of the studied varieties for different degrees of tillering, individual shoots and individual plants is described according to the units mg/cm<sup>2</sup> • 24 h. Index of efficiency of assimilation surface (F, LAR, I<sub>S</sub>) is determined in units cm<sup>2</sup>/mg. The tillering ability of vegetative shoots in plaints is a very important factor which increases the total assimilate stirfaice value and the assimilation effectivity of the plant's biomass.

Studies on the productivity of tropical pasture plants. V.* Effect of shading on growth, photosynthesis and respiration in two grasses and two legumes

1974 ◽  
Vol 25 (3) ◽  
pp. 425 ◽  
Author(s):  
MM Ludlow ◽  
GL Wilson ◽  
MR Heslehurst
Keyword(s):  
Radiant Energy ◽  
Net Assimilation Rate ◽  
Assimilation Rate ◽  
Pasture Production ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Analysis Techniques ◽  
Net Assimilation ◽  
Photosynthesis And Respiration ◽  
Pasture Plants

Two grasses and two legumes were grown at three illuminances: one grass and one legume in a growth cabinet (100, 50 and 34% relative illuminance) and one of each in a glasshouse (100, 30 and 10% relative illuminance). The response to shading was investigated by using classical growth analysis techniques, and the photosynthesis-respiration balance obtained by Watson and Hayashi's method. Shading caused a reduction in the proportion of root and a corresponding increase in the proportion of leaf, and an increase in the shoot/root ratio in all species except green panic. The relative growth rates of grasses (which were only clearly superior at the highest illuminance) were affected more by shading than were those of legumes, and the greater shading effect resulted from a greater decrease in net assimilation rate, and to a lesser extent, from a smaller compensatory increase in leaf area ratio in the grasses than in the legumes. The greater sensitivity of net assimilation rate of grasses to shading arose from a stronger dependence of the photosynthetic rate on illuminance. The significance of these findings for pasture production is discussed. Both tiller and runner production were dependent upon the total amount of radiant energy received by the plant, and in the growth cabinet, at least, were independent of its intensity, duration and sequence. ______________________ *Part IV, Aust. J. Agric. Res., 25: 415 (1974).

Genetic Variation in the Effects of Root Impedance on Growth and Transpiration Rates of Wheat and Barley

1992 ◽  
Vol 19 (2) ◽  
pp. 109 ◽  
Author(s):  
J Masle
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Time Course ◽  
Net Assimilation Rate ◽  
Root Penetration ◽  
Lower Sensitivity ◽  
Soil Resistance ◽  
Assimilation Rate ◽  
Relative Growth ◽  
Net Assimilation

Genotypes of wheat and barley, including modern and landrace lines, were compared in their response to soil resistance to root penetration during the early vegetative phase (up to 5 leaf stage). All genotypes exhibited reduced growth and transpiration rates at high soil resistance, but there was large variation in the magnitude and time course of these effects and in the mechanisms underlying the growth reduction (changes in net assimilation rate, carbon partitioning within the plant, relative effects of leaf primordia development, versus growth of expanding leaves). Similar wide ranges of responses were observed among landrace and modern wheats. In both wheat and barley, the genotypes with lower sensitivity to soil resistance, in terms of relative growth rate, were those with the slowest net assimilation rate and root growth rate at low soil resistance, and those for which carbon allocation to the impeded roots, relative to the shoot, was significantly increased, to the extent that root relative growth rate even became greater (in terms of mass, not of length) than on loose soil. For a number of genotypes, growth was slowed down throughout the experiment whereas for others it was reduced only during the first few days following germination. In contrast, transpiration rate was at all stages lower at high than at low soil resistance. This indicates that the effects of soil resistance to root penetration on stomatal conductance involve different controls - or different sensitivities to a common signal - from those operating on cell division and expansion.

The growth of maize

1978 ◽  
Vol 90 (3) ◽  
pp. 569-577 ◽  
Author(s):  
G. O. Iremiren ◽  
G. M. Milbourn
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Matter Content ◽  
Net Assimilation Rate ◽  
Dry Matter Content ◽  
Dry Matter Yield ◽  
Assimilation Rate ◽  
Maize Silage ◽  
Area Index ◽  
Net Assimilation

SummaryTotal dry-matter yield of maize silage rose asymptotically as density was increased up to 17 plants/m2. Over the range 11–17 plants/m2, which is generally higher than is used in the U.K., the increase in yield was 1–1·6 t dry matter/ha which can justify the higher seed cost and although there was no adverse affect on time of maturity the risk of lodging increased at the highest density. During the harvest period whilst whole crop dry-matter percentage was rising from 23 to 28%, the ear dry-matter content rose steadily from 29 to 35%, whereas the leaf and stem dry-matter content remained essentially constant and only dried out at a later stage after a frost.Caldera 535 had a higher leaf area index and net assimilation rate than the earlier variety Julia which it outyielded by 15%. The additional yield was mainly stem tissue and the greater vegetative production caused an 11-day delay in reaching the silage stage of maturity (25% crop D.M.). NO differences occurred between density treatments and varieties in the forage quality components considered, namely percentage drymatter digestibility, modified acid-detergent fibre, crude protein and ash. Thus in U.K. conditions, total dry-matter yield exerts an overriding influence on the yields per unit area of these quality constituents. This contrasts with reports from the U.S.A. in which a reduced grain/stover ratio adversely influences silage quality.Removal of the whole ear (including husk and rachis) at an early stage in ear development resulted in a 50% reduction in the final dry-matter yield. In the earless plants, leaf area and net assimilation rate was lower, but the dry-matter content of the leaves and stem was considerably higher, and a marked purple coloration developed indicative of excess starch concentration. These results emphasize the need in maize silage not only for an adequate leaf canopy, best obtained early in the growing season by using high planting density and subsequently by using late maturing varieties, but also for sufficient sink capacity in the ear as well as in the stem fraction.

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