Effects of CO2 enrichment on growth and photosynthesis in Desmodium paniculatum

1982 ◽  
Vol 60 (7) ◽  
pp. 1084-1091 ◽  
Author(s):  
Renata D. Wulff ◽  
Boyd R. Strain

Plants of Desmodium paniculatum (Leguminosae) were grown from seeds in normal air (0.035% CO2) and in air containing 0.1% CO2. CO2 enrichment produced an almost twofold increase in dry matter production. Leaf areas were 1.2 times higher at high CO2. Relative growth rates under high CO2 were significantly higher during the early stages of development and then declined. The increase in dry matter production was not associated with an increase in photosynthetic capacity per unit leaf area. Gas exchange measurements indicated that plants from the high CO2 regime had lower light saturation values and lower photosynthetic rates at high quantum flux densities than the controls. An opposite trend was observed if gas exchange rates were expressed on a chlorophyll basis. The depression in photosynthetic rates on a leaf area basis of plants exposed to CO2 enrichment was correlated with increased starch accumulation and reduced grana formation in chloroplasts of leaves continuously exposed to high CO2 concentrations.

Weed Science ◽  
1979 ◽  
Vol 27 (5) ◽  
pp. 549-553 ◽  
Author(s):  
David T. Patterson

The effects of shade on the growth and photosynthetic capacity of the exotic noxious weed itchgrass (Rottboellia exaltataL. f.) were determined under controlled environment conditions. The plants were grown at day/night temperatures of 29/23 C under 100, 60, 25, and 2% sunlight in a climate-controlled greenhouse. Mathematical growth analysis techniques were used to evaluate the effects of shading on dry matter production and leaf area production. Infrared gas analysis and diffusion porometry techniques were used to evaluate the effects of shading on photosynthesis and stomatal resistance. Shading markedly reduced dry matter production. At 40 days after planting, plants grown in 2, 25, and 60% sunlight had 0.3, 16, and 55%, respectively, of the dry weight of the plants grown at 100% sunlight. Leaf area production was less severely retarded by shading; the plants grown at 2, 25, and 60% sunlight had, respectively, 1.7, 42, and 99% of the leaf area of the plants grown at 100% sunlight. Ambient photosynthetic rates of recently expanded, single, fully exposed leaves were 22.5, 51.6, and 65.5 mg CO2dm-2h-1in the 25, 60, and 100% sunlight treatments, respectively. Photosynthetic rates at saturating irradiance did not differ significantly in plants grown at 25, 60, or 100% sunlight and ranged from 76.4 to 78.0 mg CO2dm-2h-1. Stomatal resistances, ranging from 6.0 to 7.5 s cm-1, also did not differ significantly among these plants. In terms of dry matter production, itchgrass is a shade-intolerant plant. However, even when grown in shade, itchgrass maintains the capacity for high photosynthetic rates and high growth rates when subsequently exposed to high irradiance. These characteristics help explain its competitiveness with crop species.


2010 ◽  
Vol 39 (8) ◽  
pp. 1666-1675 ◽  
Author(s):  
Marcio Mahmoud Megda ◽  
Francisco Antonio Monteiro

The objective of this work was to study morphogenic characteristics, and dry matter production of roots and shoots of marandu palisadegrass (Brachiaria brizantha cv. Marandu) submitted to combinations of nitrogen and potassium, in a nutritive solution, employing silica as substrate. The experiment was carried out in a greenhouse during the summer. It was used a 5² fractionated factorial scheme with 13 combinations of nitrogen and potassium, which were distributed in a randomized block design, with four replications. The nitrogen × potassium interaction was significant for the number of tillers and leaves, for leaf area, for shoots and root section dry mass, for total length and surface and specific length and surface in the roots. Production of aerial part dry mass positively correlated with the number of tillers and leaves and grass leaf area. Nitrogen rates modulated the root system development, and the root specific length and surface decreased when high rates of nitrogen and potassium were supllied. Nitrogen and potassium influence Marandu palisadegrass morphogenic characteristics, which are determinant for grass dry matter production.


1980 ◽  
Vol 31 (6) ◽  
pp. 1103 ◽  
Author(s):  
WC Morgan ◽  
DG Parbery

As well as reducing dry matter production of lucerne, infection of 15 % of the leaf area by Pseucbpeziza medicaginis reduced digestibility by 14% and crude protein content by 16%. Infection caused oestrogenic activity in green lucerne.


1982 ◽  
Vol 22 (115) ◽  
pp. 76 ◽  
Author(s):  
KA Boundy ◽  
TG Reeves ◽  
HD Brooke

The effect of serial planting on dry matter production, leaf area, grain yield and yield components cf Lupinus angustifoiius (cvv. Uniwhite, Uniharvest and Unicrop) and L. albus (cv. Ultra) was investigated in field plots at Rutherglen in 1973 and 1974. Delayed planting reduced dry matter production of all cultivars, and leaf area for Ultra. Differences in dry matter partitioning were observed between the late flowering Uniharvest, and the early flowering Unicrop and Ultra. In Uniharvest, delayed plantings resulted in a greater proportion of total dry matter being produced during the flowering phase, whereas the reverse was true for Unicrop and Ultra. The later flowering cultivars showed marked grain yield and yield component reduction with later sowing. Yields were reduced by 160.6 kg/ha and 222.5 kg/ha for each week's delay in sowing Uniharvest and Uniwhite, respectively. This effect was offset in the early flowering cultivars by greater development of lateral branches. In addition, when Unicrop and Ultra were planted in April, pod and flower abortion on the main stem resulted from low temperatures at flowering time. Optimum sowing time was early April for Uniwhite and Uniharvest, and early May for Unicrop and Ultra. Excellent vegetative growth under ideal moisture conditions highlighted the poor harvest indices of lupins and the scope for genetic improvement in the genus.


1967 ◽  
Vol 45 (11) ◽  
pp. 2063-2072 ◽  
Author(s):  
Holger Brix

Seedlings of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) were grown in growth chambers under all combinations of three temperatures (13, 18, and 24 °C) and three light intensities (450, 1000, and 1800 ft-c). Dry matter production of leaves, stem, and roots was determined at 65 and 100 days after germination. The leaf area produced per unit of leaf dry weight and the dry matter distribution to the plant organs was measured. Net assimilation rates between the ages of 65 and 100 days were calculated. Rates of photosynthesis per unit of leaf were determined at different light intensities and temperatures, and rates of respiration of plant top and of roots were found for different temperatures.Increasing light intensity affected dry matter production in two opposing ways: (i) it increased the rate of photosynthesis per unit leaf area, and (ii) it decreased the leaf area added per unit of dry matter produced. A pronounced increase in growth with increase in temperature from 13 to 18 °C was a result of a temperature influence on production of leaf area rather than the effect of photosynthesis per unit of leaf. Net assimilation rates decreased with increase in temperature at all light intensities.


1974 ◽  
Vol 10 (2) ◽  
pp. 87-95 ◽  
Author(s):  
B. A. C. Enyi

SUMMARYApplication of dimecron to cowpea plants increased grain yield, its effect being more pronounced in widely spaced plants and those planted in March. Dimecron increased grain yield by encouraging greater leaf area development, by increasing the number of flowering inflorescences and the number of pods set per inflorescence, and by decreasing the number of shrivelled pods. March planting encouraged greater dry matter production than January and May planting. Dimecron application decreased the number of Ootheca beningseni, reduced the proportion of leaf damaged by these insects, and reduced the number of plants infested with aphids and Acidodis larvae.


1972 ◽  
Vol 8 (4) ◽  
pp. 347-353 ◽  
Author(s):  
R. H. V. Corley ◽  
C. K. Mok

SUMMARYPotassium application appeared to increase dry matter production and yield of oil palms, primarily by increasing leaf area, while nitrogen increased both leaf area and net assimilation rate. Responses to phosphorus and magnesium were harder to interpret. Production of vegetative dry matter attained a fairly constant level at the higher rates of fertilizer application, while the ratio of bunch yield to total dry matter production was little affected by fertilizer treatments. The importance of these results for oil palm breeding, and their possible value in diagnosing fertilizer requirements, are briefly discussed.


Weed Science ◽  
1981 ◽  
Vol 29 (1) ◽  
pp. 53-59 ◽  
Author(s):  
D. T. Patterson

The effects of caffeic acid, chlorogenic acid,t-cinnamic acid,p-coumaric acid, ferulic acid, gallic acid,p-hydroxybenzaldehyde, 5-sulfosalicylic acid, vanillic acid, and vanillin on growth, photosynthesis, water relations, and chlorophyll content of 3-week-old soybeans [Glycine max(L.) Merr. ‘Tracy’] grown in aerated nutrient solution were determined. At concentrations of 10−3M, caffeic,t-cinnamic,p-coumaric, ferulic, gallic, and vanillic acids significantly reduced dry matter production, leaf expansion, height, leaf production, net assimilation rate (rate of dry matter production per unit leaf area), and leaf area duration (total leaf area present during treatment interval). Chlorogenic acid,p-hydroxybenzaldehyde, 5-sulfosalicylic acid, and vanillin at 10−3M did not inhibit growth. None of the 10 compounds at 10−4M inhibited growth. At concentrations of 10−3M, caffeic,t-cinnamic,p-coumaric, ferulic, gallic, and vanillic acids severely reduced net photosynthetic rate and stomatal conductance of single, fully expanded leaves. These same compounds also caused marked reductions in leaf chlorophyll content, with net losses of chlorophyll occurring over an 86-h period after treatment.


Sign in / Sign up

Export Citation Format

Share Document