Effect of leaf age on photosynthesis and transpiration of cassava (Manihot esculenta)

1977 ◽  
Vol 55 (17) ◽  
pp. 2288-2295 ◽  
Author(s):  
M. Aslam ◽  
S. B. Lowe ◽  
L. A. Hunt
Keyword(s):  
Chlorophyll Content ◽  
Manihot Esculenta ◽  
Leaf Age ◽  
Gas Analysis ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Genotypic Differences ◽  
Specific Leaf Weight ◽  
Manihot Esculenta Crantz ◽  
Leaf Weight

The effect of plant and leaf age on CO2-exchange rates (CER) and transpiration rates in 15 genotypes of cassava (Manihot esculenta Crantz) was measured in situ by infrared gas analysis. The plants were grown in a controlled-environment room with a 14-h photoperiod, day–night temperatures of 29–24 °C, and 60–70% relative humidity.Plant age had no effect on leaf CER, whereas transpiration rates in 14-week-old plants were significantly greater than those in 7-week-old plants. Both CER and transpiration rates decreased with leaf age. The decline was negligible when measured at low photosynthetic photon flux density. At saturating light, however, both CER and transpiration rates decreased significantly in most of the genotypes. Significant genotypic differences were observed in the pattern of decline. Both stomatal (rs) and residual (rr) resistances to the diffusion of CO2 increased with leafage in all the genotypes. The relative increase in rr was much greater than the increase in rs. In all the genotypes the ratio rr:rs was greater than unity, suggesting that rr is the major component of the total resistance to photosynthesis. Chlorophyll content and specific leaf weight also varied significantly among the genotypes. However, chlorophyll content decreased and specific leaf weight increased with leaf age.

Leaf photosynthetic characteristics and net primary production of the polar willow (Salix polaris) in a high arctic polar semi-desert, Ny-Ålesund, Svalbard

2002 ◽  
Vol 80 (11) ◽  
pp. 1193-1202 ◽  
Author(s):  
Hiroyuki Muraoka ◽  
Masaki Uchida ◽  
Masako Mishio ◽  
Takayuki Nakatsubo ◽  
Hiroshi Kanda ◽  
...  
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Natural Habitat ◽  
Leaf Age ◽  
High Arctic ◽  
Photosynthetic Characteristics ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Salix Polaris ◽  
Temperature Conditions

Photosynthetic characteristics and their leaf-age dependence were examined to estimate ecophysiological effects on net primary production (NPP) of a polar willow (Salix polaris), a dominant dwarf shrub species in a polar semi-desert area of Ny-Ålesund, Svalbard. Leaves of S. polaris emerged just after snowmelt in early July in 2000; flowers were initiated within 1 week, and fruits in late July. Light-saturated rate of photosynthesis and stomatal conductance to water vapor increased rapidly to their maximum values within 1 week after leaf emergence and then decreased gradually. Depending on the leaf age, photosynthetic rates saturated at photosynthetically active photon flux density (PPFD) of 200–400 µmol·m–2·s–1, which is the light level usually available in the natural habitat. Optimum leaf temperature of photosynthesis ranged from 10 to 18°C, while air temperature in the habitat ranged from 8 to 20°C. These light and temperature responses of photosynthesis of S. polaris would be suitable for efficient carbon gain in the natural habitat characterized by highly variable light and temperature conditions. Using the photosynthetic and respiratory characteristics, biomass distribution, and meteorological data, NPP of S. polaris in the current year was estimated to be 26.1 g C·m–2. A model simulation of rising temperature conditions predicted a reduction of NPP because of a large increase in respiration. It was suggested that temperature condition and leaf phenological aspects strongly influence the carbon fixation by plants in the high arctic area studied.Key words: arctic semi-desert, climate change, net ecosystem production (NEP), net primary production (NPP), Salix polaris, photosynthesis.

scholarly journals Intensity of bitterness of processed yerba mate leaves originated in two contrasted light environments

2008 ◽  
Vol 51 (3) ◽  
pp. 569-579 ◽  
Author(s):  
Miroslava Rakocevic ◽  
Moacir José Sales Medrado ◽  
Fernando Lucambio ◽  
Alice Teresa Valduga
Keyword(s):  
Leaf Gas Exchange ◽  
Leaf Age ◽  
Sun Exposure ◽  
Photosynthetic Photon Flux Density ◽  
Leaf Temperature ◽  
Forest Understory ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Ilex Paraguariensis ◽  
Yerba Mate

The bitterness intensity of beverage prepared from the leaves produced on the males and females of yerba mate (Ilex paraguariensis), grown in the forest understory and monoculture, was evaluated. The leaves were grouped by their position (in the crown and on the branch tips) and by the leaf age. The leaf gas exchange, leaf temperature and photosynthetic photon flux density were observed. Inter and intra-specific competition for light and self-shading showed the same effect on yerba mate beverage taste. All the shading types resulted in bitterer taste of the processed yerba mate leaves compared to the leaves originated under the direct sun exposure. The leaves from the plants grown in the monoculture showed less bitterness than those grown in the forest understory. This conclusion was completely opposite to the conventionally accepted paradigm of the yerba mate industries. The leaves from the tips (younger leaves) of the plants grown in the monoculture resulted a beverage of softer taste; the males produced less bitter leaves in any light environment (forest understory or in the crown in monoculture). The taste was related to the photosynthetic and transpiration rate, and leaf temperature. Stronger bitterness of the leaves provided from the shade conditions was related to the decreased leaf temperature and transpiration in the diurnal scale.

scholarly journals Genotypes by environment effect on flowering and seed set in cassava, Manihot esculenta Crantz in Uganda

2021 ◽  
pp. 26-37
Author(s):  
Lado Aquilino ◽  
A. Pariyo ◽  
Y. Baguma ◽  
R. Edema ◽  
P. Gibson ◽  
...  
Keyword(s):  
Manihot Esculenta ◽  
Seed Set ◽  
Abiotic Factors ◽  
Block Design ◽  
Weather Data ◽  
Genotypic Differences ◽  
Flower Initiation ◽  
Environment Interaction ◽  
Manihot Esculenta Crantz ◽  
Main Effect

Cassava (Manihot esculenta Crantz) production has been constrained by biotic and abiotic factors, which could be solved by conventional breeding. However, cassava hybridization is difficult because many genotypes do not flower or set seeds and yet cassava sexual reproduction is essential for breeding programs. Consequently, this study was undertaken to identify agro ecologies in Uganda that best promote cassava flowering and seed set in order to facilitate breeding. Field evaluation of eight genotypes in randomized complete block design with three replications at three agro-ecologies of Uganda for two cropping seasons was conducted. Weather data were monitored and cassava flowering/seed set-related traits were collected at one-month interval commencing from 1.5 Months after planting. Results indicated that varieties previously categorized as high flowering and seed set performed differently than those identified as poor flowering and seed set, although with varying genotypic differences in each environment. Genotypes mean performances, additive main effect and multiplicative interaction and genotype main effect and genotype by environment interaction bi-plots model’ results indicated Rwebitaba in Western savannah grassland agro-ecology and Namulonge-NaCRRI in Lake Victoria Crescent agro-ecology as the most favorable environments for the performance of all the evaluated traits, and season one as the most favorable season. However, the most stable environment for all the evaluated traits was Abi-ZARDI. Conclusively, the high proportion of variation which occurred between genotypes and environments was explained by the genotypic variances. Dry months had poorer cassava flower initiation and development than wet months of the cropping season. Therefore, Abi-ZARDI in North-western savannah grassland agro-ecology and season one could be recommended for the establishment and timing of cassava breeding nursery.

Loss of chlorophyll with limited reduction of photosynthesis as an adaptive response of Syrian barley landraces to high-light and heat stress

1999 ◽  
Vol 26 (6) ◽  
pp. 569 ◽  
Author(s):  
Michel Havaux ◽  
Florence Tardy
Keyword(s):  
High Temperature ◽  
Chlorophyll Content ◽  
Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Arid Environments ◽  
Strong Light ◽  
Carotenoid Concentration ◽  
High Solar Radiation ◽  
Barley Landraces

The Syrian barley landrace Tadmor is adapted to semi-arid environments and characterized by a reduced chlorophyll content (ca −25% on a leaf area basis) compared to improved barley genotypes, such as the European variety Plaisant. Tadmor leaves had reduced stomatal conductance (gS ) compared to Plaisant leaves both under well-watered conditions and during water stress. Both Tadmor and Plaisant barley seedlings were progressively acclimated to high temperature (39°C) and high photon flux density (1600 µmol photons m −2 s −1 ). During acclimation, the chlorophyll content of Tadmor leaves further decreased whereas the carotenoid concentration remained virtually unchanged, leading to a marked increase in the carotenoid:chlorophyll ratio. The chlorophyll content of acclimated Tadmor leaves was reduced to approximately half of the chlorophyll content of Plaisant leaves grown under the same conditions. Loss of chlorophyll in Tadmor leaves was not observed when only one environmental factor was increased (temperature or photon flux density). In the improved variety, both chlorophylls and carotenoids accumulated during acclimation to heat and strong light, leading to an almost constant carotenoid:chlorophyll ratio. The loss of chlorophyll in the Syrian landrace was associated with limited changes in the photosynthetic characteristics of the leaves (oxygen evolution, electron transport quantum yield, chlorophyll antenna size of photosystem II). Plaisant leaves, but not Tadmor leaves, exhibited symptoms of oxidative damage during growth in strong light at high temperature. When the stomata were closed, sudden exposure to bright light caused a smaller increase in leaf temperature in Tadmor than in Plaisant. Taken together, our results suggest that the ‘low chlorophyll’ feature of Syrian barley landraces is related to their drought adaptation which is manifested by a low g S : the very low chlorophyll content decreases leaf absorbance which, in turn, reduces the potentially damaging heating effect of high solar radiation in droughted plants whose stomata are closed.

Leaf nitrogen distribution in relation to leaf age and photon flux density in dominant and subordinate plants in dense stands of a dicotyledonous herb

Oecologia ◽  
1998 ◽  
Vol 113 (3) ◽  
pp. 314-324 ◽  
Author(s):  
N. P. R. Anten ◽  
K. Miyazawa ◽  
K. Hikosaka ◽  
H. Nagashima ◽  
T. Hirose
Keyword(s):  
Flux Density ◽  
Leaf Age ◽  
Leaf Nitrogen ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Nitrogen Distribution

Nitrate Reduction in Redroot Pigweed (Amaranthus retroflexus) and Common Lambsquarters (Chenopodium album) as a Function of Leaf Age and Photosynthetic Photon Flux Density

Weed Science ◽  
1980 ◽  
Vol 28 (5) ◽  
pp. 484-486
Author(s):  
Chang-Chi Chu ◽  
R. D. Sweet ◽  
J. L. Ozbun ◽  
S. L. Kaplan
Keyword(s):  
Nitrate Reduction ◽  
Chenopodium Album ◽  
Leaf Age ◽  
Photosynthetic Photon Flux Density ◽  
Amaranthus Retroflexus ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Common Lambsquarters ◽  
Redroot Pigweed

Nitrate reduction on a leaf fresh weight basis was measured in common lambsquarters (Chenopodium album L.) and redroot pigweed (Amaranthus retroflexus L.) in individual leaves as a function of the photosynthetic photon flux density (PPFD) under which the plants were grown. Common lambsquarters had greater rates of nitrate reduction than did redroot pigweed regardless of leaf age or PPFD and responded to a significantly greater degree when PPFD was increased, with a proportionately greater increase in nitrate reduction among younger leaves.

PLANT SPACING EFFECTS ON PHOTOSYNTHESIS AND TRANSPIRATION OF THE GREENHOUSE TOMATO

1988 ◽  
Vol 68 (4) ◽  
pp. 1209-1218 ◽  
Author(s):  
ATHANASIOS P. PAPADOPOULOS ◽  
DOUGLAS P. ORMROD
Keyword(s):  
Lycopersicon Esculentum ◽  
Leaf Area ◽  
Net Photosynthesis ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Plant Spacing ◽  
Greenhouse Tomato ◽  
Lycopersicon Esculentum Mill ◽  
Leaf Weight

The effect of four equidistant spacings (23, 30, 38, 45 cm) applied to four-row plantings of greenhouse tomato (Lycopersicon esculentum Mill. ’CR-6’) on plant net photosynthesis (P) and transpiration (E) was studied. Closer spacing decreased the leaf-area-based net photosynthesis (Pa) of the lower leaves but had little effect on the Pa of the upper leaves. The exposed parts of a tomato plant could adjust their Pa rates upwards to compensate for the low Pa of their shaded parts. The leaf-weight-based net photosynthesis (Pw) increased with the decrease of plant spacing and it was higher in inside compared to outside plants. The differences between the Pa and Pw results were mostly attributable to the effect of light in increasing the specific leaf weight (SLW). The E rate of plants increased at the closest spacing and there was a higher leaf weight based transpiration (Ew) in inside than outside plants. The leaf area based transpiration (Ea) and stomatal resistance (Rw) were not affected appreciably by light (photosynthetic photon flux density) other than at very low levels (i.e. less than 100 μmol m−2 s−1) where there was a sharp increase in Rw and a corresponding decrease in Ea. The P of plants growing in an environment of gradually declining duration and intensity of solar irradiance declined with the aging of plants. There was no similar effect on E.Key words: Lycopersicon esculentum Mill, plant spacing, photosynthesis, transpiration, tomato

CO2 compensation concentration in bean Leaves: Effect of photon flux density and leaf age

1979 ◽  
Vol 21 (5) ◽  
pp. 361-364 ◽  
Author(s):  
J. Čatský ◽  
Ingrid Tichá
Keyword(s):  
Flux Density ◽  
Leaf Age ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Co2 Compensation Concentration ◽  
Compensation Concentration ◽  
Bean Leaves
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