FIELD EVALUATION OF GROWTH AND NITROGEN FIXATION IN PEAS SELECTED FOR HIGH AND LOW PHOTOSYNTHETIC CO2 EXCHANGE

1982 ◽  
Vol 62 (1) ◽  
pp. 5-17 ◽  
Author(s):  
J. D. MAHON
Keyword(s):  
Leaf Area ◽  
Field Measurements ◽  
Field Evaluation ◽  
Co2 Exchange ◽  
Physiological Age ◽  
Area Index ◽  
Large Variability ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Area Basis

Six genotypes of pea (Pisum sativum L.), selected for either high or low CO2 exchange rate per unit leaf area (CER) on the basis of field measurements, were grown in field plots during 1978 and 1979. During two growing seasons, CER was determined in leaves of different physiological age at several times of the day and season. Dry weights, leaf areas and node numbers were determined 4, 7 and 10 wk after planting, and again after pod ripening. C2H2 reduction by detached roots was measured 5, 6, 8 and 9 wk after planting. Despite the large variability in CER with years, leaf numbers, and times of measurement, the mean CER of the three genotypes selected for high rates was always greater than that of the low selected group. CER was significantly correlated with growth per unit leaf area (E) and the high to low group ratios averaged 1.4 for CER and 1.3 for E. C2H2 reduction on an equivalent leaf area basis was not different in the two groups. On a land area basis, the low CER group had a significantly greater leaf area index which compensated for the decreased CER, and estimates of total CO2 exchange, growth and C2H2 reduction were similar in the two groups. Total aboveground dry matter and seed yields were greater in the low CER group, but harvest index was generally greater in those genotypes selected for high CER.

Carbon Isotope Discrimination and Gas Exchange in Coffea arabica During Adjustment to Different Soil Moisture Regimes

1992 ◽  
Vol 19 (2) ◽  
pp. 171 ◽  
Author(s):  
FC Meinzer ◽  
NZ Saliendra ◽  
C Crisosto
Keyword(s):  
Soil Moisture ◽  
Gas Exchange ◽  
Leaf Area ◽  
Coffea Arabica ◽  
Carbon Isotope Discrimination ◽  
Total Leaf Area ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Moisture Regimes ◽  
Area Basis

Although carbon isotope discrimination (Δ) has been reported to decline in plants growing under reduced soil moisture, there is little information available concerning the dynamics of adjustments in Δ and gas exchange following a change in soil water availability. In this study Δ, photosynthetic gas exchange, and growth were monitored in container-grown coffee (Coffea arabica L.) plants for 120 days under three soil moisture regimes. At the end of 120 d, total leaf area of plants irrigated twice weekly was one half that of plants irrigated twice daily, although their assimilation rates on a unit leaf area basis were nearly equal throughout the experiment. This suggested that maintenance of nearly constant photosynthetic characteristics on a unit leaf area basis through maintenance of a smaller total leaf area may constitute a major mode of adjustment to reduced soil moisture availability in coffee. Intrinsic water-use efficiency (WUE) predicted from foliar Δ values was highest in plants irrigated weekly, intermediate in plants irrigated twice weekly and lowest in plants irrigated twice daily. When instantaneous WUE was estimated from independent measurements of total transpiration per plant and assimilation on a unit leaf area basis, the reverse ranking was obtained. The lack of correspondence between intrinsic and instantaneous WUE was attributed to adjustments in canopy morphology and leaf size in the plants grown under reduced water supply which enhanced transpiration relative to assimilation. Values of Δ predicted from the ratio of intercellular to ambient CO2 partial pressure determined during gas exchange measurements were not always consistent with measured foliar Δ. This may have resulted from a patchy distribution of stomatal apertures in plants irrigated weekly and from a lag period between adjustment in gas exchange and subsequent alteration in Δ of expanding leaves. The importance of considering temporal and spatial scales, and previous growth and environmental histories in comparing current single leaf gas exchange behaviour with foliar Δ values is discussed.

Analysis of Carbon Sequestration and Oxygen Release Capabilities of 25 Afforestation Plants in Tianjin

2014 ◽  
Vol 641-642 ◽  
pp. 1087-1092
Author(s):  
Fang Wang ◽  
Hong Yuan Li ◽  
Xin Li ◽  
Jia Nan Yang
Keyword(s):  
Carbon Sequestration ◽  
Leaf Area ◽  
Test System ◽  
Diospyros Kaki ◽  
Oxygen Release ◽  
Ulmus Pumila ◽  
Area Index ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Platanus Orientalis

CI-340 portable photosynthesis test system and JYM-B leaf area meter were employed to observe the physiological velocity and leaf area index of 25 widely used afforestation plants in Tianjin. The results indicate that the diurnal change curve of net photosynthesis rates of 25 experimental species has one or two peaks. The daily carbon sequestration and oxygen release per unit leaf area are respectively 3.98-13.01 g/( m2·d) and 2.9-9.46 g/( m2·d). Among arbors, the order of carbon sequestration and oxygen release capabilities per unit leaf area is Ulmus pumila >Fraxinus velutina>Sophora japonica>Salix matsudana f. pendula>Malus micromalus cv.‘American’>Koelreuteria paniculata>Acer truncatum>Ulmus pumila cv. ‘jinye’>Prunus davidiana>Malus micromalus>Cotinus coggygria > Rhus typhina> Platanus orientalis>Catalpa speciosa>Diospyros kaki> Morus alba cv. ‘Tortuosa’. Among shrubs, the order is Weigela florida>Euonymus japonicus>Cercis chinensis>Ligustrum vicaryi >Sorbaria sorbifolia> Syringa oblata > Lonicera maackii >Cornus alba>Lonicera japonica.

Carbon Production of Sunflower Cultivars in Field and Controlled Environment. II. Leaf Growth

1980 ◽  
Vol 7 (5) ◽  
pp. 575 ◽  
Author(s):  
HM Rawson ◽  
GA Constable ◽  
GN Howe
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Leaf Growth ◽  
Field Studies ◽  
Leaf Number ◽  
Area Index ◽  
Average Growth ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Stomatal Apparatus

In field studies of several cultivars of sunflower grown on stored soil moisture or with irrigation, yield was positively related to leaf area at anthesis. The regression which described this relationship stated that 1370 kg seed ha-1 were associated with a unit increment in leaf area index. Cultivars differed in final leaf number, rate of leaf appearance, and in the vertical distribution of leaf area in the profiles. Final leaf number of plants grown on stored moisture remained the same as in irrigated plants, but the period for which each leaf grew was reduced from 19 to 16 days while the average growth rate was reduced from 13 to 6 cm2 day-1. These changes reduced the final leaf area from 5700 to 1900 cm2 per plant. As water stress increased, the period when leaves grew fastest became progressively earlier, from approximately 35% Amax to when leaves were less than 5 cm2. Water stress increased stomatal frequencies but reduced the area of individual stomata so that the area of the stomatal apparatus per unit leaf area was unchanged. This may partially explain the constancy of peak gas exchange per unit leaf area of sunflower grown under different water regimes. There was evidence that leaves could recommence growth when the stress was alleviated.

Aboveground production efficiency and canopy nutrient contents of mixed-hardwood forest communities along a moisture gradient in the central United States

1996 ◽  
Vol 26 (12) ◽  
pp. 2214-2223 ◽  
Author(s):  
Shibu Jose ◽  
Andrew R. Gillespie
Keyword(s):  
Leaf Area ◽  
Specific Leaf Area ◽  
Production Efficiency ◽  
Moisture Gradient ◽  
Light Transmittance ◽  
Nutrient Contents ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Aboveground Production ◽  
Area Basis

The significance of canopy nutrients in regulating aboveground production efficiency of mixed-hardwood forest communities (ecological land type phases, ELTPs) was examined along a moisture gradient in southern Indiana, U.S.A. A total of 39 plots were established in six ELTPs in which canopy specific leaf area, canopy nutrient contents (N, P, K, Ca, and Mg on unit leaf area basis and on unit leaf weight basis), light transmittance, aboveground net primary productivity, and production efficiency (on unit leaf area basis, i.e., Earea; and on unit leaf weight basis, i.e., Emass) were quantified. ELTPs exhibited significant differences in canopy specific leaf area and aboveground net primary productivity. Although Earea varied significantly among ELTPs, Emass exhibited no significant differences. Variation in canopy specific leaf area was significantly correlated with ELTP site water balance (R2 = 0.93, p = 0.0083). Along a decreasing moisture gradient, canopy specific leaf area decreased, which resulted in an increase in canopy nutrient content per unit leaf area. Canopy nutrient contents (N, P, and K) in turn exhibited strong positive correlations with Earea (no strong correlations with Emass), which increased along a decreasing moisture gradient. Higher canopy nutrient contents coupled with higher light transmittance through the canopy probably results in a higher canopy photosynthetic efficiency (area basis) in dry ELTPs. This is suggested as one of the reasons for higher Earea in dry ELTPs than in mesic ELTPs.

scholarly journals Coffee crop coefficient for precision irrigation based on leaf area index

Bragantia ◽  
2011 ◽  
Vol 70 (4) ◽  
pp. 946-951 ◽  
Author(s):  
Antonio Roberto Pereira ◽  
Marcelo Bento Paes de Camargo ◽  
Nilson Augusto Villa Nova
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Crop Coefficient ◽  
Initial Guess ◽  
Planting Density ◽  
Reference Surface ◽  
Area Index ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Canopy Volume

Crop coefficient (Kc) for coffee plantations was found to be linearly related to the leaf area index (L) up to 3, i.e., Kc = b L. The basic assumption is that for irrigated trees the water use per unit leaf area (ET LA) is equal to the reference evapotranspiration (ETo) expressed also on a unit leaf area basis of the reference surface (ET LA = ETo/Lo). As recommended by FAO-56 the leaf area index (Lo) for the hypothetical reference surface (grass) is equal to 2.88, then the most likely value is b = Lo-1 = 2.88-1 = 0.347. However, for L > 3 (completely covered ground surface) Kc decreased from a peak value (~1.05) tending to an asymptotic low value around 0.7 for L > 6, but the linear model gives unrealistic Kc estimates; tentatively the empirical function Kc = 1.8 L-0.5 is offered here as an initial guess due to the lack of experimental results for the interval 3.5 <L < 5.5. To become operational under commercial fields it is necessary to estimate the leaf area per coffee tree (LA, m² tree-1), and based on a very limited set of data, LA was estimated as a function of planting density (PD, trees ha-1), i.e., LA = 88.38 - 8.63 Ln (PD). Alternatively, L (< 3.4) can be computed directly as a function of canopy volume (for V < 1.2 m³).

scholarly journals The effect of rainfall amount and timing on annual transpiration in a grazed savanna grassland

2021 ◽  
Author(s):  
Matti Räsänen ◽  
Mika Aurela ◽  
Ville Vakkari ◽  
Johan P. Beukes ◽  
Juha-Pekka Tuovinen ◽  
...  
Keyword(s):  
Leaf Area ◽  
Gross Primary Production ◽  
Co2 Exchange ◽  
Wet Season ◽  
Area Index ◽  
C4 Grass ◽  
Precipitation Timing ◽  
Dry Spells ◽  
Annual Water

Abstract. The role of precipitation (P) variability on evapotranspiration (ET) and its two components, transpiration (T) and evaporation (E) from savannas, continues to draw significant research interest given its relevance to a number of eco-hydrological applications. Our study reports on six years of measured ET and estimated T and E from a grazed savanna grassland in Welgegund, South Africa. Annual P varied significantly in amount (508 to 672 mm yr−1), with dry years characterized by infrequent early-season rainfall. T was determined using annual water-use efficiency and gross primary production estimates derived from eddy covariance measurements of latent heat flux and net ecosystem CO2 exchange rates. The computed annual T was nearly constant, 331 ± 11 mm yr−1 (T/ET = 0.52), for the four wet years with frequent early wet-season rainfall, whereas annual T was 268 and 175 mm yr−1 during the dry years. Annual T/ET was linearly related to the early wet-season storm frequency. The constancy of annual T during wet years is explained by the moderate water stress of C4 grass and constant annual tree transpiration covering 15 % of the landscape. However, grass transpiration declines during dry spells. Moreover, grasses respond to water availability with a dieback-regrowth pattern, reducing leaf area and transpiration during drought. These changes lead to an anomalous monthly T/ET relation to leaf-area index (LAI). The results highlight the role of the C4 grass layer in the hydrological balance and suggest that the grass response to dry spells and drought is reasonably described by precipitation timing.

Stomatal Development During Leaf Expansion in Tobacco and Sunflower

1975 ◽  
Vol 23 (2) ◽  
pp. 253 ◽  
Author(s):  
HM Rawson ◽  
CL Craven
Keyword(s):  
Leaf Area ◽  
Stomatal Density ◽  
Stomatal Development ◽  
Developmental Patterns ◽  
Full Size ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Wide Range ◽  
Young Leaves ◽  
Different Levels

Changes in stomatal density and size were followed in tobacco and sunflower leaves expanding from 10% of final area (10% Amax) to Amax under different levels of radiation. Lower radiation increased final leaf area, reduced stomatal densities, and increased area per stoma but had little effect on stomatal area per unit leaf area at Amax. In very young leaves (20% Amax) there was a wide range in the sizes of individual stomata, some stomata being close to full size, but by Amax differences were small. The possible relationship between the developmental patterns described and photosynthesis is briefly discussed.

scholarly journals An automated procedure for estimating the leaf area index (LAI) of woodland ecosystems using digital imagery, MATLAB programming and its application to an examination of the relationship between remotely sensed and field measurements of LAI

2008 ◽  
Vol 35 (10) ◽  
pp. 1070 ◽  
Author(s):  
Sigfredo Fuentes ◽  
Anthony R. Palmer ◽  
Daniel Taylor ◽  
Melanie Zeppel ◽  
Rhys Whitley ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Gap Analysis ◽  
Digital Camera ◽  
Field Measurements ◽  
Accurate Estimation ◽  
Image Capture ◽  
Area Index ◽  
Modis Lai ◽  
Matlab Programming

Leaf area index (LAI) is one of the most important variables required for modelling growth and water use of forests. Functional–structural plant models use these models to represent physiological processes in 3-D tree representations. Accuracy of these models depends on accurate estimation of LAI at tree and stand scales for validation purposes. A recent method to estimate LAI from digital images (LAID) uses digital image capture and gap fraction analysis (Macfarlane et al. 2007b) of upward-looking digital photographs to capture canopy LAID (cover photography). After implementing this technique in Australian evergreen Eucalyptus woodland, we have improved the method of image analysis and replaced the time consuming manual technique with an automated procedure using a script written in MATLAB 7.4 (LAIM). Furthermore, we used this method to compare MODIS LAI values with LAID values for a range of woodlands in Australia to obtain LAI at the forest scale. Results showed that the MATLAB script developed was able to successfully automate gap analysis to obtain LAIM. Good relationships were achieved when comparing averaged LAID and LAIM (LAIM = 1.009 – 0.0066 LAID; R2 = 0.90) and at the forest scale, MODIS LAI compared well with LAID (MODIS LAI = 0.9591 LAID – 0.2371; R2 = 0.89). This comparison improved when correcting LAID with the clumping index to obtain effective LAI (MODIS LAI = 1.0296 LAIe + 0.3468; R2 = 0.91). Furthermore, the script developed incorporates a function to connect directly a digital camera, or high resolution webcam, from a laptop to obtain cover photographs and LAI analysis in real time. The later is a novel feature which is not available on commercial LAI analysis softwares for cover photography. This script is available for interested researchers.

Effect of Interspecific Interference, Light Intensity, and Soil Moisture on Soybean (Glycine max), Common Cocklebur (Xanthium strumarium), and Sicklepod (Cassia obtusifolia) Water Uptake

Weed Science ◽  
1993 ◽  
Vol 41 (4) ◽  
pp. 534-540 ◽  
Author(s):  
Ronald E. Jones ◽  
Robert H. Walker
Keyword(s):  
Soil Moisture ◽  
Light Intensity ◽  
Leaf Area ◽  
Water Uptake ◽  
Root Weight ◽  
Pressure Potential ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Shoot Weight ◽  
The Relationship

Greenhouse and growth chamber experiments with potted plants were conducted to determine the effects of interspecific root and canopy interference, light intensity, and soil moisture on water uptake and biomass of soybean, common cocklebur, and sicklepod. Canopy interference and canopy plus root interference of soybean with common cocklebur increased soybean water uptake per plant and per unit leaf area. Root interference with soybean decreased common cocklebur water uptake per plant. Canopy interference of soybean with sicklepod increased soybean water uptake per unit leaf area, while root interference decreased uptake per plant. Combined root and canopy interference with soybean decreased water uptake per plant for sicklepod. Soybean leaf area and shoot weight were reduced by root interference with both weeds. Common cocklebur and sicklepod leaf area and shoot weight were reduced by root and canopy interference with soybeans. Only common cocklebur root weight decreased when canopies interfered and roots did not. The relationship between light intensity and water uptake per unit leaf area was linear in both years with water uptake proportional to light intensity. In 1991 water uptake response to tight was greater for common cocklebur than for sicklepod. The relationship between soil moisture level and water uptake was logarithmic. Common cocklebur water uptake was two times that of soybean or sicklepod at −2 kPa of pressure potential. In 1991 common cocklebur water uptake decreased at a greater rate than soybean or sicklepod in response to pressure potential changes from −2 to −100 kPa.

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