Photosynthesis in Artificial Communities of Wheat, Lucerne, and Subterranean Clover Plants

1967 ◽  
Vol 20 (3) ◽  
pp. 623 ◽  
Author(s):  
RW King ◽  
LT Evans
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Dark Respiration ◽  
Subterranean Clover ◽  
Net Photosynthesis ◽  
Area Index ◽  
Light Intensities

The relation between leaf area index (L.A.I.) and rates of net photosynthesis at three light intensities, and of dark respiration, was examined throughout the course of growth of artificial communities of wheat and lucerne at 20�C, and of subterranean clover at 25� /20�C.

scholarly journals Photosynthesis in Artificial Communities of Cotton Plants in Relation to Leaf Area I. Experiments with Progressive Defoliation of Mature Plants

1965 ◽  
Vol 18 (6) ◽  
pp. 1103 ◽  
Author(s):  
LJ Ludwig ◽  
T Saeki ◽  
LT Evans
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Area Index ◽  
Light Intensities ◽  
Cotton Plants

The relation between the leaf area index (L.A.I.) of artificial communities of cotton plants and their rates of dark respiration and of net photosynthesis at three light intensities was examined. The L.A.I. was varied by the removal of successive layers of leaves, working from the base of the canopy upwards. Experiments were carried out at 20, 30, and 40�0 to vary the relative magnitudes of respiration and photosynthesis.

Productivity of Vegetable Crops in a Region of High Solar Input. IV. Field Chamber Measurements on French Beans (Phaseolus vulgaris L.) And Cabbages (Brassica oleracea L.)

1975 ◽  
Vol 2 (4) ◽  
pp. 461 ◽  
Author(s):  
PJM Sale
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Dark Respiration ◽  
Gas Analysis ◽  
Large Field ◽  
Co2 Uptake ◽  
Vegetable Crops ◽  
Area Index ◽  
French Beans

Net CO2 uptakes have been measured for crop canopies of French beans and cabbages, sown at two plant densities, using a large field assimilation chamber and a semi-closed gas-analysis system. For both species, the maximum rates of uptake were a little less than 40 mg CO2 dm-2 (ground area) h-1, and light saturation of the canopy occurred at 600-650 W m-2 (French beans) or about 800 W m-2 (cabbages). Net CO2 uptake decreased with leaf area index at values below about 5, but was relatively insensitive to temperature over the range used. Once this leaf area index was reached, the relationship between net uptake and solar radiation remained fairly constant throughout the growth period. For both species, dark respiration rates were markedly dependent on temperature, and also were lower at night than during the day when measured at the same temperature. For both French beans and cabbages, growth analyses showed the maximum growth rates to be 18-19 g dry weight m-2 (ground area) day-1. The mean growth rate from emergence to harvest for an overwintered cabbage crop was 5.5 g m-2 day-1. It is suggested that the main advantage of the region in terms of plant productivity lies in the long frost-free growing season and the ability of frost-tolerant crops to maintain fairly high growth rates throughout a mild and comparatively sunny winter.

Seed size as a factor in the growth of subterranean clover (Trifolium subterraneum L.) under spaced and sward conditions

1957 ◽  
Vol 8 (4) ◽  
pp. 335 ◽  
Author(s):  
JN Black
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Seed Size ◽  
Seed Weight ◽  
Agricultural Research ◽  
Incident Light ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Area Index ◽  
Significant Difference

The significance of seed weight in the growth of subterranean clover (Trifolium subterraneum L) , of the Bacchus Marsh strain, has been assessed under both spaced plant and sward conditions at the Waite Agricultural Research Institute. Under conditions of spacing, plants of three widely separated seed size grades were grown a t a density of 1 per 25 sq. links. The dry weights of the plants were proportional to seed weight from the time of sowing (in May) till the end of October – over almost the entire growing period of the crop. Three sets of swards were grown a t a density of 25 plants per sq. link, each sward being planted with seed of one of the three sizes. Dry weight was proportional to seed weight in the early part of the season but when the swards reached a leaf area index of about 4 (i.e. when there were 4 sq. links of leaf surface on 1 sq. link of ground), a reduction in growth rate occurred. This critical leaf area index was reached first in "large seed" swards, followed later by "medium seed" and finally by "small seed" swards. Thus there was a period in which the swards were growing at different rates, and in which the dry weights came to parity, so that on the final sampling occasion (in December) there was no significant difference between the dry weights of the swards from the three seed sizes. It is concluded that a t a leaf area index of about 4, interception of incident light energy is complete.

Photosynthesis of wheat under field conditions. IV. The influence of density and leaf area index on the response to radiation

1971 ◽  
Vol 22 (1) ◽  
pp. 11 ◽  
Author(s):  
DW Puckridge ◽  
DA Ratkowsky
Keyword(s):  
Carbon Dioxide ◽  
Solar Radiation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Net Photosynthesis ◽  
Good Prediction ◽  
Area Index ◽  
Rectangular Hyperbola ◽  
Carbon Dioxide Uptake ◽  
Good Agreement

The photosynthesis of two cultivars of wheat at three densities of sowing was measured during the growing season of 1968. When the data were plotted as carbon dioxide uptake versus leaf area index (LAI) (leaf laminae and green stem) for a fixed value of solar radiation, it was found that all of the data could be fitted by a single curve, irrespective of variety, sowing density, or time of season when the measurements were made. Since the curve was of continuously decreasing slope, the carbon dioxide uptake per unit LAI was highest for the low values of LAI and was reduced with the increased light interception at high LAI. For a solar radiation of 0.6 cal/cm2/min the approximate maximum net photosynthesis was 4.5 g CO2/m2/hr for an LAI of 6. A mathematical model for photosynthesis was found to give good prediction of carbon dioxide uptake versus solar radiation for most of the period of measurement. For each plot, a rectangular hyperbola was fitted to the data. When the parameters of the model were subsequently plotted as a function of LAI, then within a given variety, it was found that lines of common slope but differing intercepts could be drawn through the points for different sowing densities. From these fitted lines together with the measured values of LAI and respiration, carbon dioxide uptake was then predicted as a function of solar radiation by employing the rectangular hyperbola model. Good agreement between predicted and measured values of photosynthesis was obtained.

NET CARBON DIOXIDE EXCHANGE RATES IN PHASEOLUS VULGARIS L. AS INFLUENCED BY TEMPERATURE, LIGHT INTENSITY, LEAF AREA INDEX, AND AGE OF PLANT

1964 ◽  
Vol 42 (4) ◽  
pp. 393-401
Author(s):  
Douglas P. Ormrod
Keyword(s):  
Carbon Dioxide ◽  
Phaseolus Vulgaris ◽  
Light Intensity ◽  
Exchange Rates ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Planting Density ◽  
Carbon Dioxide Exchange ◽  
Area Index ◽  
Light Intensities

Plants of Phaseolus vulgaris were grown under controlled conditions for 10 to 60 days and then transferred to light intensities of from 0 to 12,000 ft-c at temperatures of 4 to 38 °C for measurement of net carbon dioxide exchange by means of an infrared analyzer. The net carbon dioxide exchange was not markedly influenced by temperature at higher light intensities, particularly with older plants and the greater planting density, but was strikingly influenced by temperature in darkness or low light intensity. The leaf area index affected the rate at which the maximum net carbon dioxide exchange rates were attained. The compensation point increased with aging and with denser planting. The net assimilation decreased at the onset of fruiting. Several features of the experimental method are discussed.

scholarly journals GAS EXCHANGE, CHLOROPHYLL CONTENT AND LEAF AREA INDEX OF OKRA AT SIX IN-ROW PLANT DENSITIES

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 689E-689
Author(s):  
Wayne F. Whitehead ◽  
Bharat P. Singh
Keyword(s):  
Gas Exchange ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Chlorophyll Content ◽  
Significant Variation ◽  
Plant Density ◽  
Net Photosynthesis ◽  
Area Index ◽  
Canopy Position ◽  
Plant Densities

The effect of in-row plant densities on gas exchange, chlorophyll content and leaf area index of okra (Abelmoschus esculentus (L.) Moench) was studied. The six in-row plant densities ranged from 8 cm to 48 cm (D1 - D6). On 11 and 27 July 1990, the photosynthetically active radiation (PAR), transpiration (E), net photosynthesis (Pn) and chlorophyll content (Chl) at top- and mid-canopy levels and leaf area index (LAI) were measured. Mid-canopy PAR was 86 ± 6% less than that of the top-canopy and E, Pn and Chl at mid-canopy were respectively 55, 90 and 10% lower than those of the top-canopy. The interaction of plant density with canopy position was significant for E and Pn. The highest E and Pn, (12.28 mmol m-2 s-1 and 22.01 μmol CO2 m-2 s-1, respectively) were recorded at the D5 top-canopy. In-contrast, the lowest E and Pn, (4.17 mmol m-2 s-l and 1.23 μmol CO2 m-2 s-1, respectively) at the D6 mid-canopy were recorded. The LAI also exhibited significant variation among plant densities with a range of 4.65 to 4.97 for D5 and D3, respectively. These results indicate that 40 cm in-row density was the most suited for gas exchange of okra.

The interrelationship of solar radiation and leaf area index in determining the rate of dry matter production of swards of subterranean clover (Trifolium subterraneum L.)

1963 ◽  
Vol 14 (1) ◽  
pp. 20 ◽  
Author(s):  
JN Black
Keyword(s):  
Growth Rate ◽  
Solar Radiation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Subterranean Clover ◽  
Crop Growth ◽  
Area Index ◽  
Specific Level ◽  
Crop Growth Rate

The relationship of crop growth rate, leaf area index, and solar radiation has been examined for swards of subterranean clover, of the variety Bacchus Marsh. Leaf area index was varied by growing swards at eight densities of sowing, and radiation varied by two levels of shading, in addition to full daylight; the whole experiment was done three times—in summer, early winter, and spring—at the Waite Agricultural Research Institute, Adelaide. Crop growth rate was measured as the difference between the dry weights of the swards on two harvest occasions, and was calculated from smoothed values obtained by fitting an appropriate equation to the yield : density relationship. Thus a set of nine curves were available, each showing the response of growth rate to varying leaf area index at a specific level of radiation. These nine curves formed a consistent series, the growth rate rising with leaf area index until a maximal value was reached at the "optimum leaf area index", thereafter falling. At low levels of radiation, growth rate fell to zero at high leaf area indices. Both the maximal growth rate and the optimum leaf area index increased with radiation, and an analysis of the data indicated that these growth indices were dependent on radiation, the effect of temperature being negligible. A generalized series of curves was calculated by extrapolation, so that crop growth rates can be derived for any combination of leaf area index and radiation. A comparison of maximal crop growth rates and percentage utilization of light energy of subterranean clover and other crops suggests that this clover is relatively inefficient in integrating its environment.

Net Photosynthesis of Barley Seedlings as Influenced by Leaf Area Index 1

Crop Science ◽  
1967 ◽  
Vol 7 (5) ◽  
pp. 545-546
Author(s):  
R. B. Pearce ◽  
R. H. Brown ◽  
R. E. Blaser
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Net Photosynthesis ◽  
Area Index
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