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

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.


1971 ◽  
Vol 22 (1) ◽  
pp. 1 ◽  
Author(s):  
DW Puckridge

Photosynthesis of two wheat cultivars grown in the field was examined during three seasons by use of a portable field assimilation chamber. There were large differences in dry weight, leaf area, and carbon dioxide uptake between seasons. Variations in carbon dioxide uptake by the community were related mainly to changes in leaf area index (LAI). There were changes in carbon dioxide uptake per unit LAI with time, and between the two cultivars in the first season, but the effects of these changes were small compared with the effects of LAI. Differences in grain yield were correlated with LAI and carbon dioxide uptake in the period after anthesis.



2021 ◽  
Vol 54 (3) ◽  
pp. 231-243
Author(s):  
Chao Liu ◽  
Zhenghua Hu ◽  
Rui Kong ◽  
Lingfei Yu ◽  
Yuanyuan Wang ◽  
...  


2013 ◽  
Vol 59 (No. 12) ◽  
pp. 543-548 ◽  
Author(s):  
P. Dąbrowski ◽  
B. Pawluśkiewicz ◽  
Kalaji HM ◽  
Baczewska AH

How light conditions affect development of park grasslands is a question that has not been satisfactory addressed. The aim of this study was therefore determination of the level to which unfavorable light conditions influence grassy parks area and relationships between parameters which determine state of turf grasses. Researches were conducted in two parks in Warsaw, in various light conditions and included measurement of: leaf density, sward height, leaf area index (LAI), and botanical composition of the communities. The leaf density of shaded areas did not exceed 70%. LAI value varied from 0.5 to 0.9-fold lower than in the areas in half-shade and in sun. The participation of basic lawn species at Skaryszewski Park was higher under shade, while at Łazienki Królewskie was higher in full-sunlight areas. The state of tested grassy areas in limited solar radiation does not satisfy the requirements of recreational and representational functions. The development processes of vegetation coverage were inhibited at the sites of lower solar radiation. LAI was influenced by both leaf coverage and sward height. Agrostis stolonifera and Poa trivialis may be recommended to create grass areas under limited solar radiation.





Agromet ◽  
2005 ◽  
Vol 19 (2) ◽  
pp. 57
Author(s):  
Z. Noor ◽  
B.F. Simatupang ◽  
Yonny Koesmaryono

<p>An experiment has been conducted in Batam Island to study the response of sweet pepper which cultivated at lowland of 20 m asl, during November 2001 to May 2002. Five varieties have been used namely, Bangkok, Gold Flame, New Zealand, Spartacus and Tropica. Plants cultivated using hydroponic system under plastic house with ultra violet protection. The radiation of 100% (control) and it reduce of 25% and 50% used as treatment in order to determine the microclimate favourable for growing pepper in lowland. The results shown that reducing radiation intensity has influenced significantly on vegetatif growth, except leaf area index. The plants were grown under 100% and 25% radiation intensity performed taller with more branches compare to the plants under 50%. Variety of Spartacus has grew tallest than others. Stem diameter of control plants performed bigger than other plants, while reducing radiation intensity has no effect significantly to leaf area index. Experiment also revealed that reducing radiation intensity has significant effect on number and weight of peppers per plant, and thickness of flesh, compare to control. In general, Gold flame has produced best quality than others varieties although it has less number of fruits compare to Tropica.</p>





1967 ◽  
Vol 20 (3) ◽  
pp. 623 ◽  
Author(s):  
RW King ◽  
LT Evans

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.



2019 ◽  
Vol 11 (9) ◽  
pp. 213
Author(s):  
Braulio Otomar Caron ◽  
Ana Paula Rockenbach ◽  
Denise Schmidt ◽  
Thaise Dieminger Engroff ◽  
Felipe Schwerz ◽  
...  

The objective of this paper was to assess the efficiency of photosynthetically active radiation (PAR) intercepted in dried phytomass of soybean cultivars of determinate and indeterminate growth habits in different spatial arrangements. All experiments were carried out during the 2013/2014 crop year, two soybean cultivars (BMX Ativa RR/determinate and BMX Turbo RR/indeterminate) in a spatial arrangements (45, crossed, 20, 20 &times; 40, 20 &times; 60, 20 &times; 80 cm). Starting from first emergence up to the point of maturation, 14 phytomass assessment were evaluated with seven days interval, in which one plant was sampled per repetition. Greater conversion efficiencies of solar radiation were obtained in paired arrangements. Paired arrangements, and 20 cm, lead to a greater leaf area index, and possibly a greater interception of the diffused radiation and an increase of conversion efficiency and the overall cultivation productivity of BMX Ativa RR and BMX Turbo RR.



Author(s):  
E. Chakwizira ◽  
D.J. Moot ◽  
W.R. Scott ◽  
A. Fletcher

'Pasja' (Brassica campestris x napus) was grown at Lincoln in 2008, with banded or broadcast phosphorus (P) fertiliser applied at 0, 20, 40 or 60 kg/ha at establishment on a Templeton silt loam soil of moderate fertility (Olsen P of 9-17 mg/ kg range for individual plots). Keywords: Brassica campestris, critical leaf area index, DM accumulation, leaf area index, leaf to stem ratio, solar radiation



Sign in / Sign up

Export Citation Format

Share Document