Effect of drought and plant density on radiation interception, radiation-use efficiency and partitioning of dry matter to seeds in cowpea

1999 ◽  
Vol 35 (3) ◽  
pp. 309-325 ◽  
Author(s):  
P. Q. CRAUFURD ◽  
T. R. WHEELER
1993 ◽  
Vol 20 (1) ◽  
pp. 1-5 ◽  
Author(s):  
J. M. Bennett ◽  
T. R. Sinclair ◽  
Li Ma ◽  
K. J. Boote

Abstract Knowledge of the interception of solar radiation by crop canopies and the use of that radiation for carbon assimilation is essential for understanding crop growth and yield as a function of the environment. A field experiment was conducted in 1990 at Gainesville, FL to determine if differences in single leaf carbon exchange rate (CER), canopy radiation interception, radiation use efficiency (g dry matter produced per unit of solar radiation intercepted), and increase in seed harvest index with time exist among several commonly grown peanut (Arachis hypogaea L.) cultivars. Four cultivars (Early Bunch, Florunner, Marc I, and Southern Runner) were grown in field plots on a Kendrick fine sand (a loamy, siliceous, hyperthermic Arenic Paleudult) under fully irrigated, intensive management. Total crop and seed dry matter accumulation were determined, and canopy radiation interception measured at weekly intervals. CER of uppermost, fully expanded sunlit leaves were determined at midday at 2-wk intervals. Single leaf CER's were similar among cultivars (25 to 35 μmol CO2 m-2 s-1) and relatively stable throughout most of the season, before declining during late seed filling. Although interception of radiation differed somewhat among cultivars during early canopy development, total crop dry matter accumulation was linearly related to the cumulative amount of radiation intercepted by all four cultivars (r2=≥0.99). Radiation use efficiency was similar among all cultivars with a mean of 1.00 g dry matter accumulated per MJ of intercepted solar radiation. The increase in seed harvest index with time was linear (r2≤0.94) and the rates of increase were similar among the Early Bunch, Florunner, and Marc I cultivars (0.0058 d-1), but lower (0.0043 d-1) for the later maturing Southern Runner cultivar. Results from this study indicated that the primary differences among these four cultivars were in early-season development of the leaf canopy and resultant radiation interception and the rate of seed growth, rather than the capacity to assimilate carbon dioxide.


Weed Science ◽  
1999 ◽  
Vol 47 (3) ◽  
pp. 291-296 ◽  
Author(s):  
Stevan Z. Knezevic ◽  
Michael J. Horak ◽  
Richard L. Vanderlip

Redroot pigweed is a troublesome weed in the sorghum-growing regions of North America. In 1994 and 1995, field studies were conducted at two locations near Manhattan, KS, to determine the influence of redroot pigweed density and environmental conditions on physiological determinants of redroot pigweed growth: duration of plant growth, light interception, radiation-use efficiency, and dry matter partitioning. In addition, specific leaf area was determined. Redroot pigweed was seeded at monoculture densities of 2, 4, and 12 plants m−1of row each year at each location. Duration of redroot pigweed growth was not influenced by plant density. Light interception was defined as a simple exponential function of leaf area index. Specific leaf area did not change over the season and averaged 135 cm2g−1. Partitioning of redroot pigweed dry matter was not influenced by plant density or environmental conditions but did not change within vegetative and reproductive stages. Radiation-use efficiency was not influenced by redroot pigweed density; the most reliable estimate was 1.74 g dry matter MJ−1of intercepted photosynthetically active radiation. Physiological determinants described were not affected by redroot pigweed density or environmental conditions and therefore provide a starting point for the development of a redroot pigweed growth module. The module could be coupled with available crop growth models (e.g., the sorghum growth model SORKAM) to simulate redroot pigweed–sorghum competition.


Helia ◽  
2001 ◽  
Vol 24 (35) ◽  
pp. 101-110 ◽  
Author(s):  
S. Sridhara ◽  
T.G. Prasad

SUMMARYA field experiment was conducted at Gandhi Krishi Vignana Kendra, University of Agricultural Sciences, Bangalore to study the effect of irrigation regimens on the biomass accumulation, canopy development, light interception and radiation use efficiency of sunflower. The treatments includes irrigating the plants at 0.4, 0.6, 0.8 and 1.0 cumulative pan evaporation. The results indicated that the aboveground biomass, canopy development, radiation interception and radiation use efficiency were influenced favorably by the irrigation regimens. Irrespective of the irrigation regimen, the radiation use efficiency of sunflower increased from 15 DAS to 75 DAS and then tended to decline. The decrease in RUE after anthesis is coupled with decrease in leaf nitrogen content. In general the RUE of sunflower ranged from 0.49 g MJ-1 to 1.84 g MJ-1 at different growth stages. The light transmission within the canopy increased exponentially with plant height and the canopy extension coefficient is found to be 0.8.


2011 ◽  
Vol 62 (10) ◽  
pp. 840 ◽  
Author(s):  
E. Chakwizira ◽  
D. J. Moot ◽  
W. R. Scott ◽  
A. L. Fletcher ◽  
S. Maley

Inadequate phosphorus (P) supply at crop establishment can reduce dry matter (DM) accumulation. A field experiment quantified the effects of banded or broadcast P fertiliser (0, 20, 40 or 60 kg P/ha) applied at establishment to moderately fertile soils on growth and development of ‘Regal’ kale (Brassica oleracea var. acephala L.) crops. DM yield increased from 8710 to ~11 400 kg/ha by the addition of P fertiliser but was unaffected by the method of P application. The control crops accumulated 630 kg DM/100 degree-day (degree-day-accumulated heat available for crop growth) compared with ~800 kg/100 degree-day for the P-fertilised crops. The yield response to P was caused by an increased rate of development of leaf area index (LAI) and consequently earlier canopy closure that led to higher accumulated radiation interception (RIcum). The maximum LAI for the control crops was 3.80 or 24% lower than for fertilised crops. At the final harvest total RIcum for P-fertilised crops was 22% higher than the 592 MJ/m2 for the control, and this accounted for 80% of their yield differences. Leaf appearance rates were unaffected by P supply, with a common phyllochron of 109 degree-day. There was a consistent relationship between light interception and LAI, with a critical LAI of 3.40, extinction coefficient of 0.90 and radiation-use efficiency of 1.56 g/MJ photosynthetically active radiation. Overall, these results support a starter P application of at least 20 kg P/ha at establishment to maximise yields for kale crops when initial soil Olsen P levels ranged from 9 to 17 mg/kg soil.


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