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This article in AJ

  1. Vol. 67 No. 4, p. 463-468
     
    Received: Apr 1, 1974


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doi:10.2134/agronj1975.00021962006700040004x

Population Density and Sampling Location Effects on Net Radiation Measurements over Corn1

  1. D. E. Linvill and
  2. R. F. Dale2

Abstract

Abstract

Little information is available on the amounts of net radiation utilized by different populations of corn (Zea mays L.). To increase the range in corn microenvironments for a weather and corn growth study, we used two planting dates and two populations in 1970 at West Lafayette, Ind.

The soil was Chalmers silt loam. Soil moisture in the top meter remained above 60% available throughout the season. Net radiation was measured 1 m above two corn populations of 42,000 (42K) and 62,000 (62K) plants/ha within an early and a late planting. Pairs of Fritschen-type net radiometers were exposed from a permanent mast within each of the four microenvironments. Replication was with two portable masts moved every week to alternate temporary locations in each population. Differences between net radiation measured within the same population at the permanent and temporary mast locations generally were larger than those between the permanent mast locations in the 42K and 62K populations. For the incompletely replicated experiment, we used a difference of differences t-test to determine that there were no significant differences (α level 0.20) between net radiation measured over the 62K and 42K populations. Sources of experimental error discussed are instrumental calibration, field measurements of net radiation, possible canopy wear associated with the temporary mast movement, and nonhomogeneous crop canopies, especially with the net radiometers exposed ≤ 1 m above the crop. Without adequate replication interpreting environmental measurementiss risky, especially in row crops.

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