Micrometeorological Influences at High Crop Density on Different Genotypes of Silage Maize

Abstract

AbstractIn the year 1979, 1981 and 1982 two‐factorial experiments with the factors genotypes and crop densities were conducted, connected with the following agrometeorological analyses:a) outside the canopies: determination of air temperature, air humidity, wind velocity, precipitation, global radiation and photosynthetically active radiation (PAR)b) in the interior of the canopies: measurements of air temperature at cobheight, of precipitation components, of the penetration of PAR and of the leaf area index.The following results were obtained:a) Influence of high crop densities1. In high crop densities the greatest part of radiation was absorbed, so that at 30 plants/m2 57% and at 70 plants/m2 only 28% of the PAR reached cob height.2. As a consequence of temperature and decrease of radiation the contents in the leaves of biological energy, of water soluble K.H. and rough protein were reduced.b) Influence of the leaf posture3. For genotypes with erected leaf posture the leaf temperatures increased by 0.3°C, on the ground even by 1.2°C above the values of the stand with horizontal leaf posture.4. Higher air temperatures were measured in the stands with erected leaf posture than in those with a horizontal one.5. In the cool year 1981 on days with temperatures above 27°C outside the stands, those temperatures were exceeded during 7 hours in canopies with erected leaf posture at a higher plant density (30 plants/m2) and only during 2 hours in canopies with a horizontal leaf posture.