Quantitative Descriptions of Foliage Display and Light Absorption in Field Communities of Corn Plants¹

Abstract

Leaf display in foliage canopies of equidistantly spaced corn plants was measured; the vertical distribution of leaf area within several angle classes are given at various stages ot growth for seven population densities. When used in computer simulations, these descriptions provide calculated light profiles which agree well with measured profiles. The canopies are compared with earlier and more general reports from other workers.

Light Interception and Radiative Exchange in Crop Stands

“…This behavior is consistent with the large values of Ls (7.8 to 9.3) reported in earlier work with dense stands (Williams et aI., 1965) and with the observation by Allen and Brown (1965) that KV may be anomalously small in the upper part of a maize canopy where young leaves tend to be clustered around the stalks. Loomis et al (1968) were unable to relate KV closely to the distribution of leaf angles, but for the species of maize studied byNichiporovich (1961) and by Ross and Nilson (1967b), the distribution was almost spherical implying KV = 1/2 sin ~ in good agreement with their measurements of transmission. drew attention to the significant amount of light absorbed by tassels and calculated that the shadow cast on foliage would reduce leaf photosynthesis by about 10% at a population of 50,000 plants/ha.…”

“…This is a special type of erectophile foliage in which the frequency of leaf angles is proportional to cos Q!. For the varieties of maize examined by De Wit and by Loomis et al (1968), there was a significant departure from spherical foliage because of a deficit of leaf angles between 45 0 and 90 0 • A photograph of isolated maize plants presented by Williams, Loomis, and Lepley (1965) suggests that the leaves of some varieties may be too short or too stiff to form a complete hemisphere, although individual leaves describe nearly circular arcs.…”

Sistemas de dessecação antecedendo a semeadura direta de milho e controle de plantas daninhas

“…Plantas de maior altura teriam maior capacidade de sombrear e, portanto, de reduzir não só a capacidade de emergência e crescimento das plantas daninhas, como também a capacidade de produção de diásporos (ROGGENKAMP et al, 2000). Além disso, em milho, uma característica importante na definição do potencial da cultura em competir por luz é a capacidade de interceptação de luz pelas folhas localizadas acima da espiga, levando a cultura a sombrear plantas concorrentes que se posicionam abaixo desse nível (LOOMS et al, 1968). A estatura das plantas de milho demonstra ser uma característica fundamental para definir a competitividade dos genótipos (ROGGENKAMP et al, 2000).…”

Manejo de plantas daninhas na cultura de milho em função do arranjo espacial de plantas e características dos genótipos

“…(REGNIER & HARRISON, 1993). Em milho, uma característica importante na definição do potencial da cultura em competir por luz é a capacidade de interceptação de luz pelas folhas localizadas acima da espiga, levando a cultura a sombrear plantas concorrentes que se posicionam abaixo desse nível (LOOMIS et al, 1968). A estatura das plantas de milho, de outra forma, demonstra ser uma característica fundamental em definir a competitividade dos genótipos (ROGGENKAMP et al, 2000).…”