Architecture of Individual Plants in a Field-Grown Tobacco Crop

Abstract

The three-dimensional display of each leaf of a number of adjacent plants was measured with a spatial coordinate apparatus on five occasions during the growth of a tobacco crop. Several architectural characteristics of the foliage display were estimated from these data.

A truncated ellipsoid adequately described plant extent and allowed the calculation and analysis of vertical profiles of leaf area distribution within the plant volume. Foliage densities ranged between 5 and 12 m^-1 in small plants and in the upper regions of larger plants. Plants with leaf areas in excess of 0.8 m² had a leaf area density of approximately 3.2 m^-1. In mature crops, the foliage extended further into the inter-row space than into the space occupied by neighbouring plants in the row.

Mean leaf angle was 40° and elevation distributions were remarkably similar throughout growth and development. Foliage inclination consistently decreased with depth in the canopy. Azimuth distributions of foliage were not significantly different from that of a uniform distribution.

The data are discussed in the context of assumptions that are commonly used in representations of canopy structure.