Photosynthate and nitrogen requirements for seed production by various crops.

Seed biochemical composition was the basis for segregating 24 crops into four distinct groups. Nitrogen requirements of pulses and soybeans were so great that sustained seed growth demanded continued nitrogen translocation from vegetative tissues. This translocation must eventually induce senescence in these tissues, restrict the duration of the seed-fill period, and limit seed yield.

The utility of a digital simulation language for ecological modeling.

Dynamic modeling of ecological phenomena has been greatly facilitated by the recent development of continuous system simulator programs. This paper illustrates the application of one of these programs, S/360 Continuous System Modeling Program (S/360 CSMP), to four systems of graduated complexity. The first is a two species system, with one feeding on the other, using differential equations with constant coefficients.

Light relations in plant canopies.

A theory of light relations in plant canopies is presented which has potential applications in remote sensing and photosynthetic modeling of plant canopies. Predictions of the model are compared with field measurements of light reflection and transmission in a corn crop. Both reflection at the top of the canopy and transmission at the bottom are predicted within 1% of the measured values.