ABSTRACT
This chapter describes exemplify the influence of natural selection in operation in cross-pollinated populations during one generation. In cross-pollinated species each plant in a population will be genetically different from all other plants in the same population and different from the plants in the next generation. The Ranger plant populations from seed originating from one generation of increase in Montana and Washington had only a small amount of winter injury. The adult plant population will be a result of the influence of environment on the genotypes. A random stone can cause late emergence, early competition from weeds can reduce the number of cultivated plants. Competition takes place when plants make demands on water, light and nutrients in excess of the supply. Higher plants can respond to competitive stresses either by varying the death rate of individuals or the rate of development of leaves, tillers, flowers and seeds, etc., in the individual plant.
