The Effect of Environmental Conditions on the Development of Pea Seeds

Abstract

The effects of environmental conditions on pea seeds developing in pods were investigated by 'growing the plants under controlled conditions in the Earhart Plant Research Laboratory. In one experiment plants were kept under a variety of conditions throughout their period of growth and of seed-pod development. In two experiments plants were grown under standard conditions until they flowered and were then transferred to a series of different environments. The environmental conditions investigated included photoperiod, light intensity, and day and night temperatures. Samples of seeds were taken at different times after flowering and seed growth was recorded by fresh weight and dry weight measurements. 'The samples were analysed for total sugar, reducing sugar, starch, total nitrogen, and protein nitrogen. The most striking results were the effects of night and day tem-peratures on the growth and composition of the seeds, particularly on the sugar content. At low temperatures, the conversion of sugar to starch was much delayed and sugar continued to increase in concentration during growth; at higher tem-peratures the sugar entering the seeds was rapidly converted to starch; thus the carbohydrate composition of seeds grown at different temperatures was markedly different. Protein synthesis was also delayed at lower temperatures. Water uptake and rate of drying out of the seeds were also affected. The possible implications and interrelations of these observations are discussed.