Growth of Kidney Beans after Cotyledon Pruning

The determination of the relation of seed weight to the growth, development, and yield of plants has been the purpose of many investigations. These have been adequately reviewed elsewhere (7, 9, 11). Two sets of observations stimulated this study. In 1951 (10) the author suggested that one possible explanation of inhibition of epicotyl growth as a result of indoleacetic acid application to the hypocotyl might be the diversion of food stored in the cotyledons from the epicotyl to the hypocotyl coupled with an inability of the cotyledons to increase their rate of supply. While a critical examination of this question was not attempted, certain of the results obtained can be interpreted as evidence against the above hypothesis. This will be discussed. The second set of observations was made by the author as a graduate student attempting, in a course problem, to determine the importance of cotyledons for the growth of bean plants. Various portions of the cotyledons were pruned seven days after planting with the harvest following at fifteen days. This limited experiment indicated a· striking correlation between the final weights and sizes of the plants and the weights of material obtained by the plants from the cotyledons or parts thereof. This work was an attempt to determine quantitatively the effect of cotyledon pruning on subsequent growth of kidney bean plants, especially considering any amelioration of injury with time. The importance of the amount of material removed versus the method of removal received critical attention. Finally, several quantitative measures of growth were compared and various calculations made in an effort to learn as much as possible about the growth of kidney bean plants from the data obtained