Researches on plant respiration. II.―Variations in the respiratory quotient during germination of seeds with different food reserves

Abstract

In Zea mais, where the reserve is chiefly starch, the R.Q. is initially about 1, but falls regularly to a min. of about 0.75, then it rises slowly towards 1. Lathyrus odoratus and possibly Pisum sativum and Vicia faba exhibit comparable behavior. In Fagopyrum esculentum, also a starch seed, the R.Q. at an early stage of germination is about 0.5, but it rises regularly and rapidly towards 1. In Lupinus luteus, which contains much hemicellulose and a little fat, the R. Q. remains for nearly 2 days at about 0.92 and then falls; in Tropaeolum majus, a hemicellulose seed containing more fat, the R. Q. is maintained at about 0.75 for 10-11 days. Of the 3 spp. examined with seeds containing much fat, Ricinus communis exhibits a R. Q. which falls regularly from about 0.85 to 0.5 in about 5 days; in Helianthus annum the R. Q. rises from an early value of about 0.75 to a maximum of 0.85, then falls regularly; and in Cucurbita pepo the changes in the R. Q. are similar but at a higher level.