Effect of Environmental Conditions on the Growth of Four Perennial Grasses. III. Nucleic Acid Concentration as Influenced by Day‐Night Temperature Combinations1

Abstract

Timothy (Phleum pratense L.), bromegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), and Kentucky bluegrass (Poa pratensis L.) were grown under controlled temperatures varying by 3.3 C intervals from 18.3 to 34.8 C during the day and from 1.8 to 18.3 C during the night. The top growth was analyzed to determine the influence of these temperature regimes on ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).Day temperatures exhibited considerably more influence on the nucleic acids than did night temperatures. As the day temperature was increased from 18.3 to 34.8 C the RNA concentration decreased in a near linear manner. The decrease was 43% in timothy and between 21 and 27% in the other three species.When grown at a day temperature of 18.3 C the RNA and DNA concentrations of orchardgrass and bromegrass increased as the night temperature increased. When grown at 34.8 C, however, the concentration of these two components decreased as the night temperature increased. With timothy and Kentucky bluegrass, night temperature had no appreciable influence on RNA, but the DNA concentration tended to increase as night temperature increased. It is proposed that the influence of day temperature on growth in the species used in this experiment may occur in part through its influence on nucleic acids while the influence of night temperature may occur through food reserves.