Ability Of Seedlings Research Articles

GROWTH AND NITROGEN METABOLISM OF SQUASH SEEDLINGS III. WITH RESPECT TO HIGH AND LOW CARBOHYDRATE SYNTHESIS

Fischer (6), Bornemann (3), Reinau (I5), Lundegardh (8), Arthur (i), and others have studied the effects of added carbon dioxid upon vegetative growth and sexual reproduction. These investigators report increased size and dry weights of many types of plants as a result of enrichment of the atmosphere with carbon dioxid. More recently, Bolas and Henderson (2) have found that addition of carbon dioxid to the air results in a large increase in the dry weight of cucumber plants as compared to results obtained with plants grown in normal air. The increase is evident within two to three days after adding the carbon dioxid. Reese (io) obtained beneficial effects by increasing the carbon dioxid content of the atmosphere in which seedlings and cuttings were growing. Leaves of Aconitum Wilsoni seedlings were three times larger than those of untreated plants. Chrysanthemum and dahlia cuttings rooted more quickly when grown in a carbon dioxid-enriched atmosphere. In previous papers (ii, 12) it has been shown that the ability of seedlings to utilize carbon dioxid depends on the amount of available nitrogen in relation to that of carbohydrates. Seedlings grown from seeds having large reserves of nitrogen in proportion to the non-nitrogenous materials benefited greatly from the utilization of carbon dioxid both when extra nitrogen was supplied and when it was not. The green weights (dry weights not determined) and sizes of all organs increased and that of the roots especially. Seedlings grown from seeds having small reserves of nitrogen in proportion to the carbohydrates (wheat and low-protein corn) were not benefited by supplying carbon dioxid unless extra nitrogen was also given. The dry weights of the organs increased slightly but the sizes did not. In fact the leaves were somewhat stunted. With an abundance of nitrogen available in the substrate, the supplying of carbon dioxid was beneficial, especially in the later stages of seedling growth when the reserves of the seed were becoming depleted. A healthy condition and relatively large size of leaves could be produced on the one hand when the nitrogen supply was limited