| 14CO2 assimilation in germinating
wheat Z. KASAI, K. ASADA, Y. KAWASHIMA and M. MATSUURA, and K. YAMASHITA Research Institute for Food Science, and Biological Laboratory, Kyoto University, Kyoto, Japan Physiological change in the process of germination from heterotrophic to autotrophic furnishes very interesting problems. Consequently, we have performed an experiment in which carbon dioxyde labelled with 14C was used for the inverstigation on photosynthetic assimilation of two kinds of the germinating wheat. Experiment 1. Material: Japanese wheat variety, Norin No. 26. 1) According to the difference in dry weight, three stages were found in the germination, namely, the stages (1) of decreasing dry weight by respiration, (2) of constant dry weight and (3) of increasing dry weight by photosynthesis. 2) Assimilation of 14CO2 increased considerbly after 6 days from sowing, and the photosynthetic products have been mostly proved to be sucrose. It is therefore suggested that sugar translocated from endosperm to leaves is monosaccharide. 3) Starch contained in leaves at the early period of germination relies on endosperm, but that found in leaves after 6 days is a new product of photosynthesis. Experiment 2. Material: X-ray induced mutant, "carotina" and "normal" of Einkorn wheat. 1) The change in dry weight was the same in "normal" and "carotina" before the consumption of endosperm nutrients. 2) "Carotina" contains a little chlorophyll, and the same carotinoids as found in "normal" although the amount is small. 3) The amount of 14CO2 fixed per plant at each stage of germination by "carotina" was about 15% of that of "normal". 4) After five days from sowing, photosynthetic products in 1, 10 and 60 min were investigated, and it has been found that the products in "carotina" are qualitatively the same as in "normal", but incorporation of 14C into sucrose and starch in "carotina" was lower than in "normal". |