Abstract
In order to make clear the effects of low oxygen concentration treatment for comparatively long period on NAR, RLGR, LAR, RGR and ΔWT in C3-plant, the experiment was conducted. Material used was two row barley (Hordeum vulgare L.). Seedlings, about 2.4 leaf stage, were grown for 10 and 20 days in a specially devised growth chamber equipped water culture facilities, at 2.5% O2-0.03% CO2(low oxygen concentration) and 2l% O2-O.O3% CO2 (normal air, control), and light intensity of 45Klx at 20°C leaf temperature under a regime of 10 hr light and 14 hr darkness. And yet, plants at low oxygen concentration were grown under normal air for darkness as same as cotrol ones. The experimental results obtained are summarized as follows: 1. NAR, LAR, RLGR, RGR and ΔWT in plants at low oxygen concentration were 132, 85, 93, 113 and 122% to control plants during 1-10 days, and 119, 75, 93, 92 and 110% during 10-20 days, respectively. 2. From the begining to the end of the experiment, NAR in plants at low oxygen concentration was still greater than that of normal air. This result suggests that the photorespiration of the plant was suppressed at low oxygen concentration throughout the experiment. 3. RGR in plants at low oxygen concentration was lesser than that of normal air during 10-20 days, while the former was greater than the latter during 1-1O days. It can be explained that RGR decreased because of greater decrease in LAR at low oxygen concentration during 10-20 days. 4. It was seemed that ΔWT in plants at low oxygen concentration was greater than that of normal air throughout the experiment, although there was not significant due to the insufficient numbers of experimental plants and so forth. ΔWT in plants at low oxygen concentration, however, will be overcom by that of normal air after longer duration at least more than 20days, because RGR decreased with prolonging of the duration of low oxygen concentration. 5. From the above stated results and previous reports1'2), effects of oxygen concentration on the growth of C3-plants may be shown schematically as fig.3
