抄録
This study examined the influence of relative humidity of the atmosphere on the dry matter production of rice at its seedling stage. The plants were grown in a growth cabinet where the relative humidity was maintained at either 60% (dry treatment), 75% (standard treatment), or 90% (wet treatment) with the day/night temperature of 28/24°C and the illumination of 34-30 klux. The plants grown in a more humid atmosphere produced more dry matter when compared over the same growing period after seeding. But, no difference was detected when compared at the same plant age measured in the number of leaves (Fig. 1). We investigated the characteristics of the leaf blade and leaf sheath and conducted grow h analysis. 1. The top to root ratio was greater in the plants grown in a more humid atmosphere when measured either on the same day after seeding or at the same plant age (Fig. 2). 2. Atmospheric humidity had little effect on the weight and length of the leaf blade. On the other hand, the weight and length of the leaf sheath were strongly influenced: the more humid the atmosphere was, the greater the weight and length of leaf sheaths. 3. With increasing atmospheric humidity, the leaf area increased and the specific leaf area increased: the specific leaf area showed a significant positive correlation with the leaf area (Fig. 4). 4. The leaf area index, which strongly influenced crop growth rate, was larger in a more humid atmosphere, which may be why the dry matter production was higher in a more humid condition when compared at the same growing period (Table 2). 5. The plants grown in a more humid condition had a larger leaves. However they were thinner and had a lower photosynthetic rate (Fig. 6). Therefore, it seemed that there was no difference in the dry matter production of the plants grown in the three different humidifies when compared at the same plant age.
