Agro-Climatological Studies on C3-Plants and C4-Plants

Abstract

Seedlings of 57 species (35 species for C3-plants, 22 species for C4-plants) were used for the measurement of increment of plant height during 25 days under submerged and upland conditions, and those of 24 species (15 species for C3-plants, 9 species for C4-plants) for the relationships between temperature (12-48 C) and photosynthetic rate under submerged and upland conditions.The results are as follows:1) All C3-winter plants were died except Welsh Onion under submerged condition and most of C4-plants had greater growth increment under submerged condition than that under upland condition. C3-summer plants had the character intermediate between C3-winter plants and C4-plants. That is, only few C3-summer plants were died under submerged condition. Most of C3-summer plants were not died, and had less growth increment under submerged condition than that under upland one.2) When the plants grew under submerged condition, the photosynthetic rate of all C3-winter plants was decreased. But the rate of most of C4-plants decreased a little or increased. C3-summer plants had the character intermediate between C3-winter and C4-plants.3) As for the photosynthetic rate, C4-plants had a strong heat tolerance and a comparatively strong wet endurance. While C3-plants had a comparatively strong cold resistance and a wide range of wet endurance. Based on the above results, we discussed the origin of rice (Oryza sativa L.).