Abstract
The reduction of carbohydrate consumption by the dark respiration at the ripening stage may increase the yield of rice. To clarify the influence of the varietal difference in the ratio of the dry-matter decrease in stem and leaf sheath to the dry-matter increase in panicle (ΔS/ΔE), which is used as an index of the remobilization of carbohydrate, on the dark respiration in shoot, and to clarify the varietal difference in the cost of panicle growth, we examined the dark respiration in the shoot and panicle using four and two rice varieties with different ΔS/ΔE in 2000 and 2003, respectively. The ΔS/ΔE in Nanjing 11 at ripening periods was higher than that of Tainung 67 in both years. The relationship between the dark respiration in the shoot and mobilization of carbohydrate was regressed to a line in both years. On the other hand, the rate of dark respiration in panicle increased with panicle growth in all varieties, but the cost of the dark respiration for panicle growth was lower in Tainung 67 than in Nanjing 11. These results showed that the varietal difference in the remobilization of reserved carbohydrate did not affect the cost of dark respiration for remobilization in shoot, and that the varietal difference in the cost of panicle growth was large.
