RATES OF ETHYLENE RELEASE, PHOTOSYNTHESIS AND TRANSPIRATION OF RICE MEASURED IN CLOSED-TYPE CHAMBER

Each rate increased until the heading stage and thereafter decreased. Ethylene release rate (E) gradually increased with day after seeding and rates of photosynthesis (P) and transpiration (T) did exponentially. At the heading stage, E, P and T were maximum and had values of about 2.0 nmol plant^-1 h^-1, 3.0 mmol plant^-1 h^-1 and 0.60 mol plant^-1 h^-1, respectively. E in the light period was 1.5–3 times as much as that in the dark period, whereas T in the light period was 5–6 times as much as that in the dark period.

E of rice per plant was lower than those of lettuce and Brassica genera which were reported previously. Especially, the rate of rice was about one-tenth that of lettuce. However, when ethylene release rates were estimated on a growth area basis, the rate of rice was about half that of lettuce, and was more than those of Brassica genera.

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