| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2011: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2010: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2009: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
|
|---|
| Research Abstract |
NH_3 emission from leaves of three rice(Oryza sativa L.) cultivars, Akenohoshi, Shirobeniya and Kasalath, was examined using a simple open chamber system. In the three cultivars, NH_3 emission rate(AER) and NH_4^+ content of leaves decreased with decreasing NH_4^+ concentration in the root medium, but these values differed significantly with the cultivar. In the daytime, AER, NH_4^+ content and glutamine synthetase(GS) activity in leaves changed similarly with maximum values around midday. Akenohoshi showed significantly lower AER and NH_4^+ content but higher GS activity than Kasalath. The difference in AER among the rice cultivars may be related to the activity of GS involved in photorespiratory NH_3 recycling. Akenohoshi can be a breeding material useful for improving nitrogen recycling.
An increase in[O_2] increased AER in the two cultivars, accompanied by a decrease in gross photosynthetic rate(PG) due to enhanced photorespiration, but did not greatly influence transpiration rate(Tr) and stomatal conductance(gs). There were significant positive correlations between AER and photorespiration in both cultivars. Increasing light intensity increased AER, PG, Tr and gs in both cultivars, whereas increasing leaf temperature increased AER and Tr but slightly decreased PG and gs.' Kasalath'(low GS activity) showed higher AER than' Akenohoshi'(high GS activity) at high light intensity, leaf temperature and[O_2]. Our results demonstrate that photorespiration is strongly involved in NH_3 emission by rice leaves and suggest that differences in AER between cultivars result from their different GS activities, which would result in different capacities for reassimilation of photorespiratory NH_3. The results also suggest that NH_3 emission in rice leaves is not directly controlled by transpiration and stomatal conductance.
|
