| Co-Investigator(Kenkyū-buntansha) |
HIRAO Kenji Kagoshima University, Fac. of Agr. Research Associate, 農学部, 助手 (70301348)
KUBOTA Fumitake Kagoshima University, Fac. of Agr. Professor, 農学部, 教授 (50136602)
KATAYAMA Tadao Kagoshima University, Honorary, Professor, 名誉教授 (10041617)
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| Research Abstract |
Oryza breviligulata, the ancestral species of African rice (O.glaberrima) showed wider ranges of inter-varietal variation in most of the characters observed than African rice, and the former was not inferior to the latter in dry matter productivity and yielding ability. In African rice, O.breviligulata and O.stapfii of series Glaberrima, and inter-specific F1 and F2 rices between African rice and O. breviligulata, however, higher tillering capacity were easy to connect with slenderer stem, and the dry matter production after heading was extremely small, as compared with Asian rice (O. sativa), O.rupfipogon, O.nivara and O. longistaminata of series Sattiva. These results suggest the possibilities and limitations of series Glaberrima strains as a genetic resource for the project of breeding African rice.
African rice strains represented significantly high nitrogen utilization efficiency ( COィイD22ィエD2 exchange rate/nitrogen content in unit leaf area), high stomatal and mesophyll conductances in leaves with low nitrogen content, and high photosynthetic efficiency per unit Rubisco activity ( COィイD22ィエD2 exchange rate/total Rubisco activity). The high nitrogen utilization efficiency detected here is unique to African rice, and is consider to be an advantageous genetic character in photosynthesis. The introduction of such a character into O, sativa is regarded as a step toward the genetic improvement of leaf photosynthetic ability of this species grown in a nitrogen-input saved condition.
From the responses of Rubisco activity, activity of the root and muximum quantum yield (Fv/Fm) after stopping the water supply and re-watering, C174, African rice strain was judged to be more susceptible to water stress than C70 of Asian rice. The inter-specific F1 hybrid rices exceled remarkably C174 in recuperative power after re-watering. This suggests that inter-specific F1 hybrid rices can become pontoneers to introduce the drought resistance.
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