The stay-green trait as a maintenance capacity of green leaves assimilating under desiccated soils in the post-anthesis period is known in several crop plants. Our objectives were to clarify if the capacity to stay green in the terminal growth stage is related to root performance in Vietnam rain-fed rice cultivars. Three Vietnam cultivars were grown under flood conditions in 130-L volume pots. Irrigation was withheld from half of the pots at the anthesis period, while the flood condition was maintained in the remaining pots. The SPAD value as an indicator of green color, green leaf area (GLA) and leaf conductance (C_L) decreased after heading, but trends of the decrease by soil desiccation differed among cultivars. The cultivar, which showed higher maintenance of the SPAD value, GLA and C_L under desiccated soils, had significantly denser roots in the surface soil layer at harvest. The water absorption rate per soil volume and per root length of almost all soil layers in the cultivar was maintained longer and higher in desiccated soils. The SPAD value and GLA of detached leaves in the cultivar incubated under dark and humid conditions were maintained significantly longer. This showed that the leaf properties contribute to the maintenance of green leaves. These results suggest that in stay-green rice cultivars the properties that keep the leaves green contribute to a delay in the suppression of assimilate processes and maintain the water absorption function of the roots by maintaining the assimilate supply to roots.

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大豆のリビングマルチ栽培において，マルチとして利用される小麦や大麦が，生育初期の大豆の根系形成にどのように影響するかを染色法により検討した．大麦をマルチとして想定した処理区では，大豆のみを栽培した処理区と比較して，大豆の地上部乾物重，総根長，総根重ともに抑制された．小麦をマルチとして想定した処理区では，大豆の地上部乾物重は，リビングマルチの影響を受けておらず，総根長および総根重のみが抑制されていた．また，小麦に比べて大麦の方が，より大豆の根域に侵入していることが示され，リビングマルチによって大豆の根系拡大が抑制されることが明らかになった．大豆の根系形成がリビングマルチの影響を受ける一方で，麦類の根系形成は隣接作物の影響を受けないことが示された．これらの結果から，麦類を利用したリビングマルチ栽培において播種直後から地下部では競合関係にあり，大麦が大豆の根域に侵入し，より強く大豆の生育を抑制していると考えられた．

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