根損傷の軽減が塩土壌における移植イネの生育と乾物重におよぼす影響

Rice root has an important role in water absorption and exclusion of sodium ion in saline soil. However, it is injured during transplanting to paddy field. The objective of this study was to examine whether prevention of such root injury reduces salinity damage in rice. Extremely early rice cultivar "Akihikari" that is not salt tolerant was grown in plastic bags filled with soil. Roots of seedlings were clipped leaving 5mm~10mm, then transplanted to 5L pots filled with soil applied with 0g, 7g and 10g of sodium chloride (NaCl). The growth and dry weight at the mature stage was compared to those of plants transplanted with intact roots. Time of transplanting was 12, 19, 26 and 33 days after sowing. Increase of number of stems was suppressed due to root clipping and salinity, but there was no interaction between the two factors. Dry weight of total above ground part and panicle decreased due to salinity though root clipping did not change them. The reduction of panicle dry weight was caused by the reduction of mean number of spikelets per panicle, thus mean panicle dry weight, as number of panicles and mean spikelet dry weight showed no changes. It was concluded that prevention of the root injury may not effectively alleviate salinity damage in less salt tolerant rice cultivars.

イネの根は吸水するとともにナトリウムイオンを排除する役割を持っている．水田移植栽培において根の損傷を防ぐことが効果的に塩害を軽減するかどうかを検討した．耐塩性の弱いイネ極早生品種アキヒカリを用い，土壌を詰めたビニール袋で育苗した．苗の根を5 ㎜～10 ㎜ 残し切除して，塩化ナトリウム（NaCl）0ｇ，7ｇ，10ｇを土壌に添加したポットに移植し，根を傷つけないように移植した植物と生育と成熟期の乾物重を比較した．移植は播種後12日，19日，26日，33日の4回行った．茎数の増加は根の切除および塩添加によって抑制されたが，二要因の交互作用はなかった．成熟期の地上部と穂の乾物重は塩添加によって減少したが，根切除の影響はなかった．穂の乾物重の減少は穂数と平均1籾重が変わらなかったため，平均1穂籾数の低下による平均1穂重の低下によっていた．以上の結果から耐塩性が小さい日本の品種において移植時の根の損傷を防ぐことは，塩害軽減に効果的でないと考えられた．

原著論文 (Original paper)