タンスイチョクハンスイトウ ニ オケル コウイブンゲツ ノ ウム ガ ツウジョウブンゲツ ノ シュウリョウカンレンケイシツ ニ オヨボス エイキョウ

Abstract

湛水直播水稲において,高位分げつが出現した分げつと出現しなかった分げつの収量関連形質を比較した。播種様式を点播とし,苗立ち密度50本/m2(低苗立ち密度)の50本区および100本/m2(適正苗立ち密度)の100本区の2区を設けた。両区とも高位分げつが多く出現し,その出現数は50本区で78.5本/m2および100本区で93.5本/m2であった。両区とも出現した高位分げつの殆どがbT3(止葉節から出現した分げつをbT1とし,求基的に示した分げつ位)とbT4であった。高位分げつが出現した分げつの方が,出現しなかった分げつより1穂籾数,1穂玄米重および登熟歩合が有意に大きかった。高位分げつが出現した分げつの中では,bT4が出現した分げつの方がbT3が出現した分げつより,収量関連形質が大きかった。また,葉数3枚の高位分げつが出現した分げつの方が葉数2枚の高位分げつが出現した分げつより,1穂籾数,1穂玄米重および登熟歩合が大きい傾向が見られた。高位分げつ自身も,bT4の方がbT3より,すべての収量関連形質が大きく,さらに葉数3枚の高位分げつの方が,葉数2枚の高位分げつより登熟歩合を除く収量関連形質が大きい傾向を示した。以上の結果,高位分げつが出現した分げつは,出現しなかった分げつより1穂籾数,1穂玄米重および登熟歩合が大きいことから,出穂期前の蓄積炭水化物が豊富で,しかも出穂期後の炭水化物生産量が多いと推察された。また,高位分げつが出現した分げつの収量関連形質が大きいほど,高位分げつ自身の収量関連形質も大きいことが明らかとなった。Using hill sowing at 50 and 100seedlings/m2, the related yield characteristics of normal tillers (tillers with UNT appearance and tillers without UNT appearance) were compared with the appearance of upper nodal tillers (UNTs) in direct sowing in flooded paddy field rice. UNTs appeared in 50-seedling and 100-seedling plots. The numbers of UNTs per square meter were 78.5 (50-seedling plot) and 93.5 (100-seedling plot). Those with UNT appearance were almost all bT3 and bT4. The number of spikelets per panicle, the weight of brown rice per panicle, and the percentage of ripened grains of tillers with UNT appearance were significantly higher than those of tillers without UNT appearance. Yield characteristics of tillers of bT4 with appearance were higher than those of tillers of bT3 with appearance compared with the tillers with UNT appearance. The number of spikelets per panicle, the weight of brown rice per panicle, and the percentage of ripened grains of tillers of three-leaf UNTs were higher than for tillers of two-leaf UNTs. All related yield characteristics of the bT4 were higher than those of bT3. All related yield characteristics of the three-leaf UNTs were higher than those of the two-leaf UNTs. Therefore, because the number of spikelets per panicle, the weight of brown rice per panicle, and the percentage of ripened grains of the tillers with UNT appearance were higher than those of tillers without UNT appearance, tillers with UNT appearance showed abundant accumulated carbohydrates before the heading stage, and showed high production of carbohydrates after the heading stage. Results clarified that the related yield characteristics of UNTs were high when the related yield characteristics of tillers with UNT appearance were high