水稻深层根系对生长和产量的影响

在穗分化期和开花期采用切根方法,研究了土表15cm和30cm以下根系对杂交水稻组合65002和汕优63的生长和产量及其构成因子的影响。与对照相比,在穗分化期切断土表15cm处根系,65002和汕优63穗长分别下降2．7和2．4cm,每穗总粒数下降36．0％和26．6％,对结实率影响不大;切断土表30mc处根系,对穗长影响较小,每穗总粒数分别下降17．2％和7．8％,结实率下降11．7％和5．％。开花期切根使结实率显著降低,切断15cm处根系使65002和汕优63的结实率分别下降17．2％和11．8％,切断30cm处根系使结实率下降14．4％。切根对大穗型品种籽粒产量的影响大于对小穗型品种的影响;在穗分化期切根的影响大于开花期。穗分化期根对叶绿素含量的影响以倒3叶最显著。穗分化期和开花期切根还显著降低了倒1叶的光合强度。

Effects of Deep Roots on Growth and Yield in Two Rice Varieties

Effects of roots below 15cm and 30cm in soil on rice growth and yield in hybrids of 65002 and Shanyou 63 were studied by cutting roots at panicle initiation (PI) and flowering (FL) stages in root box. As compared with check, cutting roots at 15cm soil depth at PI reduced panicle length of 65002 and Shanyou 63 by 2 7 and 2 4 cm, and grain number per panicle by 36 0% and 26 6%, respectively, whereas spikelet fertility was slightly influenced. Cutting roots at 30 cm soil depth at PI reduced grain number by 17 2% and 7 8%,and spikelet fertility by 11 7% and 5 8% respectively, whereas panicle length was slightly affected. Cutting roots at FL reduced spikelet fertility significantly, fertility of 65002 and Shanyou 63 decreased by 17 2% and 11 8% with 15 cm cutting and by 14 4% and 7 3% with 30 cm cutting. Yield reduction by root cutting was higher in larger panicle variety than in smaller panicle variety, and higher at panicle initiation than at flowering stage. Root cutting at PI markedly influenced chlorophyll content of third leaf. Root cutting at PI and FL also reduced photosynthetic rate of first leaf by 26 5% and 30 0% with 15 cm cutting, and by 18 0% and 12 0% with 30 cm cutting respectively.