Relationships between Root Temperature and the Transport of Ammonium and Nitrate Ions by Italian and Perennial Ryegrass (Lolium multiflorum and Lolium perenne)

AUTOR(ES)

Clarkson, David T.

RESUMO

At root temperature below 14 C the absorption of 15N from NH4+ greatly exceeded that from NO2− by tillers of Lolium multiflorum and Lolium perenne under conditions where pH, external concentration, plant N status, and pretreatment temperature were varied. There was a marked increase in the temperature sensitivity of NO3− transport below 14 C, irrespective of the temperature at which plants were grown previously. A marked increase in the temperature sensitivity was also seen for NH4+ transport, but this occurred at the lower temperature of 10 C. Pretreatment of roots at 8 C lowered this still further to 5 C. Above and below these transition temperatures the Q10 values for NO3− and NH4+ transport were similar. Thus, the increased absorption of NH4+ relative to NO3− at low temperatures seems to be related primarily to the difference in transition temperatures.

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