Sodium Nutrition of Pasture Plants I. Translocatign of Sodium and Potassium in Relation to Transpiration Rates

A study of transpiration rates, and of uptake and translocation of sodium and potassium, has supported a previous classification made for certain pasture and fodder species. The plants termed natrophiles were found to have relatively high transpiration rates and to translocate relatively large amounts of absorbed sodium from root systems into leaves. Plants termed natrophobes had lower transpiration rates and translocated less sodium from roots to leaves. In contrast, potassium was readily translocated by both natrophiles and natrophobes; consequently, compared with natrophobes, natrophiles had low K/Na ratios in their leaves. In general, transpiration rate was less associated with absorption of sodium by roots than with translocation of sodium from roots to aerial parts. The practical and ecological implications of these results are discussed.