²²Na⁺ and ³⁶Cl⁻ mobility in salinized excised leaves of several crop plants

Abstract

Excised leaves of several crop plants were cultured in a nutrient solution containing ²²Na⁺ (816 Bq mL⁻¹) or ³⁶Cl⁻ (802 Bq mL⁻¹), and the mobility of ²²Na⁺ and ³⁶Cl⁻ between and within organs was investigated. Though ²²Na⁺ and ³⁶Cl⁻ seemed to be taken up depending on the transpiration in all the examined crops, the distribution pattern of ²²Na⁺ and ³⁶Cl⁻ and the concomitance between them varied among the crops as follows: 1) Though ²²Na⁺ and ³⁶Cl⁻ were taken up concomitantly in rice and maize, ²²Na⁺ and ³⁶Cl⁻ were well distributed all over the leaf in rice and reached the lower half of the leaf blade but moved only over a short distance from the midrib and the brims of the leaf blade in maize. 2) In soybean, ²²Na⁺ and ³⁶Cl⁻ were well distributed all over the leaf, and the possibility of the preferential intrusion of ³⁶Cl⁻ to the leaf was indicated. 3) In adzuki bean, ²²Na⁺ and ³⁶Cl⁻ were intensely distributed first to the petiole, then to the leaf veins, and finally to the mesophyll. The concomitance between ²²Na⁺ and ³⁶Cl⁻ could not be determined. 4) In pumpkin, ²²Na⁺ and ³⁶Cl⁻ were retained in the petiole for transfer to the leaf blade, and ³⁶Cl⁻ was taken up preferentially. These results suggested that in the excised leaves, the mobility of Na⁺ and Cl⁻ was affected not only by the transpiration but also by the transport of Na⁺ and Cl⁻ from the xylem to surrounding tissues and / or by the structure of leaf tissues.

Key Words:

• ³⁶Cl⁻ distribution
• excised leaf
• leaf structure
• ²²Na⁺ distribution
• transpiration