Cold-acclimation and root temperature protection from chilling injury in chilling-sensitive mungbean (Vigna radiata L.) seedlings

Exposure of mungbean seedlings to 4 degreesC for 2 days induced irreversibl e chilling injury. The major cation in the leakage from tissues of unacclim ated seedlings was K+, the loss of which was 7 to 10-fold greater than that of Ca++ or Mg++. Acclimation of seedlings at 10 degreesC protected them fr om the injuries caused by the 4 degreesC treatment. Acclimation of seedling s at 10 degreesC for 2 to 3 days, significantly decreased the conductivity and the concentration of soluble sugars, free amino acids, and cations (K+, Mg++ and Ca++) in the leakage. Compared to the 28 degreesC-root/28 degrees C-shoot control seedlings, those in the 28 degreesC -root/4 degreesC-shoot treatment did not suffer noticeable injury, but seedlings in the 4 degreesC -root/4 degreesC-shoot treatment did. The solute potential, water potential , and the concentration of free amino acids and cations (K+, Mg++, and Ca+) in the cell sap of the 28 degreesC-root/4 degreesC-shoot seedlings were s imilar to those of the control seedlings.