Effects of branch pruning and seedling size on total transpiration and tissue Na and CI accumulation in Pinus leiophylla seedlings exposed to salinity

Abstract

There have been mixed reports of the link between salt uptake and transpiration in plants. An accumulation of Na and Cl in plants exposed to salinity may be linked to total plant transpiration because both ions are absorbed by roots from the soil and transported to shoots in the transpiration stream. Therefore, despite its potential negative effects on plant productivity, a reduction of transpiration area may be beneficial to plants growing in salt-affected sites. In this study, we examined the effects of seedling size and branch pruning on total transpiration and accumulation of Na and Cl in Pinus leiophylla seedlings. The seedlings were divided into two different height groups (short and tall), subjected to the branch pruning treatment, and then treated with 150 mM NaCl that was added to the soil for 30 days. Total transpiration was significantly reduced by branch pruning with short seedlings having the lowest total transpiration levels. After 30 days of treatment, NaCl significantly decreased total transpiration, stomatal conductance, net photosynthesis, root hydraulic conductance, and plant dry weights. The concentration of Na and Cl in shoots increased in all NaCl-treated plants, but short seedlings of the pruned group had lower ion concentration levels and exhibited lower needle necrosis, and greater recovery of the measured variables compared with the remaining experimental groups. We conclude that plant transpi-ration is a significant factor affecting the uptake and transport of Na and Cl in P. leiophylla seedlings and that branch pruning may be an effective treatment in increasing the chances of survival with the short seedlings after planting in salt-affected areas. © 2013 by the Society of American Foresters.