Relationships between leaf gas exchange characteristics and growth of differently adapted populations of Blue panicgrass (Panicum antidotale Retz.) under salinity or waterlogging

A greenhouse experiment was conducted to draw relationships between leaf gas exchange characteristics and growth of differently adapted populations (normal population collected from non-saline non-waterlogged soil, a population from waterlogged soil, and a population from salt affected soil) of Blue panicgrass (Panicum antidotale Retz.) under waterlogging or salt stress. Imposition of salt stress and waterlogging for 46 days caused a significant reduction in growth of all three different populations of P. antidotale. However. the population from waterlogged conditions showed markedly higher growth under waterlogged conditions and that from saline conditions under salt stress as compared to the normal population. A positive association between growth and net CO2 assimilation was observed in all three populations under these conditions. The net CO2 assimilation and stomatal conductance of all three populations were positively associated and the former variable also had a strong positive relationship with transpiration. Relative intercellular CO2 concentration (C-i/C-a) in waterlogging tolerant population reduced under saline or waterlogged conditions, and in the salt tolerant population no such reduction in C-i/C-a, was found. Water use efficiency was higher in the salt tolerant population under saline conditions as compared to other populations, but the pattern of increase or decrease in intrinsic water use efficiency was not consistent among the different populations. Although chlorophylls a and b were reduced in all three populations under salinity or flooding, they had no positive association with net CO2 assimilation or the growth of different populations under varying stress conditions. No clear relationship between data for leaf water potential and that of turgor pressure of the three populations under varying stress conditions was found. Growth of the three populations of P. antidotale adapted to saline or waterlogged habitats was associated with net CO2 assimilation and stomatal conductance, but not with any of the water relation parameters measured. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.