Salinity effects on growth and net gas exchange of carambola (Averrhoa carambola L.) examined in were greenhouse culture with ten-month-old seedlings in perlite: peat: sand: pine bark chip medium in 5.1 liter (21 cm top dia.) containers. Treatments of 0.05, 5.1, 9.5, or 13.9 dS·m-1 were obtained by dissolving ca. 0, 2.5, 5.0, or 7.5 g of dehydrated sea salt per liter of rain water and delivered from elevated tanks by gravity to dribble ring emitters in containers via polyethylene and q icro tubing. All plants except control plants received 5.1 dS·m-1 beginning 25 Nov., and concentration was gradually increased for the two highest salinity levels until reaching 9.5 dS·m-1 on 3 Dec. and 13.9 dS·m-1 on 7 Dec. Plants were watered twice weekly until 1 March 1990. Stomatal conductance was determined (LI-COR 1600 steady-state diffusion porometer) on 7 day intervals beginning 24 Nov. Growth was determined as leaf area (LI-COR 3000 area meter), plant dry weight, and trunk diameter. Stomatal conductance declined in all salinity levels to 50% or less of controls by day 12, with a gradual further decline thereafter. Leaf area, plant dry weight, and trunk diameter declined linearly with increased salinity.
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