Cotton, Gossypium hirsutum L., Cultivars Differential Response to Salinity

One impact of declining aquifer water levels is increased salinity in irrigation water, exacerbated by extended periods of drought allowing accumulation of salts in soils.  This poster summarizes efforts to develop a salt tolerance index for current cotton cultivars that can be used to both characterize varietal salinity response, and breed improved varieties.  Salt tolerant cotton varieties can improve economic viability of limited irrigation, ease transition to dry-land cotton production systems, and enhance understanding of water use and salinity interaction as it relates to crop productivity.  Salinity became an emerging issue in Texas High Plains cotton production in 2011; though effects can be eased by rainfall, impact on germination and early season root growth is expected to continue sporadically in the cotton growing regions of the Ogallala Aquifer.  A hydroponic system used to screen wild accessions collected in saline geographies from the National Cotton Germplasm Collection was modified to characterize salinity response of 35 current cotton cultivars for germination and early root development.  In the first year of testing, percent germination in salt compared to no salt ranged from 29.7 to 102.5; percent root length between salinity treatment and control ranged from 21 to 57.8.  Preliminary index combining the two parameters ranged from 25 to 80, indicating significant differences in salinity response among existing commercial cotton cultivars.  Two varieties each from the top, middle, and bottom of the index scale were selected for large-scale trials in 2014 in two producer fields with severe salinity issues, to evaluate correlation between preliminary index results and field performance.