Comparison of water status and evapotranspiration of six row crops

Abstract

Abstract During a two-year field study, we measured the water status and evapotranspiration of six row crops to determine if we could identify differences in water use from plant water measurements. The plants were corn (Zea mays L.), millet (Pennisetum americanum L.), sorghum (Sorghum bicolor L. Moench), pinto bean (Phaseolus vulgaris L.), soybean (Glycine max L. Merr.), and sunflower (Helianthus annuus L.). We analyzed water potential, osmotic potential, canopy temperature, and stomatal conductance (reciprocal of stomatal resistance). Evapotranspiration was determined from soil water content measurements. Except for sunflower, plants with the highest water potentials had the lowest evapotranspiration (sorghum and pinto bean), and plants with the lowest water potentials had the highest evapotranspiration (millet, soybean, corn). Sunflower was an exception in that it had a high evapotranspiration and a high water potential. Corn and sunflower had consistent differences during the two-year study. Sunflower had higher water potentials, higher osmotic potentials, lower canopy temperatures, higher stomatal conductances, and a higher evapotranspiration than did corn. The results showed that leaf water status did not predict crop water use.