Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 20, 1998
Publication Date: N/A
Technical Abstract: Soil hydraulic characteristics affect the amount and rate of water uptake needed for crop growth. Grain sorghum and corn were grown under limited to full irrigation in a rain shelter facility which has 48 monolithic lysimeters containing three soil types. The lower limit of water extraction for each combination of crop and soil type was estimated using neutron scattering. Net photosynthesis (P), stomatal conductance (g), and intercellular CO2 to ambient CO2 (ci/ca) ratio were measured using an LI-6200 photosynthesis system. Corn extracted about 50 mm less water from the Pullman soil and about 25 mm less water from the Ulysses and Amarillo soil series compared with sorghum. Both corn and sorghum maintained significantly higher P rates in the Ulysses soil compared with the other two soils. Corn and sorghum P rates did not decline until about 70% plant available water had been depleted. Corn maintained fairly constant ci/ca and g/P ratios over the range of soil water contents and VPD, while sorghu ratios varied between and within years. While both are C4 plants, this suggests the two crops respond differently to environmental stresses.