Canopy Temperature, Seed Yield, and Vapor Pressure Deficit Relationship in Soybean
- N. V. McKinney,
- W. T. Schapaugh and
- E. T. Kanemasu
Drought stress frequently limits soybean production. Thirty soybean [Glycine max (L.) Merr.] lines in a field trial in 1982 were tested for canopy temperatures and response to vapor pressure deficit (VPD) as criteria for yield and drought tolerance. Lines were monitored for canopy temperature differential (Td = canopy temperature — air temperature), and wet and dry bulb temperatures determined the VPD of the air. The five warmest and five coolest lines based on seasonal mean Td, or , were monitored for in 1983 and 1984 under irrigated and nonirrigated environments. Soil type was (Umucic Hapiustoll) a Muir silt loam (fine-silty, mixed, mesic in 1982 and 1984) and a Eodora silt loam soil (coarse-silty, mixed, mesic) Fluventic Hapludoll) in 1983. Differences for among the lines were negatively correlated with seed yield. Warm genotypes were not more productive under dryland conditions, nor was the ratio of dryland yield to irrigated yield (yield stability) greater than for cool genotypes. Neither nor the ratio of dryland to irrigated ( stability) was significantly correlated with yield stability. Lines did not differ significantly in their Td response to VPD (measared as the Td — VPD regression slope) on a seasonal basis. On 5 d with maximum VPD greater than 3 kPa, however, Td response to VPD differed significantly in the irrigated environment. These differences were not related to , yield, or yield stability. Indirect selection for yield using canopy temperature may be effective; however, warm genotypes are not more drought tolerant or yield stable than cooler selections.
Copyright © 1989.