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Leaf Water Potential, Stomatal Resistance, and Temperature Relations in Field‐Grown Soybeans 1
Author(s) -
Jung P. K.,
Scott H. D.
Publication year - 1980
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1980.00021962007200060029x
Subject(s) - loam , dry matter , morning , agronomy , phytotron , water potential , growing season , water content , dry season , diurnal temperature variation , soil water , horticulture , biology , vapour pressure deficit , botany , transpiration , photosynthesis , ecology , atmospheric sciences , geotechnical engineering , geology , engineering
There is a need for daily and seasonal measurements of the field water status of plants in order to characterize their response to soil water deficits. Measurements were made of leaf water potential (Ψ), stomatal diffusive resistance (R), and leaf temperature (T) of irrigated (I) and nonirrigated (N) ‘Forrest’ soybeans [ Glycine max (L.) Merr.] grown on Crowley silt loam (a Typic Albaqualf), in a dry season. Values of Ψ in the N soybeans decreased earlier in the day and increased later in the afternoon than Ψ values of I soybeans. The stomates of N plants were partially closed during the daylight hours and closed earlier in the afternoon than stomates of I plants. Leaf temperatures of the N plants increased earlier in the morning and remained higher later in the afternoon than leaf temperatures of I plants. As the drought intensified, differences in Ψ, R, and T between the N and I soybeans increased. Maximum differences during the day were approximately ∆Ψ = −4 bars, ∆R = 6.0 sec/cm, and ∆T = 5.5 C and were usually found at midday and midafternoon late in the season. Generally, the differences in these parameters between moisture regimes were lower at midmorning. The differences in these plant water and temperature parameters were reflected in lower production of total dry matter and seed.