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Effects of Nitrogen Fertility on Water Potential of Irrigated Cotton
Author(s) -
Radin J. W.,
Mauney J.R.,
Kerridge P.C.
Publication year - 1991
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/agronj1991.00021962008300040018x
Subject(s) - transpiration , stomatal conductance , vapour pressure deficit , canopy , malvaceae , agronomy , nitrogen , gossypium hirsutum , conductance , hydraulic conductivity , field experiment , horticulture , zoology , biology , environmental science , chemistry , botany , soil water , ecology , photosynthesis , mathematics , organic chemistry , combinatorics
Cotton ( Gossypium hirsutum L.) grown in controlled environments responds to N deficiency with decreased hydraulic conductance and midday leaf water potential (Ψ w ). Experiments were initiated to determine whether N deficiency similarly affects plant water relations in the field. Cotton was grown for 4 yr with adequate N or a mild N deficiency. Nitrogen fertility had little effect on Ψ w (determined with a pressure chamber) early in the season, but beginning in midseason the Ψ w of N‐deficient plants was 0.2 to 0.4 MPa higher than that of the fertilized plants. This difference was seen both before N had affected leaf area, and after canopy closure had occurred at both N levels. Stomatal conductances and transpiration rates of recently matured sunlit leaves (determined by steady‐state porometry) remained unaffected by N. This evidence indicates that N deficiency increased plant hydraulic conductance in the field, contrary to its effect in controlled environments. However, in regressions of transpiration rate on leaf Ψ w from dawn to midday, N had no consistent effects on the slopes (a putative measure of hydraulic conductance). These discrepancies have not been resolved. Nonetheless, N deficiency clearly does not decrease hydraulic conductance of cotton in the field in Arizona as it does in controlled environments.