WATER, NITROGEN AND WEED STRESS IN FIELD CORN (ZEA MAYS L.) : SHOOT GROWTH AND DEVELOPMENT

概要

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Nitrogen (N) balances of soil-crop systems must be monitored more closely in the future to minimize ground water pollution. Maize was grown in rain-sheltered plots on a Flanagan silt-loam soil under three moisture regimes: Wet (W, weekly irrigations equal to water lost by a standard evaporation pan); Limited irrigation (L or 1/2 W) and Dryland (D, no irrigation). For each soil moisture regime, supplemental nitrogen (NH_4NO_3) was applied at 0, 125 and 250kg N ha^<-1>. Seedlings of common lambsquarter were transplanted 0.15m apart into the maize rows in sub-plots of each soil moisture regime at the medium N level or 125kg N ha^<-1>. Soil moisture profiles were measured twice weekly, leaf water potential (Ψ_<leaf>) was monitored with a leaf pressure bomb and root growth was followed at weekly intervals using minirhizotron tubes. Generally yield correlated well with either Ψ_<leaf> or N per plant. Higher N or water applications led to less negative Ψ_<leaf> values, one stress substituting for the other in controlling crop stress or yield. Leaf % N as an indicator for yield was compromised by small differences among treatments within sampling dates and the N×Ψ_<leaf> interaction; Ψ_<leaf> as an indictator for when to irrigate was not compromised.
九州大学の論文