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The objective of this experiment was to determine modifications in crop canopy, grain yield, soil water availability, plant available water and soil water extraction by maize plants submitted to two water regimes and two tillage systems. Two experiments were conducted during 1999/00 and 2000/01 growing seasons in the experimental field of the Agricultural Engineering Department of the Federal University of Santa Maria, RS, Brazil. A completely randomized design, factorial (2x2), was used with four replications. Treatments were: (i) Factor A - two soil water managements (irrigated and soil water deficit) and; Factor B - two tillage systems (conventional tillage and no-tillage). Irrigations were applied to raise the soil water content to the upper limit of plant available always when cumulative maximum crop evapotranspiration (ETm) reached a value of 25 mm. Maize plants submitted to water deficit did not received any application of water through irrigation or rainfall after 27 days after emergency (DAE), 7th leaf fully expanded.

Leaf expansion, leaf area index and plant height were measured three times a week. Aboveground biomass, internodes length and grain yield were evaluated at harvest. Soil water content was measured three times a week to determine soil water extraction and plant available water to maize plants. During 1999/00 growing season maize plants cultivated under the conventional tillage and notillage system presented similar cumulative leaf expansion, leaf area index, plant height, aboveground biomass and grain yield. Results also indicated similar soil water availability and plant available water to maize plants cultivated in both tillage systems. However, during 2000/01 growing season, leaf area index was higher in plants cultivated under conventional tillage after 21 DAE. Plant height, cumulative leaf expansion, aboveground biomass and grain yield were similar in both tillage systems. Soil water availability, plant available water and soil water extraction were also similar in both tillage systems evaluated.