Effects of Water Deficit at Different Growth Stages on Maize Growth & Yield under Alternate Partial Root-Zone Irrigation

Water scarcity is an increasing constraint on maize production in semi-arid environments, where the timing and intensity of soil-water deficit can determine whether a crop maintains yield or experiences major reproductive losses. Alternate partial root-zone irrigation (APRI) is designed to keep part of the root system hydraulically active while the opposite portion dries, thereby combining water saving with physiological regulation of transpiration. This paper presents a revised analysis of a maize experiment conducted at the International Water Management Institute, Rahim Yar Khan, Pakistan, during the 2022–2023 growing season. The reported experiment used a factorial arrangement of three irrigation levels—100%, 60%, and 40% field capacity—with three replications and evaluated plant height, leaf number, leaf relative water content (LRWC), SPAD chlorophyll index, shoot biomass, root biomass, biological yield, grain yield, and harvest index. Across the available aggregate data, declining water availability reduced vegetative growth, leaf hydration, chlorophyll status, total biomass, and grain yield. Plant height fell from 198.4 cm at 100% field capacity to 149.3 cm at 40% field capacity, while grain yield declined from 7.62 to 4.93 t ha−1. Moderate deficit irrigation retained 89.4% of the full-irrigation grain yield and produced the highest reported harvest index (44.2%). Root biomass was also greatest at 60% field capacity, suggesting a possible shift toward below-ground allocation under moderate stress. Because the supplied manuscript does not include raw observations, genotype-by-irrigation means, stage-specific means, irrigation volumes, or a numerical water-use-efficiency calculation, the present revision limits quantitative conclusions to the four reported aggregate tables. The results support moderate APRI as a promising water-saving strategy, but they also demonstrate the need for complete treatment-level data and replicated field validation before making genotype-specific recommendations.