Response of Dry Matter Accumulation in Maize to Temperature: I. Dry Matter Partitioning

Dry matter partitioning during early phases of development has potentially a large impact on crop growth, but the effect of partitioning on dry matter accumulation has never been quantified. This study was conducted to quantify the response of dry matter partitioning in maize (Zea mays L.) to temperature during the period from planting to the 12-leaf stage, and to investigate the influence of partitioning on dry matter accumulation. Two maize hybrids were grown at 10 plants m⁻² under controlled environment conditions at five constant (15, 19, 23, 27, and 31 °C) and five differential (15/3, 19/7, 23/11, 27/15 and 31/19 °C) day/night temperature regimes. Leaf area partition coefficient (LAPC), i.e., increase in leaf area per unit increase in total dry weight, and its components, shoot partition coefficient (SPC), leaf partition coefficient (LPC), and specific leaf area extension (SLAE), i.e., the area per g of new leaf, were calculated from plant-component dry weights and leaf area at the 4-, 8-, and 12-leaf stage. The LAPC increased linearly with temperature in the 11 to 31 °C range and declined from the 4- to the 12-leaf stage. Among the components of LAPC, SLAE appeared to contribute most to the variation in LAPC. The LAPC was associated with dry matter accumulation; as much as 50% of the variation in growth rates due to temperature regimes may have been attributable to leaf area partitioning. Similarly, differences in growth rates between hybrids were associated with LAPC. This study demonstrates that dry matter partitioning varies substantially among temperature regimes and phases of development, and between hybrids, and that part of the response of dry matter accumulation to temperature may be attributable to dry matter partitioning. Contribution from Dep. of Crop Science, Univ. of Guelph. Research supported by Ontario Ministry of Agriculture and Food and National Sciences and Engineering Research Council of Canada.