Morphological plasticity of spring and winter wheats in response to changing temperatures

Temperature change induces morpho-physiological responses, whose significance for plant function under this modified environmental condition is mostly unclear. Plastic responses to temperature changes from optimal (25°C) to chilling (5°C) conditions or vice versa, as compared with constant temperature treatments, were studied in spring and winter wheat. Plants grown at 5°C had smaller leaves, less stomata and larger root systems than their counterparts grown at 25°C. Plants at 5°C therefore had larger effective root : shoot ratio, defined as the ratio between total area of roots and stomata. Spring and winter cultivars differed in root growth, leaf growth and stomatal frequency following a shift in temperature. Nevertheless, both cultivar types reached similar effective root : shoot ratios, which were typical for each temperature. We also found changes in leaf thickness, transverse vascular bundle area and xylem : phloem ratios. Shifting temperature triggered rapid changes in leaf and root carbohydrate content and osmotic potential. Our results suggest that temperature-induced plasticity may play a role in ameliorating possible water deficits caused by large soil-air temperature differentials in natural environments.