Is Seedling Root Morphology Predictive of Seasonal Accumulation of Shoot Dry Matter in Maize?

Seedling vigor at suboptimal temperatures is an important characteristic in maize ( Zea mays L.) growth in cool regions. Selection for improved vegetative growth and seasonal dry matter accumulation at suboptimal temperatures would be more efficient if seedling traits related to field performance could be identified under controlled conditions. This study evaluated if root traits of seedlings grown at cool or warm temperature regimes are predictive of early growth and silage yield in the field. Twenty early‐ to medium‐late maturing European hybrids (FAO maturity ratings 200–280) were grown in a solid substrate until the third leaf stage under two controlled temperature regimes (25/22.5°C and 15/12.5°C, day/night) and until silage maturity in three field environments on a Orthic Luvisol soil in Central Germany. The closest relationships with early field growth were found for the total length of the main roots ( r = 0.65, P < 0.01) and total length ( r = 0.60, P < 0.01) and number ( r = 0.68, P < 0.01) of firstorder laterals of the seminal roots at 25122.5°C. Silage yield was best correlated with the branching density of the seminal roots ( r = 0.66, P < 0.01) at 15112.5°C and the total root surface area ( r = 0.58, P < 0.01) at 25122.5°C. These root traits could potentially be used only in combination with other secondary characters for the indirect selection for shoot performance because individual root traits explained less than 50% of the variation in shoot weight in the field. Negative correlations between the chilling stability of most seedling traits, as expressed by the relative difference of trait means at 15/12.5°C and 25122.5°C, and silage yield indicated that chilling‐tolerant genotypes may be less capable of benefiting from the warmer temperatures during later growth stages.