Early heat and drought stress can have lasting effects on corn growth

Early heat and drought stress experienced by corn plants in their initial stages can have long-term consequences on their growth and flowering, even months after the stressors have subsided. This is according to new research conducted by the Donald Danforth Plant Science Center and the University of Minnesota, which was published in The Plant Journal.

The study examined the effects of drought, heat, and their combination on 47 genetically distinct corn varieties under normal conditions, drought, heat, and combined heat and drought. Researchers discovered that responses to drought alone do not accurately predict responses to combined stresses in the traits measured, emphasizing the need to evaluate both stresses simultaneously when seeking promising plants for breeding.

Using daily images taken over 13 days of treatment, the team measured changes in plant size, height, water use, and color. Both heat and drought reduced plant size, but drought also slowed development, reduced leaf number, and decreased greenness. For most varieties, the effects of combined heat and drought were greater than the sum of individual stresses.

Interestingly, an early visible response to drought did not consistently indicate more severe outcomes at the end of the treatment. Plants that showed early drought signs were not necessarily the ones most affected by the end of the stress period. This distinction could help researchers avoid overlooking valuable genetic variation that might prove useful in the future.

To further investigate the lasting consequences of early stress, the researchers conducted additional experiments with two of the most interesting corn varieties. They returned these plants to normal growing conditions after about two weeks of stress. The early drought exposure delayed flowering, while heat advanced it. The combined effects of heat and drought resulted in significantly smaller plants at 61 days after planting, weeks after the stress had ended.

These findings underscore the importance of considering early-season stress when developing crops that can withstand difficult conditions during the growing season. Giles Oldroyd, Ph.D., president of the Donald Danforth Plant Science Center, highlighted the significant variation in how plants respond to stress and the potential to leverage this knowledge to create better crops, ultimately benefiting farmers and communities.