The effects of temperature on the germination behavior of white, yellow, red and purple maize plant seeds

Even though seeds are hidden inside fruit, they differ in color; an interesting, but puzzling, phenomenon. Here, the antioxidant capacities of white, yellow, red and purple seeds from a single variegated maize plant ear were measured and the effects of temperature (15, 30 and 40 degrees C) on germination behavior assessed. The antioxidant capacity of the seeds followed the order: purple > red > yellow > white. The most favorable temperature for all of the seeds was 30 degrees C. However, the highest germination rates (GRs) were observed in purple seeds, compared to the other colored seeds, when exposed to 40 degrees C, and white seeds, when exposed to 30 degrees C. The germination speeds among the seeds remained consistent (white > yellow > red > purple), irrespective of temperature. The impaired germination observed at 40 degrees C was significantly improved by adding exogenous antioxidants, but was further impaired by adding H2O2, especially for the white seeds; similar effects on GR were observed at 30 degrees C and 15 degrees C. High negative (at 30 degrees C) and positive (at 40 degrees C) correlations were observed between antioxidant capacity and GR. However, only high negative correlations were detected between antioxidant capacity and germination speed. In addition, no significant difference in heat stress tolerance was observed in the seedlings produced by the different colored seeds. Thus, we speculate that adverse conditions favor the germination of deeper colored seeds, whereas favorable conditions favor lighter colored ones. We discuss the significance of color, from the perspective of seed antioxidant capacity and germination ability under different environmental conditions.