Mechanical Impedance Effects on Growth, Phenolics and 2,4-dihydroxy-7-methoxy-2H-1 ,4-benzoxazin-3-one (DIMBOA) in Root Exudates of Zea mays L

The purpose of this work was to evaluate the direct effect of mechanical impedance (IM) on root exudation from the indirect effect involving root morphological modifications induced by IM. Zea mays L. plants were grown in axenic hydroponic culture conditions for 4, 8, 12 and 16 days, and mechanical impedance was simulated by glass beads. At the end of the culture, exudation of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3-one (DIMBOA) for plants in a nutrient solution was measured. At harvest, plant growth and development parameters as well as DIMBOA and phenolics total in root exudate were measured. The results demonstrated a major influence of mechanical impedance on root growth with a reduction in shoot elongation. A medium which shows a higher resistance to growth, resulting in increased levels of DIMBOA y phenolic derivate. For high and low IM to 12 days of growth are obtained 6.94±0.36 and 5.47±0.37 μg DIMBOAxmL-1xseedling (n=3), showing significant differences (ANOVA, p <0.001); although the effect is time dependent growth. Correlations between plant morphology and root exudation suggest that root morphology is probably involved in the modification of root exudation. The results indicate that the resistance provided by growth medium will have a significant effect on the chemistry of the plant, and consequently on the ecology. This is important especially in crop species, where a new variable arises in crop management.