THE EFFECT OF SOIL AERATION ON SUPEROXIDE-DISMUTASE ACTIVITY, MALONDIALDEHYDE LEVEL, PIGMENT CONTENT AND STOMATAL DIFFUSIVE RESISTANCE IN MAIZE SEEDLINGS

Deficient soil aeration that causes hypoxia of maize roots frequently decreases plant biomass production. Characterizing relationships among maize physiological responses to varying levels of root hypoxia is cr itical to predicting maize plant biomass production. Maize seedlings 1 2 days old were subjected to increasing root hypoxia over a 12 day per iod by increasing soil water content in 0.06-0.07 m(3) m(-3) intervals up to soil saturation. Soil hypoxia conditions were characterized by measuring air-filled porosity (Eg), oxygen diffusion rate (ODR), and r edox potential (Eh). The objective of the study was to verify the hypo thesis that some physiological parameters can be used to relate levels of soil hypoxia to biomass production. It was found that soil hypoxia caused a decrease of shoot and root biomass, and diminuished the cont ent of leaf protein, chlorophyll, carotenoid, and malondialdehyde (MDA ). An increase, due to hypoxia, was observed in the case of stomatal d iffusive resistance (Rd) during the entire stress period and of leaf s uperoxide dismutase (SOD) activity after 8 and 12 days. The SOD activi ty in the roots increased after 2 and 8 days of hypoxia and decreased after 12 days. The results confirm the hypothesis that the shoot physi ological parameters of maize plants can be used to relate varying leve ls of soil hypoxia to biomass production. The most promising seems to be Rd and SOD activity. The best indicator of the soil aeration status appeared to be ODR. (C) 1998 Elsevier Science B.V. All rights reserve d.