Gas exchanges and growth of maize as affected by aeration porosity and soil compaction

Resumo

Based on the hypothesis that less than 10% aeration porosity is sufficient to ensure plant development, the
objective of this study was to evaluate the effect of levels of aeration porosity and soil density on the gas exchange and growth
of maize plants. The experiment was conducted in a greenhouse, in randomized blocks in a 2 × 5 factorial arrangement: two
densities (1.6 and 1.7 Mg m-3) and five aeration porosities (0.07, 0.08, 0.09, 0.10 and 0.12 m3
m-3), with five replicates. The
interaction between the factors did not have an effect on the analyzed variables. Aeration porosity had a significant effect on
photosynthesis, stomatal conductance, relative chlorophyll index (SPAD), plant height and biomass production, whose data
were fitted by quadratic models. The highest aeration porosity reduced conductance by 11%, followed by 7% reduction in
photosynthesis and 6.4% in SPAD. Aeration porosities lower than 0.10 m3
m-3 did not cause significant reduction in the values
of gas exchange and growth of maize. At soil density of 1.7 Mg m-3, photosynthesis, SPAD, chlorophyll b, total chlorophyll and
carotenoids were higher, but with no increments in biomass and leaf area. It is concluded that aeration porosities greater than
0.10 m3
m-3 are more limiting to plants due to changes in soil attributes, such as penetration resistance and water content. The
highest contents of chlorophyll b and carotenoids at the highest density are acclimatization responses to the stress condition.