Selection approaches to the variation of responses to soil compaction stress among maize hybrids (Zea mays L.)

Soil compaction stress can strongly affect plant growth, development and productivity. Effects of different levels of soil compaction were investigated in 18 maize hybrids during field and greenhouse experiments. Maize hybrids in the field experiments were subjected to low (L) or high (H) and in the greenhouse experiments to low (L: 1.10) and high (C: 1.60 g cm(-3) soil) soil compaction level. Differences between maize hybrids grown under non-stress and stress conditions were found in a decrease in grain yield (GY), grain number (GN), weight of 1,000 grain (W-1000), seedling dry matter (DM), emergence (EM), plant height (H), leaf area (LA) and leaf greening (SPAD). Stress susceptibility index (SSI), geometric mean productivity index (GMP) and tolerance index (TI) were evaluated by determining the effects of low (L) or high (H) soil compaction levels on grain yield (GY) or dry matter of the above-ground part (DM). The values of SSI, GMP and TI enabled us to rank the tested hybrids with respect to their susceptibility to soil compaction stress. SSI and TI made it possible to identify maize hybrids resistant and sensitive to soil compaction stress. Changes in growth traits were greater in the hybrids with high SSI and TI. Correlation coefficient (r) between stress susceptibility index (SSI) of maize hybrids in the field and greenhouse experiment was high and statistically significant. This observation may indicate that genetically determined susceptibility to soil compaction stress in maize hybrids was similar throughout ontogenesis.