Abstract
The effects of ozone and soil water stress, singly and in combination, on the growth, yield, seed quality and germination rate of soybean plants [Glycine max (L.) Merr. cv. Enrei] were investigated. The plants were exposed to charcoal-filtered air or 60 n1· 1-1 O3, and were split in both gas treatments between two watering regimes imposed the potted soil with a pF value of 1.8 (well-watered treatment) or 2.5 (water-stressed treatment) in naturally-lit growth cabinets for 98 days.
The exposure of the plants to O3 caused reductions in the leaf, root and whole-plant dry weights at thevegetative growth stage, and in the yield. The contents of Mg and K in the seed were significantly increased, but the seed germination rate was significantly reduced by the exposure to O3.
The soil water stress induced reductions in the whole-plant dry weight and yield of the plants. The contents of grain oil, Ca and Mn in the seed were significantly reduced, but the content of Mg in the seed was significantly increased by the soil water stress. There was no significant effect of soil water stress on the seed germination rate of the plants.
Antagonistic effects of 03 and soil water stress were detected in the whole-plant dry weight on the 26th day after sowing, the dry weight of pods with seeds on the 67th day after sowing, the seed number per plant, the weight per 100 seeds and grain protein on the 96th day after sowing. However, the additive effects of 03 and soil water stress were generally observed on the dry matter production of the plants. Therefore, the yields of the plants exposed to both stresses were markedly reduced compared with that of the well-watered plants exposed to charcol-filtered air.
