Effects of previous crops on arbuscular mycorrhizal formation and growth of maize under various soil moisture conditions

Abstract

The effects of previous crops on arbuscular mycorrhizal (AM) formation and growth of succeeding maize (Zea mays L.) were examined at different soil moisture levels. Maize was grown in pots filled with soils (Andosol) from the plots, where mycorrhizal (sunflower, maize, soybean, kidney bean, adzuki bean, potato, wheat) and non-mycorrhizal (mustard, radish, sugar beet, and buckwheat) crops were cultivated in the previous season. Soil water potential was adjusted to around -10 (wet: W), -50 (moist: M), < -63 kPa (dry: D) from 11 d after sowing. The soils after cultivation of mycorrhizal plants in the previous season contained more AM spores than those after cultivation of non-mycorrhizal plants. The influence of the previous crops on AM formation was pronounced on drier soils, in which AM colonization of maize following mycorrhizal crops occurred more frequently than that after non-mycorrhizal crops. Arbuscular mycorrhizal colonization of maize, however, improved with increasing soil moisture status even after non-mycorrhizal crops, despite the differences in the AM spore population. The influence of previous crops on maize growth was also distinct, but it declined markedly with the increase in the soil moisture status. Phosphorus uptake and maize growth were positively correlated with AM colonization. The increase in AM colonization with the increase in the soil moisture status despite the low AM spore population suggests that a higher soil moisture status improved the efficiency of AM colonization, thus promoting AM formation. Such effects may have, in turn, stimulated P uptake and enhanced plant growth, thereby reducing the influence of the cropping history.