EARLY PHOSPHORUS-NUTRITION, MYCORRHIZAE DEVELOPMENT, DRY-MATTER PARTITIONING AND YIELD OF MAIZE

We conducted a field experiment to test the hypothesis that improved p hosphorus nutrition occurs in maize plants with rapid arbuscular (AM) mycorrhizae development at early developmental stages and that this al so is reflected in dry matter allocation and final yield. A split-spli t plot design was used with previous crop (Zea mays L.-maize and Brass ica napus L.-canola), tillage practices (no-tillage or conventional ti llage) and P fertilization (5 levels) as factors chosen to modify myco rrhizae development at early developmental stages of maize. Previous c ropping with canola resulted in decreased shoot-P concentration and sh oot growth of maize at early stages. No-tillage resulted in higher sho ot-P concentration but lower shoot weight than conventional tillage. G reater shoot-P uptake was related to a rapid intraradical development of mycorrhizae (previous crop of maize) or rapid connection to a mycor rhizal mycelium network (no-tillage treatments). Maize yield and harve st index were lower after cropping With canola. The yield for conventi onal tillage was higher than that for no-tillage but the harvest index was lower. The hypothesis was supported at early stages of maize grow th by the effect of previous crop but not by results of tillage, becau se an unknown factor reduced growth in the no-tillage system. The hypo thesis was supported at maturity by increased biomass allocation to gr ain relative to total shoot weight in treatments with greater shoot-P concentration at early stages.