Mycorrhizal symbiosis and nutrient uptake in new maize hybrids with contrasting phenotypes as influenced by soil phosphorus level

Development and functioning of arbuscular mycorrhizal (AM) symbiosis in the soil-plant system are required in sustainable agriculture. AM development of maize genotypes and uptake of nutrients as influenced by soil P levels were studied. Several experiments were conducted both in the greenhouse and in the field.; In greenhouse trials, pasteurized substrates were inoculated with Glomus intraradices as mycorrhizal treatments. Mycorrhizal development varied widely among maize hybrids and inbreds. Leafy normal stature (LNS) had the highest root colonization and shoot:root ratio and was the most responsive to AM fungi. Mycorrhizal development was generally reduced at high soil P and micronutrient levels. The percentage of root colonization was correlated with the ratio of plant tissue N/P only when soil N level was intermediate. Mycorrhizal plants increased uptake of Zn and Cu only at low P and low micronutrient levels, but decreased Mn uptake at higher micronutrient level.; In field trials, soil fumigation was used to eliminate AM fungi in control plots. Again LNS was most responsive to indigenous AM fungi, closely followed by Non-leafy normal stature (NLNS). Mycorrhizae increased uptake of K, Ca and Mg only when these nutrients and available P were low in soil. Correlations between extraradicular hyphae and plant concentrations of K, Ca and Mg suggested that uptake of K was more dependent on extraradicular hyphae than uptake of Ca and Mg. Total P uptake was higher in plots where the AM symbiosis was not repressed, but soil available P was not always reduced.; There is potential for development of mycorrhiza efficient maize hybrids performing well under low input management in sustainable agriculture.