Effect of Mycorrhiza on the Nutrient Uptake of Sugarcane

Vesicular arbuscular mycorrhizae (VAM) fungi commonly infect plant roots, forming beneficial symbiotic relationships. The primary benefits of VAM plants are the enhanced acquisition and recycling of nutrients, particularly P, as well as soil moisture. This study compared the relationship between soil and leaf chemical elements of sugarcane variety N12 with low and high % mycorrhization (%myc). Seventy-one soil and leaf samples were selected from a 4000 m area in a field of ratoon cane on a sandy soil on the KwaZulu-Natal north coast, and were analysed for major plant available nutrients by the Fertiliser Advisory Service laboratory of the South African Sugar Association Experiment Station. Percentage mycorrhization was determined using the Gridline Intersect method. Data from the soil and leaf analyses were divided into two categories: those from plots with low %myc (9-26%) and those from plots with high %myc (32-53%). Relationships between soil and leaf factors were then determined using multivariate analysis (ADE-4 software). Results from high %myc plants indicated enhanced relationships between soil pH and leaf Ca, soil pH and leaf N, soil Ca/Mg and leaf N, and soil Na and leaf K while the relationship between Mg/Ca and leaf K was depressed in high %myc plants. Ca exists in the middle lamella as calcium-pectate, which helps with resistance to fungal infection. Nitrogen and Mg are required for photosynthesis, while Na may increase stomatal regulation under water limiting conditions. VAM colonisation therefore, may play a role in plant physiology in terms of resistance to bacterial and fungal pathogens, increased photosynthetic rates and enhanced stomatal regulation under water stressed conditions.