Rhizosphere dynamics influenced by arbuscular mycorrhizal fungus (Glomus deserticola) and related changes in leaf nutrient status and yield of Kinnow mandarin {King (Citrus nobilis) x Willow Leaf (Citrus deliciosa)}

Rhizosphere modification through root exudation is an important attribute that regulates not only the availability of nutrients in the soil but also their acquisition by plants. To test the above, 10-year-old Kinnow mandarin plants budded on Troyer citrange were inoculated with arbuscular mycorrhizal fungi (AMF) ( Glomus deserticola) and Azotobacter chroococcum in different combinations with organic-farm-yard manure (FYM) and inorganic fertilisers in February when the root system was active. Plants with FYM alone were treated as a control. In the present investigation, a higher release of organic acids such as malic, citric, shikimic, and fumaric acids was evident from symbiotic roots of Kinnow inoculated with AMF ( G. deserticola). Soil pH decreased significantly from 8.5 before the start of the experiment to 6.4 at the end of the experiment in the treatment where G. deserticola was applied with FYM. A decrease in soil EC and organic carbon, and an increase in soil availability of N, P, and K, leaf nutrient status, and fruit yield and quality were observed when the plants were inoculated with G. deserticola compared with all other treatments. This study indicates that G. deserticola, when compared with A. chroococcum, modifies the rhizosphere favourably to improve soil nutrient availability and consequent uptake by plants and thus result in better growth, fruit yield, and quality of Kinnow.