Time period and nutrient contents alter the mycorrhizal responsiveness of citrus seedlings

It is necessary to know the nutrient requirement of citrus plants during the growing period to ensure optimal growth. As fertilizers are limited and expensive, in addition to the unknown long-term environmental aspect, it is good practice to use plant rhizosphere mechanisms, such as mycorrhizal inoculation, to enhance growth. As citrus plants depend on mycorrhizae colonization, it is beneficial to inoculate seedlings with mycorrhizae at an early stage. Thus, investigating citrus seedling quality and nutrition, with and without mycorrhizae, under greenhouse conditions is important in order to elucidate the impact of mycorrhizae in the eastern Mediterranean region. The aim of this study was to determine the role of mycorrhizal inoculation on citrus seedling growth, nutrient uptake and mycorrhizal dependency at specific time intervals. The experiments were set up under greenhouse conditions, using mycorrhiza-inoculated and non-inoculated sour orange seedlings grown over 15 months, which were harvested seven times. Citrus seedlings were extensively colonized by mycorrhizae and root colonization started 5–6 months after germination. Mycorrhizae inoculation increased certain growth parameters including shoot diameter, shoot height, and shoot and root dry weight. As the plant developed over time, the nutrient concentration, especially P, Zn, Fe, Mn, and Cu in the leaves decreased in both inoculated and non-inoculated seedlings. Over this time period, the seedlings initially absorbed nutrients more rapidly than later on due to dilution effects. Mycorrhizal Responsiveness (MR) between harvest times was calculated and showed that MR increased with plant growth over time. © ISHS 2018