Effects of different water holding capacity and nitrogen fertilizer forms on the regulation of arbuscular mycorrhizal fungi on the growth and nitrogen accumulation of citrus seedlings

Citrus has fewer fine roots and is a plant with a strong dependence on arbuscular mycorrhizal fungi. In the report， focused on citrus orange seedlings， the chamber root box experiment was used to compare the effects of arbuscular mycorrhizal fungi （CK， AMF， RAMF） and citrus symbiosis on soil nitrogen content， plant nitrogen accumulation， and biomass under the different water treatments （Water filled pore space 60% and 80%） and two nitrogen fertilizer forms （NH₄⁺， NO₃^-）. The results indicated that water， nitrogen fertilizer form， and arbuscular mycorrhizal fungi affect the total available nitrogen content in the soil， the biomass of citrus orange seedlings， and the total nitrogen accumulation in citrus significantly. Compared with the control treatment， the average aboveground and total biomass of citrus were significantly increased by 20.66% and 8.93%， respectively. Compared with the control treatment， the average nitrate nitrogen and total available nitrogen content in the soil treated with water were significantly reduced by 26.42% and 8.28%， respectively. The average aboveground and total nitrogen accumulation in citrus was significantly increased by 13.57% and 6.21%， respectively. Compared with NH₄⁺ treatment， the average aboveground and total nitrogen accumulation of citrus under NO₃^- treatment significantly increased by 12.59% and 5.64%， respectively， and the aboveground and total biomass of citrus significantly increased by 15.68% and 9.56%， respectively. Compared with the average aboveground and total biomass of CK treated citrus， RAMF treatment significantly increased by 26.60% and 25.48%， and AMF treatment significantly increased by 18.57% and 15.06%， respectively. Compared with the average aboveground and total nitrogen accumulation of CK treated citrus， RAMF treatment significantly increased by 23.10% and 20.10%， AMF treatment significantly increased by 19.49% and 12.88%， respectively. So， under the joint treatment of water and NO₃^-， the interaction between AM fungi and citrus is more conducive to the accumulation of aboveground and total nitrogen， thereby promoting the aboveground biomass and total biomass of citrus plants.