Influence of nutrient deficiency on root architecture and root hair morphology of trifoliate orange (Poncirus trifoliata L. Raf.) seedlings under sand culture

- Initiation and elongation of root hairs were activated by P and Ca deprivation whereas K deprivation had an opposite effect.
- The results reflected that there might be some correlations between the development of root hair and AM in Poncirus trifoliata.
- Root hairs were asymmetrical distributed on roots of Poncirus trifoliate seedlings in sand culture.
- Supplying sufficient Ca, Mg, Fe, Mn fertilizer to citrus seedlings in incubation period was important to ensure favorable root architecture.

Root hairs are important to plants for nutrient and water uptake through providing an increased absorptive surface area and exploitable soil volume. Citrus, as one of the most important fruit crops in the world, is generally believed to have few or even no root hair in the field and thus strongly depends on arbuscular mycorrhizas. In this study, sand culture experiment was carried out to investigate the effect of different nutrient deficiency conditions on the root hair development and root growth of one-month-old Poncirus trifoliata seedlings. We demonstrated that root hairs were distributed asymmetrically in the whole root, indicating it might be one of the characteristics of the citrus root hair distribution. Furthermore, the density and length of root hair were much higher in P, Ca deficiency than the control, however, lower in K-deficiency, implying the critical role of those nutrients in root hair initiation and elongation. Additionally, root growth was hampered at Ca, Mg, Fe, or Mn deprivation condition, suggesting that it is necessary to supply sufficient those mineral nutrients at seedling stage to ensure better root architecture.