Root hair development of Poncirus trifoliata grown in different growth cultures and treated with 3-indolebutyric acid and ethephon

• The best root hairs were in MT agar among four cultures.
• IBA and ETH especially 1.0 M promoted root hair development.
• Root hair initiated from any epidermal cell of root on Poncirus trifoliata.

Citrus plants are generally believed to possess few or even no root hair whose function is to uptake nutrient and water from soils. This study compared the development of root hair of a citrus rootstock, Poncirus trifoliata, in four types of cultures or treated with 3-indolebutyric acid and ethephon. It was found that root hair of lateral root grew in sand culture compared with yellow-soil and solution culture in which no initiation was observed. Taproot hair grew best and evenly distributed on MT Agar culture, while in sand culture, Hoagland-solution culture, and yellow soil culture few or no root hair initiation was observed. For P. trifoliata, MT Agar culture showed the best performance on root hair. With regard to the effect of regulators such as 3-indolebutyric acid (IBA) and ethephon (ETH), our result showed that the optimum concentration of IBA and ETH for root hair growth was 1.0 μmol L−1 since IBA and ETH at this concentration could best promote root hair initiation and elongation. Besides, the effect of IBA on root hair growth was stronger than ETH at equal concentrations. Furthermore, our results showed that unlike Arabidopsis or Oryza sativa, the root hair of P. trifoliata could initiate from any epidermal cell (random type).