JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2024, Vol. 48 ›› Issue (2): 129-136.doi: 10.12302/j.issn.1000-2006.202209004

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Effects of rejuvenation and hormone treatment on the rooting of softwood cuttings of Quercus texana and anatomical observations of rooting

BU Xiaoting1(), FU Wei1, LI Shuxian1,*(), XU Zhibiao2, PENG Daqing2, XU Linqiao2   

  1. 1. State Key Laboratory of Tree Genetics and Breeding, Co-Innovation Center for Sustainable Forestry in Southern China, Key Laboratory of Tree Genetics and Biotechnology of Ministry of Education, Key Laboratory of Tree Genetics and Silvicultural Sciences of Jiangsu Province, College of Forestry and Grassland, Nanjing Forestry University, Nanjing 210037, China
    2. Yancheng Forest Farm of Jiangsu Province, Yancheng 224136, China
  • Received:2022-09-01 Revised:2023-06-21 Online:2024-03-30 Published:2024-04-08

Abstract:

【Objective】 This study was performed to investigate the effects of rejuvenation and hormone treatment on the rooting of Quercus texana cuttings and obverse the formation process of adventitious roots during the rooting process. This was done to explain the reasons behind the difficulty of rooting Q. texana cuttings to provide a theoretical basis and technical reference for the subsequent cutting propagation of Q. texana.【Method】 Using the rejuvenated (seedlings after the flat stubble of the six-year-old parent stocks) and the annual semi-woody branches cut from the six-year-old seedlings as materials to make cuttings, the bases of the cuttings were treated with the mixed solution of IBA, NAA, THB and soaked for 10 min. Furthermore, cuttings treated with water for the same duration were taken as the control (CK). After cutting for 75 days, we determined the callus rate, rooting rate, root index and root effect index of the cuttings of each treatment. Meanwhile, the formation process of the adventitious roots of cuttings from semi-woody branches of rejuvenated Q. texana was anatomically observed with the paraffin section technique.【Result】 Hormone treatments could significantly improve the rooting effect of Q. texana cuttings, and the results showed that the rooting rates of the treatment groups were higher than that of the control group in both the rejuvenated and six-year-old cuttings, with the highest rooting rate reaching 43.3%. The two-factor analysis indicated that the rejuvenation treatment was a crucial factor affecting the rooting of Q. texana cuttings. Additionally, through the comprehensive analysis and ranking of various indicators, we found that the rooting effect of the rejuvenated cuttings was better than that of the six-year-old cuttings. The anatomical structure of the stem during the rooting process of Q. texana was observed with the paraffin section method, and it was found that the stem of new cuttings did not contain latent primordia, which belonged to the induced root primordium rooting type. Callus and skin rooting existed, which were classified into the mixed rooting type. Moreover, anatomical observation found that the phloem of the stem contained continuous annular thick-walled tissue, which hindered adventitious root elongation.【Conclusion】 The best rooting effect of the cuttings was achieved when the cuttings were made from rejuvenated Q. texana seedlings, with the base part soaked in the IBA (500 mg/L),NAA (250 mg/L) and THB (50 mg/L) mixed solution for 10 min. Anatomical observation of the stem during the rooting process revealed that the stem did not contain latent root primordia, which belonged to the type of induced primordium rooting. The presence of annular continuous phloem fibers (thick-walled tissue) in the phloem is one of the reasons for rooting difficulty. There are two pathways in which adventitious root primordia can occur: one is through the emergence of adventitious root primordia from the callus, and the other is through cells that divide near the cambia to form root primordia.

Key words: Quercus texana, cutting, hormone treatment, rejuvenation, anatomical observation

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