Studies on the potential of tulasnella deliquescens as growth-promoting fungus in commercial orchid cultivation

Name: Arttapon Emsa-art

Organization : Mae Fah Luang University

keyword: Orchid cultivation

LCSH: Mycorrhizas

Classification :.LCCS: QK495.O64

LCSH: Fungi

LCSH: Orchids -- Micropropagation

Abstract: Orchid cultivation is an international business. Commercial orchids are mainly propagated by tissue culture. However, micropropagation of some important orchids still encounters many problems such as lag phase of growth and high mortality of seedlings during transplantation. This problem is mainly caused by the inability of the in vitro propagated plantlets to adapt to the drier and less nutritious ex vitro condition, therefore, an approach that can help orchid plantlets to survive during and after ex vitro transplanting would be valuable for commercial orchid cultivation. This study evaluated the effects of an orchid mycorrhizal fungus (OMF), Tulasnella deliquescens (Juel) Juel on survival and growth of three species of orchids, i.e., Phalaenopsis Newberry Parfait, Paphiopedilum gratrixianum Rolfe, and Phalaenopsis Sogo Yukidian. The first study, evaluation of OMF inoculation on survival rate and growth of micropropagated Phalenopsis Newberry Parfait after ex vitro transplantation was carried out in a completely randomized design (CRD) with three treatments (i.e., un-inoculated control, inoculation with T. deliquescens either isolates Da-KP-0-1 or Pv-PC-1-1) and 120 replicates (plants). Number of dead plants and growth parameters (i.e., number of shoots, number of leaves, and width and length of the largest leaves) were monitored every two months for six months. The survival rates of plantlets inoculated with T. deliquescens either isolate Da-KP-0-1 or Pv-PC-1-1 were found to be greater than that of the un-inoculated control. However, only the fungal isolate Da-KP-0-1 promoted the growth of the plantlets. Moreover, it was observed that the orchid mycorrhizal inoculation reduced the fungal and algal contamination on the cultivation substrate and possibly lowered the infection of pathogenic disease. The second study, evaluated the effects of mycorrhizal inoculation on growth of micropropagated plantlets of Paphiopedilum gratrixianum Rolfe after being transferred to ex vitro condition. The first inoculation was not successful, a re-inoculation was done by adding inoculum substrate (control) or inoculum of T. deliquescens (Da-KP-0-1, Pv-PC-1-1 or Ps-KT-0-1) to the pots at four months after ex vitro transplantation. At six months after the fungal inoculation, the plantlets that were inoculated with either fungal isolate Pv-PC-1-1 or Da-KP-0-1 showed significantly greater leaf sizes but the isolate Pv-PC-1-1 performed the best because it also enhanced the fresh weight and the stem length. For the numbers of leaves were not affected by the mycorrhizal inoculation. The results suggest that orchid mycorrhizal fungi can be used to improve the growth of Paphiopedilum orchids. The third study, evaluated the effect of mycorrhizal inoculation on resistance against bacterial soft rot in Phalaenopsis Sogo Yukidian. Micropropagated orchid plantlets were either left un-inoculated or inoculated with an orchid mycorrhizal fungus, T. deliquescens isolate Da-KP-0-1, for one month before they were transferred to pots. Evaluation of soft rot progression was done twice at 35-day and 75-day post ex vitro transplanting using an attached-leaf assay and three concentrations of Dickeya sp. (i.e., 1.4x1010, 7.0x109, and 2.8x109 CFU/ml). Higher percentages of plants resistant to Dickeya sp. were observed in mycorrhizal orchids compared to non-mycorrhizal orchids when 7.0x109 CFU/ml and 2.8x109 CFU/ml of bacterial inoculum were applied. However, at 1.4x1010 CFU/ml of bacterial inoculum percentages of non-mycorrhizal orchids resistant to Dickeya sp. were either indifferent or slightly higher than those of mycorrhizal orchids. Importantly, the soft rot development on leaves of mycorrhizal orchids was consistently reduced compared to that on non-mycorrhizal orchids regardless of the bacterial concentrations although significant reduction of the soft rot areas were found only at 35-day post ex vitro transplanting when inoculum concentrations of 1.4x 1010 and 7.0 x 109 CFU/ml were applied. This study suggests that mycorrhizal inoculation likely enhanced resistance against Dickeya sp. in Phalaenopsis orchid.

Mae Fah Luang University

Address: CHIANG RAI

Email: library@mfu.ac.th

Name: Sureeporn Nontachaiyapoom

Role: Advisor

Created: 2017

Issued: 2561

Modified: 2018-10-05

Issued: 2018-10-05

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: Thesis QK495.O64 A792s 2017

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Biotechnology

Grantor: Mae Fah Luang University

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