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Four Trichoderma strains (CH2, SH16, PQ34, and TN42) were isolated from soil samples collected from Quang Tri and Thua Thien Hue provinces in Vietnam. The strains exhibited high chitinolytic secretion. Strain PQ34 formed the largest zone of chitinase-mediated clearance (> 4 cm in diameter) in agar containing 1% (w/v) colloidal chitin. Analysis of the internal transcribed spacer regions of these strains indicated that they were Trichoderma asperellum. The molecular weights of the chitinases were approximately 42 kDa. Chitinase genes (chi42) of T. asperellum strains TN42, CH2, SH16, and PQ34 were 98~99% homologous to the ech42 gene of T. harzianum CB-Pin-01 (accession No. DQ166036). The deduced amino acid sequences of both T. asperellum strains SH16 and TN42 shared 100% similarity.

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The number of research on ginger microrhizome production is low, despite awareness of the drawbacks to the traditional method of cultivation and the known health benefits associated with ginger essential oils. We examined the effects of several factors on microrhizome induction in order to create a production protocol for the cultivar found in Hue, Vietnam. To determine the optimal conditions for ginger microrhizome production, different concentrations of sucrose, plant growth regulators, ammonium nitrate, and silver nitrate were investigated. Microrhizome fresh weight and diameter were increased to the maximum values with application of BAP (6-benzyl amino purine), NAA (α- naphthaleneacetic acid), IBA (indole-3-butyric acid), and a low ammonium nitrate concentration, with 0.433 g at 9.03 mm, 0.437 g at 9.73 mm, 0.478 g at 10.80 mm, and 0.449 g at 9.53 mm, respectively. Additionally, we demonstrated that kinetin has an inhibitory effect on microrhizome growth. The biggest microrhizomes were grown on MS media containing the optimal concentrations for each factor – 80 g/L sucrose, 1.9 mg/L AgNO₃, 550 mg/L ammonium nitrate, 4 mg/L BAP, 6 mg/L NAA, and 4 mg/L IBA.

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