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• Study on the Fungus Agroathelia rolfsii YBS24 Causing Basal Stem,  Root Rot Disease of Cassava

  Duong Thi Nguyen, Le Thi Hang, Tran Trung Kien, Nguyen Manh Hung, Trinh Xuan Hoat

  Date Received: 12-01-2026 / Date Accepted: 09-04-2026 / Date Published: 25-06-2026

   Abstract PDF (VIETNAMESE)

  Basal stem and root rot is one of the most destructive diseases causing serious losses in both yield and quality of cassava in many growing regions of Vietnam, particularly in the northern mountainous provinces. This study was conducted to identify the causal agent of cassava basal stem and root rot in Lao Cai province, Vietnam, and to evaluate its biological characteristics. Isolation, artificial inoculation, morphological characterization, and internal transcribed spacer (ITS) region sequence analysis were used in this study. The results indicated that isolate Agroathelia rolfsii YBS24 is the causal pathogen of basal stem and root rot of cassava. The fungus exhibited optimal growth on PDA medium. The fungus grew over a wide pH range, from 4 to 9, with optimal growth between pH 5 and 8. It also grew over a relatively wide temperature range of 15-35°C, with temperatures between 25°C and 30°C being most favorable for mycelial growth. The results of this study provide a crucial scientific foundation for developing effective and sustainable management strategies for cassava basal stem and root rot disease.

  DOI: https://doi.org/10.31817/tckhnnvn.2026.24.6.02

• Establishment of Plant Regeneration Protocol for Cassava (Manihot esculenta Crantz) via Somatic Embryogenesis from Immature Leaves

  Do Hai Lan, Le Tran Binh, Le Van Son, Chu Hoang Ha

  Date Received: 25-07-2014 / Date Accepted: 08-11-2016

   Abstract PDF (VIETNAMESE)

  The present study aimed at regenerating cassava(Manihot esculenta Crantz) via somatic embryogenesis. The explants used were immature leaves harvestedfrom 2-3-week old in vitroplantsderived from two cassava cultivars, KM94 andKM140. Somatic embryogenesis was achieved with high frequencies usingMS medium supplemented with a wide range of picloram concentrations. The results showed that the highest rate of somatic embryo formation for both cultivars was obtained when cultured in MS mediumcontaining 12 mg/l picloram. Although the number of embryos per explant was similar between two cultivars at4 weeksof culture, KM94 cultivar gave a higher rate (81,4 ± 1,7%) than KM140 cultivar (70,4 ± 2,9%). Somatic embryos were subsequently transferred to MS medium supplemented with 0.3 mg/l BAP for plantlet regeneration. All shoots with 1.0-1.5 cmin length transferredto - hormone-free MS medium formed roots in 2 weeks. Rooted plantlets were transplanted toa mixture of rice husk (40%) and sandy soil (60%) in greenhouse. This protocol required 16 to 18 weeks and was entirely appropriate for mass production of various cassava genotypes and further genetic transformation experiments.