This article aimed to investigate the forest structural characteristics, tree species diversity for plant communities of the tropical moist evergreen close forest and distribution of medicinal plant species at Ta Kou nature reserve, Binh Thuan province. In this research, the structural characteristics and tree species diversity were analyzed from data collected from 20 typical plots with the size of 0.1 hectares. The location of medicinal plant species is identifed by GPS through the route survey method. Research results show that IVi% index of dominant and co-dominant tree groups accounting for 26.4%. The number of trees is most concentrated in class D1.3 < 20 cm and H < 10 m. The basal area and volume are mainly concentrated in class D1.3 = 20 - 40 cm and H < 10 m. In the study area, 47 species of 27 plant families were found, in which the Dipterocarpaceae family has the most species; 28 medicinal plant species belong to 24 families, one of which is typical for the study area named “Thay Thim” tree (Olax obtuse Blume) and some other species are rare and threatened with extinction in Vietnam such as Streptocaulon juventas (Lour.) Merr., Eurycoma longifolia Jack, Stemona collinsae Craib, Drynaria bonii H. Christ.

Halophytes are found in high-salt environments naturally, and their roots may be associated with promising microbial candidates for promoting crop growth and salt tolerance. In this study, halotolerant bacteria were isolated from soil and root samples of Rhizophora apiculate (R. apiculate), Avicennia ofcinalis (A. ofcinalis), Thespesia populnea (T. populnea), Acanthus ilicifolius (A. ilicifolius) and Trichophorum cespitosum (T. cespitosum), five native halophytes of southeast seaside of Vietnam. Isolates were tested for maximum salt tolerant and screened for the ability of phosphate solubilization and indole acetic acid (IAA) production. Colony morphology, pigmentation, and Gram staining of each IAA production halotolerant isolate were determined. The bacterial isolates showed the highest salt tolerance and IAA production were identifed by sequencing the 16S rRNA gene. A total of 54 isolates which were able to grow in the presence of up to NaCl 3M were isolated. Twenty-three halotolerant bacterial isolates had the capacity of IAA production, 60.9% from which were Gram positive with a cocci shape, colony in opaque/transparent yellow or opaque/off white, 1 - 2 mm or 2 - 3 mm in diameter with the convex surface. Three isolates VTDD1, VTTD2, and KGOR1 were able to solubilize insoluble phosphorus. The highest IAA production was observed in VTDR1 (93.77 µg/mL) followed by VTMR1 (75.23 µg/mL) and VTDR2 (60.00 µg/mL), while the smallest IAA production was observed in CGOD1 (0.50 µg/mL). The isolates VTDR1 and VTDR2 were identifed as Salinicola tamaricis (99.58% and 99.67% identity respectively), while VTMR1 was found to be Salinicola peritrichatus (98.37% identity).

Xanthomonas axonopodis pv. citri (X. axonopodis pv. citri) is the cause of canker disease on lime trees that negatively affect plant health and fruit quality. This study focused on the comparison of the extraction yield and antibacterial properties of Euphorbia tirucalli against X. axonopodis pv. citri, phytochemical screening, quantifcation of phenolic and flavonoid contents of the fraction extract. The results showed that the ethyl acetate fraction (EA) (7.5 mg/mL) of E. tirucalli from Dak Nong province had the best activity against bacteria with diameter of inhibition zone determined 15.50 ± 0.50 mm, and the minimum inhibition concentration was 0.312 mg/mL. Alkaloids, flavonoids, tannins, and terpenoids were found in the EA fraction extract of E. tirucalli, whereas saponin did not appear in the extract. The phenolic and flavonoid content was in the range of 14.46 - 98.63 mg GEA/g and 90.34 - 408.86 µg QE/g, respectively. Column chromatography followed Nuclear Magnetic Resonance spectra were performed and the three compounds were identifed as scopoletin, gallic acid, and 3,3’,4’-tri - O - methylellagic acid. This study suggests that the extract from E. tirucalli and the isolated compounds can be used for managing of citrus canker disease.

Ben Tre is a coastal province in the Mekong Delta heavily affected by negative impacts of climate change and sea level rise, such as freshwater shortage and increased salinity intrusion during the dry season. This research aimed to develop a remote sensing approach, using time series data to assess drought development for the coastal districts (Ba Tri, Binh Dai, and Thanh Phu) in Ben Tre province. The Temperature Vegetation Dryness Index (TVDI) was analyzed based on the time-series Landsat 8 OLI data, which were obtained continuously from 2009 - 2019 to evaluate drought changes over time. The drought maps of 2009 and 2019 were established and the results showed that there were four levels of drought, including non-drought, slight drought, moderate drought and severe drought. Areas with non-drought and slight drought were reported at 5.65% and 35.34% (about 6,098 ha and 38,146 ha), respectively; while about 53.14% and 5.87% of the study areas were classified as moderate and severe drought (about 57,354 ha and 6,332 ha), respectively. The assessment of fluctuations in the period 2009-2019 showed that the areas of non-drought and slight drought tended to decrease while the areas of moderate and severe drought increased. The drought was positively related to agricultural land-use change as shown by the following formula loge(Pi/(1 - Pi)) = 7.985 * TVDI - 6.746. Drought tended to decrease in the areas where the bare land was changed to lands for perennial crops, rice crops and aquaculture, while drought tended to increase in land-use types of rice and annual crops.

Recovery starch from organic waste significantly contributes to sustainable agricultural production. This study aimed to recover starch from the waste mimicking generated from the curcumin extraction by using ethanol. The physicochemical properties of the isolated starch such as microscopic morphology, Fourier transform infrared spectroscopy, X-ray diffraction, total starch, iodine binding capacity of starch, curcumin content determined by high-performance liquid chromatography were compared to that of starch obtained from the conventional method of extraction from the fresh rhizome.  The results showed that the starch obtained from the fresh rhizome had a higher yield (21.3% vs. 8.5%) compared to that of starch isolated from the turmeric powder after extracting curcumin. The total starch analysis indicated that the former starch had a higher purity (98% vs. 77%, dw). The SEM imaging showed that both starches had irregular shapes with a thick flat and smooth surface. Although the starch isolated from the turmeric powder showed the dedicated properties of starch, the peak intensity and crystalline structure were remarkably decreased, observed under FTIR and X-ray diffraction analyses, respectively. The pasting analysis showed a clear change in starch obtained from the turmeric powder after ethanol extracting curcumin since a low peak viscosity was recorded. The HPLC curcumin quantification showed that both starches had a very low residue of curcumin (18.4 mg/100 g and 66.5 mg/100 g, dw) after isolation. The process of recovery starch after curcumin extraction from turmeric would be further improved to prevent the changes in physicochemical properties and for better yield.