This research examines sustainable agricultural development in Vietnam to improve rice production technology in the Mekong Delta. Vietnam is the third-largest rice export country worldwide, exporting 6-7 million tons of rice annually. Our survey on rice cultivation mechanization in the Mekong Delta revealed the sowing process as the most undeveloped step among the rice production processes. Among rice sowing methods currently used in the Mekong Delta, manual direct seeding (broadcasting) and manual row sowing by a drum seeder are most commonly performed, while transplanting remains a minor sowing method. In this study, we focused on three points to improve the rice production of this area. First, we conducted an economic evaluation of different sowing methods and found a clear financial advantage to machine transplanting compared with manual direct seeding and manual transplanting. Second, we investigated a suitable transplanting density and fertilizer volume with a popular short duration rice variety and found that high-density planting tends to produce a higher yield. Third, we approached the challenge of achieving sustainable agriculture by applying and plowing rice straw into a paddy field with Trichoderma supplements just after rice harvesting to produce fertile soil or quick organic compost. This study provides crucial information for optimal rice-farming conditions in one of the worldʼs top rice-exporting countries, potentially impacting the agriculture of this area, with global implications.

In this study, we investigated the possibility of popularization of bio-diesel fuel (BDF) in Vietnam. We found that by 2025, there will be an annual demand for over 18 million tons of diesel fuel in Vietnam. However, Vietnam currently has no commercial supply of BDF. Thus, it is necessary to promote commercial BDF production for future energy security and sustainable agriculture development in Vietnam. We investigated three necessary factors, enough material supply, processing technology to produce high quality bio-diesel fuel with reasonable cost, and adaptation to latest type diesel engines. First, we surveyed candidate materials, and identified three potential materials, such as cashew nut peel oil, rubber seed oil, and animal fat oil. Second, we focused on BDF production technology, and confirmed high-quality BDF with a fatty acid methyl ester ratio of 97.77% could be extracted from animal fat by our co-solvent method. As final, for adaptation of BDF to engines, we carried out diesel engine endurance test with our processed BDF, which was durability and adaptability tests using our own brand common-rail diesel engine with B0, B5, B10, B20, and B100 (100% biodiesel) BDFs. Exhaust gas monitoring was performed for NOx, THC, CO, and smoke. As a result, we found no problems with B0 to B20 fuel, and only a small amount of solid was found in the B100 test case.

Green perilla (Perilla frutescens var. crispa) is a highly functional Japanese herb. We investigated the growth of green perilla along with the levels of perillaldehyde, β-carotene, lutein, and rosmarinic acid in the plant when UV-A, blue light, and far-red light were additionally irradiated with red light to confirm the control technology using LED light to produce high-quality green perilla in plant factories efficiently. Twenty-eight-day-old seedlings of green perilla cultivated under white fluorescent lamps were transplanted to a hydroponic culture apparatus. The plants were subjected to different light treatments (red, red and UV-A, red and blue, and red and far-red light) and cultivated for more than 20 days. Perillaldehyde, β-carotene, lutein, and rosmarinic acid contents were quantified using an HPLC system during harvesting. It was observed that top fresh weight, plant height, leaf area attached to the main stem, fresh stem weight, and dry weight of leaves and stems were the highest under red plus far-red light among all light treatments. Addition of blue or far-red to red light did not affect perillaldehyde, lutein, β-carotene, and rosmarinic acid concentrations in green perilla. Irradiation with red plus UV-A light tended to increase the carotenoid concentration and decrease the rosmarinic acid concentration in green perilla, compared with red light only. To cultivate green perilla with high rosmarinic acid concentration, irradiation with only red light is effective, and to cultivate green perilla with high carotenoid concentration, red light supplemented with UV-A is effective.

Near-infrared (NIR) spectroscopy has been used to predict fruit quality. However, thereʼs few previous studies which use small and lightweight devices and they didnʼt construct models for each cultivar although each tomato cultivar has its own characteristics such as color and size. In this study, models to nondestructively determine fruit quality of tomato cultivars A (orange-colored cherry tomato), B (red-colored cherry tomato), C (red-colored cocktail tomato), and D (orange-colored cocktail tomato) were constructed using an inexpensive, portable near-infrared (NIR) spectroscopic device (spectral response range: 590-1,050 nm). We irradiated the tomato fruits and analyzed the spectra of the scattered light. The spectral data were preprocessed using four different methods (min-max normalization, 1st differential, 2nd differential and combination of normalization and 1st differential). The soluble solid content (SSC) and citric acid content (CAC) of the fruits were determined by destructive methods. Partial least-squares regression was used to construct models for predicting the SSC and CAC from the preprocessed spectra. The best preprocessing method differed by cultivar. For the best and worst models of SCC, the R² values were 0.80 and -0.1, respectively. Model performance may differ according to the color of the pericarp. Also, selection of an appropriate preprocessing method is important when using small spectroscopic devices to measure tomato fruit quality.