Abstract Increasing the domestic production of Brassica vegetables is important to sustain the local food supply, maintain the healthy diets of the population, reduce the country's foreign exchange, and improve the local economy. In this study, a column hydroponic system (CHS) of 1.2 m L × 1.2 m W × 1.5 m H was built and tested to increase Brassica vegetable production per unit area. There were 16 rectangular polyvinyl chloride tubes (10.2 cm L × 5.1 cm W × 1.5 m H) positioned upright (PVC columns) at 30.0 cm apart in four rows. Each column had 36 planting cups (4 lines × 9 levels). The seeds of curly dwarf Pak-choy were germinated on mop yarns in the cups. The nutrient solution was supplied using a 0.5HP non-submersible pump. Data were recorded on day 37 by measuring the vegetable yield, development, growth, and quality. The data were analyzed using Microsoft Excel®2019 by performing one- and two-way ANOVAs, followed by post-hoc tests (α = 0.05). The vegetable yield/area of the CHS (12.7 kg/m2, or 400 plants/m2) was 60% higher than that of a raft hydroponic system (5.1 kg/m2, or 63 plants/m2), but the mean weight/plant was 62% lower than that of the latter system (31.3 g/plant vs. 82.1 g/plant). There were statistically significant (P < 0.05) effects of column horizontal position (CHP) or vegetable vertical location (VVL) on the parameters studied. However, the effects of CHP × VVL was statistically significant only on yield and leaf area. Pak-choy in outer columns facing the morning and afternoon sunlight directly or at the top were heavier (39.2 - 71.7 g/plant) than those in inner columns or at the bottom (8.8 - 20.3 g/plant). The CHS can be used effectively to increase Brassica vegetable production/area, but its full potential is yet to be achieved. Research is recommended to determine the ideal column spacing to achieve the best balance between plant/area and weight/plant to increase further the system's growth, yield, and quality of vegetables.

Abstract The objective of this study was to evaluate the effects of different drying methods on phytochemicals and in vitro antioxidant activity of brown seaweed, Sargassum polycystum. Six different drying methods employed in this study were freeze drying, oven drying at 40 °C, oven drying at 60 °C, sun drying, vacuum drying at 40 °C and vacuum drying at 60 °C. Five different polarity solvents, methanol, ethanol, acetone, ethyl acetate, cold water and hot water were used as extraction solvents to determinephytochemicals content for total phenolic content, total flavonoid content and total carotenoid content while that antioxidant activitywas assessed by employing ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH) and beta carotene bleaching (BCB) assay. Ethyl acetate extracts vacuum dried at 40 °C showed highest total phenolic content (58.54 ± 1.30 mg PGE g^-1 dry extract), total flavonoid content (35.91 ± 1.54 mg RE g^-1 dry extract), FRAP value 379.41 ± 1.17 µmol TE g^-1 dry extract and DPPH EC50 values, 3.83 ± 0.18 mg mL^-1 among all drying methods. Sun dried extracts possessed lowest retention of phytochemicals content and antioxidant activity among other drying methods. As a conclusion, S. polycystum was best dried by vacuum drying methodat 40 °C which has the higher retention of phytochemicals and antioxidant content.