AMELIORATION OF ZINC DEFICIENCY OF CORN IN CALCAREOUS SOILS OF THAILAND: ZINC SOURCES AND APPLICATION METHODS

A variety of zinc (Zn) fertilizer sources are applied with varied responses on calcareous soils in Thailand. Seed treatment is an alternative method to deliver Zn to corn and alleviate Zn deficiency. To address this Zn delivery methods we conducted greenhouse studies on corn grown in three calcareous soils of Thailand to three Zn fertilizer sources [zinc sulfate (ZnSO₄), Zn-ethylenediaminetetraacetic acid (EDTA) and Zn citrate]. We also evaluated effectiveness of soaking corn seed in three concentrations of ZnSO₄ (0.4, 0.8 and 1.6%) prior to planting compared to soil applied methods. Applications of zinc increased the growth, dry matter yield and zinc uptake of corn with few differences observed among the types of fertilizers. Seed soaking with ZnSO₄ solution also increased Zn uptake, growth rate and yield comparable to soil-applied Zn. Seed soaking prior to planting is an effective and efficient method to supply Zn to corn grown in Zn deficient calcareous soils of Thailand.     

The onset of planet formation in brown dwarf disks

The onset of planet formation in protoplanetary disks is marked by the growth and crystallization of sub-micrometer-sized dust grains accompanied by dust settling toward the disk mid-plane. Here, we present infrared spectra of disks around brown dwarfs and brown dwarf candidates. We show that all three processes occur in such cool disks in a way similar or identical to that in disks around low- and intermediate-mass stars. These results indicate that the onset of planet formation extends to disks around brown dwarfs, suggesting that planet formation is a robust process occurring in most young circumstellar disks.     

Multiple disturbance patterns and population structure of a tropical tree species,Afzelia africana (Leguminosae–Caesalpinioideae), in two contrasting bioclimatic zones of the Republic of Benin

Understanding how multiple disturbances affect species population structure is crucial for designing a better conservation strategy of threatened species. In this paper, we assessed the disturbance patterns and evaluated their effects on the population structure of Afzelia africana, in two different bioclimatic zones of the Republic of Benin. The main disturbances in the studied area included branch pruning and debarking. Individuals of medium size (20–40 cm) were mostly pruned and debarked. The percentages of pruning and debarking were similar at population level across the two studied bioclimatic zones (t = ?0.04, p = 0.96; t = 0.73, p = 0.48). Examining this at individual level, pruning was similar but debarking was higher in the Sudanian zone (12.14 ± 0.93%) than in the Sudano-Guinean zone (7.44 ± 0.88) (W = 40859, p < 0.001). Population structure was bell-shaped in the Sudanian zone regardless of the disturbance level. In contrast, in the Sudano-Guinean zone, mildly disturbed populations showed an inverse J-shaped structure, whereas those highly disturbed were bell-shaped. This underlined the climatic (dryness) and disturbance effects on the establishment and recruitment of small trees into the next life stage in tropical savanna ecosystems. Good regeneration pattern and the largest individuals were found within the protected areas, demonstrating the prominent role of protected areas for the species conservation. Therefore, we suggested that conservation efforts should be extended to populations outside the protected areas. Forestry department should establish firebreaks networks to protect small individuals and facilitate their recruitment, as well as the regulation and enforcement should be improved on the sustainable use of the species.     

Improved purity and immunostimulatory activity of β-(1→3)(1→6)-glucan from Pleurotus sajor-caju using cell wall-degrading enzymes

The objective of this work was to improve the purity of β-(1→3)(1→6)-glucan in the native triple helical structure from the fruiting bodies of Pleurotus sajor-caju for effective biological function using cell wall-degrading enzymes. A crude carbohydrate was extracted with hot water, then treated with crude xylanase and cellulase from Paenibacillus curdlanolyticus B-6. β-Glucan in the extract was purified to homogeneity with a single and symmetrical peak using 650M DEAE Toyopearl and Sepharose CL-6B column chromatography. The purity of β-glucan was confirmed by high-performance size-exclusion chromatography. Purified β-glucan was obtained at a purity of up to 90.2%. The Congo red reaction and atomic force microscopy indicated that the purified β-glucan exhibited a triple helix conformation. Purified β-glucan was able to effectively up-regulate the functions of macrophages such as nitric oxide (NO) and tumor necrosis factor (TNF-α) production.     

Physicochemical and flavor characteristics of flavoring agent from mungbean protein hydrolyzed by bromelain

Enzymatic bromelain mungbean meal protein hydrolysate (eb-MPH) was produced from mungbean meal protein isolate (MPI). Enzymatic bromelain, with a known protease activity of 98,652 (unit/g), was used at concentrations of 0, 2, 6, 10, 14 and 18% (w/w) and with hydrolysis times of 0.5, 3, 6, 12, and 24 h. The pH and temperature were controlled at 6.0 and 50 °C, respectively. It was found that the best treatment combination for eb-MPH production by response surface methodology (RSM) was 18% bromelain and a hydrolysis time of 3 h, resulting in the greatest degree of hydrolysis (% DH) and percent yield, with values of 61.04 and 45.63%, respectively. Results also showed that the phenylalanine, tyrosine and leucine contents of the optimally produced eb-MPH were 20.88, 14.50 and 10.93%, respectively. Twelve volatile compounds were identified using gas chromatography mass spectrometry in eb-MPH; benzaldehyde, 2-pentylfuran and furfural were the predominant odorants.     

Biodegradable foam tray from cassava starch blended with natural fiber and chitosan

This work developed biodegradable foam trays from cassava starch blended with the natural polymers of fiber and chitosan. The kraft fiber at 0, 10, 20, 30 and 40% (w/w of starch) was mixed with cassava starch solution. Chitosan solution at 0, 2, 4 and 6% (w/v) was added into starch/fiber batter with 1:1. Hot mold baking was used to develop the cassava starch-based foam by using an oven machine with controlled temperature at 250 °C for 5 min. Results showed that foam produced from cassava starch with 30% kraft fiber and 4% chitosan had properties similar to polystyrene foam. Color as L^*, a^* and b^* value of starch foam tray was slightly increased. Density, tensile strength and elongation of the starch-based foam were 0.14 g/cm³, 944.40 kPa and 2.43%, respectively, but water absorption index (WAI) and water solubility index (WSI) were greater than the polystyrene foam.