Vol. 1 No. 3 (2018): Vietnam Journal of Agricultural Sciences

Genetic variability and heritability of quantitative traits, particularly of yield contributing traits, are of great importance in understanding phenotypic variation and the heritable portion of the variation when making selection choices. In the present study, the heritability for days to 50% flowering, days to maturity, plant height at maturity, total number of pods per plant, number-filled pods per plant, 100-seed weight, and grain yield per plant were estimated by variance components from variance analysis of parents and F2 and F2:3 progeny families derived from a single cross. Heritability estimates were high for days to 50% flowering and 100-seed weight, moderate for the number of pods per plant and number of filled pods per plant, and low for seed weight per plant. These results suggested that in the early segregating generations, direct selection for seed size, plant height, and a number of pods per plant might be more efficient than the direct selection for seed yield.

The objectives of this study were to investigate the morphological characteristics, grain yield, and anthocyanin content of 36 black rice accessions that were collected from different locations in Vietnam. The results showed that the black rice accessions varied in growth duration (130 to 150 days), plant height (91.5 to 143.6 cm), morphological characteristics, and yield components. Grain yield of the black rice accessions ranged from 2.8 to 8.7 tons ha-1. The black rice accessions were classified into four groups based on their anthocyanin content: group I > 0.1% anthocyanin, group II 0.05%-0.1%, group III 0.001%-0.05%, and group IV < 0.001%. BR7 had the highest anthocyanin content (0.1438%), followed by BR5 (0.1317%). Anthocyanins with the strongest antioxidant activities were extracted from BR8, BR35, BR6, BR27, BR30, BR32, BR18, BR17, BR19, and BR1 with IC50 values less than 2 µg mL-1. Seven promising black rice accessions, namely BR1, BR14, BR17, BR25, BR30, BR34, and BR35, were selected for further research based on their high anthocyanin contents, and good grain yield and yield components.

Histamine is considered to be a hazard in fish sauce, and histamine poisoning usually causes symptoms such as a runny nose, asthma (bronchospasm), urticaria, rash, itching, swelling (eyelids, puffy lips), inflammation, and redness of the conjunctiva. In this study, Cat Hai fish sauce, one of the major traditional fish sauce manufacturers in Vietnam, was used to investigate the variation in histamine content during the fermentation process and to isolate histamine-producing bacteria. Six Dich Chuop samples corresponding to the first sixth months from the beginning of fermentation were collected for these purposes. The results showed that the content of histamine in the six samples corresponding to the first six months from the beginning of fermentation tended to increase during fermentation, reaching the highest rate of 604.85 ppm in the fifth month. A total of 50 isolates were collected from TSA medium and used for screening histamine-producing bacteria on HBI medium. Among these bacteria, four isolates (CH2.4, CH3.3, CH4.4, and CH5.1) were capable of producing histamine, and the highest producing isolate, CH5.1 (from 5th month), was identified as Tetragenococus halophilus. Furthermore, this Tetragenococus halophilus was determined to have the highest histamine production in HBE supplemented with 1% histidine at 50°C, pH 6.0, and 25% NaCl.

There are currently many places in the world where water is scarce. Therefore, water reuse has been mentioned by many researchers. Evaluation of water reuse applications is the selection of the best water reuse application of the existing options; it is also one of the applications of multi-criteria decision making (MCDM). In this paper, we introduce a new dissimilarity measure of picture fuzzy sets. This new measure overcomes the restriction of other existing dissimilarity measures of picture fuzzy sets. Then, we apply it to the multi-criteria decision making. Finally, we refer to a new method for selecting the best water reuse application of the available options by using the picture fuzzy MCDM.

Most rice growing areas frequently encounter the bacterial leaf blight, Xanthomonas oryzae pv oryzae (Xoo). To prevent the disease, development of resistant varieties is considered to be the most economical and environmentally safe solution. In this study, three PCR-based markers, Npb181, RM122, and P3, were used for the identification of the genes Xa4, xa5, and Xa7, respectively, from 56 local black glutinous rice accessions of Vietnam. Phenotypic screening of the accessions for resistance to 10 Xoo strains of North Vietnam, along with IRBB4, IRBB5, and IRBB7 as resistant controls and IR24 as a susceptible control were carried out in the 2016 Autumn season. 19 accessions containing the resistant genes were found, of these, 6 accessions carried Xa4 gene, 6 accessions carried xa5 gene, and 11 accessions carried Xa7 gene. Three accessions carried two resistance genes, viz. Nep do (Xa4 and Xa7), Pau cam (xa5 and Xa7), and Pe lon cam (Xa4 and xa5). Accessions with xa5 and Xa7 alone or with a combination of two genes (Xa4 and xa5, Xa4 and Xa7, or xa5 and Xa7) were resistantto 8-9 Xoo strains (8-9R/0M/1-2S). Accessions containing Xa4 showed resistance to 5-6 strains of Xoo (5-6R/0M/4-5S). Xoo strain No1 (HUA01043) showed the lowest virulence, infecting only 14 accessions (42R/4M/14S). Strains No3 (HUA 0020131-2), No4 (HUA202361), No5 (HUA20212), and No8 (HUA 020083) showed highest virulence, and they each infected more than 40 accessions with 19R/0M/41S, 20R/0M/40S, 16R/4M/40S, and 20R/0M/40S, respectively. These strains can even infect some accessions containing effective resistant genes (Xa4 or Xa7).