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1
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
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Effects of rice blast fungus (Pyricularia grisea) on phenolics, flavonoids, antioxidant capacity in rice (Oryza sativa L.)

100%
Toan N. P., Ha P. T. T., Xuan T. D.
International Letters of Natural Sciences
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2017
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tom 61
Rice blast fungus (Pyricularia grisea) is one of the most problematic pathogen to significantly reduce rice production worldwide. In this study, after being inoculated with P. grisea, changes in phenolic components and antioxidant capacity and correlation with the resistant level against rice blast fungus were investigated. Among screened rice cultivars, AV-3 was the strongest resistant, whereas BII-3 was the most susceptible. It was found that although total contents of phenolics and flavonoids, and antioxidant capacities varied among studied varieties, no significant coefficient with the resistance against P. grisea was observed. After rice was affected by rice blast fungus, total phenolics and flavonoids were markedly reduced, but in contrast, the DPPH scavenging activities of only the susceptible rice cultivars was reduced. Among the 11 phenolic acids detected, catechol was found only in the tolerant cultivar AV-3, whereas the amount of cinnamic acid was increased after infection. Quantity of vanillin was also promoted, except in the susceptible cultivar BII-3 that was significantly reduced. Findings of this study showed that the resistant level against P. grisea was proportionally correlated to the antioxidant capacity. Catechol, cinnamic acid, and vanillin may play a role but it needs further elaboration. Observations of this study suggested that the infection of blast disease by reducing amount of phenolics and flavonoids that may weaken the resistance of rice against this detrimental fungus.
2
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Phenolic compounds and antioxidant activity of Castanopsis phuthoensis and Castanopsis grandicicatricata

76%
Tuyen P. T., Khang D. T., Minh L. T., Minh T. N., Ha P. T. T., Elzaawely A. A., Xuan T. D.
International Letters of Natural Sciences
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2016
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tom 55
In this study, total phenolic and flavonoid contents, antioxidant capacity, and phenolic compositions of Castanopsis phuthoensis and Castanopsis grandicicatricata (Fagaceae family) were investigated. It was found that bark extracts were rich of phenolic contents, whereas leaf extracts were abundant of flavonoids. The total phenolics varied from 11.20 to 35.47 mg gallic acid equivalent g-1 dry weight (DW), and the total flavonoids were from 2.24 to 12.55 mg rutin equivalent g-1 DW. The results of antioxidant activity evaluation showed that the DPPH (1,1- diphenyl-2-picryl-hydrazyl) radical scavenging activity of the free phenolic extracts were higher than the bound phenolic extracts. Regarding the reducing power and β-carotene bleaching assays, the free phenolic extracts showed remarkably strong antioxidant capacity that were similar to the levels of the standard BHT (dibutyl hydroxytoluene) did. It could be concluded that free phenolic extracts were more effective in antioxidant activities than bound phenolic extracts. Highly significant correlations were observed between phenolic contents and antioxidant activities (0.813 for DPPH and 0.841 for reducing power). By HPLC analysis, seven phenolic acids were detected including gallic, p-hydroxybenzoic, vanillic, sinapic, p-coumaric, ellagic acids, and vanillin. Of which, gallic, ellagic, and sinapic acids were the most abundant compounds in the two species. The results suggest C. phuthoensis and C. grandicicatricata contain rich sources of natural antioxidants and phenolic compounds which are probably considered in pharmaceutical use.
3
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
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Study on physical-chemical characters and heritability for yield components in rice (Oryza sativa L.)

76%
Ha P. T. T., Khang D. T., Tuyen P. T., Minh T. N., Xuan T. D., Lang N. T., Buu B. C.
International Letters of Natural Sciences
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2016
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tom 57
Present study was performed to analysis both physical and chemical properties of rice germplasm and heritability for yield components in combinations. A total of 44 lines/varieties obtained from Cuu Long Rice Research Institute genebank, and 30 F1 generation combinations were evaluated. The results showed that the rice line IR79008-B-11-B-B-1 showed overall good physical characters (head rice, grain length, grain width, chalkiness). In terms of chemical characteristics, three varieties IR75499-73-1-B, OM6162, and OM4900 were found to have good amylose content, gel consistency, protein content, gelatinization temperature, and aroma. A very notable finding was that the cross between OM6162/SwarnaSub1 that low amylose content (20.2%), high gel consistency (78.2 mm), high protein content (8.1%), appropriate gelatinization temperature (scale 5), low chalkiness (level 0), high heritability (0.9) for grain yield trait/cluster, and (0.84) for the number of panicles/cluster. Moreover these characters consist of plant height, panicle length, number of panicles/cluster, number of filled grains/panicle, number of unfilled/panicle, and grain yield/ cluster showed moderate to high heritability of mean for combination OM6162/SwarnaSub1. The results suggest that the grain yield trait/cluster and the number of panicles/cluster are important yield contributing traits to rice breeders for selecting ideal combinations for higher yield and quality of next generations.
4
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
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Effects of salinity stress on growth and phenolics of rice (Oryza sativa L.)

76%
Minh L. T., Khang D. T., Ha P. T. T., Tuyen P. T., Minh T. N., Quan N. V., Xuan T. D.
International Letters of Natural Sciences
|
2016
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tom 57
This study was conducted to determine the correlation between of salinity stress on growth and phenolic compounds in rice. It was observed that salinity stress caused a significant decrease in shoot lengths, fresh and dry weights of all rice varieties. Under salinity stress, changes of chemical contents also differed among phenolic compounds and rice cultivars. Total phenolics and flavonoids, and contents of vanillin and protocatechuic acid in tolerant varieties were strongly increased, whereas in contrast, they were markedly reduced in the susceptible cultivar. Ferulic acid and p-coumaric acid were detected only in tolerance rice. Vanillin and protocatechuic acid may play a role, but ferulic acid and p-coumaric acid may be much involved in the tolerant mechanism against salinity stress. Ferulic acid and p-coumaric acid and their derivatives are potent to be exploited as promising agents to reduce detrimental effects of salinity stress on rice production.
5
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Involvement of phenolic compounds in anaerobic flooding germination of rice (Oryza sativa L.)

64%
Khang D. T., Ha P. T. T., Lang N. T., Tuyen P. T., Minh L. T., Minh T. N., Bach D. T., Xuan T. D.
International Letters of Natural Sciences
|
2016
|
tom 56
By this study, thirty rice varieties were evaluated for anaerobic flooding tolerance using the direct sowing method. Phenolic profiles of strong and weak tolerant varieties were identified and compared based on HPLC chromatograms. The germination rates and shoot heights of rice were recorded for calculating the seedling vigor, which indicate the tolerant ability of rice in flooding condition. The results revealed a high variation of germination rate (10.01 to 100%), shoot height (0.35 to 78.17 mm) and seedling vigor (0.05 to 72.83). There was a high correlation between (r = 0.71) germination rate in 5 cm and 10 cm flood. Phenolic and flavonoid contents of the strong tolerant cultivar significantly and proportionally increased in the flooding levels (5 cm and 10 cm). There was a total difference in terms of number of phenolic acids found in the strong and weak tolerant varieties. In particular, six phenolic acids (gallic acid, catechol, caffeic acid, syringic acid, vanillin, and ellagic acid) were only identified with high concentration in the strong tolerant cultivar. The findings suggest that the phenolics presented in the strong tolerant varieties probably have a certain function in response and adaptation to anaerobic flooding condition. Further researches on exogenous application of these phenolic acids to increase the flooding tolerant level of rice should be continued at both green house and field treatments.
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