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Isolation and gene expression profiling of drought-responsive genes in upland rice (Oryza sativa L.)
Get PDFAbiotic stresses negatively affect stable crop production yield world-wide. The yield
of rice production is affected by drought or water deficit. Water shortage and uneven
rainfall distribution limit the use of available water for rice production. The irrigation
costs increase yearly in water limited area. Therefore, developing rice varieties with
high water use efficient is needed currently. Upland rice performs better and drought
tolerant under water limited environment although the yield is low. Therefore, the
upland rice can serve as genetic resources for genetic manipulation of susceptible
crops. The objectives of the study were: (i) to screen for drought-tolerant upland rice
varieties, (ii) to isolate and identify the expressed drought-responsive genes in
drought-tolerant upland rice under water limitation, and (iii) to examine the
differential expression of transcripts under drought stress and normal conditions.
Investigation was performed to evaluate 38 upland rice varieties with five drought
levels at germination and early seedling growth stage using PEG 6000 as drought
inducer. Drought tolerant variety, IR5533-15-1-1 (S24) had better germination
indices, root length, the highest enzymatic antioxidant activity and non-enzymatic
antioxidant level (proline) compared to sensitive varieties. Pot experiment was
conducted on IR5533-15-1-1 (S24) variety that were (i) watered regularly (un-treated
and control plants) and (ii) treated with PEG 6000 solution (-8 bar) for five days at
reproductive stage. Then, isolated mRNA from leaves (control and treated plants)
was used to generate subtracted cDNA library. The expressed sequence tags (ESTs)
were analyzed. Reverse transcriptase PCR and real-time PCR were conducted to
analyze the expression profiles of drought-responsive genes from upland rice. Two
EST sequences identified showed 87% and 97% similarities to that of glutathione Stransferase
(GST) and dehydrin (DHN) from rice, respectively. The expression levels
of GST and DHN transcripts in PEG-treated plants were higher than those of
untreated plants. The expression of GST was up-regulated and reached a peak at 3
days after treatment (DAT) in leaves (2.5 folds increase) and roots (2 folds increase).
On the other hand, the levels of DHN expression showed higher expression in leaves
and roots at 4 DAT (2.1 folds increase) and 3 DAT (2.7 folds increase), respectively.
The up-regulation of GST and DHN transcripts indicate upland rice defense response was activated during drought stress. This study has successfully identified the
differentially expressed drought-responsive genes in upland rice under drought
stress
Effect of humic acid application on growth of upland rice
Get PDFMalaysia produces about 3.0 t ha−1 of rice annually which can only cater to around 65% of the national domestic requirement. Malaysia still imports 35% of rice to meet the local demand. In addition, the price of chemical fertilizers is increasing yearly. Thus, measures are taken to increase rice productivity with the lower usage of chemical fertilizers. A study was conducted in an insect-proof house located at the Faculty of Sustainable Agriculture, Universiti Malaysia Sabah, Malaysia to investigate the effect of humic acid (HA) on Tadong upland rice growth performances and the yield on replacing the use of chemical fertilizer (NPK). This study consisted of T1 positive control (NPK 60:30:30), T2 (2% (w/v) HA + NPK 30:15:15), T3 (4% (w/v) HA + NPK 30:15:15), T4 (6% (w/v) HA + NPK 30:15:15), T5 (8% (w/v) HA + NPK 30:15:15) and T6 negative control (NPK 30:15:15). The growth components analyzed were plant height, number of tillers per hill, percentage of productive tillers, number of leaves, panicle length, flag leaf length and phenology. Application of 4% (w/v) HA results in an increase in the percentage of productive tillers. On the other hand, the application of 8% (w/v) HA showed an increase in the number of leaves. In addition, the application of 2% (w/v) HA leads to higher flag leaf length. Therefore, humic acid at 2% (w/v) with half of the recommended NPK (30:15:15) can be used to produce better vegetative growth of Tadong upland rice and reduce chemical fertilizer usage in rice cultivation
Effect of humic acid on growth and yield of Tadong upland rice
Get PDFMalaysia imports 35% of rice to meet local demand. To meet local demands, rice production must be increased by using sufficient chemical fertilizers. However, the cost of chemical fertilizers rises yearly. Thus, efforts are being made to increase rice productivity while using less chemical fertilizer. The study aimed to investigate the effect of humic acid on Tadong upland rice growth and yield offer the use of chemical fertilizers (nitrogen (N), phosphorus (P), and potassium (K)). The experiment was laid out in a completely randomized design with five replications. The application of different concentrations (2-8 g/mL) of human acid (HA) with half of the recommended NPK (30:15:15) was studied. It is found that using 2 g/mL HA with half of the recommended NPK led to a higher flag leaf length and grain yield per pot. Therefore, HA at 2 g/mL with half of the recommended NPK can produce better vegetative growth and yield of Tadong upland rice. Also, it can reduce chemical fertilizer usage in rice cultivation
Effect of boiler ash produced from oil palm waste on the growth and yield of TR8 lowland rice
Get PDFThe increasing global population has led to a projected rise in food demand, creating concerns over food security. Kota Belud, the “rice bowl” of Sabah has a very acidic soil (3.66 pH). The suitable soil pH for growing rice is 5.5 to 6.5. This study aims to determine the best planting media formulation for the growth and yield of TR8 rice. The analysis revealed that 50 t ha⁻¹ boiler ash produced the highest mean chlorophyll content (26.98 SPAD), mean number of tillers per hill (23.40), and mean yield per pot (795.15 g m⁻²). In addition, boiler ash at 40 t ha⁻¹ produced the highest mean percentage of filled grain (88.69%), mean number of panicles (23.0), and the lowest mean percentage of unfilled grain (11.31%), On the other hand, the control treatment (without boiler ash) produced the highest mean flag leaf length (38.22 cm). This study showed that boiler ash at 50 t ha⁻¹ potentially improved vegetative growth and increased yield of TR8 lowland rice. Future study should aim to evaluate the impact of oil palm boiler ash on various soils type and rice varieties in a field experiment
Potential antioxidant properties of pigmented rice from Sabah, Malaysia
Get PDFIn this study, the methanolic crude extracts of four Sabah rice varieties namely black, red, brown and white rice
were screened for their total phenol acids content, tocopherol content, antioxidant and free radical scavenging properties. The red rice contained the highest quantity of phenolic acids (329.93 ± 19.17 mg/100 g) and tocopherols (200.33 ± 13.61 mg/100 g). To detect antioxidant activity of the pigmented rice extracts, ferric thiocyanate (FTC) assay was used and compared with the thiobarbituric acid (TBA) method. Scavenging activity was measured by 2, 2-diphenyl-1-picrylhydrazyl(DPPH) radicals. Red rice extract showed the highest activity for all the three tests, FTC (0.302), TBA (0.329) and DPPH(65.54% ± 0.57) due to its high content of phenolic acids and tocopherols. The results indicate that the pigmented rice varieties possess protective effects against the generation of hydroperoxide and free radical scavenging activity. The antioxidant activity of the extracts differed and was dependent on the bran color of the rice. The results showed that the antioxidant activity was in the following order: red rice > black rice > brown rice > white rice. In conclusion, antioxidant activity was strongly correlated to the total phenolic acids and tocopherols content
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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