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28 September 2017, Volume 24 Issue 5 Previous Issue    Next Issue
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Effects of Polishing on Proximate Composition, Physico- Chemical Characteristics, Mineral Composition and Antioxidant Properties of Pigmented Rice Koteswara Reddy Chagam, Kimi Lalmuan, Haripriya Sundaramoorthy, Kang Nayoung 2017, 24(5): 241-252.  DOI: 10.1016/j.rsci.2017.05.002 Abstract ( )   HTML ( )   PDF (684KB) ( )   The effects of polishing on proximate compositions, physico-chemical characteristics, mineral compositions and antioxidant properties of the rice flours obtained from three different pigmented rice varieties (Chak-hao Angangba, Chak-hao Amubi and Chak-hao Poireiton) were investigated. The rice varieties were significantly (P < 0.05) different in the contents of the test characteristics. Lipids, ash, minerals, phytochemicals (phenolic acids and flavonoids) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity of rice flours were decreased after polishing (9% degree of milling), while amylose content and lightness were increased. X-ray diffraction pattern of rice flours exhibited A-type crystalline pattern with reflections at 15.1º, 17.1º, 18.2º and 23.0º. Pasting properties and transition temperatures were decreased after polishing treatment. Polishing resulted in changes in the crystallinity, enthalpy and morphology of rice flours.

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Screening for Osmotic Stress Responses in Rice Varieties under Drought Condition Swapna Simon, Samban Shylaraj Korukkanvilakath 2017, 24(5): 253-263.  DOI: 10.1016/j.rsci.2017.04.004 Abstract ( )   HTML ( )   PDF (607KB) ( )   Drought is the major abiotic stress factor that limits rice production worldwide. To evaluate the osmotic stress responses in rice varieties under drought condition, a total of 42 high-yielding rice varieties were collected from various research stations of Kerala Agricultural University in India. The experimental setup comprises of initial hydroponic treatments at different osmotic potentials, artificially induced by desired strengths of polyethylene glycol (PEG6000), and followed by the pot planted experiments in the rain-out-zone. The activities of antioxidant enzymes, relative water content, cell membrane stability, photosynthetic pigments, proline content, along with plant growth parameters of the varieties under drought condition were evaluated. Moreover, the standard scores of these rice varieties were assessed under stress and recovery conditions based on the scoring scale of the Standard Evaluation System for rice. Among the 42 rice varieties, we identified 2 rice varieties, Swarnaprabha and Kattamodan, with less leaf rolling, better drought recovery ability as well as relative water content, increased membrane stability index, osmolyte accumulation, and antioxidant enzyme activities pointed towards their degree of tolerance to drought stress. The positive adaptive responses of these rice varieties towards drought stress can be used in the genetic improvement of rice drought resistance breeding program.

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Enhancement of Growth and Grain Yield of Rice in Nutrient Deficient Soils by Rice Probiotic Bacteria Mohibul Alam Khan Md, Haque Effi, Chandra Paul Narayan, Abdul Khaleque Md, M. S. Al-Garni Saleh, Rahman Mahfuzur, Tofazzal Islam Md 2017, 24(5): 264-273.  DOI: 10.1016/j.rsci.2017.02.002 Abstract ( )   HTML ( )   PDF (744KB) ( )   Plant associated bacteria are promising alternatives to chemical fertilizers for plant growth and yield improvement in an eco-friendly manner. In this study, rice associated bacteria were isolated and assessed for mineral phosphate solubilization and indole-3-acetic acid (IAA) production activity in vitro. Six promising strains, which were tentatively identified as phylotaxon Pseudochrobactrum sp. (BRRh-1), Burkholderia sp. (BRRh-2), Burkholderia sp. (BRRh-3), Burkholderia sp. (BRRh-4), Pseudomonas aeruginosa (BRRh-5 and BRRh-6) based on their 16S rRNA gene phylogeny, exhibited significant phosphate solubilizing activity in National Botanical Research Institute phosphate growth medium, and BRRh-4 displayed the highest phosphate solubilizing activity, followed by BRRh-5. The pH of the culture broth declined, resulting in increase of growth rate of bacteria at pH 7, which might be due to organic acid secretion by the strains. In presence of L-tryptophan, five isolates synthesized IAA and the maximum IAA was produced by BRRh-2, followed by BRRh-1. Application of two most efficient phosphate solubilizing isolates BRRh-4 and BRRh-5 by root dipping (colonization) of seedling and spraying at the flowering stage significantly enhanced the growth and grain yield of rice variety BRRI dhan-29. Interestingly, application of both strains with 50% of recommended nitrogen, phosphorus and potassium fertilizers produced equivalent or higher grain yield of rice compared to the control grown with full recommended fertilizer doses, which suggests that these strains may have the potential to be used as bioinoculants for sustainable rice production.

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Estimating Glycemic Index of Rice-Based Mixed Meals by Using Predicted and Adjusted Formulae Maziah Hanum Osman Nur, Mohd-Yusof Barakatun-Nisak, Ismail Amin 2017, 24(5): 274-282.  DOI: 10.1016/j.rsci.2017.06.001 Abstract ( )   HTML ( )   PDF (589KB) ( )   The estimation of glycemic index (GI) of rice-based mixed meal either by using predicted GI (GIpred) or adjusted GI (GIadj) formula is unclear. This study aimed to determine the glycemic response of rice in rice alone or mixed meals and to identify the appropriate formula for estimating the GI of rice-based mixed meals. The glycemic responses produced by the rice alone (red rice, fragrant white rice or parboiled rice) and the rice-based mixed meals (fried red rice, fried fragrant white rice or fried parboiled rice) which provided 25 g available carbohydrate were assessed in 11 healthy individuals. To determine the measured GI (GImeasured) of rice alone and rice-based mixed meals, participants underwent three repeated tests of a reference food (Glucolin®). Tests were performed in random order on nine separate visits after an overnight fasting for at least 8 h. Capillary glucose at baseline (0 min), 15, 30, 45, 60, 90 and 120 min from starting the meals was assessed and used to determine the incremental area under the curve (iAUC120). The agreement between GImeasured and the estimation formulae (GIpred or GIadj) were determined using Bland-Altman analysis. The iAUC120 after consuming rice alone was significantly higher than the rice-based mixed meals except for fried fragrant rice, which was comparable to the rice alone (P > 0.05). The GImeasured values of rice were categorized as medium (61 for parboiled rice, 67 for fragrant white rice, and 68 for red rice). GIpred (r = 0.40, P < 0.01) and GIadj (r = 0.41, P < 0.01) were significantly correlated with iAUC120. The agreement between GImeasured and GIadj is apparent suggesting the usefulness of GIadj in estimating meal GI of rice-based mixed meals.

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Effects of Silicon-Based Fertilizer on Growth, Yield and Nutrient Uptake of Rice in Tropical Zone of Vietnam Xuan Cuong Tran, Ullah Hayat, Datta Avishek, Cong Hanh Tran 2017, 24(5): 283-290.  DOI: 10.1016/j.rsci.2017.06.002 Abstract ( )   HTML ( )   PDF (368KB) ( )   Application of silicon (Si) could greatly boost rice yield and mitigate abiotic stress, especially drought. A field experiment was conducted during 2015 at the research farm of Hong Duc University, Thanh Hoa City, Vietnam, to evaluate the effects of five different combined doses of standard fertilizer practice and Si fertilizer on growth, yield and yield components, as well as nutrient uptake of rice. The treatments consisted of the recommended dose of fertilizer (RDF, 110 kg/hm2 N + 90 kg/hm2 P2O5 + 80 kg/hm2 K2O) as the control, RDF + 100 kg/hm2 SiO2, RDF + 200 kg/hm2 SiO2, RDF + 300 kg/hm2 SiO2 and RDF + 400 kg/hm2 SiO2. The results showed that the growth, grain and straw yields as well as yield components (number of grains per panicle, seed-setting rate and 1000-grain weight) were significantly affected by Si application. The highest grain yield of 3 705 kg/hm2 was obtained with the highest level of Si fertilizer in combination with RDF (RDF + 400 kg/hm2 SiO2), however, it was statistically at par with the yields obtained with RDF + 300 kg/hm2 SiO2 (3 664 kg/hm2) and RDF + 200 kg/hm2 SiO2 (3 621 kg/hm2). The optimum dose of Si fertilizer with maximized grain yield (3 716 kg/hm2) was 329 kg/hm2 SiO2. The nutrient (Si, N, P and K) uptakes of rice were also significantly enhanced by Si application. Si application at the level of 329 kg/hm2 along with RDF would help in the sustainable production of rice in the tropical zone of Vietnam.

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Identification and Characterization of Genes Responsible for Drought Tolerance in Rice Mediated by Pseudomonas fluorescens Saakre Manjesh, Meera Baburao Thirthikar, Puthenpeedikal Salim Abida, Mary Ffancies Rose, Poothecty Achuthan Valasala, Thomas George, Radha Sivarajan Sajeevan 2017, 24(5): 291-298.  DOI: 10.1016/j.rsci.2017.04.005 Abstract ( )   HTML ( )   PDF (588KB) ( )   Drought is one of the major abiotic stresses which adversely affect crop plants limiting growth and yield potential. Structural and functional characterization of drought stress-induced genes has contributed to a better understanding of how plants respond and adapt to the drought stress. In the present study, differential display technique was employed to study the gene expression of rice plants at the reproductive stage that were subjected to drought stress by withholding water, Pseudomonas fluorescens strain (Pf1) treated plants subjected for drought stress by withholding water and control (well-watered). Differentially expressed cDNAs of six genes (COX1, PKDP, bZIP1, AP2-EREBP, Hsp20 and COC1) were identified, cloned and sequenced. Real-time qPCR analysis showed that all the six genes were upregulated in drought-stressed plants treated with Pf1. This revealed that the remarkable influence of Pf1 colonization leads to drought tolerance at the reproductive stage. These results showed that high levels of gene expression in plants lacking adequate water can be remarkably influenced by Pf1 colonization, which might be a key element for induced systemic tolerance by microbes.