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  • Author or Editor: I. Sharma x
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Two hundred and seventy wheat varieties developed in India during the past 100 years were assessed for allelic diversity of waxy genes and two hundred varieties for starch pasting properties. Large variation was exhibited in starch pasting properties such as peak viscosity (159.3 to 303.2 RVU), RVA breakdown (28.5 RVU to 111.4 RVU), setback (73.2 to 116.3) and final viscosity (109.2 to 309.1 RVU) measured by Rapid Visco-Analyzer. Flour swelling power varied from 10.25 to 16.19 with the average value of 13.24. Final viscosity showed strong positive correlation with peak viscosity (R2 = 0.55). Significant positive correlation was observed between peak viscosity and flour swelling power (R2 = 0.37). Because flour swelling can be measured using 40 mg of the flour, it has utility in breeding programme to identify desirable recombinants in early segregating generations. Polymerase chain reaction (PCR) amplification of Wx-B1 locus showed the presence of Wx-B1 null in 60% of the varieties and exhibited significant positive correlation with peak viscosity (P < 0.01), flour swelling power (P < 0.001) and RVA breakdown (P < 0.001). Therefore, the combination of both the PCR for Wx-B1 null and microlevel test for starch properties such as FSP can be used for the improvement of flour properties suitable for various end-use products of wheat.

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Energy dispersive X-ray fluorescence spectroscopy (EDXRF) has been used for elemental analysis of Cu−Ni alloy, neodymium aluminide, and iron and nickel powder. The preparation of Cu−Ni alloy and neodymium aluminide has been carried out by aluminothermic reduction of mixed oxides of copper and nickel and neodymium oxide respectively. Aqueous electrorefining technique has been followed for the preparation of iron and nickel powder using Fe−Ni alloy as anode. The determination of major and trace elements present in the Cu−Ni and, electrolytically refined nickel and iron has been accomplished by EDXRF using Cd109 radioisotope source. In the case of Nd−Al alloy Am241 radioisotope source has been used. The rapid and multielement analysis of the thermit product by EDXRF has aided in the appropriate variation of the charge constituents during the standardization of the optimum charge composition for Cu−Ni alloy. EDXRF analysis of electrolytically refined nickel and iron revealed heavy contamination of iron in nickel as compared to that of nickel in iron. Neodymium content has been found to be 67.68% in Nd−Al alloy.

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Two hundred and forty diverse set of wheat cultivars released in India during the last several decades were evaluated for HMW and LMW glutenin alleles, for assessing their diversity and effect on sedimentation volume and mixograph parameters. Both SDS-PAGE and PCR based markers were employed in identifying alleles encoded at Glu-1 and Glu-3 loci. Extensive allelic variation was observed at both the Glu-1 and Glu-3 loci. There was prevalence of Glu-A1b, Glu-B1i, Glu-D1a, Glu-A3c, Glu-B3b, Glu-B3g and Glu-D3b. The alleles Glu-A1b, Glu-B1i, Glu-D1d, Glu-A3b, Glu-B3g/h and Glu-D3b exhibited high SDS-sedimentation volume. Glu-B1i and Glu-D1d showed highly significant positive effect (p < 0.001) on sedimentation volume and also had additive effects. However, surprisingly overall there was decline in the frequency of Glu-B1i allele during last two decades in Indian wheat breeding and not a single 1B/1R translocation cultivar possessed this allele. Glu-A1b showed significant positive effect on mixograph peak time, peak slope and peak width. Glu-B3g exhibited significantly higher mixograph peak time and width at 8 and Glu-B3h showed higher dough stability. Glu-B3j (1B/1R translocation) exhibited highest peak slope indicating the negative effect on dough strength. This information can be useful in designing breeding program for the improvement of Indian bread wheat quality.

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Silver tellurite, prepared by precipitation, crystallized in tetragonal form and DSC studies show that it undergoes phase transformations on heat-treatment in the temperatuae ranges 578–604 K and 695–717 K. X-ray diffractometry suggests that in the first transformation, which is irreversible, the tellurite transforms to monoclinic form. The second transformation is reversible and the high temperature phase reverts back to the monoclinic form on cooling. The reversible phase transformation could be ascertained by electrical resistivity and reflectance spectrum measurements. The kinetic parameters, computed from the DSC data, show that the energy of activation, entropy of activation and the frequency factor are high. This is attributed to the effectiveness of a large number of vibrations.

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Loose smut of wheat is a disease of world wide significance. Resistant cultivars constitute a potentially useful and environmentally benign method of controlling this disease. The genetic basis of resistance in 20 wheat genotypes with resistance to Ustilago tritici race T11 was studied in crosses with the widely grown but susceptible Indian cultivar, PBW 343. These lines were also involved in 10 ‘resistant × resistant’ crosses, to infer diversity for resistance genes in this set. All 30 crosses were developed to the F3 stage. Fifteen parents were inferred to carry dominant genes for resistance to race T11. Ten of these resistant lines (ML 521, W 59, W 1616, W 2484, W 2531, W 5915, W 6202, WL 1786, WL 2956 and WL 3450) had resistance controlled by 2 dominant genes acting in a complementary manner whereas in 4 lines (W 4461, W 5100, W 2615 and WL 3951), there was a single dominant gene and in a single genotype, WL 5907, there were 2 dominant genes with duplicate gene action governing the resistance. In lines W 2139, W 3899, W 4985, W 5450 and W 5792 a single recessive gene conferred resistance. Inheritance in two crosses, one derived from a line possessing a single dominant gene and the other from a line possessing a single recessive gene was re-analyzed and successfully confirmed in F5 generation. The segregation of most of the ‘resistant × resistant’ crosses conformed to the inferences drawn about the parents in the ‘resistant × susceptible’ crosses.

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The role of antibiosis components and antioxidant defense of rice genotypes, namely CR3006-8-2, RP4918-221, KAUM182-1, T12, IHRT-ME-25, W1263, Ptb33 (resistant check) and TN1 (susceptible check) was studied by phenotyping them against brown planthopper (BPH). Three genotypes, namely KAUM182-1, RP4918-221 and CR3006-8-2 were resistant to BPH and significantly low damage score (1.97–3.00); honeydew excretion area (46.76–49.64 mm2); nymphal survival (60.60–66.40%) and growth index (2.98–3.86) was recorded on them. Higher constitutive and induced level of soluble phenolics, peroxidase and polyphenol oxidase was observed in resistant genotypes without and with BPH infestation. A negative relationship between honeydew excretion, nymphal emergence, growth index and nymphal survival was observed with these biochemical constituents. Likewise, a reverse trend was observed between nymphal development period and biochemical constituents. These genotypes have emerged as a new source of resistance to BPH which can be used in hybridization programme to breed durable BPH resistant rice varieties.

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Distribution coefficients of a number of uni-, di-, tri- and quadrivalent metal ions have been determined on chromium ferrocyanide gel loaded with [Co(NH3)6]3+ and [Co(en)3]3+ ions at 25 °C, and the observed Kd values are compared with those obtained on the unloaded exchanger in H-form. The gel is found to develop ion-sieve properties after being loaded with the complex cations. The variation in Kd values with the pH of Rb+, Cs+, Ti+ and Ag+ solutions has also been studied to understand the mechanism of their uptake.

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In the present investigation, expression of genes related to Na+ exclusion such as salt overly sensitive (TaSOS1) and Na+/H+ antiporter (TaNHX1) and proline accumulation such as pyrroline-5-carboxylate reductase (P5CR) and glutamate synthase (GOGAT) was studied in seedlings of Kharchia 65 (Kh 65, salt tolerant) and HD 2009 (sensitive) under salt stress (ECe, 12 dSm–1) and controlled conditions. As compared to HD 2009, Kh 65 showed significantly lower accumulation of Na+ (p < 0.01) and higher accumulation of proline (p < 0.05) in leaf blade under salt stress. The relative expression of TaSOS1 increased significantly (p < 0.001) in roots of Kh 65 (4.31-fold) while it decreased in HD 2009. There was significantly higher (p < 0.01) relative expression of TaNHX1 (27.57-fold) in leaf and 3.07-fold in roots of Kh 65 as compared to 3.65- and 0.87-fold increase in leaf and roots of HD 2009, respectively, under salt stress. There was significantly (p < 0.05) higher accumulation of proline as compared to HD 2009 in leaf tissues. There was significantly higher (p < 0.01) expression of P5CR (5.23-fold in leaf and 8.77-fold in the root) and glutamate synthase (6.0- fold in roots) in Kh 65 as compared to HD 2009. The study demonstrated that upregulation of genes for Na+ exclusion in root and compartmentation in leaf and increased proline concentration are associated with tolerance to salinity stress in wheat. The information will be useful for improving wheat genotypes for salt tolerance.

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