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  • Author or Editor: S. Sharma x
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The experimental material comprised three crosses, namely Cocorit 71 × A-9-30-1, HI 8062 × JNK-4W-128 and Raj 911 × DWL 5002, generated from six diverse parents. Twelve populations of each of these three crosses revealed that sufficient genetic variation was recorded among generations for all the traits in three crosses. The results of a correlation study demonstrated that the grain yield per plant was significantly and positively associated with peduncle area and flag leaf area in the cross Cocorit 71 × A-9-30-1. However, the spike area had poor correlation with grain yield. In the cross HI 8062 × JNK-4W-128, grain yield per plant was positively associated with peduncle area and spike area, whereas flag leaf area showed a positive but weak association with grain yield. In the cross Raj 911 × DWL 5002, grain yield per plant was positively associated with all three physiological traits studied, indicating that improvement in grain yield may be made by these traits in this material. Peduncle area appeared to be the most important trait in the present study because of its association with grain yield in all three crosses. Although flag leaf area and spike area showed a positive association with grain yield in all three crosses, their relative magnitudes and significance changed from one cross to the other. Correlation studies revealed that selection for peduncle area would lead to high yield in durum wheat. However, due consideration should also be given to flag leaf area and spike area during the selection of plants for further tangible advances in grain yield in durum owing to their positive association with grain yield.

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The results obtained for the parental, F 1 and F 2 generations of a 10 × 10 diallel set (excluding reciprocals) of durum wheat revealed that there were significant differences between all the hundred genotypes for all the characters. The genotypes represented a wide range of expression for almost all the characters. High estimates of GCV (genetic coefficient of variation) were observed for the number of effective tillers, grain yield per plant, harvest index and 1000-grain weight. The low values of GCV recorded for days to heading, grain protein content and plant height indicated their limited scope for improvement. High heritability (h 2 ) values ranging from 92.27% (grain yield/plant) to 99.00% (protein content) were observed for all the characters. The highest expected GA (genetic advance) as a percentage of the mean was manifested for harvest index, followed by plant height, number of effective tillers per plant and grain yield per plant. These traits also possessed high estimates of heritability, indicating that most of the variation in these characters was due to additive gene effects. For protein content high heritability was observed with low genetic gain, indicating non-additive gene effects. Thus, a systematic approach based on selection for harvest index, plant height and number of effective tillers per plant on the basis of high per se performance would be the most effective approach for improving the yield level of durum wheat. The wealth of variability available in the hybrid populations offers good prospects for its improvement in the near future.

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The genetics of yield and related traits was studied in barley ( Hordeum vulgare L.) by means of 10 × 10 half-diallel progenies (F 1 and F 2 ) at three sowing dates. An additive-dominance model fitted only for flag leaf area, spike length and 1000-grain weight at different sowing dates. Both additive (D) and dominance components (H 1 and H 2 ) were significant for all the traits studied, indicating the preponderance of dominance components in controlling the inheritance for these traits. The value of (H 1 /D) 1/2 indicated over-dominance for all the traits except for flag leaf area. Values of ‘F’ indicated an excess of dominant alleles in the parents for all traits except for flag leaf area. The environmental component ‘E’ was significant for all traits. The ratio of H 2 /4H 1 indicated the symmetrical distribution of genes for all the traits studied. The value of h 2 /H 2 was less than one for all traits except for spike length, suggesting that a dominant gene was involved in controlling the inheritance of spike length, whereas multiple genes controlled the inheritance of the remaining traits. The heritability estimates were relatively moderate for flag leaf area and 1000-grain weight, but low for all other traits. However, epistatic interactions had an important role in the expression of other traits. Breeding methods such as bi-parental mating in early segregating generations or diallel selective mating may be advantageous to combine important yield component characters for a tangible advance in six-rowed barley.

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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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A field study conducted for two years (1995-96 and 1996-97) at the Indian Agricultural Research Institute, New Delhi on a sandy clay loam soil showed that the application of NP increased the total grain production of a rice-wheat-mungbean cropping system by 0.5-0.6 t ha -1 , NK by 0.3-0.5 t ha -1 and NPK by 0.8-0.9 t ha -1 compared to N alone, indicating that the balanced use of primary nutrients was more advantageous than their imbalanced application. The application of farmyard manure (FYM) along with NPK further increased the total productivity of the rice-wheat-mungbean cropping system by 0.3-0.6 t ha -1 , the organic C by 0.13%, the available N by 10.7 kg ha -1 , the available P by 4.7 kg ha -1 and the available K by 15 kg ha -1 compared to NPK after two crop cycles of the system. The results of the present study thus indicate that integrated nutrient management involving FYM and NPK fertilizers is a must for the sustainability of a cropping system.

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Abstract  

Dissolution effect on recoil128I retention in the form of IO 4 ion following /n,/ process in potassium periodate target has been studied. A remarkable variation in retention is found both in solid and solution phase with the pH of dissolution. A suitable mechanism is suggested to explain the observed results.

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Abstract  

Based on solvent extraction and fractional precipitation methods, the retention in iodate and periodate targets were measured. Influence of temperature of irradiation in crystalline and solution phase have been observed. Higher retentions were observed in crystalline solids than in corresponding solution phase irradiation at room temperature. The role of physicochemical properties of the salts and the solvent is discussed.

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Abstract  

The retention and yields after neutron irradiation under standard conditions by ionizing radiation have been studied as a function of the mole fraction of nitrate in NaIO3–NaNO3 mixed-crystals. The effect of nitrate ion on the retention in solid-solution after irradiation was observed. A probable mechanism is suggested.

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Seventy-eight doubled haploid (DH) lines, derived from 21 elite and diverse winter × spring wheat F 1 hybrids, following the wheat × maize system, were screened along with the parental genotypes under in vitro and in vivo conditions for cold tolerance. Under in vitro conditions, the 2,3,5-triphenyl tetrazolium chloride (TTC) test was used to characterize the genotypes for cold tolerance. Based on the TTC test, only one doubled haploid, DH 69, was characterized as cold-tolerant, seven DH and five winter wheat parents were moderately tolerant, while the rest were susceptible. Analysis of variance under in vivo conditions also indicated the presence of sufficient genetic variability among the genotypes (DH lines + parents) for all the yield-contributing traits under study. The correlation and path analysis studies underlined the importance of indirect selection for tillers per plant, harvest index and grains per spike in order to improve grain yield. It was also concluded that selection should not be practised for grain weight per spike as it would adversely affect the grain yield per plant. When comparing the field performance of the genotypes with the in vitro screening parameters, it was concluded that in addition to the TTC test, comprising a single parameter, other physiological and biochemical in vitro parameters should be identified, which clearly distinguish between cold-tolerant and susceptible genotypes and also correlate well with their performance under field conditions.

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