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The cultivar Ajaya (IET 8585) exhibits durable broad-spectrum resistance to bacterial blight (BB) disease of rice and is widely used as a resistance donor. The present study was carried out to decipher the genetics of BB resistance in Ajaya and map the gene(s) conferring resistance. Genetic analysis in the F2 indicated a quantitative/additive nature of resistance governed by two loci with equal effects. Linked marker analysis and allelic tests revealed that one of the resistance genes is xa5. Sequence analysis of a 244 bp region of the second exon of the gene-encoding Transcription factor IIAγ (the candidate gene for xa5) confirmed the presence of xa5. Bulked-segregant analysis (BSA) revealed the putative location of the two quantitative trait loci (QTLs)/genes associated with resistance on chromosomes 5 and 8. Composite interval mapping located the first locus on Chr. 5S exactly in the genomic region spanned by xa5 and the second locus (qtl BBR 8.1) on Chr. 8L. Owing to its differential disease reaction with a set of seven hyper-virulent isolates of Xanthomonas oryzae, a map location on Chr. 8L, which was distinct from xa13 and data from allelism tests, the second resistance locus in Ajaya was determined to be novel and was designated as xaAj. A contig map spanning xaAj was constructed in silico and the genomic region was delimited to a 13·5 kb physical interval. In silico analysis of the genomic region spanning xaAj identified four putatively expressed candidate genes, one of which could be involved in imparting BB resistance in Ajaya along with xa5.
High fluences of low energy Ge+ ions were implanted into Si matrix. We have also deposited Ge and SiO2 composite films by using the Atom beam sputtering (ABS). The as implanted/as-deposited films were irradiated by Swift Heavy Ions (SHI) with various energies and fluences. These pristine and irradiated samples were subsequently characterized by XRD and Raman to understand the crystallization behavior. Raman studies of the films indicate the formation of Ge crystallites as a result of SHI irradiation. Glancing angle X-ray diffraction results also confirm the presence of Ge crystallites in the irradiated samples. Moreover, the crystalline nature of Ge improves with an increase in fluence. Rutherford back scattering was used to quantify the concentration of Ge in SiO2 matrix and the film thickness. These detailed results have been discussed and compared with the ones available in literature. The basic mechanism for crystallization induced by SHI in these films will be presented.
An attempt is made to establish a probable link between mean September upper-air temperatures at Indian stations and the ensuing winter monsoon rainfall over eight individual meteorological subdivisions of southern India where the winter monsoon accounts for a large percentage of mean annual rainfall. For this purpose, linear correlations between the winter monsoon rainfall of the subdivisions and the mean September upper-air temperatures and vertical temperature differences at the Indian stations have been evaluated using the data set for the period 1959 to 1988. The inter-correlations between the significant parameters were calculated and then tested to derive multiple linear regression equations containing the best combination of predictor variables. There is a significant positive relationship between the winter monsoon rainfall over Tamilnadu and the mean temperature difference at 500–300 hPa levels at Nagpur in September. Secondly, the winter monsoon rainfall over Coastal Andhra Pradesh is significantly negatively correlated with the mean September temperature over Visakhapatnam at 700 hPa. The most significant inverse relationship exists between the winter monsoon rainfall over Rayalaseema and the mean September temperature over Visakhapatnam at 850 hPa. By using significant parameters, algorithms have been formulated and tested for each subdivision for six succeeding years, 1989–94. These results assisted to some extent in the prediction of winter monsoon rainfall over subdivisions of South India. Finally, stationarity is tested by evaluating another set of multiple linear regression equations using the data set for the period 1965–94 and then testing the algorithms on the preceding six years.
Al alloys were infiltrated into alumina preforms without the aid of pressure in N2 as well as in air at and above 750 °C. It was possible to eliminate termination of infiltration that was seen in open conditions (where N2 was in continuous contact with the melt) by modifying the infiltration geometry. This configuration enables the infiltration to continue for longer periods of time, consequently producing greater thickness of composite. In air, Mg placed at the interface getters the in-coming oxygen until the alloy billet melts and seals off the front from the ingress of the furnace atmosphere thereby eliminating the need for prealloying Al with Mg and N2 atmosphere. In addition, experiments in argon revealed that the infiltration requires some critical amount of N2 in the atmosphere.
Trends and periodicities of annual rainfall for 29 sub-divisions of India and all India (area-weighted average of the sub-divisions) are studied by using the rainfall series for a period of 124 years (1871–1994). The trends are evaluated by using a linear regression technique. To identify the climatic changes, the rainfall series are subjected to 11-year moving averages. These averages show some epochs. From this, it is found that in some sub-divisions the trend in one direction reverses its direction after some years. The years pertaining to these changes are identified and the trends are calculated for the segments of the series. The significance of the trend values are tested. Power spectra are obtained using the maximum-entropy method. The periods in the range 2.0–2.5 years are present in the rainfall series of the sub-divisions to the north of 20 °N, on the west coast, and in Tamilnadu and for all India. This periodicity may be attributed to the quasi-biennial oscillation. Rainfall series of the most of the sub-divisions and all India indicate a triennial cycle. Significant periods in the range from 3.0 to 8.0 years and 8.0 to 12.0 years are also identified.
Hypocotyl length in groundnut is a function of sowing depth. In field experiments deep sowing increased the mass of hypocotyl but decreased that of roots, pods and haulm. Few nodules were formed on the hypocotyls of plants from shallow sown seeds (4–5 cm deep). More hypocotyl nodules occurred on Virginia types when deep sown but the number and activity of nodules on the roots decreased. Nodules on the hypocotyl appeared later and fixed less nitrogen than root nodules. Although hypocotyl nodules fixed nitrogen during the later stages of plant growth, this activity could not compensate for the loss in nitrogenase activity due to deeper sowing. Deeper sowing also resulted in decreased pod yields.
Different subspecies of Arachis hypogaea show variation in their ability to nodulate in the hypocotyl region. Some cultivars belonging to subspecies hypogaea nodulate profusely on the hypocotyl, while those of fastigiata nodulate rarely in this region. The utilization of this character in breeding for increased nitrogen fixation is discussed.
A systematic study of the stress distribution in an infinite elastic solid when time dependent and time independent body forces act on certain regions of the solid is made by Eason, Fulton and Sneddon(l). They have stated the importance of studying problems concerning moving point charges in electrodynamics. Mukhopadhyay(2) has discussed the disturbance created by the propagation of torsional disturbance in an infinite elastic solid due to time dependent rotating body forces.
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