Estimation of genetic diversity in rice (Oryza sativa L.) genotypes using SSR markers and morphological characters

Thirty rice genotypes comprising land races, pure lines, somaclones, breeding lines and varieties specifically adapted to costal saline environments were characterized by SSR markers and morphological characters in this study. Out of 35 primers of SSR markers, 28 were found to be polymorphic. The PIC value ranged from 0.064 (RM 274) to 0.72 (RM 580) with an average of 0.46. The Jaccard’s similarity coefficient ranged from 0.42 to 0.90. At the genetic similarity of 56% the genotypes were grouped into five clusters. PCA components explained 41.6% of variation. There was overlapping of tolerant genotypes and susceptible genotypes within the cluster. Morphological traits of each genotype were measured on five randomly chosen plants. The matrix of average taxonomic distance was estimated using Euclidian distance. The average taxonomic distance ranged from 1.5 to 7.78. At a Euclidean distance of 3.49, the 30 genotypes were grouped into IV clusters. The clustering pattern clearly grouped the genotypes based on their response to salinity and clustering was not based ontheir geographical origin. PCA components explained 38.4% of variation

Yield and fibre quality components analysis in upland cotton (Gossypium hirsutum L.) under salinity

Cotton being an important cash crop of India plays a distinguished role in energizing the economy of the country by fetching appreciable amount of foreign exchange annually. The cotton production of country is improving significantly but the yield per unit area is still lower than that of the other countries due to some biotic and abiotic factors. Amongst the abiotic stresses, salinity is a serious threat next to drought. Keeping in view, the present study was conducted to assess the salt tolerance of 32 popular upland varieties released for general cultivation between 1980 and 2001 in India. The study was carried out in normal as well as saline-alkaline condition; in which salinity were created using bore well water irrigation and the average electrical conductivity level of bore well water is 3.10 ds/m. The 32 upland cotton genotypes under both salinity and normal conditions revealed high GCV and genetic gain for number of bolls per plant, boll weight, lint yield per plant, 2.5 per cent span length, leaf area index, Na-K ratio and seed cotton yield and these traits could be improved by simple selection. Correlation and path analysis studies revealed that the seed cotton yield was highly influenced by lint yield per plant in both normal and salinealkaline condition. Significant positive correlations exists between Bartlett's rate index with uniformity ratio, 2.5 per cent span length with bundle strength, uniformity ratio with micronaire and elongation percent, specific leaf area with leaf area index. These results clearly indicated that selection for any one of these traits might lead to concurrent improvement of other traits as well as seed cotton yield. The characters boll weight (-0.347), ginning out turn (-0.528), 2.5% span length (-0.312) and uniformity ratio (-0.440) registered high order negative direct effect on seed cotton yield. This result further confirms the negative association between the quality and yield

Analysis of Stability and G × E Interaction of Rice Genotypes across Saline and Alkaline Environments in India

Genotype × environment (G × E) interaction effects are of special interest for identifying the most suitable genotypes with respect to target environments, representative locations and other specific stresses. Twenty-two advanced breeding lines contributed by the national partners of the Salinity Tolerance Breeding Network (STBN) along with four checks were evaluated across 12 different salt affected sites comprising five coastal saline and seven alkaline environments in India. The study was conducted to assess the G × E interaction and stability of advanced breeding lines for yield and yield components using additive main effects and multiplicative interaction (AMMI) model. In the AMMI1 biplot, there were two mega-environments (ME) includes ME-A as CARI, KARAIKAL, TRICHY and NDUAT with winning genotype CSR 2K 262; and ME-B as KARSO, LUCKN, KARSA, GOA, CRRI, DRR, BIHAR and PANVE with winning genotypes CSR 36. Genotypes CSR 2K 262, CSR 27, NDRK 11-4, NDRK 11-3, NDRK 11-2, CSR 2K 255 and PNL 1-1-1-6-7-1 were identified as specifically adapted to favorable locations. The stability and adaptability of AMMI indicated that the best yielding genotypes were CSR 2K 262 for both coastal saline and alkaline environments and CSR 36 for alkaline environment. CARI and PANVEL were found as the most discernible environments for genotypic performance because of the greatest GE interaction. The genotype CSR 36 is specifically adapted to coastal saline environments GOA, KARSO, DRR, CRRI and BIHAR and while genotype CSR 2K 262 adapted to alkaline environments LUCKN, NDUAT, TRICH and KARAI. Use of most adapted lines could be used directly as varieties. Using them as donors for wide or specific adaptability with selection in the target environment offers the best opportunity for widening the genetic base of coastal salinity and alkalinity stress tolerance and development of adapted genotypes. Highly stable genotypes can improve the rice productivity in salt-affected areas and ensure livelihood of the resource poor farming communities

Self-saturation of amplified spontaneous emission in a fiber amplifier

The dependence of erbium-doped fiber amplifier (EDFA) performance on amplifier self-saturation is studied by tuning the pump wavelength over a 5 nm band centered at 980 nm. Gain and noise figure are degraded at the peak pump absorption wavelength, which shows the strongest effect of amplifier self-saturation. It is shown experimentally that tuning the pump wavelength away from the peak pump absorption provides 1 -2 dB improvement in pump­ to-signal conversion. The effect of amplifier self-saturation is also dependent on the signal wavelength where high gain and noise figure penalties are obtained at 1530 nm (± 5 nm) band

Effect of Positive Deviance Approach on Promotion of Safe Disposal of Child’s Faeces in Rural Tamil Nadu: A Community-Based Quasi-Experimental Study

Background: Unsafe disposal of child’s faeces plays a crucial role in disease transmission and environmental pollution. These areas are overlooked by many sanitation promotion interventions. The objective was to determine the effect of Positive Deviance (PD) approach on safe disposal of child’s faeces among households who owned a toilet. Methodology: A community-based quasi-experimental study was carried out in the four field practice villages of UHTC, Villupuram for 18 months. Households who owned a toilet and had a child <5 years were included. After IEC clearance, information was collected from a representative sample of 100 households before intervention and another 100 households after intervention. PD approach was applied for six months to promote safe disposal practices. Data was analyzed in SPSS 24 software. Chi square test and Effect size (Cramer’s V) were employed. Results: Before intervention, only 3% households disposed the faeces into a toilet. While, after intervention, almost 38% households disposed in the toilet (c2=37.39; df=1; p=0.001). Effect size was found to be 0.43. Conclusion: PD approach demonstrated considerable improvements in safe disposal of child’s faeces in rural settings. Further, in order to sustain the behaviour, change frequent reinforcement of key messages at frequent intervals need to emphasized

Why Villagers Use Toilets Only During Specific Time and Season? A Mixed-Methods Study in Rural Tamil Nadu

Background: Due to the efforts of sanitation promotion interventions in India, majority of the villagers started using toilets. But there is an inconsistency in toilet usage with regard to time and season. Objectives: The objectives were to determine the time and seasonal variations in toilet usage among villagers who use toilets and to identify the reasons for time and seasonal variations in toilet usage. Methodology: A community-based mixed-methods study was executed in the four field practice villages of UHTC, Villupuram. After IEC clearance, 405 individuals who were using an owned toilet were selected by Simple Random Sampling. Qualitative component (free listing) was used for questionnaire development and quantitative component (survey + observation) was used for data collection. Results: Majority, 52% villagers used toilets only in the night and 64% villagers used toilets during rainy season. Fear of darkness and snakes, emergency and large family size were the common reasons for night time toilet usage. While, non-availability of open space, illness on exposure to rain and quick filling of toilet pit contributed to toilet usage in the rainy season. Conclusion: The study findings would help in the development of culturally-sensitive and socially-acceptable key messages for future sanitation promotion interventions

Efficiency of honeycomb selection design in early segregating generation inADT45 × Nona Bokra cross under salt stress

Salt stress is a major abiotic stress that limits rice productivity worldwide including India. As modern rice varieties aresalt sensitive, infusing salt tolerance through breeding is a viable farmer-friendly approach. Breeding salt tolerant ricevarieties has been slow due to complexity of the trait and high Genotype x Environment interaction.in the salt affected field.Selection practiced in such a situation using conventional selection method, in the presence of competition, would bemisleading. On the otherhand, selection is effective in the absence of competition in honeycomb selection and counteractsthe disturbing effects of competition on effectiveness of selection. The present study was conducted to test the efficiency ofhoneycomb selection design in early generation of a rice cross to study genetics of yield and practice selection. All thecharacters studied in both the design showed non normal distribution except for panicle length in CSD. All the charactersstudied in both the design had lower coefficient of variation, high mean and high standard deviation in the HSD compared toCSD. Large number of genes with duplicate epistasis governs days to flowering whereas panicle length and single plantyield are governed by few number of genes with complimentary epistasis. Twenty nine F2 plants each in CSD and HSDwere selected based on mean and plant index (SPY), respectively. Plants selected in HSD recorded higher percentage ofincrease over base population compared to CSD and found HSD to be superior to CSD because of enhancedphenotypic expression in the former by eliminating confounding effects of negative correlation between yielding andcompetitive ability

Efficiency of honeycomb selection design in early segregating generation in ADT45 × Nona Bokra cross under salt stress

463-470Salt stress is a major abiotic stress that limits rice productivity worldwide including India. As modern rice varieties are salt sensitive, infusing salt tolerance through breeding is a viable farmer-friendly approach. Breeding salt tolerant rice varieties has been slow due to complexity of the trait and high Genotype × Environment interaction in the salt affected field. Selection practiced in such a situation using conventional selection design (CSD), in the presence of competition, would be misleading. On the otherhand, selection is effective in the absence of competition in honeycomb selection and counteracts the disturbing effects of competition on effectiveness of selection. In the present study, we tested the efficiency of honeycomb selection design (HSD) in early generation of a rice cross genetically in improving the yield and practice selection. All the characters studied in both the design showed non normal distribution except for panicle length in CSD. All the characters studied in both the design had lower coefficient of variation, high mean and high standard deviation in the HSD compared to CSD. Large number of genes with duplicate epistasis governs days to flowering whereas panicle length and single plant yield are governed by few number of genes with complimentary epistasis. Twenty nine F2 plants each in CSD and HSD were selected based on mean and plant index (SPY), respectively. Plants selected in HSD recorded higher percentage of increase over base population compared to CSD and found HSD to be superior to CSD because of enhanced phenotypic expression in the former by eliminating confounding effects of negative correlation between yielding and competitive ability

Effects of self-saturation in an erbium-doped fiber amplifier

The dependence of erbium-doped fiber amplifier performance on amplifier self-saturation is studied experimentally by tuning the pump wavelength over a 5-nm band centered at 980 nm. Gain and noise figure are degraded at the peak pump absorption wavelength, which shows the strongest effect of amplifier self-saturation. It is shown experimentally that tuning the pump wavelength away from the peak pump absorption provides 1-2 dB improvement in pump-to-signal conversion. The effect of amplifier self-saturation is also dependent on the signal wavelength where high gain and noise figure penalties are obtained at the 1530-nm (+/-5 nm) band. (C) 2000 Academic Press