Search Results
You are looking at 1 - 10 of 39 items for
- Author or Editor: R.P. Singh x
- Refine by Access: All Content x
Abstract
Extraction of U(VI), Zr(IV) and Th(IV) has been investigated from perchlorate media using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) dissolved in toluene. The extraction of U(VI), Zr(IV) and Th(IV) was found to be quantitative in the pH range 1.6 to 3.2, 2.0 to 4.7 and 2.3 to 3.8, respectively, with 3.0.10-3, 5.6.10-4 and 1.0.10-2M PC-88A dissolved in toluene. U(VI) was stripped with 4.0M HCl, Zr(IV) with 2.5M NaF and Th(IV) with 8.0M HCl from the metal loaded organic phase containing PC-88A dissolved in toluene. The probable extracted species have been ascertained by plotting log D vs. log [HR] as UO2R2 .2HR, ZrR4 .2HR and ThR4 .4HR, respectively. U(VI) was separated from Zr(IV) and Th(IV) and from other associated metals. This method was proved by the determination of U(VI) in some real samples.
The role of blue green algal (BGA) biofertilizers has been limited to its relevance and utilization in rice crops, and scanty information is available on their use in conjunction with organic amendments and their influence on wheat (Triticum aestivum) . An experiment was conducted from November 2003 to April 2004 in the fields of the Indian Agricultural Research Institute (IARI), New Delhi, India to evaluate the effect of vermicompost, farmyard manure and biofertilizers (BGA and Azotobacter ) in different combinations with chemical fertilizers (N 40 P 30 K 30 ) in wheat (var. HD 2687). Selected soil biological parameters (cyanobacterial diversity/abundance, nitrogenase activity and the phototrophic biomass of soil cores) were measured. The application of vermicompost in combination with BGA biofertilizer (B+V+N 40 P 30 K 30 ) brought about a significant increase in nitrogenase activity (from 0.1 in N 80 P 30 K 30 to 2.0 nmoles mg chl −1 h −1 ), while Azotobacter + BGA (+N 40 P 30 K 30 ) treatment gave the highest values of chlorophyll (1.19 μg g −1 soil). The addition of vermicompost and farmyard manure (+N 40 P 30 K 30 ) enhanced cyanobacterial abundance, and cyanobacterial genera such as Nostoc, Anabaena, Calothrix, Oscillatoria and Phormidium were the dominant forms observed under the wheat crop. The synergistic effect of organic amendments, biofertilizers and chemical fertilizers, especially BGA inoculants, advocates their utilization in wheat crops to improve soil fertility.
In the present study on the self-incompatibility in inbred lines of ten local Indian cultivars (Pusa Chetki, Chetki Long, Aushi, Alipur Local White, Jaunpuri, Half Red, Scarlet Red, Chinese Pink, Desi Red and Khasi Kata) of radish ( Raphanus sativus L.), Pusa Chetki, Chetki Long, Aushi, Alipur Local White and Jaunpuri were classed as selfcompatible, Half Red, Scarlet Red and Chinese Pink as intermediate and Desi Red and Khasi Kata as self-incompatible. The highest number of germinated pollen grains and pollen tubes was observed in Pusa Chetki, followed by Alipur Local White, Jaunpuri, Aushi and Chetki Long. The discrepancy in the number of germinated pollen grains in the stigmas may be explained by the inhibitory action of large numbers of self-incompatible pollen grains on the stigma. When two lines, Desi Red and Khasi Kata, were grown under different temperature and photoperiod conditions, no breakdown in self-incompatibility was observed, and the flowering periods of these lines are naturally well synchronized. It is well known that uniform and effective cross-pollination may be of great importance for obtaining a high quantity of hybrid seed in self-incompatible types. To produce single cross hybrid seed, the inbred lines Desi Red and Khasi Kata can be used as parental lines.
Abstract
Uranyl ion is photochemically reduced to uranium(V) with triphenyl phosphite, tri-o-tolyl phosphite and tri-m-tolyl phosphite in the presence of trimethylacetic acid in dry acetone. Spectroscopic techniques have revealed the primary process involves an electron transfer mechanism followed by uranyl oxygen atom transfer to phosphorus (III). Quantum yields and Stern-Volmer quenching constant measurements exhibit competition between photochemical and photophysical annihilation of optically excited uranyl ion with triaryl phosphites in non-aqueous medium.
This study was carried out to compare composition, density and diversity of species between dryland and irrigated agroecosystems and between agroecosystems and the marginal grassland ecosystem in dry tropics. Main management characteristics of these ecosystems are: (1) Dryland cropping, low fertilizer input, rainfed (no irrigation) and seed sown rice; (2) Irrigated cropping, high fertilizer, water (irrigation) inputs, flooded rice by transplanting; (3) Grassland, post-rainy season herbage removal and light grazing. All ecosystems showed comparable number (12-14) of species in winter, but in the rainy season higher number of species (21) were recorded in the grassland ecosystem. The species composition of the grassland was entirely different from both agroecosystems (similarity <1%). Dryland and irrigated agroecosystems showed only 25% and 38% similarity with each other during winter and rainy cropping seasons, respectively. Occurrence of few grasses (e.g., Cynodon dactylon, Dichanthium annulatum and Sporobolus diander) in the agroecosystems depends on the propagules dispersed from the marginal grassland. The change from dryland to irrigated agroecosystem involved elimination of 4-5 species during both cropping seasons and simultaneous recruitment of 2 new species in winter and 6 species in rainy season. In both agroecosystems, forbs (C_ type) dominated over graminoids (C_ type) during winter season but the dominance was reversed during the warm, rainy season. During winter some forbs were abundant in both agroecosystems due to their tolerance to widely varying moisture conditions (e.g.,Chenopodium album), others were dominant in either drier soil conditions (e.g., Anagallis arvensis in dryland) or wet conditions (e.g., Melilotus indica and Phalaris minor in irrigated). Higher species diversity occurred in the grassland relative to both agroecosystems. The seasonal trends of species diversity and species evenness were broadly similar in both agroecosystems but irrigated agroecosystem exhibited relatively higher species diversity. The changes in species composition and species diversity in agroecosystems are mainly attributed to differences in water management. The water management in irrigated agroecosystem tends to reduce weed diversity but leads to the dominance of some potentially noxious weeds (e.g., Phalaris minor).
The present investigation was conducted to study the impact of bio-inoculants under low input field conditions on the magnitude and direction of gene effects and the mean performance of nitrogen (N) and phosphorus (P) use in wheat. Three wheat cultivars suitable for different agro-ecological conditions, i.e. WH 147 (low mineral input), WH 533 (water deficit), Raj 3077 (high mineral input), and six generations (P 1 , P 2 , F 1 , F 2 , BC 1 and BC 2 ) of three crosses, namely WH 147 × WH 533, WH 533 × Raj 3077 and WH 147 × Raj 3077, were evaluated in a randomized block design with three replications under low input field conditions (80 kg N + 40 kg P + 18 kg ZnSO 4 doses applied in each treatment) with three treatments, i.e. control, inoculation with arbuscular mycorrhiza fungi (AMF, Glomus fasciculatum ) and dual inoculation with AMF and Azotobacter chroococcum ( Azc ). Bioinoculation with AMF and AMF+ Azc had a positive impact on the mean performance of all the wheat crosses. The mean performance of AMF was maximum in the cross WH 147 × WH 533 for N and P response (%), N and P use index (%) and P content (ppm), whereas for N and P uptake it was maximum in the cross WH 147 × Raj 3077. The response and use index for N and P were better in the combined AMF+ Azc treatment in all three crosses. The adequacy of the additive-dominance model for the phosphorus uptake (mg/plant) by all three crosses in all three treatments (i.e. control, AMF, AMF+ Azc ) suggested that additive (d) and dominance (h) gene effects mainly governed the inheritance of this trait. In all cases, digenic interactions were present, where the duplicate type of epistasis prevailed except for the P content in the control in the cross WH 147 × WH 533, where the complementary type of interaction was present. Pedigree selection in crosses WH 147 × WH 533 and WH 147 × Raj 3077 could be effective for breeding pure lines of wheat for sustainable agriculture (low input genotypes responsive to biofertilizers such as AMF and Azotobacter ).
The present investigation was conducted to investigate the impact of bio-inoculants on the magnitude and direction of gene effects and mean performance for root length density, root biomass per plant, AMF colonization in roots and micronutrient uptake (Cu, Fe, Mn, Zn) in wheat under low input field conditions. The material for study comprised three wheat cultivars, WH 147 (low mineral input), WH 533 (drought-tolerant), Raj 3077 (high mineral input) and six generations (P 1 , P 2 , F 1 , F 2 , BC 1 and BC 2 ) of three crosses, namely WH 147 × WH 533, WH 533 × Raj 3077 and WH 147 × Raj 3077. The experiment was conducted in a randomized block design with three replications having three treatments, i.e. (i) control; (ii) inoculation with arbuscular mycorrhizal fungi (AMF, Glomus fasciculatum ); (iii) dual inoculation with AMF and Azotobacter chroococcum ( Azc ). The fertilizer doses in all three treatments were 80 kg N + 40 kg P + 18 kg ZnSO 4 ha −1 . Root length density, root biomass per plant, AMF colonization in roots and Zn and Mn content were found to be maximum after dual inoculation with AMF+ Azc in all three crosses. Joint scaling tests revealed that additive-dominance gene effects were mainly operative in governing the expression of root biomass, Cu and Zn content in all three crosses for all three treatments (i.e. control, AMF and AMF + Azc ). Pedigree selection in crosses WH 147 × WH 533 and WH 147 × Raj 3077 could be effective for breeding pure lines of wheat for sustainable agriculture (low input genotypes responsive to biofertilizers such as AMF and Azotobacter ).
Pre-harvest sprouting (PHS) in bread wheat (Triticum aestivum L.) is one of the major abiotic constraints influencing production of high quality grain. Selection for pre-harvest sprouting (PHS) resistance in bread wheat (Triticum aestivum L.) in early generations is difficult because it is expressed as a quantitatively inherited trait and subject to environmental effects. The objectives of this study were to validate a major quantitative trait locus (QTL) for PHS resistance on chromosome 4A in bread wheat and to isolate near-isogenic lines for this QTL using marker-assisted selection. A total of 60 Canadian wheat cultivars and experimental lines were screened with three SSR markers in a QTL region for PHS resistance. The SSR markers DuPw004, barc170 and wmc650 explained 67%, 75% and 60% of total variation in germination (%), respectively, among different wheat genotypes. Marker assisted back crossing with DuPw004 reduced the population size in BC1F1 and BC2F1 generation by 41% and 59%, respectively. A survey of pedigrees of different genotypes revealed that the parental line RL4137 is a major source of increased PHS resistance in a number of western Canadian wheat cultivars. Microsatellite markers (DuPw004, barc170 and wmc650) will be useful for plant breeders to pyramid QTL from different PHS resistance sources.
