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  • Author or Editor: R. K. Singh x
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Maize protein quality is deficit in essential amino acids, lysine and tryptophan. These constraints of o2 (opaque2) are corrected in genetically improved, hard endosperm QPM (Quality Protein Maize). An integrated strategy of phenotypic selection for endosperm modifiers and molecular marker-assisted foreground and background selection has been used in present study. The QPM donors were, CML 161, DMRQPM 58, CML 176 and CML 141 whereas, normal maize inbreds were CM 212, V338, V361, V336, V341, V351, CM 141 and V335. The inbreds were subjected to parental polymorphism survey between non-QPM and QPM using CIMMYT based three SSR markers, viz. phi057, umc1066 and phi112. Two markers, viz. phi057 and umc1066 exhibited co-dominant reactions, while phi112 was dominant in nature. Finally, two combinations V335 × CML 141 and V351 × CML 141 were considered for conversion program. Foreground selection was exercised using o2 specific marker umc1066 in BC1 and BC2 generations, while background as well as foreground selection was exercised in BC2F3 generation to recover the genome of recurrent parent up to extent of 80 to 100% with the help of SSR markers distributed across the whole maize genome. The tryptophan concentration in endosperm protein was significantly enhanced and the converted maize lines had almost twice the amount of lysine and tryptophan than normal maize inbreds.

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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).

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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 ).

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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 ).

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The present report is in continuation to our earlier reports on the identification and fine mapping of three aroma QTLs in basmati rice using a bi-parental mapping population derived from a cross between Pusa 1121, a basmati rice variety, and Pusa 1342, a non-aromatic rice variety. We used a combination of genetic mapping and transcriptome profiling to narrow down the number of differentially expressed genes in rice to identify potential candidate genes for rice grain aroma. Highly aromatic and non-aromatic recombinant inbred lines (RILs) were identified through sensory analysis of mature milled grains. RILs with similar phenotypes were bulked together using bulk segregant analysis approach which drastically reduced the number of differentially expressed genes from 4016 to 1344. The transcriptome profiles generated were analyzed through Affymetrix rice genome array containing probe sets designed from all the predicted rice gene sequences. Microarray-based transcriptome profiling revealed one down-regulated gene co-located in QTL region aro3.1 on chromosome 3, eight genes co-located in the aro4.1 region on chromosome 4 and the badh2 gene on chromosome 8 to be differentially expressed in the aromatic parent and aromatic bulk. These genes are the most suitable candidates for future validation and development of new molecular functional markers to facilitate marker assisted breeding.

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A comparative examination of the morphological attributes of freshly separated and cultured cyanobionts of six species of Azolla, namely A. microphylla, A. filiculoides, A. rubra, A. caroliniana, A. mexicana and A. pinnata, was carried out. Distinct variation with respect to colour and nature of filaments, size and frequency of heterocysts was observed when counterparts of cultured and freshly separated cyanobionts from each species of Azolla were compared. The cyanobionts from A. pinnata showed distinctly larger cells compared with the cyanobionts from other Azolla species, whereas the cyanobiont of A. mexicana resembled Nostoc in exhibiting coiled filaments. The other cyanobionts exhibited mostly straight filaments similar to Anabaena. This investigation brings out clearly the morphological variations existing among the cyanobionts belonging to the different species of Azolla and the transitional changes under in vitro conditions, need to characterise the cyanobionts at inter- and intraspecific level using molecular tools in the future for a more reliable classification system of the cyanobionts associated with Azolla.

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A set of 286 recombinant inbred lines (RILs) along with the parents and a popular wheat variety in India were grown for two consecutive years at three locations belonging to the two major wheat growing zones of India and evaluated for four grain quality traits. Rare recombinants with high trait value appeared for protein content (PC), thousand-kernel weight (TKW), sedimentation value (SV), and kernel hardness (KH). The magnitude of environmental effects was more pronounced than genotypic effects and genotype-environment interaction (GEI). The cumulative contribution of environment and GEI components to the total variance was highest in the expression of PC followed by TKW, SV, and KH. The top five percent (14 RILs) of genotypes with high trait value were subjected to Eberhart and Russell (1966) (ER), genotype and genotype-environment (GGE) and additive main effects and multiplicative interaction (AMMI) stability models. Five RILs were identified as stable in all the three stability models. RIL61 with 38.8%, RIL101 with 8.9%, RIL226 with 26.1% superiority over check variety were the most stable genotypes in all the three stability models for PC, TKW and KH, respectively. RIL113 was found to be stable genotype in ER and GGE models, whereas, RIL231 was the most stable genotype in AMMI and GGE models in the expression of SV. These common stable genotypes with high trait value identified through ER, AMMI and GGE models could be potential donors in active breeding programs to develop high yielding wheat varieties with improved PC, TKW, SV and KH.

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Abstract

Chromite Spinel materials were synthesized in this study by the citrate precursor method using four divalent cations (Ni2+, Co2+, Zn2+, and Cu2+). Citrate precursors consisting of mixed chromium citrates were first subjected to a thermogravimetric (TG) analysis for determining optimum temperatures for annealing. TG of coprecipitated chromium(III) citrate–zinc citrate gel has been carried out separately in N2 and O2 atmospheres. In both the cases, dehydration is followed by a four-step decomposition. The TG data were subjected to kinetic/mechanistic analysis, and the values of activation energy and Arrhenius factor were approximated. TG curves of various powders which were obtained on annealing at the two temperatures did exhibit thermal instability when carried out in N2 atmosphere. A large coercivity of 2701.01 Oe was observed for NiCr2O4 at 650 °C. On the basis of the results, 450 °C has been chosen for annealing treatment of the four gels. The samples were accordingly annealed at two different temperatures (450 and 650 °C) in a muffle furnace for 1 h in each case. The annealed powders were characterized using X-ray diffraction (XRD), SEM, and vibrating sample magnetometer (VSM). The XRD patterns show that annealing of CuCr2O4, NiCr2O4, and CoCr2O4 at 450 °C yields very small crystallites with poor Bragg reflections, although ZnCr2O4 samples show better peaks in XRD data. Annealing at 650 °C resulted in particle size range of 8–89 nm in the four cases. In the case of ZnCr2O4, the particle size was 8 nm.

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