Arsenic (As) and cadmium (Cd), two major carcinogenic heavy metals, enters into human food chain by the consumption of rice or rice-based food products. Both As and Cd disturb plant-nutrient ...homeostasis and hence, reduces plant growth and crop productivity. In the present study, As/Cd modulated responses were studied in non-basmati (IR-64) and basmati (PB-1) rice varieties, at physiological, biochemical and transcriptional levels. At the seedling stage, PB-1 was found more sensitive than IR-64, in terms of root biomass; however, their shoot phenotype was comparable under As and Cd stress conditions. The ionomic data revealed significant nutrient deficiencies in As/Cd treated-roots. The principal component analysis identified NH4+ as As-associated key macronutrient; while, NH4+/NO3− and K+ was majorly associated with Cd mediated response, in both IR-64 and PB-1. Using a panel of 21 transporter gene expression, the extent of nutritional deficiency was ranked in the order of PB-1(As)<IR-64(As)<PB-1(Cd)<IR-64(Cd). A feed-forward model is proposed to explain nutrient deficiency induced de-regulation of gene expression, as observed under Cd-treated IR-64 plants, which was also validated at the level of sulphur metabolism related enzymes. Using urea supplementation, as nitrogen-fertilizer, significant mitigation was observed under As stress, as indicated by 1.018- and 0.794-fold increase in shoot biomass in IR-64 and PB-1, respectively compared to that of control. However, no significant amelioration was observed in response to supplementation of urea under Cd or potassium under As/Cd stress conditions. Thus, the study pinpointed the relative significance of various macronutrients in regulating As- and Cd-tolerance and will help in designing suitable strategies for mitigating As and/or Cd stress conditions.
The statistical growth analysis of field crop has become a great challenge in agriculture. Analyzing the growth of crop through automation provides extensive significance to the farmers for getting ...information about the problem arising in plants due to irregular growth monitoring. The idea behind this work is the importance of mapping with pixel-based clustering technique for growth analysis in terms of height calculation of rice crop (rice variety is MTU-1010). Height measurement plays a vital role in regular assessment for a healthy crop, and the approach proposed in this work achieves 97.58% accuracy of 14 sampled datasets taken from Indira Gandhi Agriculture University of Raipur, Chhattisgarh; a real-time dataset has been prepared. Proposed work is used for analyzing vertical as well as horizontal scaling technique. Vertical mapping provides the height of a single plant whereas horizontal mapping using k-means clustering provides an average height of the whole field. This work uses machine learning, and image processing techniques are used for this work.
Rice is a major cereal crop, negatively impacted by soil-salinity, both in terms of plantgrowth as well as productivity. Salinity tolerant rice varieties have been developed using ...conventionalbreeding approaches, however, there has been limited success which is primarily due to thecomplexity of the trait, low yield, variable salt stress response and availability of genetic resources.Furthermore, the narrow genetic base is a hindrance for further improvement of the rice varieties.Therefore, there is a greater need to screen available donor germplasm in rice for salinity tolerancerelated genes and traits. In this regard, genomics based techniques are useful for exploring newgene resources and QTLs. In rice, the vast allelic diversity existing in the wild and cultivated germplasmneeds to be explored for improving salt tolerance. In the present review, we provide anoverview of the allelic diversity in the Quantitative Trait Loci (QTLs) like Saltol, qGR6.2, qSE3and RNC4 as well as genes like OsHKT1;1, SKC1 (OsHKT1;5/HKT8) and OsSTL1 (salt tolerancelevel 1 gene) related to salt tolerance in rice. We have also discussed approaches for developingsalt-tolerant cultivars by utilizing the effective QTLs or genes/alleles in rice.
A RIL population (F12 and F13 generation) developed from a cross between the two indica cultivars, Danteshwari (high yielding variety) and Dagad deshi (drought tolerant local land race). The ...population was phenotyped under combination of absolute rainfed (RF), terminal stage drought (TSD) and irrigated (I) conditions with direct seeding and transplanting during 2011 and 2012 to identify QTL for grain yield. Genotyping of all 122 RIL lines were done using 162 polymorphic SSR and HvSSR markers. The phenotypic and genotypic data was analyzed using QTL cartographer 2.5 and QTL IciMapping 3.2. The recombinant inbred lines exhibited significant interaction with conditions. In general, the lines performing better under stress were poor under non-stress condition; however, two lines (#17 and 57) performed well under all sets of conditions. These lines had high tillering, ~10 and 27 and spikelet fertility, ~80 and 95% under stress and non-stress conditions, respectively. A total of 20 QTL were detected for grain yield under different conditions by employing QTL cartographer 2.5 and 7 QTL by employing QTL IciMapping 3.2; out of which 5 QTL were common under both the software. Among the major QTL, QTL on chromosome 1 (qDTY1.1) under rainfed transplanted condition between RM 3825 (143.7cM) to RM 302 (147.8cM) had LOD score of 5.09, QTL on chromosome 3 (qDTY3.3) under irrigated transplanted condition between RM 7 (64.0cM) to RM 232 (76.7cM) had LOD score of 6.59 and QTL on chromosome 11 (qDTY11.1) under TSD transplanted condition between RM 21 (85.7cM) to RM 26334 (90.0cM) had LOD score of 7.39. This study has resulted in identification of new major QTL, one on chromosome 11 (qDTY11.1) under TSD condition, which is different than most of other QTL reported by earlier workers. These QTL except qDTY 3.3, had positive additive effects, indicating that alleles at these loci increase grain yield under different conditions and come from tolerant parent Dagad deshi. Two regions of chromosome #1 and 3 had QTL for grain yield under stress as well as non-stress conditions. These genomic regions associated with grain yield under different conditions will be useful in marker assisted breeding for drought tolerance in rice.
ABSTRACT
Drought is one of the most severe constraints reducing rice (Oryza sativa L.) yield in rainfed environments. ‘Sahbhagi Dhan’ (IR74371‐70‐1‐1) is a drought‐tolerant rice variety that was ...released in India in 2010—and subsequently in Nepal as ‘Sukha Dhan 3’ and in Bangladesh as ‘BRRI Dhan 56’—and has performed well in rainfed farmers’ fields. This study was conducted to understand the physiological drought response characteristics of Sahbhagi Dhan that contribute to its increased yield under drought. Physiological characterization of Sahbhagi Dhan and other newer breeding lines was conducted across multiple seasons at one site in the Philippines and at four sites in India. Several distinct traits of Sahbhagi Dhan were observed: high emergence rates under direct‐seeded germination‐stage stress, a high proportion of total root length as lateral roots in some seasons, high harvest index under drought, and high yield stability across wet seasons. However, some unfavorable responses of Sahbhagi Dhan were observed: impaired growth when sown during seasons with early‐stage cold temperatures or low solar radiation, resulting in relatively low yield stability across dry seasons. These results point to the importance of combining multiple traits for yield stability across drought‐prone environments. Some of the newly developed breeding lines showed even greater yield stability than Sahbhagi Dhan, reflecting the effectiveness of ongoing improvement through direct selection for grain yield under drought that has resulted in advantageous combinations of physiological traits to increase yield in farmers’ fields.
Aims/ objectives: This study aims to improve stable and sustainable rice varieties adaptable to changing climatic conditions. It involves assessing genetic variability and Genotype X Environment ...interaction (G x E) among 186 diverse rice genotypes. The goal is to select genotypes with high breeding value, contributing to the development of rice varieties well-suited to varying climatic conditions. Study Design: The study employed an augmented design in a Randomized Complete Block Design (RCBD). Swarna, Madhuraj-55, Safri-17, Improved Samba Mahsuri, Thavalkannan, and IR64 checks were replicated across environments. Place and Duration of Study: The study took place in College of Agriculture, Raipur, IGKV over two years (wet season-2020 and 2021). Methodology: Analysis of genetic variability and G X E interaction among 186 rice genotypes. Execution of the experiment in an augmented design with a randomized complete block design. Replication of standard rice checks across different environments. Assessment of yield-attributing traits such as plant height, number of effective tillers, panicle length, number of grains per panicle, biological yield per plot, and grain yield. Evaluation of stability was done using univariate (Shukla stability variance, Wricke’s ecovalence, Kang stability statistic) and multivariate (AMMI yield stability index and GGE biplot) stability parameters. Selection of stable genotypes with high yield based on stability analyses. Results: Significant phenotypic variation was observed in yield-attributing traits across seasons. Genetic variability and G x E interaction effect demonstrated by variable genotype performance across environments. Univariate and multivariate stability parameters (S2i, W2i, KSi, AMMI stability value, GGE biplot) were used for stability analyses. Identification of stable genotypes with high yield across environments, including IR13f167, ARC13156, IR93354, F50, Ngalongyi, Giza 178, Arc 10159, Sadajira 19-317, Arith, IR 57920-Ac 25-2-B, Pesagro 102, Mekenzie small, Nasaenge, Kula Karuppan, Vary Gony, MR 69, Kanu Dam, IRRI 123, Sativa IRGC17083-1, Kalia, and Swarna. Conclusion: The study concludes that stability in genotype performance across diverse environments is crucial for the development of sustainable rice varieties. Genotypes with high stability and yield, as identified through stability analyses, hold potential breeding value for developing rice varieties adaptive to climate change. The stable genotypes listed, including IR13f167, ARC13156, IR93354, and others, are recommended for further breeding and development efforts to enhance rice productivity and adaptability.
Fifteen experiments testing seven sets of genotypes under irrigated non-stress and drought stress situations were conducted from 2004 to 2006 with the objective to study the effect of different ...severity levels of drought on tolerant and susceptible advanced breeding lines, current varieties, and traditional and improved donors, and to study the effect of selection for high early vigor on yield. With the onset of drought, a yield reduction due to a decrease in biomass was observed in both susceptible and tolerant lines. However, after an initial reduction in yield, tolerant lines were able to sustain a yield loss more effectively than susceptible lines by better maintenance of biomass and higher harvest index. Under intermittent drought stress, genotypes with the ability to maintain higher biomass, reflected in terms of high early vigor recorded 3
wk after transplanting, recorded higher grain yield than genotypes with low early vigor. Lines with high early vigor yielded higher under both irrigated non-stress and intermittent drought stress situations. Under intermittent stress, plants with high vigor, low vigor, or random plants with high or low vigor coming from tolerant
×
susceptible crosses yielded higher than did the plants with the same vigor coming from susceptible
×
susceptible crosses. Under both irrigated non-stress and intermittent drought stress situations, early vigor showed significant genetic correlation with grain yield and could be included as an efficient selection criterion to improve yield in the lowlands.
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