Browsing by Author "Shashi Shekhar"

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Agronomic management: irrigation scheduling, mulching and integrated nutrient management influences growth, yields, quality, and economics of summer groundnut in a subtropical condition of India
(Taylor and Francis Ltd., 2024) Avinash Chandra Maurya; Sunil Kumar Verma; Sushil Kumar; Shashi Shekhar; Sukumar Taria; Badre Alam; Ashok Yadav; Tej Ram Banjara
In changing climate scenarios, practically sound and suitable agronomic management options are of utmost need for sustainable crop production. An experiment involving three irrigation scheduling, two mulching, and four integrated nutrient management (INM) treatments was undertaken for consecutive two years at the Research Farm of the Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India in a split-split plot design with three replicates. This study evaluated the effect of irrigation scheduling, mulching, and INM on the performance of summer groundnut under sub-tropical conditions. Irrigation scheduling, mulching, and INM had a significant influence on growth and developmental parameters, yield attributes, yields, shelling (%), harvest index, quality parameters, and economics. Scheduling irrigation at lower cumulative pan evaporation (CPE) hugely benefited crops through increased pod yield (8.3%) haulm yield (5%), kernel yield (8.4%), oil yield (8.6%), and net returns (12.7%) over higher CPE (100 mm). The use of paddy straw mulch enhanced pod yield, haulm yield, kernel yield, oil yield, and net returns by 8.2, 3.6, 8.3, 9.0, and 13.2%, respectively as compared to dust mulch. Among INM, 75% RDN (recommended dose of nitrogen) + 25% N (FYM) + 60 kg S (gypsum) adjudged significantly better and recorded higher biological yield (16%), net returns (39%), and B:C ratio (16.2%) than 100% RDN. It is concluded that scheduling irrigation at 60 mm CPE along with paddy straw mulch and 75% RDN + 25% N (FYM) + 60 kg S (gypsum) can be adopted for better yield and economics of summer groundnut under sub-tropical conditions. © 2024 Taylor & Francis Group, LLC.
An Integrative Analysis of Metagenomic and Metabolomic Profiling Reveals Gut Microbiome Dysbiosis and Metabolic Alterations in ALS: Potential Biomarkers and Therapeutic Insights
(American Chemical Society, 2025) Priyanka Gautam; Rahul Yadav; Ranjeet Kumar Vishwakarma; Shashi Shekhar; Abhishek Pathak; Chandan L. Singh
ALS is a severe neurodegenerative disorder characterized by motor neuron degeneration, gut dysbiosis, immune dysregulation, and metabolic disturbances. In this study, shotgun metagenomics and1H nuclear magnetic resonance (NMR)-based metabolomics were employed to investigate the altered gut microbiome and metabolite profiles in individuals with ALS, household controls (HCs), and nonhousehold controls (NHCs). The principal component analysis (PCA) explained 33% of the variance, and the partial least-squares discriminant analysis (PLS-DA) model demonstrate R2and Q2values of 0.97 and 0.84, respectively, indicating an adequate model fit. The relative bacterial abundance was 99.34% in the ALS group and 98.94% in the HC group. Among the ten identified genera, Bifidobacterium, Lactobacillus, and Enterococcus were more prevalent in ALS individuals, while Lactiplantibacillus and Klebsiella were more abundant in the HC group. We identified 70 metabolites, including short-chain fatty acids (SCFAs), branched-chain amino acids (BCAAs), carbohydrates, and aromatic compounds, using NMR. Orthogonal partial least-squares discriminant analysis (O-PLS-DA) explained 15.8% of the variance, with a clear separation between the ALS and HC groups. Univariate receiver operating characteristic (ROC) analysis identified three fecal metabolites with AUC values above 0.70, including butyrate (0.798), propionate (0.727), and citrate (0.719). These metabolites may serve as potential biomarkers for ALS. The statistical model for metabolic pathway analysis revealed interconnected pathways, highlighting the complexity of metabolic dysregulation, as well as potential microbial and metabolic biomarkers in ALS. These results highlight the role of gut microbiome alterations in ALS and suggest potential avenues for therapeutic intervention. © 2025 American Chemical Society
Correction: Salicylic Acid and Methyl Jasmonate Synergistically Ameliorate Salinity Induced Damage by Maintaining Redox Balance and Stomatal Movement in Potato (Journal of Plant Growth Regulation, (2023), 42, 8, (4652-4672), 10.1007/s00344-023-10956-7)
(Springer, 2023) Shashi Shekhar; Ayushi Mahajan; Prashasti Pandey; Meenakshi Raina; Anjana Rustagi; Ram Prasad; Deepak Kumar
In this article the wrong figure appeared as Fig. 4; the corrected Fig. 4 is given below. (Figure presented.) Effect of foliar application of salicylic acid (SA) and methyl jasmonate (MeJA) on the generation of hydrogen peroxide and free radical superoxide anion in the leaves of two potato varieties under salt stress (100 mM NaCl) and unstressed conditions. T1, 0 mM NaCl; T2, 100 mM NaCl; T3, 100 mM NaCl and 0.25 mM SA; T4, 100 mM NaCl and 50 μM MeJA; T5, 100 mM NaCl and 0.25 mM SA and 50 μM MeJA. A Histochemical detection of H2O2 and B histochemical detection of superoxide anion in the leaves of KS and KB, C Free radical superoxide anion accumulation and D H2O2 accumulation in the leaves of KS and KB shows significant reduction as compared to T2. Values represent means (± SE) (n = 3). Significant differences between T1 and T2 were determined using unpaired t-test with Welch’s correction. Significant differences between T2, T3, T4 and T5 were determined using one-way ANOVA with Dunnett's multiple comparisons test; T2 was used as control. Level of significance at p < 0.05: ***p < 0.001, **p < 0.002 and *p < 0.033 © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Effect of chitosan coating on postharvest quality and enzymatic activity of eggplant (Solanum melongena L.) cultivars
(Blackwell Publishing Ltd, 2021) Swati Sharma; R.N. Prasad; Shailesh Tiwari; S.N.S. Chaurasia; Shashi Shekhar; Jagdish Singh
Eggplant (Solanum melongena L.), an important fruit vegetable exhibits very limited postharvest marketability, particularly due to rapid moisture loss. This study assessed the variation due to chitosan coating on different eggplant cultivars (purple long, purple round, and white long). Fruit were coated with chitosan (1%) and stored at 10 ± 2°C. The chitosan-coated purple round cultivars (BR-14 and PR-5) had minimum weight loss and polyphenol oxidase (PPO) and peroxidase (POD) activity than long cultivars (Kashi Taru, IVBL-22, and Kashi Himani), while the functional quality (anthocyanins, total phenolics, and flavonoids) of long cultivars was higher. Chitosan was effective in minimizing weight loss by about two fold and retained higher flavonoids by about 1.2–2.3 fold over uncoated fruit in different eggplant cultivars. Chitosan-coated round (PR-5 and BR-14) and long (Kashi Himani, IVBL-22, and Kashi Taru) cultivars showed an increase in storability by 8 and 6 days, respectively, over uncoated fruit. Practical Applications: The coating of eggplants with chitosan is an easy to use, effective, economical, and biologically safe technique to enhance the postharvest keeping quality of eggplants. It can be employed in the postharvest supply chain to maintain quality and extend marketability of eggplants. © 2020 Wiley Periodicals LLC.
Effect of stage-specific and multi-stage drought on grain nutrient quality in rice
(Springer Science and Business Media B.V., 2023) Sahana Basu; Shashi Shekhar; Alok Kumar; Surbhi Kumari; Nitu Kumari; Sonal Kumari; Santosh Kumar; Ram Prasad; Gautam Kumar
Drought is a multidimensional stress that affects the grain nutritional quality of high yielding rice genotypes. The present study evaluated the impacts of stage-specific (seedling, vegetative, and reproductive stages) and cumulative (multi-stage) drought on ionome, starch, and protein contents in grains of two rice genotypes of eastern Indo-Gangetic plain, viz. Sahbhagi Dhan and IR64 with contrasting drought tolerance. The study showed drought to negatively affect the physiological and nutritional traits of rice grains. Following the study, stage-specific and multi-stage drought caused significant reduction in grain size, test weight, starch, amylose, amylopectin, and total soluble protein contents of rice grains. Drought during different developmental stages of rice caused significant variations in micro- (Cu, Fe, Mn, Na, Zn) and macro-nutrient (P, K, Ca, Mg) contents in the grains. Stage-specific and cumulative drought exposure of the rice genotypes also governed the ionomes in grains resulting in specific ionomic networks. Hierarchical cluster analysis showed two discrete clusters for elements as well as different drought treatments in the studied rice genotypes, which supported the results obtained from the principal component analysis, displaying five clusters based on stage-specific and multi-stage drought treatments. Variation in drought treatments and elements in different rice genotypes also altered the ionomic interactions represented by differential ionomic networks. In this study, Sahbhagi Dhan maintained the morphological and nutritional qualities of grains across the drought treatments and therefore, can be used as a suitable donor in breeding for stage-specific and cumulative drought tolerance with superior grain quality for eastern Indo-Gangetic plain. © 2023, The Author(s), under exclusive licence to Springer Nature B.V.
Effective antioxidant defense prevents nitro-oxidative stress under arsenic toxicity: A study in rice genotypes of eastern Indo-Gangetic plains
(Elsevier B.V., 2022) Alok Kumar; Sahana Basu; Surbhi Kumari; Shashi Shekhar; Gautam Kumar
Arsenic (As) toxicity in humans and animals has become a major concern in the last few decades. Rice growing on As-contaminated soil is the principal dietary source of As that poses a significant health hazards to rice patrons, making it a global issue of concern to take necessary steps to counteract the problem. Eastern Indo-Gangetic plains (EIGP) is one of the world's hotspot for As pollution. Arsenic contaminated irrigation is the principal reason for elevated As levels in the agricultural fields of EIGP, which affects rice productivity. The present study intended to explore the influences of As toxicity (arsenite and arsenate) on the morpho-physiology, ionomics, and biochemical performances of 18 rice genotypes of EIGP at the seedling stage. Arsenic exposure negatively affected plant height, root length, and biomass in rice. It also induced membrane degradation thereby, decreasing total chlorophyll content. It also impaired the nutrient uptake and root-to-shoot translocation abilities of plants. Arsenic toxicity led to the accumulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) consequently, inducing nitro-oxidative stress in rice. Arsenic tolerance in rice was related to the antioxidant defense system that decreased the malondialdehyde (MDA) content and improved the membrane stability thereby, sustaining plant growth. Additionally, proline facilitated ROS eradication conferring protection against the As-induced nitro-oxidative stress. In this study genotypic variation was obvious in all traits associated with As toxicity. Among the rice genotypes studied, Sahbhagi Dhan and Sabour Ardhjal displayed considerably higher As tolerance with sustainable plant growth, membrane stability, nutrient homeostasis, enhanced antioxidant enzyme activities, lower ROS/RNS and MDA accumulations under different As treatments. Overall, the study revealed the association between proteomic and ionomic profiles in rice to understand the potential adaptive mechanisms in plants under As toxicity. © 2022 Elsevier B.V.
Impact of COVID-19 lockdown on prices of potato and onion in metropolitan cities of India
(Emerald Group Holdings Ltd., 2022) Kuldeep Rajpoot; Saurav Singla; Abhishek Singh; Shashi Shekhar
Purpose: This study focuses on accessing the impact of lockdown implemented to curb the pandemic of coronavirus disease 2019 (COVID-19) on prices of potato and onion crops using the time series analysis techniques. Design/methodology/approach: The present study uses secondary price series data for both crops. Along with the study of percent increase or decrease, the time series analysis techniques of autoregressive integrated moving average (ARIMA) and generalized autoregressive conditional heteroskedasticity (GARCH), as well as machine learning; neural network autoregressive (NNAR) models were used to model the prices. For the purpose of comparison, the data from past years were taken as the period of normalcy. The behaviour of the forecasts for the normal periods and during the pandemic based on respective datasets was compared. Findings: The results show that there was an unprecedented rise in prices during the months of lockdown. It could be attributed to the decline in arrivals due to several reasons like issues with transportation and labour availability. Also, towards the end of lockdown (May 2020), the prices seemed to decrease. Such a drop could be attributed to the relaxations in lockdown and reduced demand. The study also discusses that how some unique approaches like e-marketing, localized resource development for attaining self-sufficiency and developing transport chain, especially, for agriculture could help in such a situation of emergency. Research limitations/implications: A more extensive study could be conducted to mark the factors specifically that caused the increase in price. Originality/value: The study clearly marks that the prices of the crops increased more than expectations using time series methods. Also, it surveys the prevailing situation through available resources to link up the reasons behind it. © 2021, Emerald Publishing Limited.
Micronutrient and redox homeostasis contribute to Moringa oleifera-regulated drought tolerance in wheat
(Springer Science and Business Media B.V., 2023) Sahana Basu; Amlan A. Prabhakar; Surbhi Kumari; Aabha; Ravi Ranjan Kumar; Shashi Shekhar; Krishna Prakash; Jitendra P. Singh; Gyanendra P. Singh; Ram Prasad; Gautam Kumar
Global food security is being severely affected by the rapid increase in population and drastic climate change. Drought stress is the most important limiting factor for the sustainable production of several important crops, including wheat. The gradual temperature rise and reduced precipitations are likely to cause the frequent onset of droughts around the world. Therefore, alleviation of drought stress in crop plants has become an essential requirement to meet the increasing food demand. The present study explored the role of foliar application of Moringa leaf extract (MLE) in conferring drought tolerance in wheat during the anthesis stage. A wheat genotype of Indo-Gangetic Plains (HI1544) was exposed to drought stress during the anthesis of the spikes and simultaneously foliar sprayed with MLE for 10 days. The results showed the MLE treatment to improve the concentrations of macro- (K, Ca) and micronutrients (B, Cu, Fe, Mn, Zn, Si) in flag-leaves of wheat under non-stressed conditions. Application of MLE also maintained the flag-leaf nutritional contents under drought stress. The micro-nutrients, including Cu, Fe, Mn, and Zn being the co-factors of the enzymes also stimulated the antioxidant enzyme activities; eventually leading to a significant reduction in the reactive oxygen species and malondialdehyde accumulations under drought stress. Furthermore, micronutrients played a crucial role in osmotic adjustment and sustainable plant growth under drought stress. Overall, the study provided insights into the functional role of micronutrients in improving drought tolerance and also indicated the potential to commercialize MLE as an effective bio-stimulant for sustainable agriculture in drought-prone regions. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.
Modelling price volatility in onion using wavelet based hybrid models
(The Society of Economics and Development, 2021) Saurav Singla; Ranjit Kumar Paul; Shashi Shekhar
The performance of wavelet-based hybrid models using different combinations of wavelet filters was compared to that of other conventional models to model volatility in the onion prices and arrivals at the Lasalgaon market of Maharashtra, which is known to be one of the largest markets in terms of arrivals. Monthly data of more than twenty-three years from 1996 onwards were taken into account. The results of hybrid models were compared to that of the ARIMA model. A normality test was conducted for both data series, and both of them were found to be non-normal. Therefore, a suitable nonparametric approach, namely wavelet decomposition of the data, was called for. For the price data, too, the wavelet-GARCH model with LA8 filter at five-level decomposition performed best for single value forecast, whereas the ARIMA performed well at expanded horizons. For the arrivals data, the Wavelet-GARCH model with LA8 filter at four level decomposition outperformed all models for single value forecasts. However, the wavelet-ANN model was able to perform better as the horizon expanded to twelve months. The study concluded that the wavelet hybrid models do pretty well for single value forecast, but as the horizon expands, the accuracy of the models decreases. ©2021 The Society of Economics and Development, except certain content provided by third parties.
Overexpression of flowering locus D (FLD) in Indian mustard (Brassica juncea) enhances tolerance to Alternaria brassicae and Sclerotinia sclerotiorum
(Springer Science and Business Media Deutschland GmbH, 2023) Shashi Shekhar; Ruby Panwar; Subhash Chandra Prasad; Deepak Kumar; Anjana Rustagi
Key message: Overexpression of BjFLD in Brassica juncea imparts resistance against fungal pathogens and increases the yield. These transgenics could lower the use of fungicides, which have detrimental effects on the environment. Abstract: Productivity of Indian mustard (Brassica juncea) is adversely affected by fungal phytopathogens, Alternaria brassicae and Sclerotinia sclerotiorum. Arabidopsis flowering locus D (FLD) positively regulates jasmonic acid signaling and defense against necrotrophic pathogens. In this study, the endogenous FLD (B. juncea FLD; BjFLD) in Indian mustard was overexpressed in B. juncea to determine its role in biotic stress tolerance. We report the isolation, characterization, and functional validation of BjFLD. The transgene expression was confirmed by qRT-PCR. The constitutive overexpression of BjFLD enhanced the tolerance of B. juncea to A. brassicae and S. sclerotiorum, which was manifested as delayed appearance of symptom, impeded disease progression, and enhanced percentage of disease protection. The transgenic lines maintained a higher photosynthetic capacity and redox potential under biotic stress and could detoxify reactive oxygen species (ROS) by modulating the antioxidant machinery and physiochemical attributes. The BjFLD-overexpressing lines showed enhanced SA level as well higher NPR1 expression. The overexpression of BjFLD induced early flowering and higher seed yield in the transgenic lines. These findings indicate that overexpression of BjFLD enhances the tolerance of B. juncea to A. brassicae and S. sclerotiorum by induction of systemic acquired resistance and mitigating the damage caused by stress-induced ROS. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Plant growth promoting rhizobacterium Bacillus sp. BSE01 alleviates salt toxicity in chickpea (Cicer arietinum L.) by conserving ionic, osmotic, redox and hormonal homeostasis
(John Wiley and Sons Inc, 2023) Sahana Basu; Surbhi Kumari; Pritee Subhadarshini; Aniket Kumar Rishu; Shashi Shekhar; Gautam Kumar
Soil salinity leading to sodium toxicity is developing into a massive challenge for agricultural productivity globally, inducing osmotic, ionic, and redox imbalances in plants. Considering the predicted increase in salinization risk with the ongoing climate change, applying plant growth-promoting rhizobacteria (PGPR) is an environmentally safe method for augmenting plant salinity tolerance. The present study examined the role of halotolerant Bacillus sp. BSE01 as a promising biostimulant for improving salt stress endurance in chickpea. Application of PGPR significantly increased the plant height, relative water content, and chlorophyll content of chickpea under both non-stressed and salt stress conditions. The PGPR-mediated tolerance towards salt stress was accomplished by the modulation of hormonal signaling and conservation of cellular ionic, osmotic, redox homeostasis. With salinity stress, the PGPR-treated plants significantly increased the indole-3-acetic acid and gibberellic acid contents more than the non-treated plants. Furthermore, the PGPR-inoculated plants maintained lower 1-aminocyclopropane-1-carboxylic acid and abscisic acid contents under salt treatment. The PGPR-inoculated chickpea plants also exhibited a decreased NADPH oxidase activity with reduced production of reactive oxygen species compared to the non-inoculated plants. Additionally, PGPR treatment led to increased antioxidant enzyme activities in chickpea under saline conditions, facilitating the reactive nitrogen and oxygen species detoxification, thereby limiting the nitro-oxidative damage. Following salinity stress, enhanced K+/Na+ ratio and proline content were noted in the PGPR-inoculated chickpea plants. Therefore, Bacillus sp. BSE01, being an effective PGPR and salinity stress reducer, can further be considered to develop a bioinoculant for sustainable chickpea production under saline environments. © 2023 Scandinavian Plant Physiology Society.
Reactive oxygen species and reactive nitrogen species induce lysigenous aerenchyma formation through programmed cell death in rice roots under submergence
(Elsevier B.V., 2020) Sahana Basu; Gautam Kumar; Nitu Kumari; Surbhi Kumari; Shashi Shekhar; Santosh Kumar; Ravi Rajwanshi
Nitric oxide (NO) plays a significant role in plants under different abiotic stress. However, the influence of NO and other reactive nitrogen species (RNS) in employing nitrosative stress in rice seedlings under submergence remains unexplored. Submergence also stimulates the development of lysigenous aerenchyma, facilitating oxygen supply to roots but the contribution of NO and RNS in aerenchyma formation under submergence is not known. Present study investigated the major components of the nitro-oxidative stress and their association with lysigenous aerenchyma development in the Sub1 near isogenic line of rice under submergence. Following submergence, Swarna showed increased NADPH oxidase (NOX) activity with excess reactive oxygen species (ROS) production in roots. Submergence also caused increased NO content and membrane lipid peroxidation in Swarna roots. Submergence-induced ROS and RNS accumulation in roots disturbed the redox homeostasis leading to the formation of lysigenous aerenchyma through programmed cell death (PCD). PCD was also accompanied by altered cytoplasmic streaming and DNA damage. In the present study Swarna Sub1 exhibited increased SOD, CAT, POX, APX, GR and GSNOR activity with subsequent detoxification of ROS and RNS; eventually decreasing the aerenchyma formation in root under submerged conditions. Overall, the study established ROS and RNS-mediated unique mechanism in lysigenous aerenchyma formation in rice roots under submergence. © 2020 Elsevier B.V.
Redox imbalance disrupts spikelet fertility in rice: A study under stage-specific and multi-stage drought in eastern Indo-Gangetic plain
(Elsevier B.V., 2023) Santosh Kumar; Sahana Basu; A.K. Choudhary; J.S. Mishra; Surajit Mondal; Shashi Shekhar; S.K. Dwivedi; Rakesh Kumar; Surbhi Kumari; Narayan Bhakta; Sanjeev Kumar; Ujjwal Kumar; Arvind Kumar; Gautam Kumar
To support the increasing food demand of the drought-prone eastern Indo-Gangetic plain (EIGP), we assessed the effects of natural drought stress on the individual (seedling stage drought; SSD, vegetative stage drought; VSD, reproductive stage drought; RSD) as well as the multiple growth stages (multi-stage drought; MSD) of twenty-four rice genotypes (n = 24) under field conditions for two consecutive rice growing seasons (2019–2020). High temperature and low rainfall during both the trial years exerted moderate to severe drought stress to the rice genotypes leading to average grain yield reduction of 43.5%, 28.9%, 59.3%, and 69.9% under SSD, VSD, RSD, and MSD conditions, respectively. The present study also revealed that drought stress caused enhanced accumulation of reactive oxygen species (ROS) in the spikelets of rice genotypes thereby, impeding the spikelet fertility. The promising rice genotypes showed an average decrease of 3.18%, 4.83%, 13.9%, and 13.06% in spikelet fertility under SSD, VSD, RSD, and MSD conditions, respectively. Identified promising rice genotypes, IR83929-B-B-291–2–1–1–2, IR93827–29–1–1–2 and IR84899-B-183–20–1–1–1 showed extreme drought tolerance and better maintained photosynthetic rate, stomatal conductance, relative water content, membrane stability index, and total chlorophyll content under drought conditions irrespective of growth stages. Following the study, drought tolerance in the tolerant rice genotypes was associated with increased antioxidant enzyme mediated efficacious ROS detoxification, which contributed in maintaining pollen viability and spikelet fertility. Overall, the study identified drought tolerant rice genotypes for EIGP and established a comprehensive understanding of the complexity and plasticity of the rice genotypes under stage-specific and cumulative drought stress. © 2022 Elsevier B.V.
Robustness of sequential third-order response surface design to missing observations
(Taylor and Francis Ltd., 2022) M. Hemavathi; Eldho Varghese; Shashi Shekhar; C.K. Athulya; Sanal Ebeneezar; Reshma Gills; Seema Jaggi
Response surface designs are generally used in process/product optimization studies. Sequential third-order response surface designs are advantageous when the experimenter encounters the significance of lack of fit of a fitted second-order model while establishing the relationship between the input and response variables. In some experimental situations, responses pertaining to certain design points may be destroyed or unobtainable or inaccessible. The unavailability of the observations pertaining to certain experimental run(s) affects the design property and affects the analysis of variance. In this paper, we have examined the robustness of sequential third-order rotatable design and investigated the loss of information when one or two observations pertaining to experimental run(s) is (are) missing, which are at different radii from the design centre. It has been found that the maximum loss of information occurs when the observation at the design points which are at higher radii from the design centre is lost and the design has the minimum efficiency. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
Run order consideration for sequential third order rotatable designs
(Taylor and Francis Ltd., 2024) Hemavathi M; Eldho Varghese; Shashi Shekhar; Seema Jaggi; Arpan Bhowmik; T.V. Sathianandan
Random execution of run sequences is employed in response surface designs to avoid bias in the response. Since the randomization of run sequences may induce frequent changes in the factor levels, which makes it difficult or expensive for the experimenter, especially when hard-to-change factors are involved in the experiment. Mostly, second order response surface designs (SORDs) are being used to explore the functional relationship between the response and the input variables. But when the lack of fit of the model becomes significant, it is desirable to explore the relationship with a polynomial model of order three. This requires third order rotatable designs (TORDs), which can be sequentially implemented by adding few more runs to the SORDs. In this paper, the construction of sequential TORDs with minimum level changes in the run sequences has been discussed. © 2022 Taylor & Francis Group, LLC.
Salicylic Acid and Methyl Jasmonate Synergistically Ameliorate Salinity Induced Damage by Maintaining Redox Balance and Stomatal Movement in Potato
(Springer, 2023) Shashi Shekhar; Ayushi Mahajan; Prashasti Pandey; Meenakshi Raina; Anjana Rustagi; Ram Prasad; Deepak Kumar
Susceptibility of plants to salinity stress is a looming threat to crop productivity worldwide, thereby warranting the strategies to counter stress. We investigated the effects of combined foliar treatment with salicylic acid (SA) and methyl jasmonate (MeJA) on the growth and development of two elite varieties of potato under salinity stress. The salinity stress manifested membrane damage, electrolyte leakage, and production of H2O2 and free radical superoxide anion. Application of SA or MeJA individually could not significantly improve the performance of potato plants exposed to salinity stress. However, treatment with combinations of SA and MeJA synergistically mitigated the adverse effects of salinity, as reflected by reduced membrane damage and electrolyte leakage and lower accumulation of H2O2 and free radical superoxide anion. Moreover, plants treated with the combination treatment had higher relative water content and redox pools of ascorbate and glutathione under salinity stress. The treatment promoted the accumulation of K+ and lowered the Na+ content. SA and MeJA synergistically enhanced the activities of the antioxidant enzymes in the Halliwell-Asada pathway and modulated the photosynthetic and transpiration rates. Overall, our results indicate that the combined foliar treatments with SA and MeJA have positive effects on the growth, development, and yield of potato through maintenance of ion homeostasis and photosynthetic traits. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Sequential asymmetric third order rotatable designs (SATORDs)
(Taylor and Francis Ltd., 2022) M. Hemavathi; Eldho Varghese; Shashi Shekhar; Seema Jaggi
Rotatable designs that are available for process/ product optimization trials are mostly symmetric in nature. In many practical situations, response surface designs (RSDs) with mixed factor (unequal) levels are more suitable as these designs explore more regions in the design space but it is hard to get rotatable designs with a given level of asymmetry. When experimenting with unequal factor levels via asymmetric second order rotatable design (ASORDs), the lack of fit of the model may become significant which ultimately leads to the estimation of parameters based on a higher (or third) order model. Experimenting with a new third order rotatable design (TORD) in such a situation would be expensive as the responses observed from the first stage runs would be kept underutilized. In this paper, we propose a method of constructing asymmetric TORD by sequentially augmenting some additional points to the ASORDs without discarding the runs in the first stage. The proposed designs will be more economical to obtain the optimum response as the design in the first stage can be used to fit the second order model and with some additional runs, third order model can be fitted without discarding the initial design. © 2020 Informa UK Limited, trading as Taylor & Francis Group.
Sequential submergence and drought induce yield loss in rice by affecting redox homeostasis and source-to-sink sugar transport
(Elsevier B.V., 2024) Santosh Kumar; Sahana Basu; A.K. Choudhary; Shashi Shekhar; J.S. Mishra; Sanjeev Kumar; Kumari Shubha; Rachana Dubey; Surajit Mondal; S.K. Dwivedi; N. Bhakta; Rakesh Kumar; Sujoy Sarkar; Srustidhar Dhamudia; Sunny Kumari; Anup Das; Arvind Kumar; Gautam Kumar
Rice cultivation in the rainfed ecosystems of the eastern Indo-Gangetic plain (EIGP) frequently comes across abrupt alternation of submergence and drought during the vegetative and reproductive stages, respectively, within one growing season, and this may be exaggerated with climate change. Therefore, development of combined submergence and drought tolerant rice genotypes might be a timely effort to meet the growing food demand. However, till date no study has been executed on the combination of submergence and drought stress in the field conditions of the EIGP. The present study elucidated the performance of near isogenic lines (NILs) of rice developed for the EIGP through marker assisted pyramiding of quantitative trait loci (QTL) associated with submergence (Sub1) and drought (qDTY1.1 + qDTY2.1 + qDTY3.1) in the background of the popular, high yielding Indo-Gangetic rice variety Swarna. This study included the screening of sixteen rice NILs along with the check varieties Swarna and Swarna Sub1 under cumulative submergence and drought for four consecutive rice growing years (2019–2022). Individual submergence or drought or cumulative stress caused 76, 47, and 85% respective loss in average productivity compared to that of the control conditions. However, rice NILs IR96321–558–563-B-2–1–1, IR96321–315–323-B-3–1–3, IR96321–315–294-B-1–1–1–1, and IR96321–558–209-B-6–1–1 showed outstanding cumulative stress tolerance with sustainable photosynthetic performance and membrane stability. Furthermore, these rice NILs exhibited effective reactive oxygen species scavenging mediated by enhanced antioxidant enzyme activities in source (flag-leaf) and sink (anther) tissues that contributed to conserving the source-to-sink mobilization, leading to improved pollen viability and spikelet fertility under sequential stress conditions. The study identified combined submergence-drought tolerant rice NILs along with an optimum yield level to support global food security and also represented a model crop system to establish mechanisms of multi-stress tolerance in plants. © 2024 Elsevier B.V.
TESTING OF VARIANCE COMPONENTS FOR CONTINUOUS DATA FROM NESTED UNBALANCED DESIGNS
(DAV College, 2022) Ankita; Susheel Kumar Sarkar; Anil Kumar; Sanjeev Panwar; Shashi Shekhar; Rajan Kumar
Under unbalanced design, testing of variance ratios are generally neither independent nor distributed as chi-square variates and does not follow standard F-distribution. In this case, exact testing of variance ratios is not available in the literature. Procedure for unbalanced data (generally not independent and are not distributed as chi-square variates) has been developed for testing the variance components in one way and two way unbalanced nested designs. © 2022 DAV College. All rights reserved.
Theoretical developments in response surface designs: an informative review and further thoughts
(Taylor and Francis Ltd., 2022) M. Hemavathi; Shashi Shekhar; Eldho Varghese; Seema Jaggi; Bikas Sinha; Nripes Kumar Mandal
Response Surface Designs (RSDs) are widely used in process or product optimization studies to explore the input-response relationship. This paper is an attempt to provide a compilation of theoretical developments in the RSDs, since its inception in early 1950s to 2020. Part I (1951–1999) consists of important reviews on basic concepts and its development, which fueled further development during the period 2000 to 2020, included in Part II and concluded with future scope of research. We hope this compilation will be a one-stop platform for researchers to know about the advancements in this field. © 2021 Taylor & Francis Group, LLC.