Agro-ecological Regions Of India Research Articles

Soil erosion in diverse agroecological regions of India: a comprehensive review of USLE-based modelling.

Soil erosion caused by water refers to the removal of topsoil by rainfall and runoff. Proper selection of an assessment method is crucial for quantifying the spatial variance of soil erosion. The Universal Soil Loss Equation (USLE) and its revised version (RUSLE) are widely used for modelling soil erosion. This study aimed to evaluate the effectiveness of the USLE-based soil erosion modelling in different agroecological regions of India, identify potential issues, and provide suggestions for future applications. The review revealed that little attention has been given to estimate soil erosion in high-priority land degradation regions of India. Additionally, many studies failed to thoroughly verify the authenticity of stated soil loss rates in their research regions either by overestimating or underestimating at least one of the five soil loss parameters. Furthermore, flaws in the application of methods to calculate these parameters leading to erroneous values were identified and suggestions for improvement were made. The USLE-based soil erosion modelling is an effective tool for quantifying soil erosion risk, but researchers should put emphasis on thoroughly verifying the methodologies adopted, unit conversions, and data availability for the estimation of soil loss parameters to improve the accuracy of their final results. This paper provides valuable insights to assist researchers in implementing USLE-based erosion models in diverse agroecological regions in India and elsewhere. However, for effective soil conservation and sustainable agriculture, further research is necessary to develop efficient techniques for using USLE-based soil erosion modelling to achieve a comprehensive understanding of erosion risk across different agroecological regions.

Spatio-temporal trend of crop phenology, SPEI, and their interactions over different agro-ecological regions of India

Spatio-temporal trend of crop phenology, SPEI, and their interactions over different agro-ecological regions of India

The relative role of soil moisture and vapor pressure deficit in affecting the Indian vegetation productivity

Atmospheric aridity (vapor pressure deficit, VPD) and soil moisture (SM) deficit limit plant photosynthesis and, thus, affect vegetation carbon uptake. The strong correlation between SM and VPD makes it challenging to delineate their relative contributions to regional vegetation productivity. Addressing this gap is vital to understand the future trajectory of plant productivity in India—the second-highest contributor to global greening. Here, we separate the controls of SM and VPD on the Indian vegetation using statistical and causal analysis. We found that vegetation productivity in India is primarily controlled by SM limitation (87.66% of grids) than VPD limitation (12.34% of grids). Vegetation has a varying association with SM and VPD across different agroecological regions in India. The negative impact of VPD on vegetation carbon uptake is not visible in high-rainfall areas of India. These findings advance our understanding of vegetation dynamics under regional dryness stress and can enhance dynamic vegetation model estimates for India under changing climate scenarios.

An Agroecological Analysis of Livestock Wealth in India

This study aims to analyze the livestock population dynamics, adoption pattern of livestock and infrastructure facilities across different agroecological regions of India. The results revealed that more than 50 per cent of all livestock species were found in rain-fed areas. In irrigated region, 36 per cent of the livestock population depended upon 15 per cent of the geographical area. The cattle population growth rate declined for all regions because of a faster decline in indigenous cattle in all the agroecological regions. The number of crossbred cattle increased from 26 to 44 million among the cattle population at the India level. It may be due to the acceptance of insemination techniques with the expectation of high milk yield. Whereas, in irrigated region, the situation was very different, with a marginal increase in the share of crossbred cows. The findings indicated that India’s large and uniquely structured livestock sector was growing with compound annual growth of 4.3 per cent. For the sustainable development of the sector, suitable efforts should be taken to improve the genetic potential of indigenous cattle and buffalo and enhance the milk yield of crossbred cows by supportive technical, institutional and policy initiatives

Varietal Threat Index for Monitoring Crop Diversity on Farms in Five Agro-Ecological Regions in India

Our knowledge about the status of agrobiodiversity on farms is still very limited. While several studies to assess the crop genetic diversity on farms have been undertaken, there are no systematic documentation and monitoring practices for varietal diversity in space and time. Achievement of the agrobiodiversity Aichi Target 13, established under the Biodiversity Strategy Plan 2011–2020, have failed due to the lack of existing data on varietal diversity at country, regional and global levels. Here, we propose a method for calculating the Varietal Threat Index using the four-cell analysis (FCA) participatory methodology at different geographical scales to monitor changes in the varietal diversity on farms and to compare between areas. We tested the method with datasets collected from the UN-Environment GEF project implemented in India, in which data on crop and varietal diversity were collected across seven states in India, covering five agroecological regions. Results showed that landraces are still commonly grown in the study sites, especially in the central and western regions, and that more than 50% of landraces are considered threatened, suggesting that conservation interventions are required to prevent large-scale genetic erosion. A long-term monitoring framework for varietal diversity in India is proposed.

Seed and seedling diversity delimitation and differentiation of Indian populations of Melia dubia cav.

Melia dubia is one of the most important industrial tree species in the South East Asia. In last few decades, the populations of M. dubia has rapidly expanded in the Indian sub-continents, leading to an increase in the genetic diversity of species. However, very less information is available on intra-specific variation in Melia under the Indian subcontinent. Therefore, a present investigation was undertaken, to assess the level of diversity in seed and saplings of the Melia populations (ecotypes) collected from three agro-ecological regions of India. Results revealed that the seed and saplings of all the ecotypes are significantly different for all the traits, except for number of branches per plant, and the maximum variability was recorded in germination percentage, seed weight, internodal length, and sapling height of the species. The high heritability for seed weight (0.99), length (0.99), and width (0.97), and germination percentage (0.99) indicated that selection and genetic gain for these traits would be effective during the commencement of improvement program. Trait association analysis explained that higher seed weight significantly reduced sapling height, collar diameter, number of leaves per plant, internodal length, petiole length, and germination percentage (r = −0.86; p < 0.001) that ultimately reduced the seedling vigor in Melia dubia. Interestingly, the number of branches per plant were not associated with any of the morphological traits. The first principal component explained 50.09% of the entire variation and all the traits contributed greatly to the variation for this principal component, except for number of branches, leaf width and seed length. The clustering approach assorted geographic variation of M. dubia populations into three main sub-clusters i.e. South, North, and North East populations each consisting of five, seven and one populations (including cultivar), respectively. Among different ecotypes, Bahumukhi, Varsha and US Nagar seed sources outperformed all others in seedling vigour (sapling height) and rest of the growth parameters. Overall, findings explained that considerable scope exists for the development of superior planting material of M. dubia through exploration of seeds and selection at the early seedling stage.

Impact of natural resource management interventions on water resources and environmental services in different agroecological regions of India

Natural resource management is critical for addressing issues of water scarcity, land degradation and poor agricultural and livestock productivity especially in rainfed ecologies. This study was conducted in 13 Gram panchayats (cluster of villages) of three states in India representing different agroecological regions. Natural resource management works undertaken through the Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA) covering water harvesting, pasture land and orchard development were evaluated between November 2015 and January 2016. Density of water harvesting varied from 10 to 250 m3 ha−1 depending on topography and works completed in different villages. These structures have contributed significantly to harvesting surface runoff, enhancing groundwater recharge, reducing soil erosion, and flood control. Irrigation acreage increased between 4 ha and 95 ha which is about 5–10% of the total cultivable area in study villages. In addition, crop productivity increased from 30 to 50% both in rainy and post-rainy seasons compared to non-beneficiary fields. The study showed that the selected natural resource management works have the potential to generate additional economic gain from US$ 60 ha−1 year−1 to US$ 225 ha−1 year−1 along with some indirect benefits to strengthen environmental services and rural livelihood. Overall, the MGNREGA has helped in strengthening ecosystem services, viz., provisioning, regulatory, and supporting services in addition to providing employment opportunities. The study also suggests to follow science-led approach in designing and implementation of various NRM works for further improvements and achieving long term sustainability.

Agroforestry environment, potentiality and risk in India: a remote sensing and GIS understanding

The study utilized the tree covers per cent, agroforestry suitability, present and future (2050) climate, agriculture vulnerability (2050), percentage of people living Below Poverty Line (BPL) data sets and manoeuvered them in GIS platform to understand the agroforestry extent, potentiality and the critical multidimensional relationship among them. The total agroforestry area in India (if defined the tree cover per cent greater than 10% on agricultural land) was found to be 28 million hectares that is approximately 17% of the total agriculture land area which is remarkably less (global average 43%). The analysis further revealed that the agriculture land potential in India towards the agroforestry suitability category (S1: High suitability) is alone 75.6 million hectares that are 2.7 times of total existing agroforestry extent. Among all agro-ecological regions of India, the Eastern Plain agro-ecological region has high cropland potentiality which will help significantly in magnifying agroforestry set-up in the future. The analysis further revealed a very high poverty per cent (41–80%) category has approximately 5.3 million hectares of land under agroforestry, whereas the cropland potentiality (category S1) towards agroforestry was found approximately four times of the present agroforestry extent. The Western Ghats and the Coastal Plain agro-ecological region maintain a diversified agroforestry environment that will face double risk in the future (2050) due to precipitation deficit and also from significant temperature increase. Our analysis highlights the important agroforestry-related findings that will assist crucially to the decision-makers of India for implementing synergic strategies/planning of agroforestry at country/state/district/village levels.

Synergistic Use of Radar and Optical Satellite Data for Improved Monsoon Cropland Mapping in India

Monsoon crops play a critical role in Indian agriculture, hence, monitoring these crops is vital for supporting economic growth and food security for the country. However, monitoring these crops is challenging due to limited availability of optical satellite data due to cloud cover during crop growth stages, landscape heterogeneity, and small field sizes. In this paper, our objective is to develop a robust methodology for high-resolution (10 m) monsoon cropland mapping appropriate for different agro-ecological regions (AER) in India. We adapted a synergistic approach of combining Sentinel-1 Synthetic Aperture Radar (SAR) data with Normalized Difference Vegetation Index (NDVI) derived from Sentinel-2 optical data using the Google Earth Engine platform. We developed a new technique, Radar Optical cross Masking (ROM), for separating cropland from non-cropland by masking out forest, plantation, and other non-dynamic features. The methodology was tested for five different AERs in India, representing a wide diversity in agriculture, soil, and climatic variations. Our findings indicate that the overall accuracy obtained by using the SAR-only approach is 90%, whereas that of the combined approach is 93%. Our proposed methodology is particularly effective in regions with cropland mixed with tree plantation/mixed forest, typical of smallholder dominated tropical countries. The proposed agriculture mask, ROM, has high potential to support the global agriculture monitoring missions of Geo Global Agriculture Monitoring (GEOGLAM) and Sentinel-2 for Agriculture (S2Agri) project for constructing a dynamic monsoon cropland mask.

Characterization of Some Vertisols of Different Agro-ecological Regions of India

Vertisols have the capacity to shrink and swell, inducing cracks and distinctive soil structure throughout the soil profile. In India they occur in various agro-ecological regions such as humid tropical (HT), sub-humid moist (SHM), sub-humid dry (SHD), semi-arid moist (SAM), semi-arid dry (SAD) and arid dry (AD) climatic environments and thus indicate an array of soils in a climosequence. In this study benchmark Vertisols, series Panjari is from sub-humid (dry), Kheriis from sub-humid (moist) region, Teligi and Akola series are from semi-arid (dry) and Nimone is from arid agro-ecological region. All the Vertisols in general are characterized by dark colour, angular to sub-angular blocky structure and clay in texture and calcareous. These soils have high bulk density and high water retention capacity. These soils have deep, wide-opened desiccation cracks at the surface which extend deep into the profiles and the depth of cracks increases with aridity. Soils of all climates are dominated by Ca2+ ion in their exchange complex throughout the depth. However, in the sub-humid climate Mg2+ ions tends to dominate in the lower horizon. Whereas the semi-arid dry (Akola) soils have high Na+ ions in their exchange complex. The soils are slightly alkaline to strongly alkaline in nature and poor in organic matter. The CEC varied from 59.3 to 68.2cmol (p+) kg-1 in soil of Panjari series which is highest followed by Teligi series profile. The calcium carbonate (CaCO3) shows gradual increase with depth in all the soil profiles, though it is preferentially accumulated in the sub-surface horizons of lower rainfall region soils.In climosequence the soils of the sub-humid region are generally Typic Haplusterts, soils of semi-arid region are Typic/Sodic/Calcic Haplusterts and soils of arid region are Sodic/ Calcic/ Aridic Haplusterts. The present study demonstrates how the soil properties of Vertisols in a different climate may help in inferring the change in climate in a geologic period.

High nitrous oxide fluxes from rice indicate the need to manage water for both long- and short-term climate impacts

Global rice cultivation is estimated to account for 2.5% of current anthropogenic warming because of emissions of methane (CH4), a short-lived greenhouse gas. This estimate assumes a widespread prevalence of continuous flooding of most rice fields and hence does not include emissions of nitrous oxide (N2O), a long-lived greenhouse gas. Based on the belief that minimizing CH4 from rice cultivation is always climate beneficial, current mitigation policies promote increased use of intermittent flooding. However, results from five intermittently flooded rice farms across three agroecological regions in India indicate that N2O emissions per hectare can be three times higher (33 kg-N2O⋅ha-1⋅season-1) than the maximum previously reported. Correlations between N2O emissions and management parameters suggest that N2O emissions from rice across the Indian subcontinent might be 30-45 times higher under intensified use of intermittent flooding than under continuous flooding. Our data further indicate that comanagement of water with inorganic nitrogen and/or organic matter inputs can decrease climate impacts caused by greenhouse gas emissions up to 90% and nitrogen management might not be central to N2O reduction. An understanding of climate benefits/drawbacks over time of different flooding regimes because of differences in N2O and CH4 emissions can help select the most climate-friendly water management regimes for a given area. Region-specific studies of rice farming practices that map flooding regimes and measure effects of multiple comanaged variables on N2O and CH4 emissions are necessary to determine and minimize the climate impacts of rice cultivation over both the short term and long term.

Assessment of potassium release threshold levels of Vertisols (shrink-swell soils) in different agro-ecological regions of India

Abstract Studies to evaluate the release threshold level of potassium in Vertisols (shrink-swell soils) in different agro-ecological regions of India and how that may help in K fertility interpretations are rare. Thus the objectives of this study were (i) to evaluate the K status of Vertisols through release threshold levels and (ii) to relate the findings with soil K release and fertilizer management. Three established soil series samples were collected from Vertisols of different agro-ecological regions of India. Release threshold level (RTL) was assessed after equilibrating soil with 0.01 M CaCl2 solution having series of soil: solution ratio, after which the remaining amount of exchangeable K was extracted with 1 N NH4OAc (pH 7). Total amount of K extracted (KT = K desorbed in CaCl2 solution plus K extracted with 1 N NH4OAc) remained more or less constant with decreasing K-level up to a certain value (say threshold value) below which KT increased sharply indicating K release from non-labile form. The threshold value in terms of K concentrations (Release Threshold Concentration) of Panjari, Nagpur, Maharashtra (Typic Haplusterts, Sub-humid dry), Teligi, Bellary, Karnataka (Sodic Haplusterts, Semi-arid dry) and Kheri, Jabalpur, Madhya Pradesh (Typic Haplusterts, Sub-humid moist) soils were 0.044–0.049, 0.034–0.062 and 0.043–0.11 mm, respectively. The high release threshold K levels in terms of concentration and activity ratio (AR) were observed in soils of Teligi and Kheri series as compared to soils of Panjari series due to high content of trioctahedral mica in the former two soils. The relationships between clay minerals, release threshold level, exchangeable potassium and non-exchangeable potassium determined by 1 N HNO3 and sodium tetra-phenyl borate (NaBPh4) have been discussed.

Analysis of Multi-location Data of Hybrid Rice Trials Reveals Complex Genotype by Environment Interaction

The All India Coordinated Rice Improvement Project of ICAR-Indian Institute of Rice Research, Hyderabad organizes multi-location testing of elite lines and hybrids to test and identify new rice cultivars for the release of commercial cultivation in India. Data obtained from Initial Hybrid Rice Trials of three years were utilized to understand the genotype × environment interaction (GEI) patterns among the test locations of five different agro-ecological regions of India using GGE and AMMI biplot analysis. The combined analysis of variance and AMMI ANOVA for a yield of rice hybrids were highly significant for GEI. The GGE biplots first two PC explained 54.71%, 51.54% and 59.95% of total G + GEI variation during 2010, 2011 and 2012, respectively, whereas AMMI biplot PC1 and PC2 explained 46.62% in 2010, 36.07% in 2011 and 38.33% in 2012 of the total GEI variation. Crossover interactions, i.e. genotype rank changes across locations were observed. GGE biplot identified hybrids, viz. PAN1919, TNRH193, DRH005, VRH639, 26P29, Signet5051, KPH385, VRH667, NIPH101, SPH497, RH664 Plus and TNRH222 as stable rice hybrids. The discriminative locations identified in different test years were Coimbatore, Maruteru, VNR, Jammu, Raipur, Ludhiana, Karjat and Dabhoi. The AMMI1 biplot identified the adaptable rice hybrids viz., CNRH102, DRH005, NK6303, NK6320, DRRH78, NIPH101, Signet5050, BPH115, Bio452, NPSH2003, and DRRH83. The present study demonstrated that AMMI and GGE biplots analyses were successful in assessing genotype by environment interaction in hybrid rice trials and aided in the identification of stable and adaptable rice hybrids with higher mean and stable yields.

Evaluation of drought using SPEI drought class transitions and log-linear models for different agro-ecological regions of India

Markov chain and 3-dimensional log-linear models were attempted to model drought class transitions derived from the newly developed drought index the Standardized Precipitation Evapotranspiration Index (SPEI) at a 12 month time scale for six major drought prone areas of India. Log-linear modelling approach has been used to investigate differences relative to drought class transitions using SPEI-12 time series derived form 48 yeas monthly rainfall and temperature data. In this study, the probabilities of drought class transition, the mean residence time, the 1, 2 or 3 months ahead prediction of average transition time between drought classes and the drought severity class have been derived. Seasonality of precipitation has been derived for non-homogeneous Markov chains which could be used to explain the effect of the potential retreat of drought. Quasi-association and Quasi-symmetry log-linear models have been fitted to the drought class transitions derived from SPEI-12 time series. The estimates of odds along with their confidence intervals were obtained to explain the progression of drought and estimation of drought class transition probabilities. For initial months as the drought severity increases the calculated odds shows lower value and the odds decreases for the succeeding months. This indicates that the ratio of expected frequencies of occurrence of transition from drought class to the non-drought class decreases as compared to transition to any drought class when the drought severity of the present class increases. From 3-dimensional log-linear model it is clear that during the last 24 years the drought probability has increased for almost all the six regions. The findings from the present study will immensely help to assess the impact of drought on the gross primary production and to develop future contingent planning in similar regions worldwide.

Morphological, Morphometric, and Molecular Characterization of Intraspecific Variations within Indian Populations of Meloidogyne graminicola

Fourteen populations of Meloidogyne graminicola were collected from different agroecological regions of India. Morphological and morphometrical comparisons were made for various nematode life stages. Three populations (Hisar, New Delhi, and Samastipur) were different from typical M. graminicola on the basis of the length of eggs; J2 length, a-value, hyaline tail portion; male length, distance up to excretory pore, spicule and gubernaculum lengths; female length and width, stylet length, distance up to excretory pore, EPST (distance of excretory pore from anterior end / stylet length [females]) ratio, and vulval length. Morphological and morphometrical comparison with closely related species M. graminis, M. oryzae, M. salasi, M. triticoryzae, and M. lini clustered these populations into two groups: Anand, Bhubaneswar, Hyderabad, Jammu, Jorhat, Kalyani, Kanpur, Ludhiana, Mandya, Palampur, Vellayani grouped with M. graminicola, M. triticoryzae and M. salasi; whereas, Hisar, New Delhi, Samastipur grouped with M. oryzae and M. graminis. Molecular phylogenetic analysis using internal transcribed spacer (ITS) suggested that in spite of morphological differences, these populations belonged to M. graminicola.

Study of arbitrarily amplified (RAPD and ISSR) and gene targeted (SCoT and CBDP) markers for genetic diversity and population structure in Kalmegh [Andrographis paniculata (Burm. f.) Nees

Andrographis paniculata is a medicinal herb also known as ‘King of Bitter’. This herb was studied using arbitrary amplified (RAPD and ISSR) and gene targeted (SCoT and CBDP) molecular markers. Thirty-nine accessions were collected from five agro-ecological regions of India. Eighteen RAPD and five ISSR primers generated a total of 124 and 32 amplicons with an average of 6.89 and 6.4 amplicons per primer respectively. Similarly, 22 SCoT and 19CBDP primers were used to characterize A. paniculata accessions. A total of 132 and 97 amplicons were generated, with an average of 6.0 and 5.11 amplicons per primer, respectively. Polymorphic information content (PIC) for RAPD and ISSR primers ranged from 0.32 to 0.45 and 0.25–0.42, with resolving power (Rp) ranging from 2.13 to 10.03 and 2.46–3.96, respectively. PIC values ranged from 0.09 to 0.48 and 0.30–0.46, with an average value of 0.34 and 0.41 per primer for SCoT and CBDP markers, respectively. The resolving power for SCoT and CBDP primers ranged from 2.36 to 10.54 and 1.39–13.15 per primer, respectively. Unweighted pair group method with arithmetic mean (UPGMA) based clustering grouped 39 accessions into three broad clusters based on all four marker systems studied, did not correlate with their agro-ecological regions. Population structure based analysis divided 39 accessions into seven populations, six populations and four populations using RAPD, ISSR and SCoT markers respectively. Whereas only three populations were observed using CBDP primers which corresponded to the grouping observed with the UPGMA. Analysis of molecular variance (AMOVA) based analysis showed that the maximum variation (10%) among agro-ecological regions was observed using CBDP primers; whereas, minimum variation (2%) was observed using SCoT markers. Taken together, our data suggest CBDP markers are better markers for genetic diversity study in A. paniculata.

Genetic Variability and Diversity Pattern for Agromorphological Traits in Indian Mustard Germplasm

Genetic diversity studies were carried out on 302 indigenous accessions of Indian mustard [Brassica juncea (L.) Czern & Coss] for variability assessment and identification of trait-specific germplasm. The Indian mustard germplasm was evaluated for eight important morpho-agronomic traits. Geographic information system (GIS), principal component and cluster analysis were carried out to analyse major clusters. Four principal components were identified explaining more than 74% of total variation. Three promising germplasm accessions (IC342781, IC570320 and IC426354) identified with maximum number of seeds per siliqua (>18.0 seeds) were collected from districts Patna (Bihar) and Adilabad (Andhra Pradesh). Similarly, three promising accessions (IC426398, IC521376 and IC395557) were identified with high oil content (>40%) from districts Nizamabad (Andhra Pradesh), Godda (Jharkhand) and Gorakhpur (Uttar Pradesh) respectively. The cluster analysis grouped mainly in two major clusters I and II and further sub-divided into a and b sub-groups. In cluster I sub-group b which indicates a close relationship between traits-the days to mean flowering and days to mean maturity while the plant height was grouped individually. In cluster II, number of primary branches and number of seeds/siliqua showed close relationship with oil content as compared to other traits. GIS based grid maps using Shannon-Weaver diversity index (0–4.0) were generated for showing high variability areas (light red/dark red grids) in different agro-ecological regions of India. The results indicated that Indian mustard germplasm collected by NBPGR from different parts of India has broad genetic base. Thus, promising genotypes identified for various economically important morpho-agronomic traits can be utilized to develop improved varieties of Indian mustard.

In Vitro Propagation and Conservation of Bacopa monnieri L.

Bacopa monnieri L. (common name brahmi) is a traditional and renowned Indian medicinal plant with high commercial value for its memory revitalizer potential. Demand for this herb has further escalated due to popularization of various brahmi-based drugs coupled with reported anticancer property. Insufficient seed availability and problems associated with seed propagation including short seed viability are the major constraints of seed conservation in the gene banks. In vitro clonal propagation, a prerequisite for in vitro conservation by enhanced axillary branching was standardized. We have developed a simple, single step protocol for in vitro establishment, propagation and medium-term conservation of B. monnieri. Single node explants, cultured on Murashige and Skoog's medium supplemented with BA (0.2 mg/L), exhibited shoot proliferation without callus formation. Rooting was achieved on the same medium. The in vitro raised plants were successfully transferred to soil with ~80 % survival. On the same medium, shoots could also be conserved for 12 months with high survival and genetic stability was maintained as revealed by molecular markers. The protocol optimized in the present study has been applied for culture establishment, shoot multiplication and medium-term conservation of several Bacopa germplasm, procured from different agro-ecological regions of India.

Sensitivity Analysis of FAO-56 Penman-Monteith Method for Different Agro-ecological Regions of India

This paper analyzes the sensitivity of reference evapotranspiration (ETo) to climatic variables for different agro-ecological regions of India: semi-arid (Kovilpatti and Parbhani), humid (Mohanpur), and sub-humid (Ludhiana and Ranichauri). The FAO-56 Penman-Monteith (FAO-56 PM) method is used to estimate ETo, and sensitivity of ETo has been studied in terms of change in maximum air temperature (T max ), minimum air temperature (T min ), solar radiation (R s ), average relative humidity (RH avg ), and wind speed (W s ). Sensitivity analysis is performed by increasing and decreasing the climate variables such as T max , T min , R s , and RH avg by one unit of increment and decrement, respectively, up to five units (except for W s ) while keeping the other variables and parameters constant. However, wind speed W s (km h−1) is only increased with an increment of one km h−1 up to five km h−1. The results showed that the change in ETo is linearly related to change in all climate variables (r 2 = 0.97 in most cases) at all sites. Further, ETo is most sensitive to R s at Kovilpatti, Mohanpur and Ranichauri, and to W s at Ludhiana and Parbhani. However, the sensitivity of ETo to the same variable shows considerable variation from site to site and at the same site within the year. ETo is less sensitive to RH avg followed by T min at all sites.

Development of Generalized Higher-Order Synaptic Neural–Based ETo Models for Different Agroecological Regions in India

AbstractThis paper aims at developing generalized higher-order synaptic neural (GHSN), i.e., generalized quadratic synaptic neural (GQSN) and generalized cubic synaptic neural (GCSN), reference eva...