Rajkumar Dhakar

• Ph.D
• Researcher at Indian Agricultural Research Institute

A field experiment was conducted during 2022–23 and 2023–24 at the International Rice Research Institute-South Asia Regional Centre, Varanasi, Uttar Pradesh to assess the performance of wheat (Triticum aestivum L.) crop in 5-year long-term conservation agriculture (CA) based rice (Oryza sativa L.)-wheat (Triticum aestivum L.) system (RW) rotation u...

A two-season field experiment (2022-23 and 2023-24) was conducted at the IRRI-South Asia Regional Centre, Varanasi, Uttar Pradesh, to assess the impact of conservation agriculture (CA), irrigation methods, and nitrogen (N) levels on rabi maize in a long-term rice-maize system. The randomized complete block design included nine treatment combination...

A two-season field experiment (2022-23 and 2023-24) was conducted at the IRRI-South Asia Regional Centre, Varanasi, Uttar Pradesh, to assess the impact of conservation agriculture (CA), irrigation methods, and nitrogen (N) levels on rabi maize in a long-term rice-maize system. The randomized complete block design included nine treatment combination...

Water, a crucial input in agricultural production, is distributed based on geographical and topographical patterns. However, anthropogenic climate change has intensified water scarcity in semi-arid regions. This research aims to precisely estimate crop evapotranspiration (ET) and examine the diurnal and seasonal patterns of surface energy fluxes in...

Crop residue burning is one of the prime factors behind air pollution in Northern India. Every year air quality of National Capital Region (NCR) and adjoining areas crosses danger line due to residue burning especially during winter time. The present study was conducted in Sangrur district of Punjab and Kaithal district of Haryana due to highest in...

Nitrogen serves as an essential nutrient for plant growth, significantly influencing crop performance and nitrogen use efficiency (NUE). Both deficit and excess supply of N in agricultural systems is detrimental to either crops or environment or both. Therefore, accurate assessment of canopy N content in crops is crucial for optimizing agricultural...

Agricultural drought has multi-dimensional adverse impacts on food security, livelihood of farmers, and socio-economic conditions in India. An integrated novel index named as ‘Multivariate Hierarchical Agricultural Drought Index (MHADI)’ was developed for near real-time monitoring of agricultural drought at 1 km grid and 16-day interval during the...

Agricultural drought has multi-dimensional adverse impacts on food security, livelihood of farmers, and socioeconomic conditions in India. An integrated novel index named as 'Multivariate Hierarchical Agricultural Drought Index (MHADI)' was developed for near real-time monitoring of agricultural drought at 1 km grid and 16-day interval during the k...

Agricultural field experiments are costly and time-consuming, and often struggling to capture spatial and temporal variability. Mechanistic crop growth models offer a solution to understand intricate crop-soil-weather system, aiding farm-level management decisions throughout the growing season. The objective of this study was to calibrate and the C...

Artificial Intelligence (AI) is a relatively new branch of information technology. It is one of the pillars of many industrial innovations, as well as a critical component in supporting and advancing them. There are numerous studies and innovations that employ AI techniques in a variety of fields. AI has played an important role in agriculture, hea...

With the increasing water scarcity and the demand for sustainable agriculture, precise estimation of crop evapotranspiration (ET) is crucial for effective irrigation management, crop yield assessment, and equitable water distribution, particularly in semi-arid regions. In this study, a large aperture scintillometer (LAS) was used to validate the re...

Plant nitrogen (N) is one of the key factors for its growth and yield. Timely assessment of plant N at a spatio-temporal scale enables its precision management in the field scale with better N use efficiency. Airborne imaging spectroscopy is a potential technique for non-invasive near real-time rapid assessment of plant N on a field scale. The pres...

Evapotranspiration (ET) plays a crucial role in the energy and water balance of agricultural ecosystems and is a vital component of the hydrological cycle. Efficient irrigation water management relies on accurate spatiotemporal coverage of crop ET across a farm. Thanks to the availability of multi-temporal high-resolution satellite datasets and rem...

The measurement of evapotranspiration (ET) is essential in maintaining the energy and water balance in agricultural ecosystems, and it plays a vital role in the hydrological cycle. Precision irrigation water management requires accurate spatiotemporal coverage of crop ET across the farm. Fortunately, with the availability of multi-temporal high-res...

Drought is one of the complex natural hazards having multi-dimensional harmful impacts on agriculture and economy. Evapotranspiration is a good indicator of crop water stress, therefore, an evapotranspiration-based index can be used to monitor the agricultural drought. Standardized Evaporative Drought Index (sEDI) is such an index which is derived...

Sustaining crop yield under abiotic stresses with optimized resource use is a prerequisite for sustainable agriculture, especially in arid and semi-arid areas. Water and heat stress are major abiotic stresses impacting crop growth and yield by influencing complex physiological and biochemical processes during the life cycle of crops. In a 2-year (2...

Sustaining crop yield under abiotic stresses with optimized resource use is a prerequisite for sustainable agriculture, especially in arid and semi-arid areas. Water and heat stress are major abiotic stresses impacting crop growth and yield by influencing complex physiological and biochemical processes during the life cycle of crops. In a 2-year (2...

Quantitative estimation of crop nitrogen is the key to site-specific management for enhanced nitrogen (N) use efficiency and a sustainable crop production system. As an alternate to the conventional approach through wet chemistry, sensor-based noninvasive, rapid, and near-real-time assessment of crop N at the field scale has been the need for preci...

Sensible heat flux (H) plays a crucial role in the energy balance of crop surfaces to estimate crop evapotranspiration and can be estimated based on atmospheric turbulence theory. Large aperture scintillometer (LAS) is an efficient method to record sensible heat fluxes over a larger foot print area which works on the Monin-Obukhov similarity princi...

Scarcity of fresh water and climate change are the two main threats for wheat production in South Asia. Tweaking wheat planting period could be an effective cost-smart strategy to mitigate these stresses. To evaluate the performance of three leading wheat varieties under different planting periods in pragmatic on-farm environments, trials were carr...

Terminal heat stress is becoming a major factor in limiting wheat production with increasing evidence of heat stress in present scenario of climate change. Gibberellic acid is one of the major plant hormones playing crucial role in plant development from germination to seed development, but there is huge gap in knowledge about its role under heat s...

CONTEXT An accurate crop yield forecast with sufficient lead time is critical for various applications, such as crop management, resources mobilization, agri-commodity trading, crop insurance, etc. Accurate yield forecasting well ahead of harvest at field scale with minimal field input data remains a challenge. OBJECTIVE This study aimed to develo...

Among the various constraints experienced by the small farms on their management and policy intervention, an estimate of crop yields is critical for decision making relating to agro-advisories, crop insurance, resource use, profitability, supply chains, etc. Remotely sensed data could be effectively integrated into empirical models to assess yields...

Prediction of local scale frost events can be helpful for farmers to minimize crop loss due to frost damage. This study aims to detect a temporal trend in the occurrence of frost events and develop frost prediction models using multivariate statistical techniques like logistic regression, artificial neural network model, and thumb rules for two div...

Understanding the physiological mechanism of tolerance under stress conditions is an imperative aspect of the crop improvement programme. The role of plant hormones is well-established in abiotic stress tolerance. However, the information on the role of gibberellic acid (GA) in abiotic stress tolerance in late sown wheat is still not thoroughly exp...

With the growing concern of water scarcity in agriculture, aerobic rice (Oryza sativa L.) is a promising mode of cultivation for reducing water use, although the reduced optimal plant growth and yield are major constraints. Arbuscular mycorrhiza (AM) are known to readily colonize rice roots under aerobic conditions, however, the response of upland...

Understanding the behavior of crops under interactive effect of different abiotic stresses is the need of hour. Present study aimed to examine the interactive effect of late planting and deficit irrigation on wheat (Triticum aestivum L.) growth and development in semi-arid environment. The field experimentation with two planting dates and three lev...

Paddy residue burning after harvest is a common practice followed by farmers’ in the north western India to clear the land for succeeding wheat crop sowing in-time. But it emits particulate matter and greenhouse gases leading to atmospheric pollution in the region. The state governments are implementing schemes for promotion of in-situ management o...

Farmers are increasingly practicing crop residue burning in northern states of India to clear the fields and sow subsequent crops. The issue is a critical concern for the government and policymakers for its adverse pollution impacts on the environment and human health. This chapter summarizes the spatiotemporal pattern of rice residue burning and r...

An experiment was conducted in the Free Air Ozone and Carbon dioxide Enrichment (FAOCE) facility to study the impact of elevated O3, CO2 and their interaction on chickpea crop (cv. Pusa-5023) in terms of phenology, biophysical parameters, yield components, radiation interception and use efficiency. The crop was exposed to elevated O3 (EO:60ppb), CO...

Present experiment was conducted (2015-16 and 2016-17) comprising different levels of water stress and environmental conditions for the model parametrization and validation of Info Crop-wheat v2.1 model. The model was calibrated and validated for popular wheat variety HD-2967 under semi-arid environmental conditions. The important genetic coefficie...

Evapotranspiration (ET) is an indispensable component of earth surface energy exchange studies and forms basis for various environmental applications. The present study attempts to estimate Landsat-8 satellite-based spatial distribution of crop ET using Operational Simplified Surface Energy Balance (SSEBop) model and validate through ET estimated u...

Crop weather calendars (CWC) serve as tools for taking crop management decisions. However, CWCs are not dynamic, as they were prepared by assuming normal sowing dates and fixed occurrence as well as duration of phenological stages of rainfed crops. Sowing dates fluctuate due to variability in monsoon onset and phenology varies according to crop dur...

The micro-level Agromet Advisory Services (AAS) are issued by All India Coordinated Research Project on Agrometeorology of Indian Council of Agricultural Research (ICAR) through its 25 cooperating centres located across the country. Micro-level advisory based on weather forecast is the innovative and first of its kind in the country. This study exp...

All India Coordinated Research Project on Agrometeorology (AICRPAM) of ICAR has started the micro-level Agromet Advisory Service (AAS) through its 25 cooperative centers across the country. Microlevel advisory based on weather forecast is the newer dimension of the AAS in the country. Studies on economic impact of these micro-level advisories are u...

Global dimming has many environmental and climatic implications. India has also experienced a steady and continuous radiation dimming since 1960s due to increasing load of dust and aerosol in the atmosphere. Radiation interception, temperature, humidity and wind profile are altered under reduced light condition which are determining factor for crop...

Spring wheat is a major food crop that is a staple for a large number of people in India and the world. To address the issue of food security, it is essential to understand how the productivity of spring wheat varies with changes in environmental conditions and agricultural management practices. The goal of this study is to quantify the role of dif...

This study analysed gridded temperature dataset for the last six decades over India and its different agro-climatic zones to determine the changes in land area affected by extreme warm day temperatures. The results indicated an unequivocal increase in the area influenced by different levels of extreme warm days over the country; the rate was signif...

Abstract. Spring wheat is a major food crop that is a staple for a large number of people in India and the world. To address the issue of food security, it is essential to understand how productivity of spring wheat changes with changes in environmental conditions and agricultural management practices. The goal of this study is to quantify the role...

This study assessed the effect of atmospheric correction algorithms, inversion techniques and image spatial and spectral resolution on wheat crop LAI retrieval using Sentinel-2 MSI and Landsat-8 OLI imagery. The LAI retrievals were validated with in-situ measurements collected in farmers’ fields. The MSI-based LAI retrievals improved significantly...

This study presents two aspects of heat waves over India. Firstly, we have analysed the gridded daily temperature data (1° × 1°) for six decades (1951–2015) to understand the changes in heat waves using the heat wave magnitude index daily (HWMId). Secondly, we have post-facto assessed the impact of the March 2010 heat wave on the growth and yield o...

Evaluation of crop simulation model for growth and development of crops at farmers' field is uncommon, as large variability exists in management practices at farmers' fields. The present study was attempted to evaluate the suitability of the InfoCrop v2.1 model for prediction of growth, development, and yield of the wheat crop at farmers' fields us...

In India, stubble burning is frequently practiced in the dominant rice-growing states of the Indo-Gangetic Plains, primarily in Punjab, Haryana and Uttar Pradesh. We attempted monitoring and mapping of the active fire events in real time for all the 3 states by acquiring thermal datasets from 3 different sensors i.e. Visible Infrared Imaging Radiom...

Climate information of any place is of prime importance for understanding the dynamics of natural resources in general and agriculture in particular. But availability of good quality, long-term weather data over large region remains a challenge. Hence, in this study a comparative analysis of temperature (maximum and minimum temperature) and rainfal...

This study attempts to quantitatively understand the impact of changes in meteorological drivers due to climate change on spring wheat in northern India using numerical experiments with the Simple and Universal CRop growth Simulator (SUCROS) model.The model was calibrated and evaluated for spring wheat cultivar HD2967 using observed crop and meteor...

The impact of climate change is most visible through extreme weather events. The information on extreme weather events in India are scattered and there has been very less efforts to analyze it. There is an immediate exigency to collect, compile and analyze micro level data on incidence of extreme weather events. This information is used for designi...

The impact of climate change is most visible through extreme weather events. The information on extreme weather events in India are scattered and there has been very less efforts to analyze it. There is an immediate exigency to collect, compile and analyze micro level data on incidence of extreme weather events. This information is used for designi...

Melatonin (N-acetyl-5-methoxytryptamine) is a tryptophan derived indolic compound. Because of its widespread presences, conserved structure and diverse action it is been considered as new master regulator in living beings. In plants melatonin is establishing itself as new signaling molecule and plant growth regulator. It controls diverse function a...

Paddy residue burning is practiced in the states of Punjab, Haryana and Uttar Pradesh (UP) after crop harvest. During 2018, a Central scheme was implemented in these states by providing subsidy to farmers’ to provide suitable machinery and other interventions, coordinated through State Agriculture Departments. On behalf of ICAR, spatio-temporal mon...

This study used gridded daily maximum temperature data (1° × 1°) for 1951–2014 period to analyze the trend in monthly extreme warm days (ExWD) and changes in its probability distribution in each grid. It also analyzed the trend in spatial spread of annual ExWD over the study period at four exceedance levels and further related the number of ExWDs w...

Accurate yield estimation has always been a matter of challenge to the scientific community especially so in the recent times due to the heightened risk of climatic variability. This study explored the statistical technique of fixed effect panel regression for estimation of the district-wise wheat yield using weather as well as satellite remote sen...

Improving water productivity is a major concern globally and more problematic in arid and semiarid regions. Decision support system based on crop simulation models can be a handy tool for improving water use efficiency. In this chapter, we have described and compared how water stress factor is quantified in seven widely used crop models, viz. DSSAT...

With changing environmental conditions, such as climate and elevated atmospheric CO2 concentrations, questions about food security can be answered by modeling crops based on our understanding of the dynamic crop growth processes and interactions between the crops and their environment in the form of carbon, water and energy fluxes. These interactio...

A new methodology for crop-growth stage-specific assessment of agricultural drought risk under a variable sowing window is proposed for the soybean crop. It encompasses three drought indices, which include Crop-Specific Drought Index (CSDI), Vegetation Condition Index (VCI), and Standardized Precipitation Evapotranspiration Index (SPEI). The unique...

Climate change will influence crop distribution and production and increase risks associated with agriculture. Crop productivity has already experienced detrimental impacts, underlining the necessity of taking adaptive measures. Although, in few regions (mainly in temperate latitudes) may experience improved conditions for production. Globally, cli...

The virtual certainty of the anticipated climate change will continue to raise many questions about its aggregated impact of environmental changes on our regional food security in imminent future. Crop responses to these changes are certain, but its exact characteristics are hardly understood at regional scale due to complex overlapping effects of...

In the present study, 20 years (1995-2014) data has been used to study the trends of weather parameters of maximum and minimum temperature, morning and evening relative humidity, rainfall, bright sunshine hour, average wind speed and climatic water balnce components. Climatic water balance for all the months of a year was calculated following the c...

Amount of available net energy and its partitioning into sensible, latent and soil heat fluxes over an agricultural landscape are critical to improve estimation of evapotranspiration and modelling parse (ecosystem modelling, hydrological and meteorological modelling). Scintillometry is a peculiar and robust methodology to provide structure paramete...

Advance information about the anticipated weather and agromet advisories in-line with the weather forecast, when disseminated on time can have a greater impact on farmers' livelihood. Agrometeorological advisory services (AAS) assumes greater importance in the present climate change scenario. The article briefly explains the history and present sta...

The study presents a methodology to assess and map agricultural drought vulnerability during main kharif crop season at local scale and compare its intra-seasonal variations. A conceptual model of vulnerability based on variables of exposure, sensitivity, and adaptive capacity was adopted, and spatial datasets of key biophysical factors contributin...

Terminal heat stress is one of the limiting factors in wheat production and it is expected to rise under present scenario of climate change. The present study was conducted to evaluate the performance of 40 wheat genotypes under terminal heat stress conditions based on eight physiological traits. The plants were sown late (i.e. on 5th January) to e...

Scintillometry is one of the best tools for measuring areal averaged sensible heat flux and frictional velocity and finally estimating latent heat flux, actual evapotranspiration, bowen ratio and evaporative fraction from a landscape. These fluxes/parameters over a cropland are important to understand the interaction between the crop surface and at...

Numerous estimates for the coming decades project changes in precipitation resulting in more frequent droughts and floods, rise in atmospheric CO2 and temperature, extensive runoff leading to leaching of soil nutrients, and decrease in freshwater availability. Among these changes, elevated CO2 can affect crop yields in many ways. It is imperative t...

Drought is an important limiting factor for wheat production in most agricultural areas of the world. A study was conducted to analyze the effect of cytokinin [benzyl amino purine (BAP), 40 µM] on growth and yield vis-à-vis nitrogen metabolism in two contrasting wheat cultivars, viz., C-306 (drought tolerant) and PBW-343 (drought susceptible) under...

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Use of rainfall anomaly based Standardized Precipitation Index (SPI) and satellite-derived Vegetation Condition Index (VCI) are becoming common to assess the impacts of drought on crops. This study analyzed spatio-temporal intra-seasonal and inter-seasonal relationships for 24 years between rainfall and NDVI and between SPI and VCI to understand cr...

Often geographical boundaries of the climatic zones identified differ from the administrative boundaries. Eventually planners and administrators are unable to use these classifications while formulating new develop-mental programmes. Though few studies attempted to bring the climatic classification to district level in the past, the climatic datase...