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Aim: The present study was taken up to assess the imidacloprid residue pattern in order to define strategies for improvement of quality and safety mainly healthfulness in grapes. Place and Duration of Study: The present study was carried out in Tamil Nadu during the period 2020-2021. Methodology: Dissipation studies were carried out in a farmer’s field at Theni, India (9o N latitude and 76o E longitude and 375m above mean sea level) with all good agricultural practices. During this study Grapes (Muscat Hamburg variety) was grown and the commercial formulation of imidacloprid 17.8% SL was applied at recommended dose (53 a.i ha-1) and double dose (106 a.i ha-1) Two sprays were given with an interval of 10 day by using a power operated sprayer as 500 L ha-1 spray fluid for dissipation study. The samples were processed by adopting modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method. Results: The initial deposit imidacloprid in grape berries was 0.65 and 1.56 mg kg-1 at the recommended dose (53 g a.i ha-1) and double dose respectively (106 g a.i ha-1). The insecticide exhibited a slower dissipation rate and reached below its quantification level (

Climate influences the spread of the any crop by imposing environmental restrictions. The present investigation was carried to understand the effect of climate on cocoa in various cocoa growing regions. In order to establish the relationship between weather parameters and cocoa productivity, Coimbatore, Theni, and Tenkasi were chosen as the study regions. Historical climate data was acquired from India Meteorological Department (IMD) for the past 30 years (1991-2020). Cocoa yield was simulated by using the Agricultural Policy/Environmental eXtender (APEX) and it was correlated with the weather variables such as rainfall, maximum temperature, minimum temperature, atmospheric water demand (PET), and crop water requirement (ET). Cocoa crop had positive correlation with rainfall and Actual Evapotranspiration. Whereas, both maximum and minimum temperature had significantly negative effect. Climatic conditions, such as decrease in rainfall, increase in temperature and increase in PET, would significantly reduce the cocoa bean yield. The anticipated increase in temperature and erratic rainfall distribution requires suitable management measures for sustainable cocoa productivity.

Climate change, as well as an increase in extreme weather, are posing a serious threat to socioeconomic and livelihood security. For this study, the Cauvery delta zone (CDZ) was chosen to examine current and anticipated climate variability and trend. The four largest districts of Tamil Nadu's Cauvery delta region are Thanjavur, Thiruvarur, Mayiladuthurai, and Nagapattinam. The Indian meteorological agency provided the baseline data sets (IMD). Using IPCC AR5 RCP4.5 and RCP8.5 scenarios, the maximum and minimum temperatures, as well as precipitation, were investigated. The maximum temperature could rise to 1.1oC to 3.6oC, while the minimum temperature could rise to 2.8 to 4.5oC, according to the findings. It was also concluded that there will be 15-16% rise in the rainfall during end of the century.

Increased concentration of greenhouse gases is expected to alter the radiative balance of atmosphere, causing increase in temperature and changes in precipitation patterns. Climate variability has been principal source of fluctuations in Indian food production. Even though there is no long-term trend, inter - annual variability of Indian monsoon rainfall leading to frequent droughts and floods has profound influence on agriculture and intern, national economy. It is well recognized that El Niño / Southern Oscillation (ENSO) is the dominant mode of climate variability on seasonal to inter-annual scales and its impacts are felt worldwide. ENSO often affects seasonal temperature, precipitation and thus crop yields in many regions, however, the overall impacts of ENSO on global yields are uncertain Maximum and minimum average temperature was calculated for different seasons such as Cold Weather Period (CWP), Hot Weather Period (HWP), South West Monsoon (SWM), North East Monsoon (NEM) for each El Niño, La Niña and neutral years at various districts of Tamil Nadu. Relation between ENSO and temperature was analyzed by computing the anomaly in temperature at different districts of Tamil Nadu. The temperature deviation between the ENSO and neutral phases was not significant as the deviation was within + 0.3oC in all the seasons.

Control of weeds in nursery is necessary for production of healthy and sturdy seedlings. In this regard, field experiments were conducted to study the effect of different weed management practices on weed control efficiency and performance of onion seedling in nursery at two phases. The results from the first experiment revealed that, among the herbicide treatments, lowest weed density and weed dry weight was observed in Pre-emergence (PE) application of oxyfluorfen at 0.250 kg a.i ha-1 followed by PE application of oxyfluorfen at 0.125 kg a.i ha-1. Whereas, the highest weed control efficiency was observed in hand weeded plots followed by pre-emergence application of oxyfluorfen at 0.250 kg a.i ha 1. In the second experiment, lower weed density, weed dry weight and higher weed control efficiency was observed in lay by application oxyfluorfen @ 0.125 kg ha-1 as PE + 2nd application @ 0.0625 kg ha-1 at 20 DAS. Seedling characters viz., higher root length, seedling height, 100 seedling weight and seedling yield was recorded in PE application of oxyfluorfen at 0.125 kg a.i ha-1 and PE application of oxyfluorfen at 0.125 kg a.i ha-1 + oxyfluorfen at 0.0625 kg a.i ha-1 (lay by) at 20 DAS in the first and second experiments respectively.

Drought happen aimlessly and there is no periodicity in its event and can't be anticipated ahead of time. In semiarid stations, the event of precipitation is occasional and is known something else for its changeability regarding reality. Meteorological drought is characterized as the time of drawn-out dry weather pattern because of underneath ordinary precipitation. Drought is an extensive stretch of incredibly low precipitation that essentially affects crop result and individuals' prosperity. Recent study has made substantial progress in understanding drought in Tamil Nadu, as well as the implications of climate change, but more research is needed because regional climatic responses remain unknown. The Meteorological Drought Indicator was also a useful and appropriate index for drought monitoring in the research area since it provided drought analysis on a variety of timeframes. This study might help us better understand the features of drought.

Fertigation, a latest technology wherein nutrients are applied along with irrigation water. Fertigation opens new possibilities for controlling water and nutrient supplies to crops besides maintaining the desired concentration and distribution of water and nutrients to the soil. Research works on drip fertigation under intercropping situation is very limited. Input information on optimal schedules for micro-irrigation and fertigation to cotton and maize with intercropping of pulses will have to be generated, thus enabling the option of micro irrigation under intercropping situation. The experiment was laid out in split split plot design with three replications. The main plot consists of two irrigation levels viz., 75 and 100 % PE reading, sub plot contains three drip fertigation levels viz., 75, 100 and 125 % and sub sub plot consist intercropping with short duration pulses viz., sole crop of maize/cotton, intercrop with cow pea, blackgram and cluster bean. The result revealed that no significant differences were noticed in number of bolls, boll weight under different irrigation regimes. Among the fertigation level, 125% RDF recorded higher number of bolls plant-1 and boll weight. The cotton equivalent yield of 3860 kg ha-1 with water saving of 24 per cent was accrued under cotton intercropped with blackgram and irrigation regime of 100% PE with application of 125% RDF (150:75:75 kgs NPK/ha) and it was followed by irrigation regime at 75% PE it increased 18.9% cotton yield compared to control (2099 kg ha-1) with water saving of 40.6%. Regarding maize based intercropping system, maize + black gram intercropping with irrigation regime of 100% PE and 100% RDF (250: 75: 75 kg NPK/ha) gave higher maize equivalent yield of 7735 kg/ha. In cotton – maize sequence, intercropping of black gram found to be best suitable system with the irrigation level of 100% PE and 125% RDF (150:75:75 kg NPK/ha) for cotton and 100% RDF (250: 75: 75 kg NPK/ha) for maize is recommended to get higher yield.

Aims: The purpose of the present paper was to study the toxicity of aqueous and methanol Red macro algal extracts against the cosmopolitan pest, Tobacco cutworm: Spodoptera litura Fabricius. Place and Duration of Study: Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu. Methodology: The bioassay was carried by treating aqueous and methanol extracts of three different Red macroalgae at 0.7, 1.00, 3.00, 5.00, 7.00 and 10.00 per cent concentration with three replications of ten larvae per treatment and the mortality data was recorded every 24 hours up to adult emergence. Results: The aqueous and methanol extracts of three different Red macroalgae viz., Acanthophora spicifera, Gracilaria corticata and Jania rubens were used to find out their lethal effects against tobacco cutworm, Spodoptera litura under laboratory condition. The larval mortalities were observed for both extracts. Percentages of mortalities, after 96 hours of exposure, increased at the highest concentration of 10 per cent of A. spicifera, G. corticata and J. rubens, extracts. Respectively, 60.00, 46.66 and 26.66 per cent of larvae mortalities were observed in aqueous extracts and 40.00, 26.66 and 23.33 per cent of lethality were recorded in methanol extracts. The pre-pupal and pupal mortalities were recorded in all the concentrations showing malformations during the growth. The pupation and the adult emergence were also affected with the highest inhibition by the extracts of A. spicifera. Conclusion: The Red macroalgae possess an insecticidal and growth inhibitory potential which can be exploited for eco-friendly management of Spodoptera litura. Further studies should be carried out to purify the active biomolecules of the tested extracts and to evaluate the effect of Red macroalgae on other lepidopteran larvae.

Aim: Forage preference of Indian honey bee on neonicotinoid insecticides treated sunflower Study Design: Randomized Block Design (RBD) Place and Duration of Study: Insectary, Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore between August 2021 to December 2021 during the Adipattam season Methodology: Bee activity was recorded by in situ counting method. Seven treatments with three replications (5flowers/replication) in Randomized Block Design were followed. Different treatments viz., Imidacloprid 17.8 SL @ 280µl/l, Clothianidin 50 WDG @ 80µg/l, Thiamethoxam 25 WG @ 250µg/l, Thiacloprid 21.7 SC @ 1100/µl, Dimethoate 30 EC @ 1400µl/l (chemical check), Water control (Water spray) and Absolute control (no spray) were given at 50% flowering period using Knapsack sprayer. The number of bees visiting 5 flowers per 5 minutes was observed during morning (09.00-11.00), afternoon (13.00-15.00) and evening (16.00-18.00) hours of the day for seven days after spray (DAS). DAS. Statistical Analysis Software (SAS) academics was used to statistically analyse the data. Results: The mean population of Apis cerana indica Fab. was more in absolute control (5.97) followed by water control (4.77), imidacloprid (4.10), clothianidin (3.40), thiacloprid (3.21), thiamethoxam (3.14) and dimethoate (1.90) during morning hours (09.00-11.00) of the day. The mean bee visitation rate was high in control (3.40), followed by water control (2.65), imidacloprid (1.77), clothianidin (1.52), thiacloprid (1.55), thiamethoxam (1.40) and dimethoate (1.17) during afternoon hours (13.00-15.00) of the day. In the evening hours (16.00-18.00), mean bee activity was high in control (4.95) followed by water control (4.27), imidacloprid (3.40), clothianidin (3.13), thiamethoxam (2.75), thiacloprid (2.53) and dimethoate (1.88). Among these different hours, morning forage activity of the bees are high in morning hours of the day followed by evening and very less in afternoon hours. Conclusion: The present study revealed that Indian honey bees preferred to forage both on neonicotinoid treated, however at a reduced rate, and untreated flowers. Since, neonicotinoids are odourless, tasteless compounds that increase the risk of pesticide exposure for the bee colony owing to less capability for segregation of insecticide treated surfaces.

A field experiment was conducted to study the effect of soil drenching and foliar application of different biostimulants on physiological and quality parameters of curry leaf (Murraya Koenigii Spreng.) at Karamadai, Coimbatore during 2019 to 2021. This study was laid out in factorial randomized block design with control, factor 1 as soil drenching (D1- humic acid @ 5 ml/plant and D2- jeevamrutham @ 50 ml/plant), factor 2 as foliar spray of different biostimulants (S1- Effective microorganism culture @ 2 %, S2- Egg amino acid @ 1%, S3-Panchagavya @ 3%, S4- Sea weed extract @ 2% and S5- Pink Pigmented Facultative Methylotrops (PPFM) @ 1 % and control as farmer practices. The experimental results revealed that significantly higher leaf area (9.88 cm2), leaf area index (15.36), chlorophyll a (0.89 mg/g), chlorophyll b (0.66 mg/) and total chlorophyll (1.80 mg/g), relative water content (74.41%) and fresh herbage yield (840.18g) in the treatment D1S3 (Humic acid + Panchagavya @3 %). Quality parameters like essential oil (0.19%) and oleoresin (2.86%) were significantly higher in the treatment D1S4 (Humic acid + sea weed extract).

The FAO Penman-Monteith equation is used by the ETo calculator software to calculate reference evapotranspiration – ETo from meteorological data. FAO chose this technique as the standard because it is physically based, roughly approximates grass ETo in the studied region, and explicitly considers both physiological and aerodynamic aspects. The application can handle climate data on a daily, ten-day, and monthly basis. The data may be supplied in a variety of units, and it can be analyzed using regularly used meteorological parameters. In this study, ETo calculator version 3.2 is used to estimate the ETo in Bhavanisagar. The results revealed that, it is possible to estimate ETo by using the ETo calculator. The concept of the reference evapotranspiration was introduced in this study and the result obtained are used further to estimate the evaporative demand of the atmosphere independently of crop type, crop development and management practices.

Rainfall is one of the most important climatic variables that determine the spatial and temporal patterns of climate variability of a region, which also provides useful information for the planning of water resources, agricultural production, and others. Climate change is one of the most significant worldwide issues talked among scientists and researchers, and one of the consequences of climate change is the alteration of rainfall patterns. 'India's population and the economy is linked to climate-sensitive activities, including rainfed agriculture and excess climate anomalies, deficient and flooded rainfall years have a dramatic impact on the economy as well as on the living conditions of the inhabitants of the affected region. An understanding of current and historical trends and variation is inevitable to her future development, especially in agricultural and hydrological sectors. In the present study, historical weather data for 33 years (1981-2013) was analyzed for rainfed cropping season (September - December) to understand the climatic variability in the Kanyakumari district of Tamil Nadu. The maximum daily air temperature increased on average by 0.02°C per year, whereas minimum daily air temperature remained constant during the rainfed cropping season. The high rainfall zone receives an annual and rainfed cropping average rainfall of 1307and 672 mm, respectively. Analysis of rainfall during rainfed cropping period over 33 years showed ten years had standard RF, nine years had deficit rainfall, six years had below standard RF, one year had above standard RF and seven years had excess RF. Analysis indicates that the deficit condition prevailed in every alternate year in recent decades. The onset of rainfed cropping season varied over the years (1981-2013), 13 years had onset in the slot from 1st to 5th September, and in others, years onset occurred between 6 and 30th September. Cessation also had a variation over 33 years and 16 years had cessation from 26 to 31st December while remaining years had cessation in the period of 1-25th December. LGP ranged from 57 to 143 days, with an average LGP of 106 days. Dry spell varied from 3 to 12 days with the mean of 6 days, and wet spell varied from 2 to 8 days with an average of 5 days.

Rainfall has a greater impact on agricultural, hydrological, economic, environmental and social systems. Inconsistencies in rainfall pattern could lead to extremities like drought and flood. Drought is a long period of unusually low rainfall that severely affects crop production and welfare of the people. Understanding the impacts of drought is crucial for planning, mitigation and responses. The Standardized precipitation index (SPI) method was employed for identifying drought occurrence in Parambikulam aliyar basin based on rainfall data of 37 years (1981–2017). SPI method indicated PAP basin had drought once in 4 years. In 19 per cent times, wet situation found to exist in PAP basin, five years exhibited moderately wet condition (1984, 1996, 2010, 2015 and 2017) and two years (1992 and 2005) fell under extremely wet event. Quantification on the drought events forms the scientific basis for decision makers to reduce the societal vulnerability to drought.

Drought tends to be a creeping phenomenon occurs gradually with the deficiency in rainfall further extending its impact on sectors which are dependent on water. The drought characteristics were analysed in Parambikulam Aliyar Project (PAP) basin based on the European Centre for Medium range Weather Forecasts Interim Reanalysis (ERA-Interim) gridded data with resolution of 0.125° ×0.125° during 1981-2017. Reconnaissance Drought Index (RDI) was applied for monitoring the drought. The variables used in RDI are rainfall and potential evapotranspiration (ETo), the required meteorological data were taken from the ERA Interim dataset and ETo was calculated using Penman-Monteith method. RDI indicated that 41% of the time had drought condition over 37 years. Two years (1982 and 2012) faced severe drought across all the parts of the PAP basin and the highest number of mild drought events were observed than the other drought conditions in PAP basin. Results showed that Plain areas in PAP basin experienced maximum number of drought events compared to the other areas in PAP basin during the investigation period.