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A field experiment was carried out during the summer season to study the effect of microclimate modification on growth and yield of paddy straw mushroom under outdoor cultivation as maize intercrop. A Randomised Complete Block Design (RCBD) with eight treatments comprising the combination of spacing (60 x 25 cm, 45 x 25 cm, paired row 45/75 x 25 cm, and paired row 30/60 x 25 cm) and mulching (with or without application), in three replications was used for this study. The study concluded that maximum average yield was obtained in normal spacing 45x25 cm coupled with mulching (578 g bed-1) with high biological efficiency of 19.3 per cent. The results inferred that both the afternoon (14.22 hours) microclimate variables viz., temperature (low) and relative humidity (high) had played major role for higher yield and Biological Efficiency (BE) of paddy straw mushroom as maize intercrop. Normal row spacing (45 x 25 cm) with or without mulch and paired row spacing (30/60 x 25 cm) with mulch provided favourable microclimate during summer for faster growth, higher yield and biological efficiency for paddy straw mushroom intercropped maize which in turn might be adopted by the farmers for the outdoor cultivation of paddy straw mushroom.

Crop phenology and yield are highly influenced by prevailing weather condition during the crop growth phases. A research work was carried out at Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore during June to August 2022 to determine the suitable sowing window for Greengram. The field experiment was laid out in CO 8 Greengram variety with two sowing windows of D1 - 15 June 2022 (24th SMW) and D2 - 22 June 2022 (25th SMW). The best time of sowing was established by using Growing Degree Days (GDD), Helio thermal Units (HTU), Photo thermal Units (PTU) and Heat Use Efficiency (HUE). The study revealed that the 25th Standard Meteorological week (SMW) recorded higher yield due to higher values of GDD, HTU, PTU and HUE at different crop growth stages.

Temperature is one of the key weather parameters, which is a necessity for all life on Earth. Any variation from the normal can impede the physical, chemical, and biological processes of life. Extremes would produce permanent changes that would halt the plant's growth and may cause complete withering. Advance information on temperature events will be helpful in protecting the plant and sustain the productivity under any temperature related disasters. Astrometeorology is one of the oldest organized knowledge systems that interplay between planetary movement and weather. In Tamil Nadu Agricultural University (TNAU), Astrometeorological weather forecast rules for rainfall, wind speed and cyclone events were already well defined. In continuation of this research, identification of Astrometeorological rules for the temperature events had been taken up during 2021-2022 at Agro climate Research Centre, TNAU, Coimbatore. Hourly temperature data from 2011-2016 was collected for 30 districts of Tamil Nadu. In each districts one particular location is selected and is correlated with ephemeris developed for a particular location using Alcyone ephemeris calculator. The findings clearly demonstrated the differential impact of individual planets and their azimuth on the temperature events. The study revealed that low temperature events were influenced when most planets are away (271- 300 degree azimuth) whereas the high temperature events were influenced by the planets that are directly above the location (91 to 120 degrees azimuth) and the in between temperature events were influenced by both 61-90 and 241-270 degrees. The specific azimuth of the Sun, Mercury, Venus, Jupiter, Saturn, Uranus, and Neptune had a makeable influence on a particular temperature event, however all the azimuths of the Moon and Mars had only a mild effect on any temperature event. Based on the results, Astrometeorological rules for the temperature events could be defined and used for the development of hybrid forecasting by overlapping the astromet forecast output on the numerical forecast output. This will produce more accuracy than individual forecast, reduce missing forecast, falls alarms, and improve the usability of forecast.

Evapotranspiration is an important phenomenon of hydrological cycle mainly influenced by meteorological factors and other vegetation characteristics. In this study, the relationship between Actual Evapotranspiration (AET) with Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) were analysed using Moderate Resolution Imaging Spectroradiometer (MODIS) TERRA satellite data products with the help of Geographic Information System (GIS) software. The duration of study was during South West Monsoon (SWM) season from June to September, over a period of ten years (2011 to 2020) for all seven Agro Climatic Zones (ACZ) of Tamil Nadu, India. The results showed that moderate to strong positive correlation were observed between AET and NDVI (r= 0.3 to 0.9) in all seven ACZ. The AET and LST showed a weak to strong negative correlation (r= -0.4 to -0.7) in six ACZs except High Rainfall Zone (HRZ) which might be due to lower LST and high NDVI values recorded in the HRZ which exhibited a weak positive relationship (r=0.2). Relationship between AET, LST and NDVI are highly useful for parametrizing evapotranspiration in different climatic conditions, analyzing different crop growth and production and helps in planning water management strategies at regional scale.

The proportion of agricultural water consumption is continuously decreasing due to increased competition for water resources by urban, industrial, and agricultural users. Drip irrigation is more efficient in terms of water and energy utilization. These considerations are critical in view of the ongoing struggle for water resources among various consumers due to water scarcity. Some of the most critical criteria in the effective design and maintenance of drip irrigation systems are the shape and size of the volume of wet soil beneath the emitter. Hence several statistical models were constructed in this research to estimate the dimensions of wetting patterns, which are critical for designing an optimal drip irrigation system. The Nash-Sutcliffe efficiency (NSE), coefficient of correlation (CC), and root mean square error (RMSE) criteria were used to assess the models' performance. The results showed that the Polynomial model was the most accurate for horizontal advance, with 0.94, 0.93, and 1.33 (cm) values for CC, NSE, and RMSE, respectively. For vertical advance, the logarithmic model showed 0.96, 0.96, and 0.72 (cm) values for CC, NSE, and RMSE. Thus, in the absence of a wetting pattern and under identical conditions, these models can be utilized to generate synthetic horizontal and vertical advances data.

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.

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.

In the world of rapid change in climate, irregular rainfall pattern tends to pose serious impact on water availability for agriculture. Rice is one of the important food crops to get affected by the low water availability because of its high water requirement. Various techniques were used in the past to mitigate low water availability and increase productivity but most techniques will improve one aspect at the expense of the other. System of Rice Intensification (SRI) is being tried by many countries with several modifications based on their priorities, with the aim of enhancing productivity besides reducing the water demand for rice cultivation. It is essential to have more insight into the individual and compounding effect of multiple components of SRI on yield, and water productivity of rice for identifying the potential and suitable SRI practices. Investigating the influence of different practices of SRI viz., planting of young and single seedlings per hill in wider spacing, water saving irrigation like Alternate Wetting and Drying (AWD), and weed control using cono-weeders on rice using the data obtained from the field experiment carried out during 2021 in Tamil Nadu Agricultural University, Coimbatore, India. Water productivity of rice plants under SRI were compared with conventional practices. The results revealed that plants grown with complete SRI practices had increased water productivity by 0.25 kg grain/m3 of water which is almost twice that of conventional cultivation system. The yield obtained in SRI treatments was higher about 39% than conventional treatments. The total water savings were 20 % higher in AWD treatments than continuous flooding treatments.

There is a need for increasing rice productivity to cope up with increasing population and water shortages, especially in Tamil Nadu, India. Efforts were made in the past, mainly to increase the genetic potential of the crop, by developing high yielding varieties. However, adoption of improved agronomic practices and production technologies could further increase the productivity besides saving water. System of Rice Intensification (SRI) comprises the various altered agronomic practices and is proved to be an effective cultivation method by enhancing the rice growth and productivity. It is important to understand influence of individual practices and their combinations on rice growth and productivity for deriving the maximum growth and yield advantages of SRI features. A field experiment was conducted at Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu to study the growth responses of rice to different practices of SRI viz., 14 days old seedling with single seedling per hill, square planting pattern with wider spacing, Alternate Wetting and Drying (AWD) method of irrigation and, use of cono-weeders to control weeds. It was found that planting younger seedlings with single seedling per hill greatly increased dry matter assimilation in rice plants and the use of cono-weeders encouraged the tiller production in rice. The treatments with complete SRI practices produced 3 times higher number of tillers and panicles per hill and 38.9 percent more dry matter content than conventional practices. SRI practices could be adopted by the farmers to boost the growth attributes of rice and to achieve higher rice productivity in Tamil Nadu.

Aims: The main aim of the study is to reduce the irrigation quantity for maize and intercrop adds extra value to the sole crop by generating additional income to the farmers. Study Design: Factorial Randomised Block Design (FRBD). Place and Duration of Study: Eastern block farm, Tamil Nadu Agricultural University, Coimbatore during summer and Kharif 2021. Methodology: Maize as a sole crop and inter crop was grown under drip and flooded conditions. To quantify the irrigation with different set of irrigation as treatments (75% PE, 100% PE and 125% PE) was followed. Irrigation under flooded conditions was quantified using parshall flume. Different inter crops like Lab Lab, Green gram, Black Gram and Cow pea was raised within the rows of maize. The duration of inter crops was less than 60 days than that of maize. Results: During its peak cob formation stage (61-90 days), the quantity of water applied to the plant was higher with 125 % PE (205858.8 l/day) followed by 100% PE (123515.3 l/day) and 75 % PE (164687.1 l/day). The higher plant height was observed with 280.5 cm in Maize + Lab Lab followed by black gram, green gram and cowpea. Irrigation level varied significantly with 100% open pan evaporation on plant growth (254.8 cm) followed by 75% open pan evaporation. Interaction effect was significant in Maize + Lab Lab cropping system alone, irrespective of the irrigation treatments (75, 100, 125 % PE and flooding). Conclusion: Water requirement with the month and stage wise during the crop growth clearly indicates that the minimum amount of water is required for the crop growth and development.

High temperature stress severely interrupts the physiological and biochemical functions in plants which hinders the growth, development and productivity of cowpea. The present study evaluates the potential roles of Naphthalene Acetic Acid and Brassinolide for mitigating the adverse effects of high temperature in cowpea. The study was carried out during the year 2021 in cowpea variety CO 7 using Temperature Gradient Tunnel (TGT) located at Agro Climate Research Centre, Tamil Nadu Agricultural University (TNAU), Coimbatore. The experimental design followed was Factorial Completely Randomized Design (FCRD). Different treatments were imposed on plants exposed to ambient and ambient +2oC temperature. The effect of treatments on leaf area index, photosynthetic rate, chlorophyll index and seed yield were studied. The application of brassinolide @ 0.2ppm showed a positive effect on stressed plants and produced the highest seed yield of 8.78 g plant-1.

Selecting the appropriate row proportion in the intercropping system is required for the effective harnessing of solar radiation. In Semi-arid areas, Sorghum based intercropping is commonly adopted by the farmers for effective utilization of the available resources. The treatments consisted of T1-Sorghum Sole crop (SS), T2-2rows of Sorghum+2rows of Cowpea (2S:2C), T3-2rows of Sorghum+1row of Cowpea (2S:1C), T4-2rows of Sorghum+2rows of Greengram (2S:2G), T5-2rows of Sorghum+1rows of Greengram (2S:1G), T6-2rows of Sorghum+2rows of Lablab (2S:2L), T7-2rows of Sorghum+1rows of Lablab (2S:1L). The results of the study showed that sorghum under 2:1 pattern had enhanced LAI, Radiation absorption efficiency which resulted in a high photosynthetic rate. The intercrops under 2:2 pattern were suffered from shading of sorghum than 2:1 pattern which affected the photosynthetic rate of intercrops under 2:2 pattern. Hence, planting sorghum under 2:1 pattern with Lablab will be the ideal row ratio to harness maximum sunlight.

India encountered numerous drought years in the decades. It is a matter of concern with increased frequency as well as intensity, mainly due to factors related to changing climate in recent years. In India livelihoods of more than 75% of the population are directly or indirectly dependent on agriculture sectors. The strong and recurrent link between drought and farmer's livelihoods has highlighted the importance to understand the drought scenario of a place for designing coping strategies. To address the issue, this paper was formulated to characterize the drought scenario over Periyar Vaigai Command (PVC) area. To summarize the results, the locations Edayapatti and Periaaruvi had the highest number of annual drought occurrence (8) while the location Madurai airport had the lowest (2) based on the analysis of 30 years. On comparing the monsoons, there are no wide variations in drought characteristics between Southwest monsoon (SWM) and Northeast monsoon (NEM). Anomalies in rainfall during the monsoon seasons were studied through SPI, consecutive drought years were well presented through SPI, which gives relevant information for crop planning. In both the monsoons, the locations Viraganur, Pulipatti and Usilampatti witness consecutive droughts. The highest of three consecutive years (1999, 2000 and 2001) were witnessed in Usilampatti during the major NEM season.

An investigation was carried out at the Agro Climate Research Centre, Tamil Nadu Agricultural University, on the effect of weather parameters on the green gram yield sown at various sowing dates during the rabi season of 2019. At various sowing dates, two green gram cultivars, VBN 4 and ADT 3, were sown. For both cultivars, the phonological crop length decreased with delays in sowing dates beyond October 23rd. The yield of green gram sown on 23rd October was significantly higher than the crops sown on 30th October and 6th November. The weather parameters Maximum Temperature (Tmax), Diurnal Range (Trange), Bright Sunshine Hours (BSS), Relative Humidity (RH I), Wind Speed (WS) were found to be negatively correlated with seed yield whereas Minimum Temperature (Tmin), Relative Humidity (RH II), Vapour Pressure (VP) were found to be positively correlated with the yield of green gram. The accurate prediction of green gram yield could be done with the maximum temperature, bright sunshine hours, wind speed and with thermal indices especially hygrothermal unit II with 82 percent, accuracy level.

Aim: Identifying the astrometeorological relationship between two planet’s aspect and cyclone events over Bay of Bengal (BOB). Study Design: Correlating the two planet aspects calculated from the ephemeris and different stages of Cyclone event. Place and Duration of Study: The study was conducted as a part of post graduate thesis research at Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. Methodology: Collection of Cyclone track and their stage for each cyclone event observed from 1990 to 2016 over Bay of Bengal (BOB). Calculating planetary position for the cyclone track (eye point) and developing two planet’s aspects from the ephemeris. Correlating the two planet aspects and Cyclone event to identify frequency. Results: Among the 36 two planets aspects studied, Uranus – Neptune and Sun – Mercury and Sun – Venus had higher influence on all the cyclone categories, whereas the Saturn – Uranus, Saturn - Neptune and Venus – Mars had high influence on high intensity cyclones from Very Severe Cyclone to Super Cyclone system. The highest number of category ‘D’ cyclones were observed with the conjunction of Uranus – Neptune (69.8%), category ‘DD’ in the Uranus – Neptune (67.6%), category ‘CS’ in the Uranus - Neptune (64.8%), category ‘SCS’ in the Uranus - Neptune (66.8%), category ‘VSCS’ in the Uranus – Neptune (68.3%), category ‘VSCS’ in the Uranus – Neptune (64.7%) and the category ‘SUCS’ in the Saturn conjunction with Uranus and Neptune (76.9%). Conclusion: The study inferenced that, irrespective of 36 two-planet combinations, the 0-30 degrees two-planet aspects had more influence on cyclone intensity than other aspects of any two planets, in particular 0 – 10 degree aspects. Squares and oppositions angles between Mars, Saturn, Uranus and Neptune are considered to be storm breeders and these angle between Mars and Saturn or Mars and Uranus can influence the formation of very energetic storm systems.

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.

Weather forecasting is an important subject in the field of meteorology all over the world. The pattern and amount of rainfall are the essential factors that affect agricultural systems. The present paper describes an empirical study for modeling and forecasting the time series of monthly rainfall patterns for Coimbatore, Tamil Nadu. The Box-Jenkins Seasonal Autoregressive Integrated Moving Average (SARIMA) methodology has been adopted for model identification, diagnostic checking and forecasting for this region. The best SARIMA models were selected based on the Autocorrelation Function (ACF) and Partial Autocorrelation Function (PACF) and the minimum values of Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC). The study has shown that the SARIMA (0,0,0)(2,0,0)12 model was appropriate for analysing and forecasting the future rainfall patterns. The Root Means Square Error (RMSE) values were found to be 52.37 and proved that the above model was the best model for further forecasting the rainfall.

Timely and accurate medium range weather information is critical to conquer the impact of highly dynamic next few days’ weather on the farming. Advances in weather forecast models, as well as their increased resolution, have resulted in more accurate and realistic forecasts. An attempt was made during 2019 – 2021 at Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore to develop cluster of village level (@ 3km resolution) Medium Range Weather Forecast (MRWF) for Tamil Nadu with higher accuracy. In this study, Weather Research and Forecast Model (WRF v4.2.1) with four microphysics viz., Kessler, WSM3, WSM5, WSM6 schemes were tested for Tamil Nadu during CWP, HWP, SWM and NEM 2020. The MRWF generated from the WRF model v4.2.1 with WSM3 had better BSF, higher Forecast Accuracy Index (FAI) and Forecast Usability Percent (FUP) for Tamil Nadu followed by Kessler scheme. The WSM5 and WSM6 were poor performer during the study. In general, CWP had higher FAI followed by HWP, NEM & SWM. The FAI from WSM3 was 0.65 - 0.74 during NEM and 0.55 - 0.69 during SWM. Among the season, the MRWF generated during SWM were over forecasted the rainfall quantity, where the NEM and HWP had better rainfall forecast nearing actuals. The FUP was higher in NEM followed by CWP, SWM & HWP, which was 57 – 88 per cent during NEM and 46 – 82 per cent during SWM. A decreasing trend in the quantitative FUP was observed with increase in lead times, irrespective of the microphysics and seasons. Finally, the study concluded that the accuracy of village level medium range rainfall forecasts from WRF model v4.2.1 varied temporally by season and the WSM3 microphysics option having superiority in all seasons.

The face of the earth surface has been changed by the human activities particularly land use changes. World agriculture occupies about 38% of Earth’s terrestrial surface. The modern day agricultural economy has become more energy-intensive. Sustainability in agriculture should ensure both agricultural productivity and environmental safety. Agriculture being one of the important consumer of energy, particularly fossil fuels, generates greenhouse gas emissions. It is very important to curtail the use of high energy and non-renewable energy sources in farming activity. Further, reducing the use of non-renewable energy sources and increasing the efficiency of energy use, would reduce the greenhouse gas emissions from the agriculture sector. Energy auditing is a method to understand which component of the technology involves high energy and inefficient in generating outputs. TNAU Energy Soft 2016 is an energy audit tool, which helps the scientists working on agricultural technologies to identify the better input energy source combination (renewable/non-renewable/commercial/non-commercial) of technology without doing repeated and expensive field trials. This is a simple, user-friendly windows based desktop application which facilitates easy selection of input sources; adds new energy source, crop and field operations; compares six treatments at a stretch. The resulting output includes detailed analysis and abstract of energy use of a single treatment, individual field operation-wise energy use within a treatment, net energy benefit, energy efficiency and category-wise energy use. The TNAU Energy Soft 2016 helps scientist to ensure sustainability in agricultural productivity, environmental safety and sustainable bioeconomy through finding the ways and means of reducing non-renewable fossil fuel based inputs and increasing the use of renewable and biological resources.