Agro-climatic Zone Of Tamil Nadu Research Articles

Absolute Growth Rate (AGR) - A Statistical Tool for Body Weight and Age Calculation in Large White Yorkshire Pigs

This study provides crucial insights into the growth performance of Large White Yorkshire (LWY) pigs in the North-Eastern Agro-Climatic Zone of Tamil Nadu, which is essential for optimizing breeding and management practices. Growth performance data were collected over six years at the Pig Breeding Unit, Post Graduate Research Institute in Animal Sciences (PGRIAS), Kattupakkam. Information on pedigree, sex, growth performance, and disposal weights from 2011 to 2016 was utilized for this study. Statistical analyses were conducted using SPSS to determine the Absolute Growth Rate (AGR). The overall AGR measures for the age intervals from birth to 56 days, 56 to 120 days, 120 to 180 days, and 180 to 240 days were 118.77 ± 0.75 g/day, 268.80 ± 2.24 g/day, 270.93 ± 2.75 g/day, and 385.98 ± 7.19 g/day, respectively. The maximum AGR (412.57 ± 9.92 g/day) was found during the post-weaning growth period, while the minimum AGR (114.87 ± 1.73 g/day) occurred during the pre-weaning growth period. These insights can lead to better resource allocation, improved animal welfare, and increased economic returns in pig farming.

Assessing the impact of climate change on water requirement and yield of sugarcane over different agro-climatic zones of Tamil Nadu

The DSSAT CANEGRO model was calibrated and verified using field experimental data from five Tamil Nadu Agroclimatic Zones (1981–2022). The genetic coefficients of the sugarcane cultivar (CO-86032) were calculated. R2 obtained between measured and simulated stalk fresh mass was 0.9 with the nRMSE (0.01) and RMSE (1.6) and R2 between measured and simulated sucrose mass was 0.9 with the nRMSE (0.16) and RMSE (1.2). For yield R2 obtained between measured and simulated was 0.9 with the nRMSE (0.01) and RMSE (1.6). As a result, the CANEGRO model may be used to mimic the phenology and yield features of the sugarcane cultivar in Tamil Nadu's Agro Climatic Zones. Temperature increases in Agro Climatic Zones resulted in varying yield reductions, with 2 °C increases causing a 3% loss, 3 °C increases 5%, and 4 °C increases 9%. The Water Requirement rose throughout all of the ACZ due to the high temperature, but to differing degrees. A 2 °C increase often results in an average 4% increase in the WR. 3 °C rise in temperature increased WR to 9% and WR rose by 13% when the temperature was raised by 4 °C.

Climate Change and its Impact on Water Requirement and Productivity of Bengal Gram Over Different Agro-climatic Zones of Tamil Nadu

Background: The AquaCrop model for bengal gram successfully matches the biomass and yield of reported crop data under various planting dates, according to results that have been validated. Further this study was carried out in different agroclimatic zones of Tamil Nadu to assess variations in yield and water requirement. Methods: In order to simulate realistic yields for the Bengal gram in response to planting date impacts in the Guziliamparai Block in the Dindugal District of Tamil Nadu, the study parameterized and verified performance of the AquaCrop model. Four field trials planted in D1 - 1st November, D2 - 15th November, D3 - 1st December, and D4 - 15th December provided the model calibration data. Result: Fruit yield and biomass had R2 values of 0.9 and 0.8, respectively, indicating strong agreement between observed and model-simulated data. Fruit output and biomass were found to have RMSE values of 0.4 and 0.2, respectively. The NRMSE values for fruit yield and biomass were determined to be 0.3 and 0.1, respectively. The AquaCrop model somewhat overestimated fruit production and biomass since the BIAS was less than 0.4 and 0.2 for yield and biomass, respectively. Fruit production and biomass showed less agreement between simulated and actual D levels (0.4 to 0.6). Across Tamil Nadu's ACZ, a 20C temperature increase decreased the yield by an average of 6%, with minimums of 2% and maximums of 13%. An rise in temperature of 3°C and 4°C, respectively, decreased the yield by 9% and 19% on average.

Understanding the Knowledge Level of Farmers towards Climate Smart Agricultural Technologies in Agro-climatic Zones of Tamil Nadu, India

Aims: Although farmers experience various technical, technological, production, labor-related and marketing constraints to carry out agricultural activities, climate change acts as the root cause of several other constraints. Climate change consequences drastically reduce agricultural yield by affecting critical changes of crop growth and questions food and nutritional security; additionally it also imposes economic loss to the country. Hence, to ensure food and nutritional security for the growing population and to ensure sustainable income for the farming community, a farmer has to tackle the consequences of climate change by adoption of CSA technologies Farmer’s knowledge level towards any technology, determine its rate of adoption. Hence, this study aims to assess the knowledge level of farmers towards CSA technologies in Agro-climatic zones of Tamil Nadu.
 Study design: Ex-post facto research design was employed in the study.
 Place and Duration of Study: The study was carried out in seven agro-climatic zones of Tamil Nadu viz., Villupuram district of North Eastern Zone, Namakkal district of North Western Zone, Coimbatore district of Western Zone, Tiruvarur district of Cauvery Delta Zone, Ramanthapuram district of Southern Zone, Kanyakumari district of High Rainfall Zone and the Nilgiris district of the Hilly Zone of Tamil Nadu during 2022-2023.
 Methodology: From each of Agro-climatic zones of Tamil Nadu, the vulnerable districts or the districts with NICRA project have been identified and the CSA technologies adopted by the farmers were documented. Thirty farmers who adopts CSA technologies from each agro-climatic zone were selected and interviewed personally to assess their knowledge level towards those technologies in a five point continuum ranging from ‘No knowledge’ (1), ‘Minimal knowledge’ (2), ‘Basic knowledge’ (3), ‘Adequate knowledge’ (4) and ‘Superior knowledge’ (5) respectively. The gathered responses were subjected to percentage analysis.
 Findings: The findings revealed that Villupuram, Coimbatore and Tiruvarur farmers had superior knowledge on precision based nutrient management, Namakkal farmers had superior knowledge on use of additives and supplements in livestock feed, Ramanathapuram farmers had superior knowledge on utilization of weather based agro-advisory services, Kanyakumari farmers had superior knowledge on adoption of moisture conservation practices and Nilgiris farmers had superior knowledge on adoption of improved seed varieties and use of biofertilizers.
 Conclusion: Villupuram, Coimbatore and Tiruvarur farmers had superior knowledge on precision based nutrient management; Namakkal farmers had superior knowledge on use of additives and supplements in livestock feed; Ramanathapuram farmers had superior knowledge on utilization of weather based agro-advisory services; Kanyakumari farmers had superior knowledge on adoption of moisture conservation practices and, The Nilgiris farmers had superior knowledge on adoption of improved seed varieties and use of biofertilizers. Thus, it can be concluded that farmers had superior knowledge on CSA technologies based on their perceived climatic change consequences and their accessibility to location specific technologies.

Economic Analysis of drip fertigation, Organic product for rice-fallow-greengram (Vigna radiata L.) in Western Agroclimatic Zone of Tamil Nadu, India

Background: Rice fallow pulse cropping system was familiarized in Tamil Nadu. There is reduction in yield due to inappropriate management of pest, disease, weed, fertilizer and nutrient management moreover cultivated as rainfed/ mixed cropping system. However, succeeding crop is sown without any preparatory cultivation in the stubbles of the previous crop. It minimizes the labour and fuel cost. The present study investigated the economic analysis of drip fertigation, Organic product for rice-fallow-greengram. Methods: A field experiment was conducted at Wetland farms of Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore during 2019-21. There are thirteen treatments in randomized block design with replicated thrice which is imposed with fermented fish waste and fermented egg product applied through drip at vegetative stage and peak flowering stage. Result: The field experiment result revealed that the application drip fertigation @ 125% RDF, 100% PE with FFW (2 times) (T11) recorded higher net return (₹ 48,958 and ₹ 33,402 during summer 2020 and Kharif 2021, respectively).

Yield model and yield table construction in Albizia (Albizia lebbeck (L.) under the western agro-climatic zone of Tamil Nadu, Southern India.

The woody legume, Albizia lebbeck, is native to tropical Asia, Africa, and Northern Australia. Owing to its multi-utility, it is widely planted as block plantation and in boundary across community lands. A field study was conducted by measuring the biometric value of trees, viz., height and diameter at every 2-m height using a tree telescope. Besides biometric attributes, age was assessed in order to correlate the age-wise yield. The study was carried out in the western agro-climatic zone of Tamil Nadu in different age classes of trees, viz., 1-5 years, 6-10 years, 11-15 years, 16-20 years, 21-25 years, 26-30 years, and 31-35 years. The uniqueness of the present study is that the yield model construction for Albizia was done for standard stem timber (Volume at diameter 20 cm over bark) and standard stem small wood (Volume between diameter limits of 20 cm and 5 cm both measured over bark). After computing the data and subjecting for multiple linear regression analysis, the model was constructed, so as to develop yield table accurately for Albizia without the help of form factor. The study result developed two exclusive yield models; namely, the standard stem timber yield model for Albizia was Y = (-1.212) + (-0.012*age) + (6.506*diameter) and the standard model for stem small wood was Y = (-0.945) + (-0.045*age) + (2.769*diameter) + (0.262*no. of branches). The prominence of the present study is that yield table computation for Albizia is possible accurately without destructive analysis and the cumbersome process of developing form factor.

Invasive Whitefly (Hemiptera: Aleyrodidae) Complex and Diversity in Coconut Landscapes in Tamil Nadu

Abstract Coconut, Cocos nucifera L., in Tamil Nadu, India, was invaded by four whitefly (Hemiptera: Aleyrodidae) species between 2016 and 2019, increasing the total to six, along with Aleurodicus dispersus Russell and Aleurocanthus arecae David and Manjunatha. We examined the complexity and diversity of whiteflies in coconut across different agroclimatic zones of Tamil Nadu and found high and low damage levels by whiteflies at Veppankulam (70.4%) and Rameswaram (11.0%), respectively. The rugose spiraling whitefly, Aleurodicus rugioperculatus Martin, was the most dominant species but was effectively managed by the parasitoids Encarsia guadeloupae Viggiani and E. dispersa Polaszek, with the highest rate parasitism of 83.8% at Aliyar Nagar and the lowest (2.9%) in the Kanchipuram district. Aleurodicus rugioperculatus and Bondar’s nesting whitefly, Paraleyrodes bondari Peracchi, have spread throughout Tamil Nadu. The population of A. rugioperculaus was high at Veppankulam and that of P. bondari was higher at Dharmapuri (28.6 and 31.1 adults/leaflet, respectively). All five invasive whitefly species in coconut were found only in 7 of 34 locations—Coimbatore, Sirumugai, Salem, Dharmapuri, Krishnagiri, Vellore, and Erode. Paraleyrodes minei Iaccarino and Aleurotrachelus atratus Hempel were distributed in the northwestern zone adjoining the western ghats of Tamil Nadu. Coconut plantations at Sirumugai (western ghats) supported the most diverse collection of whiteflies, with 0.61 and 1.09 Simpson and Shannon diversity indices. Among the 29 districts, adjoining Dindigul and Theni districts showed the highest Bray–Curtis Similarity Matrix. Butterfly palm, Dypsis lutescens H. Wendel, custard apple, Annona squamosa L., and guava, Psidium guajava L., are whitefly hosts in coconut landscapes.

Insights into Rainfall Extremities Across the Agroclimatic Zones of Tamil Nadu, India

Rainfall is a crucial agrometeorological parameter that impacts hydrology and agricultural planning in a region. The spatiotemporal changes in the occurrences of precipitation extremes must be monitored to reduce the hazards caused by the fluctuating rainfall pattern. The extreme rainfall indices for each year categorized under excess, normal and deficit rainfall categories were calculated over the agroclimatic zones of Tamil Nadu using the high-resolution CHIRPS datasets from 1991 to 2022. The results highlighted that High Rainfall Zone has more consecutive wet days (22 days), minimum consecutive dry days (25 days) and Daily Intensity Index with threshold of 2.5 mm (28.6 mm) compared to other zones. The maximum consecutive dry days of 99 days, a high rainy day of 142 days, and minimum daily intensity of 8.9 mm are experienced by the Cauvery Delta Zone, High Altitude and Hilly Zone, and Western Zone, respectively. Overall, the High Rainfall Zone faces a higher number of extreme rainfall events in terms of wet days and intensity, whereas the average maximum consecutive dry days and minimum rainfall intensity is observed over the north eastern zone and north western zone, respectively indicating high dry periods.

Impact of soil fertility characteristics on artificial fertility gradient approach developed using sorghum (Sorghum bicolor) in Alfisols

In the advent of precision agriculture, applying fertilizer based on soil testing is a crucial tool to prescribe nutrient levels for crops, to increase nutrient use efficiency and production. A field experiment was conducted in a farmer's field in the Dindigul district, Southern agro-climatic zone of Tamil Nadu to ascertain the effect of artificial soil fertility gradient method on soil fertility, green fodder production of sorghum (Sorghum bicolor (L.) Moench) (var. CO 30) and nutrient absorption. A fertility gradient technique has been investigated to produce fertilizer recommendations for location-specific in red soils (Alfisols, Typic Rhodustalf). The experimental field was separated into three equal strips: strip I, II, and III, which received applications of the three graded levels of ertilizer N0P0K0, N1P1K1, and N2P2K2, respectively. Urea, single super phosphate, and muriate of potash fertilizers, respectively, were used to apply NPK. As a gradient crop, S. bicolor was raised. The N1 level was set based on the general fertilizer recommendation of feed sorghum, while the P1 and K1 values were set based on the soil’s ability to fix 100 kg ha-1 of phosphorus and 100 kg ha-1 of potassium, respectively. Plant samples were taken at harvest time, and their NPK content and nutrient uptake were determined. With addition of graded doses of nitrogen, phosphorus and potassium fertilizer in Strip I, II & III increased the soil's available N, P & K status substantially in the order of Strip I<II<III and minimize the heterogeneity in the soil population , management strategies employed, and prevailing climate conditions to induce fertility variations in the same field. The outcomes showed that sorghum crop yields for fodder (Strip III – 25.01 t ha-1) and NPK uptake were significantly impacted by the application of graded amounts of NPK fertilizers.

Influence of Vermicompost and Foliar Applications on Growth, Physiological and Yield Parameters of Irrigated Blackgram (Vigna mungo L. Hepper)

Field experiments were conducted at the South farm in Karunya Institute of Technology and Sciences, Division of Agronomy, Coimbatore, during the Rabi season of 2022. The experimental site is situated in the western agro-climatic zone of Tamil Nadu, at a latitude of 10°56'N and longitude of 76°44'E, with an elevation of 474 meters above mean sea level. The soil composition of the experimental field was identified as clay loam, moderately drained, and exhibited low availability of nitrogen (202 kg/ha), high availability of phosphorus (12.3 kg/ha), medium availability of potassium (415 kg/ha), and organic carbon content of 0.51%. The experiment followed a randomized block design (RBD) with 10 treatment groups, each replicated three times viz.,T1 - Control, T2 - Vermicompost 100% (on N Equivalent basis)+ Cowdung slurry, T3 -Vermicompost100% (on N Equivalent basis)+TNAU Biomineralizer,T4 -Vermicompost100% (on N Equivalent basis) + (Effective microorganism),T5 - Vermicompost 100% (on N Equivalent basis) + Pleurotus sp + Urea, T6- Vermicompost (50%) +RDF (50%) + Cowdung slurry, T7- Vermicompost (50%) +RDF (50%) + TNAU Biomineralizer, T8 -Vermicompost (50%) + RDF (50%) + EM (Effective Microorganism),T9 -Vermicompost (50%) + RDF (50%) + Pleurotus sp ,T10 - RDF alone. The objective of the study was to investigate the impact of vermicompost and other foliar applications on the growth, physiological characteristics, and yield parameters of an irrigated Black gram (VBN8 variety). The promotion of yield can be attributed to the increased vegetative growth and the balanced carbon-to-nitrogen (C: N) ratio, which likely stimulated the synthesis of carbohydrates. This, in turn, facilitated the overall improvement in seed yield. The application of RDF played a significant role in enhancing growth, leading to various positive changes in yield-related characteristics. Ultimately, the increased seed yield observed can be largely attributed to the improved plant growth and subsequent positive effects on yield-related attributes resulting from the RDF application. Thus, From this Experiment it was Concluded that the RDF (T10) Shows a highest range in growth, physiological and yield parameters of irrigated Blackgram due.

Sustaining Soil Fertility and Yield by Inductive cum Targeted Yield Model-based Fertilizer Prescriptions for Finger millet (Eleusine coracana L.) in Alfisols of Tamil Nadu, Southern India

Background: Finger millet cultivation in Alfisols (Typic rhodustalf, Palaviduthi soil series) demands an optimal integrated plant nutrient supply to achieve desired yields. In order to develop the soil test crop response to fertilizer and farm yard manure (FYM) through integrated plant nutrition system (STCR-IPNS) in terms of nutrient uptake, yield and pre-sowing STVs, a field investigation on Finger millet [Eleusine coracana (L.) Gaertn.] was conducted at the farmer’s field of Thoppupatti village, Dindigul district, Southern Agro-climatic zone of Tamil Nadu, Southern India during December 2021-August 2022. Methods: By adopting the Inductive cum Targeted Yield Model before the test crop of Finger millet, a artificial soil fertility gradient was created by the application of graded levels of NPK fertilizers with fodder sorghum as a gradient crop. Result: The basic data viz., N, P and K nutrients for producing 1 tonne of finger millet grain were 48 kg, 23 kg and 44 kg; the soil contributed 14.86%, 19.18% and 18.95%; fertilizer contributed 44.16%, 32.79% and 59.75% for N, P and K and farmyard manure (FYM) contributed 28.47%, 11.77% and 33.78%, respectively. Fertilizer prescription equations for finger millet and ready reckoners for the operational range of soil test results for the intended yield target under NPK alone and IPNS (NPK + FYM) were produced using the basic data.

Evaluation of SPI and Rainfall Departure Based on Multi-Satellite Precipitation Products for Meteorological Drought Monitoring in Tamil Nadu

The prevalence of the frequent water stress conditions at present was found to be more frequent due to increased weather anomalies and climate change scenarios, among other reasons. Periodic drought assessment and subsequent management are essential in effectively utilizing and managing water resources. For effective drought monitoring/assessment, satellite-based precipitation products offer more reliable rainfall estimates with higher accuracy and spatial coverage than conventional rain gauge data. The present study on satellite-based drought monitoring and reliability evaluation was conducted using four high-resolution precipitation products, i.e., IMERGH, TRMM, CHIRPS, and PERSIANN, during the northeast monsoon season of 2015, 2016, and 2017 in the state of Tamil Nadu, India. These four precipitation products were evaluated for accuracy and confidence level by assessing the meteorological drought using standard precipitation index (SPI) and by comparing the results with automatic weather station (AWS) and rain gauge network data-derived SPI. Furthermore, considering the limited number of precipitation products available, the study also indirectly addressed the demanding need for high-resolution precipitation products with consistent temporal resolution. Among different products, IMERGH and TRMM rainfall estimates were found equipollent with the minimum range predictions, i.e., 149.8, 32.07, 80.05 mm and 144.31, 34.40, 75.01 mm, respectively, during NEM of 2015, 2016, and 2017. The rainfall data from CHIRPS were commensurable in the maximum range of 1564, 421, and 723 mm in these three consequent years (2015 to 2017) compared to AWS data. CHIRPS data recorded a higher per cent of agreement (>85%) compared to AWS data than other precipitation products in all the agro-climatic zones of Tamil Nadu. The SPI values were positive > 1.0 during 2015 and negative < −0.99 for 2016 and 2017, indicating normal/wet and dry conditions in the study area, respectively. This study highlighted discrepancies in the capability of the precipitation products IMERGH and TRMM estimates for low rainfall conditions and CHIRPS estimates in high rainfall regimes.

Development and standardization of a qualitative tool to measure the attitude of farmers towards the conservation of Nattukuttai cattle

Indigenous breeds of cattle play a significant role in the livelihood of resource poor farmers in rural areas of India. Nattukuttai cattle are short and stout cattle reared under zero input system in North Eastern agro-climatic zone of Tamil Nadu. A qualitative tool consisting of four projective techniques, viz. Sentence completion test, Verbal projection test, Story completion test and Thematic Apperception Test (TAT) to measure the attitude of the farmers towards the conservation of Nattukuttai cattle was developed and standardized as per the standard protocol. The study was carried out for a period of one year 2021-22 in the selected districts of North Eastern agro-climatic zone of Tamil Nadu. Nearly two third of the respondents had favourable to most favourable attitude towards the conservation of Nattukuttai cattle breed. This study discusses the methodology of developing projective tools and their importance in measuring the attitude of farmers towards conservation of Nattukuttai cattle.

Land Use Changes and Extent of Crop Diversification in North Western Zone of Tamil Nadu

Tamil Nadu, one of the important agrarian states in India, has experienced remarkable growth in the agricultural sector. Among the seven agro-climatic zones of Tamil Nadu, north western zone is known for intensive agrarian economy of which, the economy of Salem district is predominantly agrarian having 2.20 lakh hectares of net cultivated area (42.31 percent of total geographical area). The district has distinctive cropping patterns and the major crops grown in the district include Paddy, Tapioca, Maize, Sorghum and Vegetables. Given the importance of changing scenarios in cropping patterns, this study was undertaken to analyze the land use and cropping pattern changes and to examine the extent of crop diversification in Salem District over the year using the time series data for 20 years, i.e., from 2000-01 to 2019-20. Direction of changes in land use and cropping pattern was investigated using Markov chain analysis and for each year, crop diversification index was calculated. It was concluded from the study that the compound annual growth rate of area under crops like cereals and millets, pulses, spices and condiments, fruits, fibres. drugs, narcotics & plantation crops and other non-food crops were positive whereas it was negative for sugar crops, oilseeds, vegetables, fodder and green manure. Based on the crop diversification index value, it is evident that Salem district is moving towards crop diversification rather than specialization however the process as analysed on a time series basis is stagnant.

Detection of Theileria and Anaplasma spp. in carrier buffaloes (Bubalus bubalis) by polymerase chain reaction in Tamil Nadu, India

A total of 150 heparinised blood samples and equal number of blood smears were collected from buffaloes in three agro-climatic zones of Tamil Nadu viz., Cauvery delta, North - western and Southern zones to detect Theileria and Anaplasma by blood smear examination and Polymerase Chain Reaction. The blood smear examination revealed that none of animals were found to harbour any haemoprotozoan parasites. Whereas PCR detected Theileria and Anaplasma in 26.9% and 48.0%, and 10% and 15% of the animals, respectively in north- western zone and Cauvery delta, however no animal from south zone was detected positive for any protozoan. Besides, mixed infection of Theileria and Anaplasma was recorded in 8 (5.3%) animals. The analysis of data collected to determine the risk factors associated with occurrence of haemoprotozoan parasites revealed that the pure breed Murrah showed higher percentage of Theileria and Anaplasma positivity (30.7% and 46.1%) than non - descriptive breed (8.7% and 16.0%). The percentage of positivity of haemoprotozoan parasites was found to be higher among animals of 1 year, followed by 2 years and > 4 years of age.

Economic Analysis of Dryland Integrated Production System in Western Agroclimatic Zone of Tamil Nadu, India: A DEA Approach

Background: Efficiency of production system is calculated by the input spent to amount of output produced. The Agronomic efficiency has been found to be below 48% than the world efficiency standard of 40 kg ha-1. The average fertilizer usage of India is 133 kg ha-1, 232% higher than the global standard fertilizer of 40 kg ha-1. The certified seeds and agriculture machinery usage has been increased by 15% and 13% in India but the efficiency of farm stays behind. Methods: With this back ground the present study applied cost approach variable return to scale Data Envelopment Analysis (DEA) model to evaluate the Indian farms resource using 200 rural farms of Tamil Nadu state. The data envelopment analysis models have the advantage of simultaneous measure of technical, allocative and cost efficiency of the individual farms. Result: The cost efficiency among the respondents ranged from 0 to 1 with a mean efficiency of 0.66. The study found that Decision-Making Units (DMU) have cost inefficiency, suggesting that most of the DMU operated very far away from the efficiency frontier. Allocative inefficiency (0.55) is worse than the technical inefficiency (0.80), implying that the lower economic efficiency is the result of high allocative inefficiency.

Characterization of assembled clones of Pongamia pinnata (L.) Pierre for its genetic variability using ISSR

Genetic diversity of Pongamia pinnata within and among 5 populations collected and assembled from two different agroclimatic zones of Tamil Nadu, India. Totally 25 accesions were examined with eight inter simple sequence repeat (ISSR) primers. A total of 120 scorable bands were generated, among which 80% were polymorphic. Jaccard similarity coefficient was calculated for pairwise comparisons. Within all 25 accessions and ranged from 0.30 to 0.88 while average within population similarity ranged from 0.50 to 0.60. Within populations variability was estimated as percentage polymorphic loci (ranging from 50% to 80%). Shannon’s information index among two zones were detected. Between and within accessions relatedness was estimated among populations with a principal coordinate analysis and also estimated with cluster analysis (UPGMA). These estimation depicts outcrossing rates both within population and between-population diversity. Molecular marker characterization can however be used to identify the most suitable zone for collection of high polymorphic accessions for tree improvement program with the yield.

Molecular epidemiology on seasonal variation of yellow mosaic disease incidence in blackgram (Vigna mungo L. Hepper) with its vector Bemisia tabaci.

The yellow mosaic disease (YMD) of blackgram caused by Mungbean yellow mosaic virus has emerged as a serious threat to grain legume production, especially in Southeastern Asia. Seasonal incidence of YMD with its vector population was assessed in three different agroclimatic zones of Tamil Nadu in India for three consecutive cropping seasons namely, Rabi 2018 (October-December), Summer 2019 (March-May), and Kharif 2019 (June-August) at three different time intervals viz., 20, 40, and 60days after sowing (DAS). For all three seasons, disease incidence and whitefly count were recorded for a resistant and susceptible variety of blackgram in fields without any vector control intervention. The highest disease incidence (87%) was observed in the Panpozhi location during the summer season followed by Vamban and Coimbatore locations. The whitefly count was made through both visual count and yellow sticky traps. The whitefly population was highest at 20 DAS and decreased with the increasing age of crop for all the three locations assessed. Molecular epidemiology was analyzed by determining latent infection of mungbean yellow mosaic virus (MYMV) using molecular diagnosis. Latent infection was found to be well pronounced in the Coimbatore location during the Kharif season, where the crop was asymptomatic in both the resistant and susceptible varieties for all the three time periods assessed. The latent infection of MYMV observed in Coimbatore and Vamban ranged from 16.6 to 83.3% in both resistant and susceptible varieties for all three seasons. In Panpozhi, the latent infection of MYMV ranged from 16.6 to 66.6% for the susceptible variety (CO-5) for all three seasons observed. However, in the Panpozhi location, the resistant variety (VBN-8) failed to record any latent infection.

"Impact of Climate Change on Water Requirement and Yield of Tomato Over different Agro-climatic Zones of Tamil Nadu"

"Impact of Climate Change on Water Requirement and Yield of Tomato Over different Agro-climatic Zones of Tamil Nadu"

Drought Analysis in Southern Agroclimatic Zone of Tamil Nadu using Standardized Precipitation Index

Drought differs from other natural hazards in the fact that the initiation and the termination is extremely difficult to determine and that its drastic effects continue to persist well after the cessation of the event which adds to the complexity as well as the casualties. The Southern Agro Climatic Zone (ACZ) of Tamil Nadu is heavily rain shadowed during the South West Monsoon Season, several complications arise with respect to drought, causing crop failures and depleted moisture concentration in certain cases. With that idea in perspective, a study was conducted in Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore, India to study the frequency of drought over the Southern Agro-Climatic Zone of Tamil Nadu, India. Since precipitation that occurs over a region determines mainly the occurrence and cessation of drought events, precipitation-based Rainfall Deviation and Standardized Precipitation Index (SPI) was used to quantify the extent of rainfall deficit or surplus over the region. The analysis of 30 years (1991 – 2020) historical rainfall data of various districts of the Southern Agroclimatic Zone of Tamil Nadu using SPI showed that the annual SPI value ranged from +3.3 to -4. The study showed that Tirunelveli and Thoothukudi districts were most prone to moderate drought and severe drought. The region showed more frequency of Moderate drought than Severe and Extreme drought.