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Item Ecological engineering for pest management in rice Oryza Sativa L(Department of Agricultural Entomology, College of Agriculture , Vellanikkara, 2024-03-15) Meera Krishnan; Sreeja, PEcological engineering (EE) for pest management is a strategy to enhance the abundance, diversity, and effectiveness of natural enemies in an agricultural ecosystem. Although EE has gained acceptance as a pest management tactic, there still exist knowledge gaps in the identification of the best floral resources for the population build up and biocontrol potential of natural enemies. Hence, the present study entitled Ecological engineering for pest management in rice Oryza sativa L was carried out during 2022-23 to identify suitable flowering plants for habitat management in rice and evaluate their efficacy for ecological pest management. The olfactory response of predators viz.,lady bird beetle (Micraspis discolor), ground beetle (Ophionea nigrofasciata), green mirid bug (Cyrtorhinus lividipennis) and parasitoids Trichogramma chilonis and T. japonicum to different the flowers was assessed in a six arm olfactometer. In each arm of the olfactometer, ten flowers each of sesame, cowpea and cosmos were individually inserted and for marigold and okra, only one flower was used. The arm without flower served as the control. Ten adults of each predator and twenty adults of each parasitoid were released at the center of the olfactometer. The number of predators and parasitoids settled per arm at 5, 10, 15 and 20 min. after release (MAR) as well as the distance covered per min. was assessed. Micraspis discolor showed the highest attraction towards flowers of cowpea and okra (2.33 each arm-1) at 20 MAR followed by marigold (1.00 arm-1) and sesame and cosmos (0.67 each arm-1). The distance covered towards cowpea was 10.61 cm min-1. and whereas for okra it was 7.37 cm min-1. Similarly, for O. nigrofasciata, the highest response was recorded towards cowpea (2.00 arm-1) followed by marigold (1.67 arm-1) and sesame (1.00 arm-1). The distance covered was also higher in cowpea (3.50 cm min 1 ). Cyrtorhinus lividipennis recorded the highest attraction towards sesame (2.67 arm-1) followed by cowpea (1.33 arm-1) and marigold (1.00 arm-1), which showed significant difference with the control. The distance covered was also high in sesame (4.82 cm min 1 ) followed by cowpea (3.42 cm min-1). As for parasitoids, highest attraction of T. chilonis was found towards cowpea (4.33 arm-1), while that of T. japonicum was towards sesame (2.67 arm-1). Thus, the behavioural response studies of predators and parasitoids revealed a significantly higher preference towards the flowers of cowpea, sesame and marigold. To identify the attractive compounds in the volatiles of flowers, through GCMS analysis, their extraction was conducted through head space method and solvent extraction. The headspace analysis of marigold flowers identified seven major compounds, with insect attractant properties. The compounds were alpha ocimene, myrcene, limonene, cis ocimene, trans ocimene and beta caryophyllene. The attractant compounds of marigold flowers through solvent extraction were caryophyllene, heneicosane, squalene, eicosane, tetrapentacontane, tetracontane, hexatriacontane, heptadecane, octadecane 1-chloro- and dotriacontane and that of cowpea flowers were eicosane, heneicosane, hexadecane, dotriacontane, tetracosane, heptadecane, octadecane 1-chloro- and diisoctyl phthalate. Similarily, the attractant compounds from sesame flowers were eicosane, octacosane, nonacosane, beta-bisabolene, heptadecane, dotriacontane, tetracontane, octadecane 1-chloro- and hexatriacontane. A field experiment was laid out to study the effect of flowering plants in ecological pest management in rice with four treatments: T1- PoP of KAU, T2- PoP in combination with flowering plants, T3- farmers practice and T4- untreated control. The seedlings of best three flowers selected from the olfactometer studies viz., marigold, cowpea and sesame were planted around the rice bunds on the day of transplanting to evaluate their effect on natural enemies and insect pests in rice. The population of major insect pests and natural enemies was recorded at 15,30,45,60,75 and 90 days after transplanting. The extent of damage of stem borers (Scirpophaga incertulus and S. fusciflua) was significantly lower in ecological engineering plot (T2) (2.52 %) followed by the PoP (2.86 %), farmers practice (3.26 %) compared to untreated control (5.39 %). Similarly, the mean damage of leaf folder (Cnaphalocrosis medinalis) was lowest in T2 (1.24 %) which was on par with T1 (1.28 %). The mean population of leafhoppers (Nephotettix nigropictus, N. virescens and Cofana spectra) was lowest in PoP (0.37 m 2 ), while for hispa, Dicladispa armigera, the population in all the treatments was non significant. The population of rice bugs (Leptocorisa spp.) was lowest in PoP (4.43 m 2 ) followed by farmers practice (4.86 m-2), and PoP with flowering plants (7.06 m-2) at 90 DAT. Ecological engineering plot recorded a significantly higher population of all natural enemies as against the control, PoP and farmers practice. Five species of coccinellids were recorded from the ecological engineering plot, viz., M. discolor, Coccinella transversalis, Harmonia octomaculata, Cheilomenes sexmaculatus, and Brumoides suturalis, The highest population of ground beetles (O. nigrofasciata) was recorded in ecological engineering plot (1.60 m-2) followed by control (0.90 m-2). Similarly, significantly higher population of rove beetles and damselflies (2.94 and 1.41 m-2 respectively) were recorded in EE plot. Seven species of spiders viz., Tetragnatha javana, T. mandibulata, Pardosa pseudoannulata, Neoscona theisi, N. elliptica, Argiope catenulate and Oxyopes javanus were documented wherein the population was highest in ecological engineering plot (1.97 m-2). The hymenopteran parasitoids were recorded through sweep netting and significantly higher population was recorded in ecological engineering plot (2.20 /5 sweeps), followed by control (1.06 /5 sweeps). The major parasitoids recorded under Ichneumonidae were Xanthopimpla sp., Trathala flavoorbitalis, Amyosoma sp., Isotima sp., Metopius rufus, Goryphus sp. and Stenobracon nicevelli, whereas Tropobracon sp., and Cardiochiles sp. were documented under Braconidae.The parasitization on stem borer egg mass by Tetrastichus sp. and Telenomus sp. was observed, in which the extent of total parasitism was 92.5 per cent in ecological engineering plot, followed by 72.5 percent in the control. The yield recorded in PoP and ecological engineering plot was 529.73 g m-2 and 513.80 g m-2 respectively and was on par with each other, while the control plot recorded the lowest yield of 263.46 g m-2. The benefit-cost ratio in the ecological engineering plot is 2.16 while the control recorded a ratio of 0.95. The present study identified three flowering plants viz., cowpea, marigold and sesame having the potential to enhance the population of predators and parasitoids in the rice ecosystem. Hence the study will pave the way to develop a habitat management module for pest management in rice. Further studies to identify additional plant species for habitat management are to be carried out. Detailed investigations on the impacts of floral resources on the growth and development of entomophagous insects have to be undertaken to fortify conservation biological control strategiesItem Forcasting major pests of rice using weather variables(Department of Agricultural Statistics, College of Agriculture,Vellanikkara, 2025-03-06) Abishek Krishnan.Rice is the staple food crop of majority of the global population and production of rice has been affected by various factors. Insect pest attack in rice causes significant yield loss in rice. Forecasting models can be developed to determine the incidence of the pest using various weather parameters and it is a significant step in helping the farmers to mitigate the loss of crop due to insects. The forecasting of two major insect pests of rice namely Yellow stem borer (YSB) and Brown plant hopper (BPH) has been taken up in this study. Population count data of YSB and BPH from light trap catches installed at Regional Agricultural Research Station (RARS), Pattambi, Kerala was utilised for the study. The objectives of the study were to establish the relationship of YSB and BPH population with the weather variables which includes maximum temperature (TMAX), minimum temperature (TMIN), morning relative humidity (RH I), evening relative humidity (RH II), rainfall (RF) and sunshine hours (SSH); to develop suitable forecasting models for YSB and BPH using weather variables; and to study the dynamics of these pests under pre and post flood conditions. Two period of peak incidence of the YSB population was revealed from the analysis of their distribution during the study period ranging from 1997 to 2023. These periods of peak incidence were 10th to 16th standard meteorological week (SMW) and 38th to 48th SMW. Relationship of pest population with weather variables was studied using correlation analysis. The peak week corresponding to the 12th SMW had significant negative correlation with TMAX, TMIN, RH I, RH II and SSH, whereas count of YSB for the 43rd SMW had an association with TMIN, RH I and RH II. The weekly distribution of BPH showed one prominent peak incidence corresponding to the 39th to 44th SMW and it was found that minimum temperature, morning and evening relative humidity, rainfall, sunshine hours were the weather variables that had significant correlation with the BPH population. Multiple linear regression model for to predict the incidence of YSB at 12th week of peak incidence, had weather variables TMAX, TMIN, RH I and SSH as explanatory variables and the model yielded an adjusted R2 of 81%. The interaction of temperature and relative humidity was found to be significant in case of composite regression models. Multinomial logistic regression models developed for determining the pest infestation status, in terms of low, medium and high incidence of the YSB population had an accuracy of 92% and 72% for the 12th and 43rd peak weeks respectively. In case of BPH population, multiple linear regression model to predict BPH incidence during 39th – 44th SMW yielded a model with adjusted R2 value of 39% with weather variables TMIN, RH I and RH II. For 42nd SMW, model with variables TMIN, RH I and RH II yielded an R2 value of 45%. In case of BPH also, interaction of temperature and relative humidity was found to be significant in the fitted composite regression models, with a greater model R2 in comparison to that of multiple linear regression model. An accuracy of 66% and 64% was obtained for the model fitted using multinomial logistic regression analysis during peak period and peak week respectively. Autoregressive Integrated Moving Average (ARIMA) model, ARIMA with exogenous variables (ARIMAX) and Integer valued generalized autoregressive conditional heteroscedasticity with exogenous variables (INGARCHX) models were employed for the time series analysis of the pest data. Three different trend periods were identified for both YSB and BPH population. In the case of YSB population during first period, ARIMAX (2,1,1) was the best fit model with MAPE value of 11.29%. For second period, ARIMAX (2,1,1) with MAPE of 11.36% and for the third period, ARIMAX (2,0,1) with a MAPE of 15.02% were the best fitted models. In the case of BPH, ARIMAX (2,0,2) was the best fit model for first period, ARIMAX (2,1,2) and ARIMAX (1,1,1) for the second and third period respectively. INGARCHX models fitted for YSB and BPH population were of poor fit, as these models did not have any significant weather variables in the model, with only model parameters turning out to be significant. Further, pre and post flood analysis of pest dynamics with weather variables revealed that there is a shift in the peak period of incidence for both YSB and BPH and further there is an overall decline in both YSB and BPH population for post flood period. The individual and joint effect of the weather variables were determined using the multiple linear regression analysis and composite regression analysis respectively, wherein composite regression provided better model accuracy in comparison to multiple linear regression analysis. Multinomial logistic regression analysis helped to determine the epidemic status of YSB and BPH at different peak periods of incidence. These epidemic status can be used as a warning alert for the farmers on the level of incidence of these pests. Time series analysis of the pest population count revealed that ARIMAX models performed better than INGARCHX models in predicting population of YSB and BPH and it also shed light into the various trend breaks observed in the pest population count for both YSB and BPH across the time period studied.Item Radiofrequency heating for the management of rice weevil Sitophilus oryzae (L.)(Coleoptera:Curculionidae) and lesser grain borer Rhyzopertha dominica (Fabricius)(Coleoptera:Bostrichidae)(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2025-03-04) Prashanth PatilIndia is the leading country in the export of rice. The infestation of storage pests, notably the rice weevil, Sitophilus oryzae and lesser grain borer, Rhyzopertha dominica causes a significant loss in the quantity and quality of stored grains. Phosphine use effectively manages stored pests, but insect resistance, residue concerns, strict import regulations, and rising demand for organic products highlight the need for chemical-free alternatives like radiofrequency (RF) heating to protect high-value commodities.. Hence, this study was carried out to assess the effectiveness of RF heating for the management of rice weevil, S. oryzae and lesser grain borer, R. dominica, and to study the impact of RF disinfestation on the quality parameters of rice grains. Eggs, grubs (15 ± 2 day old), pupae, and adults (one week old) of S. oryzae and R. dominica were exposed to RF dryer (40.68 MHz, 10 kW) at three different levels of electrode height (190, 195, and 200 mm) and conveyor speed (6, 8, and 10 m/h) and compared with an untreated control. The order of susceptibility among different life stages of lesser grain borer at 195 mm electrode height and 8 m/h conveyor speed was adult>grub>egg>pupa. S. oryzae was highly susceptible to RF heating, leading to complete mortality of all the stages except pupa at all the treatment combinations. The susceptibility of grubs, eggs, and pupae of R. dominica were comparable, whereas adults were highly vulnerable to RF heating. The mortality of immature stages was assessed based on the per cent decrease in adult emergence over control. Lowering the electrode height of RF dryer increased the mortality of all life stages of S. oryzae and R. dominica. Highest mortality of eggs, larvae, pupae, and adults was obtained at the lowest electrode height of 190 mm. Similarly, the mortality of eggs, larvae, pupae, and adults of S. oryzae and R. dominica increased significantly by decreasing the conveyor speed. The lowest conveyor speed of 6m/h significantly reduced adult emergence and recorded the highest mortality of all the developmental stages of S. oryzae and R. dominica. The analysis of the interaction effect of electrode height and conveyor speed of RF dryer demonstrated that the mortality of different developmental stages of S. oryzae and R. dominica increased with a decrease in electrode height and conveyor speed. There was no adult emergence when the eggs, grubs and pupae of S. oryzae were exposed to RF heating. Meanwhile, the adult emergence of R. dominica was completely inhibited only at the lowest conveyor speed of 6 m/h at all three electrode heights. RF heating resulted in the complete mortality of adults of rice weevil at all the treatment combinations. Lesser grain borer adults were more tolerant to RF heating, with complete mortality observed at all the electrode heights at a conveyor speed of 6 m/h and at the electrode heights of 190 and 195 mm at a conveyor speed of 8 m/h. All other treatment combinations did not cause complete mortality of R. dominica adults. Per cent weight loss was significantly reduced over control when R. dominica and S. oryzae eggs were exposed to RF heating. Meanwhile, weight loss was significantly reduced over control only when S. oryzae grubs were subjected to RF heating. The impact of RF heating on the quality parameters of rice grains was analysed after exposure to RF heating. Moisture, amylose, and cooking time of rice grains decreased with the decrease in electrode height of RF dryer. The moisture content at all the treatment combinations was significantly lower over control. Amylose content and cooking time did not vary significantly over control by RF heating at various combinations of electrode height and conveyor speed. Similarly RF heating did not adversely affect the colour of rice as there was no significant colour change over control after RF heating. Three combinations of electrode height and conveyor speed (190 -6 mm m/h, 195-6 mm-m/h,200- 6mm-m/h) resulted in the complete mortality of all life stages of S. oryzae and R. dominica. Also, there was no significant difference in amylose, cooking time, and colour values of rice grains at these treatment combinations over control. The lowest temperature recorded after RF treatment was 56.9°C in the 200 mm-6 m/h treatment combination. This indicates that a temperature of 56.9°C generated through RF heating can effectively control all life stages of S. oryzae and R. dominica by retaining the quality parameters of the rice grains. Hence, radiofrequency heating at an electrode height of 200 mm and a conveyor speed of 6 m/h can be commercially employed in the complete disinfestation of all the stages of S. oryzae and R. dominica without compromising the quality of rice grains.Item Paddy procurement in major rice growing tracts of Kerala : an exploratory analysis(Department of Agricultural Extension, College of Agriculture, Vellanikkara, 2025-02-22) Reshma Siju.; Smitha BabyThe Food Corporation of India (FCI), in collaboration with the State agencies, serves as the central organization for paddy procurement in India. FCI purchases paddy at the Minimum Support Price (MSP) set by the Government of India (GOI) to protect farmers' interests, maintain buffer stocks for national food security, and ensure the timely and affordable distribution of food grains to intended beneficiaries. Paddy procurement in India operates under two primary systems: the Centralized Procurement System, where FCI directly handles procurement, and the Decentralized Procurement (DCP) System, where State governments and their agencies manage the procurement, storage, and distribution of food grains. In Kerala, the DCP system has been in place since 2006, with the Kerala State Civil Supplies Corporation Limited (SupplyCo) serving as the State agency for paddy procurement. SupplyCo assigns private rice millers to specific regions to carry out the procurement process. These millers process the paddy into Custom Milled Rice (CMR) and deliver it to SupplyCo for distribution through the Public Distribution System (PDS). The study adopted an exploratory research design with specific objectives of assessing farmers’ perception on the effectiveness of paddy procurement, farmers’ satisfaction with the online procurement system, the role of different agencies involved in paddy procurement, and exploring the constraints in paddy procurement in the State. Palakkad and Alappuzha districts of Kerala, the leading paddy-producing regions, were purposively selected for the study. Two procurement centres with the highest procurement volumes were purposefully selected within each district. Four Panchayats were randomly chosen from these centres, resulting in sixteen Panchayats forming the study area. Ten farmers were randomly selected from each Panchayat to constitute a total sample of 160 farmers. Additionally, 20 officials were selected to examine the roles of various stakeholders involved in the procurement process. These stakeholders included the Paddy Marketing Officer (PMO), Paddy Quality Assurance Officer (PQAO), Paddy Payment Officer (PPO), Agricultural Officers (AO), mill owners or mill agents, and Padasekara Samithi members. The farmers’ perception on the effectiveness of procurement was studied using the semi structured interview schedule developed based on the scale developed for the study. The results of the study showed that the effectiveness parameters such as Price Risk Mitigation (84.16), and State Policy Intervention (86.62) gained a very high percentage score, and Market perception (74.18), institutional support (62.64), and Influence on crop choice and Decision making (74.35), had a high percentage score. The effectiveness was found to be less in relation to the procedural formalities in procurement, indicated by its very low score (39.46). This shows the various procedural glitches related to payment mechanisms, quality management aspects and lengthy and tiresome procurement process. The farmers’ satisfaction with the online procurement system was analysed using, the parameters, such as farmers’ satisfaction with the SupplyCo website and the online registration process showed a satisfaction score of 86.64 and 89.84, respectively, indicating famers’ high satisfaction with the online procurement process. Eighty five percent of farmers have done online registration through the Akshaya Centres, and fifteen percent registered on their own. The Paddy Marketing Officer (PMO) is the technical staff involved in the procurement process. The PMO plays a major role in creating awareness among the farmers about the quality of the paddy produced, conducting random inspections at fields, allotment of mills, grievances redressal between the mill agents and farmers on quality standards, and issuing of Paddy Receipt Slip (PRS). The Paddy Quality Assurances Officer (PQAO) is the staff dealing with the quality assurances of the milled rice and record maintenance at the mills. Paddy Payment Officer (PPO) authorises the payment order to individual farmers through banks, coordinating the activity between the SupplyCo head office and banks. The Agricultural Officer (AO) verifies the field and approve the applications for procurement and issues the excess yield certificate, if needed. After fixing the rejection rate by considering the quality parameters, the Mill agent collects and transports the procured paddy and supply the processed rice to NFSA godowns. Padasekhara Samithi facilitates synchronised farming, coordinates the online registration, field verification and deals with the mill agents. The constraints faced by the farmers in procurement were identified using focus group discussions and literature review. The Garrett ranking technique was used to rank the ten identified constraints based on their relevance. The major constraint identified was the absence of ready payment; the paddy in the state is procured at Rs. 28.20 per Kg, out of which the central government give Rs. 21.36 as MSP and the State provides a State Incentive Bonus of Rs. 6.70. The central government pays the state government only after the procured paddy reaches the consumers through PDS. Hence, the State government makes arrangements with banks for paying the farmers as PRS loans. Difficulty in meeting the quality standards was identified as the second major problem faced by the farmers due to the varying climaticItem Assessment and Management of rice sheath blight disease in Kuttanad(Department of Plant Pathology, College of Agriculture , Vellayani, 2025-01-30) Archana Gilbert; Surendran, MThe study entitled “Assessment and management of rice sheath blight disease in Kuttanad” was conducted at Department of Plant Pathology, College of Agriculture, Vellayani and M. S. Swaminathan Rice Research Station, Moncompu during 2022-2024 with the objectives of assessment of extent of rice sheath blight disease incidence caused by Rhizoctonia solani in Kuttanad region, screening for host plant resistance and evaluation of different management strategies. A survey was conducted in forty locations of agro ecological unit (AEU) – 04 (Kuttanad) in Alappuzha, Kottayam and Pathanamthitta districts to assess the extent of sheath blight disease incidence in rice. The symptomatology was studied and plants with grey water soaked lesions with brown margins were observed on leaf sheath near the water level. Presence of brown coloured sclerotia were observed in severely infected plants. Disease parameters such as disease incidence and disease severity were recorded. The highest disease incidence (72.73%) and disease severity (80.19%) were observed in Neelamperoor region of Alappuzha district. The diseased samples were collected for the isolation of the pathogen and 40 isolates were obtained. The pathogenicity was confirmed by artificially inoculating the isolates in rice variety, Uma. Days taken for symptom development and sclerotia formation was recorded and isolate from Neelamperoor region took least number of days for symptom development (3 days) and sclerotia formation (5 days). Cultural and morphological studies of the isolates were conducted and the colony colour varied from white to dark brown in PDA medium. The mycelia formed were aerial and flat type. The number of days for complete growth in Petri plate (90 mm) and for sclerotia formation was 3 to 11 days and 3 to 9 days respectively. The isolate from Neelamperoor took least number of days for complete growth in Petri plate (3 days) and for the formation of sclerotia (3 days). Pattern of sclerotia formation was scattered or confined to centre or periphery. Sclerotia was white to dark brown in colour with smooth and rough surface. Size of sclerotia varied from 1.05 – 1.48 mm. The mycelia were hyaline and septate with right angled branching. Hyphal width ranged from 1.12 – 1.98 μm. The molecular characterization of the virulent isolate was done using ITS primers. The DNA sequence comparison showed similarity with R. solani. The sequences obtained was submitted in GenBank and was allotted with accession number PQ658187. In vitro evaluation of biocontrol agents in growth inhibition of R. solani was tested by dual culture technique. Biocontrol agents Bacillus amyloliquefaciens (B15) and Pseudomonas fluorescens (PN026) were tested and highest mycelial growth inhibition (68.64%) was observed in B. amyloliquefaciens. Efficacy of fungicides in growth inhibition of R. solani at different concentrations was tested under in vitro conditions by poisoned food technique. Fungicides, azoxystrobin 18.2% + difenoconazole 11.4% SC, kresoxim methyl 40% + hexaconazole 8% WG and trifloxystrobin 25% + tebuconazole 50% 75 WG were evaluated against virulent isolate of R. solani. Complete mycelial inhibition was recorded with azoxystrobin 18.2% + difenoconazole 11.4% SC at 1 mlL-1 and in Kresoxim methyl 40%+ Hexaconazole 8% WG at 0.5 gL-1 and 1 gL-1. Fifteen varieties released by KAU were subjected to screening for host plant resistance against sheath blight disease. The disease parameters were analyzed and among these, Aiswarya and Kanchana were observed to be resistant with least disease severity (15.55% and 20.01% respectively) whereas varieties Uma, Jyothi and Karishma were found to be more susceptible exhibiting disease severity of 80.11%, 77.78% and 72.23% respectively. In vivo evaluation of efficacy of biocontrol agents and fungicides along with different fertilizer dose for the management of sheath blight disease was conducted in rice variety Uma in split plot design. Highest per cent reduction in disease over control was observed in treatment combination kresoxim methyl 40% + hexaconazole 8% WG at 1 gL-1 with 75%N, 100%P, 125%K of recommended dose of fertilizers (RDF) (73.93%) followed by treatment combination of kresoxim methyl 40% + hexaconazole 8% WG at 1 gL-1 with 100% RDF (70.31%). Among biocontrol agents, treatment combination of B. amyloliquefaciens (B15) and 75%N, 100%P, 125%K of RDF had better control with 38.79% reduction in disease severity. Highest per cent increase in grain yield was recorded in treatment combination of kresoxim methyl 40% + hexaconazole 8% WG at a concentration of 1 gL-1 and 75%N, 100%P, 125%K of RDF (97.23%) followed by kresoxim methyl 40% + hexaconazole 8% WG at 1 gL-1 and 100% RDF (90.10%). The present study concludes that sheath blight disease incidence ranged from 15.39 to 72.73% in AEU – 04 (Kuttanad). The varieties Aiswarya and Kanchana exhibited resistance to the disease. Sheath blight disease can be effectively managed by foliar spraying of commercial fungicide kresoxim methyl 40% + hexaconazole 8% WG at a concentration of 1 gL-1 at maximum tillering stage along with 75%N, 100%P, 125%K of RDF. Biocontrol agent B. amyloliquefaciens (B15) given as seed treatment (10 gkg-1 seed), soil treatment (1 kg acre-1) at 35 days after planting and foliar spray (20 gL-1) at maximum tillering stage combined with 75%N, 100%P, 125%K of RDF also reduces the disease incidence along with increasing yield parametersItem Yield prediction of kharif rice (Oryza sativa L.) in Kerala by various crop weather models(Department of Agricultural Meteorology, College of Agriculture,Vellanikkara, 2025-02-04) Chandana B Jyothi.Rice is a staple crop in Kerala, but its production faces challenges from adverse weather and climate changes, leading to yield fluctuations. Accurate yield forecasts are vital for farmers, policymakers, and exporters to ensure efficient resource allocation and strategic planning. Tools like DSSAT and Info-Crop simulate rice growth for yield prediction, while statistical models like Artificial Neural Networks (ANN) and Stepwise Multiple Linear Regression (SMLR) offer additional predictive capabilities. The present study “Yield prediction of kharif rice (Oryza sativa L.) in Kerala by various crop weather models” is aimed to predict kharif rice yield in different districts of Kerala using statistical and crop simulation models and compare above yield prediction models. Short duration variety, Jyothi and Manu Ratna were raised at Agricultural Research Station, Mannuthy, Kerala Agricultural University, Thrissur. The split plot design was used with five dates of planting (June 5th, June 20th, July 5th, July 20th and August 5th) as main plot treatments and two varieties as subplot treatments, with four replications. Various observations like weather, phenological, biometric, computed parameters, yield and yield attributes had been recorded to study the crop weather relationship. The data analysis has been done by using SPSS software and it was found that with increase in the maximum temperature (°C), minimum temperature (°C), temperature range (°C), bright sunshine hour (hrs) and rate of evaporation (mm) has reduced the crop duration, while amount of rainfall (mm), number of rainy days, forenoon and afternoon relative humidity (%) has positively influenced with the crop duration. A significant variation in the biometric and computed observations was also obtained. Plant height were found to be higher in Manu Ratna, when compared to Jyothi. Dry matter accumulation was higher in Manu Ratna during 75 DAP and there was no significant difference between varieties in the later stages. Both plant height and dry matter accumulation had significant variations among different planting dates. Leaf area index did not show any significant variation among varieties and date of planting. In Jyothi highest grain yield was found in July 5th planting, while in Manu Ratna July 20th planting was found to be higher. Maximum temperature in the P5 and P6 stage had a negative influence on the yield. Wind speed also showed a negative correlation with yield in the later stages. The genetic coefficients influencing the growth and yield of rice in the CERES- DSSAT model and Info-Crop model were calibrated to achieve the optimum agreement between observed and simulated values. Predicted yield of both rice varieties, Jyothi and Manu Ratna, under different planting dates were reasonably close to the observed values. These observations indicate that the DSSAT model generally performs better in districts like Thrissur, Pathanamthitta and Kollam, while the Info Crop model excels in Thrissur. However, both models require improvements in districts like Kottayam, Kasaragod and Alappuzha to enhance prediction accuracy. A dataset of 105 yield records (2013–2022) and weather indices was used for calibration. Stepwise regression identified the best statistical model having highest R2 for yield prediction. The ANN model, trained using the ‘caret’ package in R Studio, utilized 12 input variables. The dataset was split into 80% training and 20% testing. The developed model predicted 2023 yields for 12 districts. For comparing the accuracy of these models for districts of Kerala, MAPE and MAE were calculated. The data highlights the district-wise performance of both models, showing the ANN model generally outperforms the SMLR model in terms of accuracy, particularly in Kasaragod and Ernakulam. Yield prediction is crucial for ensuring food security, optimizing resource use and guiding agricultural planning and policy decisions. In conclusion, the comparison of crop-weather models for rice yield prediction reveals distinct strengths among the approaches. Machine learning models demonstrate superior accuracy with extensive datasets. A hybrid approach combining these models can optimize rice yield predictions, supporting sustainable and resilient rice farming systems.Item Etiology and management of sheath rot disease of rice(Department of Plant Pathology, College of Agriculture, Vellayani, 2023-03-16) Boya Sreekanth.; Surendran, MThe study entitled "Etiology and management of sheath rot disease of rice" was conducted at Department of Plant Pathology, College of Agriculture Vellayani and Rice Research Station, Moncompu during 2020-2022, with the objective to isolate and characterize the pathogen associated with sheath rot disease of rice and evaluate the efficacy of the available Bacillus sp.and commercial fungicides against sheath rot disease of rice. Purposive sampling survey conducted in four rice growing districts of Kerala during 2021-2022 to collect the sheath rot infected panicles and to access the disease incidence (DI) and disease severity (DS). Among the surveyed locations, maximum DI (49.23 per cent) and DS (46.32 per cent) were recorded from Neelamperoor and Palakkad. S. oryzae was isolated from the collected specimens; a total of five pure cultures of S. oryzae (Isolate I1 to Isolate I5) were obtained and Koch's postulates were proved for all the isolates in rice var. Uma. All the S. oryzae isolates were screened for its virulence and pathogenicity in rice var. Uma. The isolate I5, from Thrithala produced the symptom within 24 h of artificial inoculation. On 4th day of artificial inoculation, isolate I5 recorded a maximum lesion size of 2.50 cm; and thus, concluded as the most virulent isolate. The cultural characters of these 5 isolates were whitish orange with some radial foldings and morphological characters of hyphae was septate and whitish orange in color and spores single celled and cylindrical in shape. Average size of the spore was 5.53 x 1.66 µm. Dual culture assay of Bacillus sp. B15, Bacillus sp. B17, Bacillus sp. B33, Bacillussp. B42 and Pseudomonasfluorescens(PN026) in potato dextrose agar (PDA) medium indicated that the beneficial endophytic bacteria significantly inhibited the growth of the pathogen through multiple antagonistic properties. Maximum growth inhibition of S. oryzae (70.95 per cent) by P. fluorescens (PN026) followed by Bacillus sp. B17 (64.45 per cent) and Bacillus sp. B 42 (50.95 per cent) were observed on 12 th day of dual culturing. Among the four commercial fungicides tested in vitro, trifloxystrobin 25%+tebuconazole 50 % 75 WG (400ppm), propineb 50 WP (2500ppm) and hexaconazole 5EC (2000ppm) completely inhibited (100%) the sheath rot pathogen compared to copper hydroxide 77 WP (2000ppm) which inhibited the growth of the sheath rot pathogen by 86.42% per cent. Considering the overall performance, recommended doses of trifloxystrobin 25%+tebuconazole 50 % 75 WG (400ppm), propineb 50 WP (2500ppm) and hexaconazole 5 EC (2000ppm) were more effective against sheath rot pathogen. The isolation of DNA from sheath rot pathogen was carried out by using CTAB (cetyltrimethyl ammonium bromide) method of DNA isolation. Quality and quantity of sample DNA were 1.73 and 60 µg ml-1 . Size of the amplicon is 608bp. This sheath rot associated pathogen was identified from Rajiv Gandhi Centre for Biotechnology (RGCB), Thiruvananthapuram as Sarocladium oryzae through molecular characterization (GenBank Accession no. OP716814). This sheath rot pathogen was used for further studies. Pot culture experiment was conducted for screening rice varieties (20 numbers) for resistance to sheath rot pathogen. Artificial inoculation was done at panicle initiation stage. Aathira and Shreyas showed tolerant reaction to sheath rot disease whereas Uma variety showed the highest susceptibility nature. The biocontrol agents and fungicides were evaluated in the field against sheath rot disease of rice during Kharif 2022 at RRS, Moncompu. Management of disease before panicle emergence is very much essential. Prophylactic application of talc-based formulation of Bacillus sp. B15, Bacillus sp. B17, Bacillus sp. B33, Bacillus sp., B42, B 15+ B17+ B 33+ B 42 consortium and Pseudomonas fluorescens (PN026) as seed treatment (10g kg-1 ) + soil application (1kg/acre) + foliar spray (20g L-1 of water at booting stage) for the management of sheath rot disease of rice and thereby improving the yield. Among all the bioagent treatments, the application of B 15+ B 17+ B 33+ B 42 consortium showed more efficacy nature for the management of sheath rot disease of rice and improving the yield. Four commercial fungicides viz., copper hydroxide 77 WP @ 2 g L-1 , trifloxystrobin25%+tebuconazole 50 % 75 WG @ 0.4 g L -1 , propineb 50 WP @ 2.5 g L -1 and hexaconazole 5 EC@2 ml L-1 were given as foliar spraying at booting stage. Among all the fungicides tested in the field, trifloxystrobin 25%+tebuconazole 50 % 75 WG @ 0.4 g L -1 and hexaconazole 5 EC@ 2 ml L-1 applied as foliar spraying were significantly superior in reducing the disease and increasing the yield followed by propineb 50 WP @ 2.5 g L-1 and copper hydroxide 77 WP @ 2 g L-1 . Benefit cost ratio was also more in case of B 15+ B 17+ B 33+ B 42 consortium and trifloxystrobin 25%+tebuconazole 50 % 75 WG @ 0.4 g L-1 . Thus, the present study revealed that sheath rot of rice could be managed by using Bacillus sp. B 15+ B 17+ B 33+ B 42 consortium as seed treatment (10g kg-1 ) + soil application (1kg/acre) + foliar spray (20g L-1 of water at booting) and commercial fungicide, trifloxystrobin 25%+tebuconazole 50 % 75 WG @ 0.4 g L -1 and hexaconazole 5 EC at 2 ml L -1 . The results may be subjected to multi-location and multi- seasonal field trails before recommendation. The compatibility of Bacillus sp. consortium with new generation fungicides and the residue of fungicides in grain may further be studied.Item Endophyte mediated biofortification of zinc in rice .(Department of Agricultural Microbiology, College of Agriculture , Vellanikkara, 2025-01-25) Reenashri, R.; Boby, V UnnikrishnanItem Performance of intercrops and weed suppression in paired row planted rice in low land summer fallows(Department of Agronomy, College of Agricultuture,Vellayanire , Vellayani, 2025-02-04) Hemand, J; Jacob JohnA field experiment entitled “Performance of intercrops and weed suppression in paired row planted rice in low land summer fallows” was conducted at Department of Agronomy, College of Agriculture, Vellayani and Integrated Farming System Research Station, Karamana, Thiruvananthapuram, Kerala, during 2022 to 2024. The main objective was evaluation of intercrops in paired row planted rice in summer fallows of double cropped lowland rice field, in terms of weed dynamics, biological efficiency and economics. The field experiment was conducted during summer season of 2023-24 at Integrated Farming System Research Station (IFSRS), Karamana, Thiruvananthapuram, Kerala, India. The field experiment was laid out in randomized complete block design with ten treatments and three replications. The treatments were T1: Paired row of rice + grain cowpea, T2: Paired row of rice + finger millet, T3: Paired row of rice + Foxtail millet, T4: Paired row of rice + proso millet, T5: Sole crop of paired row rice, T6: Sole crop of grain cowpea, T7: Sole crop of finger millet, T8: Sole crop of foxtail millet, T9: Sole crop of proso millet, T10: Fallow. The varieties used for the study for rice, grain cowpea, finger millet, foxtail millet and proso millet were Uma, Bhagyalekshmi, Co 15, Co (Te)7 and TNAU 202, respectively. FYM and fertilizers were applied as per the recommendations (KAU, 2024 and TNAU, 2024) to rice, grain cowpea and millets, respectively. The growth attributes of rice and intercrops were recorded at monthly intervals. The analyzed data revealed that growth attributes of rice were significantly influenced by treatments. Among the treatments, the higher number of tillers m-2, and leaf area index were in sole crop of paired row rice (T5). Among the yield attributes, rice recorded the highest number of productive tillers m-2, grain yield and straw yield in the sole crop treatment(T5). The analyzed data showed that T5 recorded 8 to 15 per cent yield increase over intercropping treatments. The highest harvest index (0.48) of rice was obtained when intercropped with finger millet (T2). Sole crop of grain cowpea (T6) recorded the highest growth attributes when compared to intercropped treatments. Among the yield and yield attributes, number of pods per plant (15.87), grain yield (4526 kg ha-1), haulm yield (4526 kg ha-1) and harvest index (0.43) were the highest in sole crop of grain cowpea (T6). Analyzed data revealed that the plant height and number of tillers of finger millet, foxtail millet and proso millet were significantly influenced by intercropping treatments. The highest mean plant height and number of tillers m-2 were recorded in their sole crops. The sole crop yield of finger millet, foxtail millet and proso millet were higher than their intercropping treatments. Grasses were the predominant weed flora in the field. Total weed count and weed dry weight were significantly influenced by treatments. At 15 DAS, weed smothering efficiency (WSE) was highest in T4 (44.94%), while at 30 DAS and at 45 DAS, the highest efficiency of 43.79 and 40.57 per cent, were recorded in T1. The results on nutrient removal by weeds showed that significantly lower N, P and K were removed by weeds in T1 (Paired row of rice + grain cowpea). Total NPK uptake of crops were also influenced by the treatments. Higher nutrient uptake of all crops was seen in their sole cropping treatments. In rice, P uptake was significantly influenced by the treatments. The results on soil data revealed that the dehydrogenase activity (150.89 μg TPF g-1 soil d-1) was the highest in T1.The available N and P was higher in T6 and available K was higher in T9. The LER value was greater than unity in all intercropping treatments. Among the intercropping treatments, the highest RCC was observed in T1. Product of RCC was greater than one in all treatments. Aggressivity values were found positive in rice and negative in intercrops. Results indicated that rice equivalent yield from all intercropping system was significantly higher than sole crop of rice except in intercropping with proso millet. Highest monetary advantage was obtained from T1. Higher BCR and net income was observed in T1 (Rice + grain cowpea). Results revealed that net income of T1 was 39.27% higher than T5. The study on the performance of various intercrops in paired row planted rice in lowland summer fallows revealed that paired row planted rice intercropped with grain cowpea can be adjudged as the best treatment in case of weed control, biological efficiency and had higher net income and BCR.Item Efficacy of foliar sprays in alleviating heat stress in rice (Oryza sativa L.) during different growth periods(Department of Agricultural Meteorology, College of Agriculture , Vellanikkara, 2025-01-28) Devanshi Maharana; Ajithkumar, B.