1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Valuing the Complementarity in Rice-Fish Integrated Farming: The Case of Pokkali Ecosystem(Department of Agricultural Economics, college of agriculture, Vellanikkara, 2025-08-26) SUMITHRA,S; Indiradevi,PIntegrated Farming Systems (IFS) are known for their mutually complementary relations. The coastal saline ecosystem along the Ernakulam, Alappuzha and Thrissur districts of Kerala, referred to as Pokkali lands, follow the traditional practice of integrating paddy and fish/prawn farming. Despite the ecological resilience and economic viability, IFS in Pokkali ecosystem has experienced a significant decline in recent decades, shifting to monoculture practices of aquaculture. In this background, the study was conducted with the main objectives of understanding the dynamics of rice-fish rotational system and assessing the relative economics, estimating the economic value of complementarity between the systems based on empirical analysis, estimating the value based on stakeholder knowledge, and effecting the comparison between the two estimates. The study was conducted in Ernakulam district, which holds the largest share (64%) of Pokkali lands focussing on five prevalent farming systems: Rice–Prawn IFS, Rice–Fish IFS, Prawn monoculture, Fish monoculture, and fallowing. Multistage sampling method, was adopted with district, block panchayat (BP) and grama panchayat (GP) as the respective stages of selection. The BP and GP with highest area under respective farming practice were purposively selected, while the sample respondents were chosen on random basis. The total sample size was 250 farmers (random sample of 50 from each system) and 120 other stakeholders, which include officers of agriculture department as well as fisheries department, farm labourers, and general public, working/residing in the locality. Data was gathered from the respondents through personal interview method employing structured pre-tested interview schedule. Soil samples were also collected from the selected farms following IFS system, before and after the rice crop and were analysed in soil testing laboratory under KAU. Analytical tools employed include partial budgeting to assess the relative economics of various systems, productivity change method for capturing the positive externality due to complementarity in IFS, and contingent valuation method. The Pokkali ecosystem in Kerala, a unique agro-ecological unit, has witnessed significant decline over the past two decades. Though official data is not published, informal reports show Pokkali paddy cultivation area shrinking from about 25,000 hectares in the 1980s to merely 5,707 hectares by 2021, driven by low rice profitability, rising wages, labour scarcity, and large-scale land conversion for non-agricultural use. Remote sensing studies further underscore the impact of urbanization and infrastructure growth in altering land use patterns, along with a significant shift toward monoculture aquaculture, threatening the sustainability of this ecologically sensitive system. The Rice–Aquaculture IFS in Pokkali operates in a seasonal rotation: rice is cultivated from June to October, followed by prawn or fish farming from November to April. Despite receiving policy and legal support for rice component, subsidies and mandatory rice cultivation certificates for aquaculture licensing, the system faces declining trend. Rice cultivation yields 1,326 kg/ha, with negative net returns of ₹40,383/ha, it remains financially unviable without support. Conversely, prawn farming is capital intensive (₹2,01,889/ha) but highly profitable, yielding returns of ₹4,88,373/ha and net profit of ₹2,86,484/ha. Together, the rice–prawn IFS yields a total return of ₹5,57,325/ha with a net return of ₹2,46,101/ha and a favourable benefit-cost ratio (BCR) of 1.79. On the other hand, the rice–fish IFS, offers limited economic benefits with relatively low fish yield and losses from rice cultivation, this system yields only ₹10,028/ha in net returns and a marginal BCR of 1.03. Comparative analysis indicates prawn monoculture which is resource-intensive and environmentally less sustainable, generates lower net returns (₹1,68,338/ha) and a reduced BCR (1.60) compared to integrated systems, primarily due to higher operational expenses especially feed costs. Monoculture practice, particularly fish farming, delivers higher net returns (₹3,97,311/ha) and a BCR of 2.32 outperforming the rice–fish IFS, incentivizing farmers to abandon traditional IFS practices. The higher profitability in monoculture is primarily due to the ability to rear more number of fish species, including long-duration and high-value species. Such practices are not feasible in the rice-fish IFS, where aquaculture is typically restricted to six-months. However, partial budgeting reveals that shifting from monoculture to integrated farming results in net economic gains, particularly in the rice–prawn system, which offers an additional gain of ₹69,837/ha, despite higher cultivation costs. This gain stems from reduced input expenses in aquaculture (artificial feed, eradicants, electricity) and dual income sources. In monoculture systems, only aquatic species typically high-value prawns like Tiger prawns or commercially viable fishes are cultivated by skipping Pokkali rice cultivation. The relatively poor economic gains along with cultivation challenges act as major drivers for shifting from IFS to monoculture practices, which are very fast and visible in certain pockets like Kumbalam, Kumbalanghi, Chellanam panchayats. At the same time, the ecological complementarity in IFS, particularly the effect of improved soil quality, is also significant. Statistical analysis shows that a 1% increase in Soil Quality Index (SQI) leads to a 0.25% rise in rice yield, which is equivalent to 3.23 kg/ha or ₹167.96/ha. When scaled across 5,000 ha, the realized value of this yield benefit is ₹8.40 lakh. Empirical studies (Sreelatha and Joseph, 2019) confirm that IFS improves SQI by 41.6% over monoculture, equating to a benefit of ₹3.49 crore ecosystem-wide. The study underscores that IFS is both economically viable and ecologically beneficial, especially when complemented with improved management and varietal selection. High-yielding Pokkali varieties provide 29.14% higher yields than traditional types. Yet, current subsidy policies fail to incentivize full-cycle crop management, often resulting in low yield realization and misuse of support mechanisms. Additionally, perceived rice yield gains, though lower than realized, still affirm this ecological value, estimated at ₹97.76/ha. The undervaluation of soil quality benefits among stakeholders reveals a critical perception gap, particularly among aquaculture farmers and fisheries officials, who tend to favour short-term economic returns from monoculture over long-term ecological gains. Stakeholder perceptions reveal wide variation. While agricultural officers’ express optimism about IFS yield potential, fisheries officials lean toward aquaculture. Farm labourers report higher perceived yields, reflecting their hands-on experience. Farmers practicing monoculture acknowledge the ecological benefits of IFS but cited labour shortages, profitability concerns, and climatic risks as key barriers. The study recommends scientific mapping of Pokkali areas using remote sensing, developing a database of Pokkali landholders, linking subsidy to yield or performance metrics to ensure proper crop management, applying externality gains in extension methods, strengthen compliance mechanisms to ensure rice cultivation precedes aquaculture licensing, reinforcing the Pokkali Land Development Authority and establishing targeted support programs to address region-specific socio-economic barriers, and considering the scope of introducing a targeted Green Granary Support Scheme for Pokkali farmers that provides financial incentives, technical support, and market linkages to promote eco-friendly farming practices. Further research focus is to be on assessing the role of water quality in influencing prawn/fish yield across IFS and monoculture systems, examining the efficacy of current subsidy schemes, conducting longitudinal studies on soil health, salinity, and system resilience. IFS being an effective system that ensures food security, profitability and sustainability, is considered as a powerful tool for enhancing the economic status of small and marginal farmers. There should be programme to conserve and support the traditional rice-fish IFS models, especially in view of the climate change challenges.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 Nitrogen use efficient varieties for enhanced productivity in rice (Oryza sativa L.)(Department of Agronomy, College of Agriculture, Vellayani, 2025-07-29) Merin Jose; Shalini Pillai, PThe research entitled “Nitrogen use efficient varieties for enhanced productivity in rice (Oryza sativa L.)” was conducted at the Department of Agronomy, College of Agriculture, Vellayani, during 2021 to 2025. The objectives of the study were to screen selected rice varieties for nitrogen use efficiency (NUE) based on germination and root characteristics, to evaluate the field performance of selected nitrogen-efficient rice varieties at graded doses of nitrogen (N), and to work out the economics. The study was conducted in three parts. The first part was a lab study wherein, 14 popular rice varieties released from Kerala Agricultural University (KAU) were screened for NUE based on germination characteristics. The experiment was laid out in completely randomized design (CRD) with 14 varieties and 5 media, replicated thrice. The treatments comprised seven short duration varieties (SDVs) viz., v1- Makom (MO 9), v2- Prathyasa (MO 21), v3- KAU Manuratna, v4- Jyothi (PTB 39), v5- Harsha (PTB 55), v6- Varsha (PTB 56) and v7- Kanchana (PTB 50) and seven medium duration varieties (MDVs) viz., v8- Bhadra (MO 4), v9- Uma (MO 16), v10- Sreyas (MO 22), v11- Pournami (MO 23), v12- KAU Manuvarna, v13- Athira (PTB 51) and v14- Aiswarya (PTB 52), and Modified Arnon Hoagland (AH) media [(m1- AH media with urea (7.5 mM), m2 - AH media with ammonium chloride (15 mM), m3- AH media without N source, m4- AH media and m5 - distilled water]. In general, the presence of urea or any other additional source of N tends to inhibit germination. However, this inhibitory effect was not observed in the case of Harsha (v5) and Varsha (v6), as both varieties took 39 h each to reach 50 per cent germination in distilled water and in AH media with urea. In the case of MDVs, the germination of all the varieties were inhibited. The SDVs, viz., Varsha (v6), Harsha (v5) and Prathyasa (v2) had longer shoots (10.25 cm ± 1.27 cm, 7.95 cm ± 0.52 cm and 6.63 cm ± 0.79 cm respectively) in the presence of urea as compared to distilled water. In the case of MDVs, Aiswarya (v14), Athira (v13), Sreyas (v10) and Uma (v9) produced longer shoots (9.20 cm ± 0.36 cm, 8.20 cm ± 0.39 cm, 8.13cm ± 0.85 cm and 6.53 cm ± 0.75 cm respectively) in the presence of urea as compared to distilled water. In the presence of urea, Varsha (v6) and Harsha (v5) recorded longer roots (9.13 cm ± 1.91 cm and 9.03 cm ± 2.78 cm). With respect to MDVs, Sreyas (v10) recorded longer roots (12 cm ± 0.28 cm) and this was on par (11.73 cm) with that under distilled water. Higher seedling dry weight (23.15 mg ± 2.25 mg) was recorded in Varsha (v6) which was on par with Kanchana (v7), Harsha (v5) and Jyothi (v4). In the presence of urea, Uma (v9) recorded higher seedling dry weight (23 mg ± 1.83 mg) which was on par with Aiswarya (v14), Sreyas (v10) and KAU Manuvarna (v12). Urease enzyme activity was found to be the highest (0.59 ± 0.01) mM NH4+ min-1 g-1 in Varsha (v6) followed by Harsha (v5). A similar trend was observed in urea and NH₄Cl, where Varsha (v6) recorded higher urease enzyme activity than Harsha (v5). In case of MDVs, urease enzyme activity was the highest (0.47 ± 0.01) mM NH4+ min-1 g-1 in Aiswarya (v14) followed by Sreyas (v10). Seedling vigour index I (SVI I) was higher in Varsha (v6) followed by Harsha (v5) and higher seedling vigour index II (SVI II) was recorded by Kanchana (v7), followed by Varsha (v6) and Harsha (v5). In case of MDVs, Aiswarya (v14) recorded higher SVI I (885.15), followed by Sreyas(v10) (717.28). Whereas, Sreyas (v10) recorded higher SVI II (2288.25) which was followed by Aiswarya (v14) (2278.50). The second part of the study comprised screening the 14 rice varieties in field, under two contrasting N levels. It was carried out in the wetlands of the Integrated Farming System Research Station (IFSRS), Karamana, during June to October 2023. The experiment was laid out in randomised block design (RBD) with the 14 varieties at two levels of nitrogen (n0- 0 % RDN and n1- 100 % RDN), replicated thrice. Among the SDVs, Harsha (v5) and Varsha (v6) and among MDVs, Sreyas (v10) and Aiswarya (v14) proved superior in terms of growth attributes including plant height, tillers m-2, rooting depth and root volume. The same trend was observed in yield attributes and yield. The lower percentage in yield reduction observed in Harsha (23.89%), Varsha (22.50%), Sreyas (27.89%) and Aiswarya (20.61%) at zero per cent RDN compared to 100 per cent RDN pointed towards their higher NUE. These varieties also exhibited higher root dry weight efficiency index (RDWEI) which is also an indicator of NUE. The Partial factor productivity of N (PFPN) also exhibited a similar trend. Based on the cumulative ranking of germination traits (part I) and RDWEI, yield and PFPN (part II) the varieties Harsha, Varsha, Sreyas and Aiswarya were chosen as promising candidates for further field evaluation aimed at validating their production potential, NUE and profitability. The third part of the study entitled ‘Field evaluation of nitrogen- efficient rice varieties’ was also conducted at IFSRS, Karamana from November 2023 to February 2024 (second crop 2023-’24 referred to as season I) and July to November 2024 (first crop 2024 ’25 referred to as season II). The field performance of the four nitrogen-efficient rice varieties chosen from part I and part II were assessed at graded levels of recommended dose of nitrogen (RDN). The experiment was laid out in split plot design with four main plots (n1- 100 % RDN, n2 - 75 % RDN, n3 - 50 % RDN and n4- absolute control) and four sub plots [v1- Harsha (PTB 55), v2- Varsha (PTB 56), v3- Sreyas (MO 22) and v4- Aiswarya (PTB 52)], replicated four times. The results revealed that during seasons I and II, while Harsha at 100% RDN (n1v1) recorded the highest grain yield (4567 kg ha-1 ± 64 kg ha-1 and 4703 kg ha-1 ± 35 kg ha-1 respectively), the yield of Varsha at 100% RDN (n1v2) (4507 kg ha-1 ± 81 kg ha-1 and 4720 kg ha-1 ± 89 kg ha-1) and 75 per cent RDN (n2v2) (4440 kg ha-1 ± 82 kg ha-1 and 4603 kg ha-1 ± 68 kg ha-1) were statistically comparable. The MDVs, Sreyas and Aiswarya also behaved in a similar manner with comparable yields at 100 per cent RDN and 75 per cent RDN. Chlorophyll content was significantly the highest at 100 % RDN in Harsha, Varsha and Sreyas throughout the growth stages. Whereas in Aiswarya, the chlorophyll content at 100 per cent RDN was statistically comparable to that at 75 per cent RDN. In terms of NUE indices, all the four varieties exhibited significantly higher PFPN and agronomic efficiency of nitrogen (AEN) at 50 per cent RDN. However, during season II AEN of both Varsha and Aiswarya at 50 per cent RDN and 75 per cent RDN were comparable. Harsha recorded the highest BCR (1.41± 0.02 and 1.45± 0.01) at 100% RDN (n1v1), while, Varsha recorded the same (1.42 ± 0.03 and 1.49 ± 0.02) at 75 per cent RDN (n2v2). Among the MDVs, Sreyas and Aiswarya recorded higher BCR at 75 per cent RDN. Screening of 14 popular rice varieties released from KAU based on germination characters, RDWEI and PFPN showed that the short duration varieties viz., Harsha (PTB 55) and Varsha (PTB 56) and the medium duration varieties viz., Sreyas (MO 22) and Aiswarya (PTB 55) could be considered as nitrogen efficient. Field evaluation of the nitrogen efficient varieties showed that while the productivity and profitability of Varsha could be sustained at 75 per cent RDN, the variety Harsha required 100 per cent RDN. The study also revealed that, the recommended dose of N (90 kg ha-1) for the nitrogen efficient MDVs, could be reduced by 25 per cent without compromising yield and profitability.Item 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 Unnikrishnan