1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item 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 Development of high yielding backcross inbred lines stacked with drought yield QTLs in rice (Oryza sativa L.)(Department of Genetics and Plant Breeding, College of Agriculture, Vellayani, 2025-01-13) Pooja Pavithran; Adheena Ram, AThe present study entitled “Development of high yielding backcross inbred lines stacked with drought yield QTLs in rice (Oryza sativa L.)” was carried out at the Department of Genetics and Plant Breeding, College of Agriculture, Vellayani during 2022-2024 with an objective to identify high yielding drought tolerant rice lines from BC₂F₃ lines of Manu Ratna stacked with drought yield QTLs. The BC₂F₃ population used in the study were derived from the cross between Manu Ratna and Improved White Ponni stacked with drought yield QTLs qDTY ₁.₁ and qDTY₁₂.₁ developed as a part of PhD project of this department. The field evaluation was conducted at Integrated Farming System Research Station, Karamana where BC₂F₃ lines were screened under water stress conditions. In the laboratory experiments, the selected BC₂F₃ lines were analysed for biochemical and physiological characteristics and the BC2F4 lines were further screened for drought stress tolerance using PEG 6000. One thousand fifty BC₂F₃ plants from 10 different families, along with parents Manu Ratna and Improved White Ponni, were raised in family block design with three replications for each family. Water was withheld for fourteen days to induce drought stress during panicle initiation stage. Biometric observations were recorded from 210 BC₂F₃ plants, selected based on early flowering, plant height, higher number of productive tillers and leaf rolling score. Analysis of variance showed significant differences between the families. Based on plant height, earliness of flowering, number of productive tillers and leaf rolling score, 20 plants were selected. Among these, MIB29-2-3-1, MIB-29-2-3-21, MIB-29-8-4-4, MIB-29-8-5-10, MIB-29-8-5-30, MIB-29-85-35 and MIB-84-3-3-4 showed superior performance for yield traits viz. number of productive tillers per plant, panicle length, number of spikelets per panicle, number of filled grains per panicle, grain yield per plant, 1000 grain weight, grain length and grain width. The selected 20 plants of BC₂F₃ generation were analysed for biochemical and physiological parameters viz relative water content, cell membrane stability index, total chlorophyll content, proline content and peroxidase activity. Analysis of variance showed significant differences among the selected lines for these biochemical and physiological parameters. Among the lines, MIB-29-8-5-35, MIB-29-2-3-1, MIB-84-3-3-4, MIB-119-5-7-33 and MIB-29-8-5-10 showed superior performance for all biochemical and physiological characters. Seeds from the selected superior 20 BC₂F₃ plants were further screened for drought stress tolerance at different PEG 6000 concentrations. The experiment was conducted using factorial completely randomized design with two factors and three replications. The main factor was 20 lines while the second factor was PEG concentrations with three levels (0, 10 and 15%). The observations on root length, shoot length and number of seeds germinated were observed. The computed parameters recorded include germination percentage, mean germination time, germination index, root shoot ratio, germination stress tolerance index, fresh weight stress tolerance index, dry weight stress tolerance index and seedling vigour index. The analysis of variance also showed a significant difference among the 20 lines for all the traits except mean germination time and root shoot ratio. Based on the mean performance of the lines under drought stress induced by PEG, MIB-29-2-3-1, MIB-29-8-5-35, MIB-43-5-3-66 and MIB-119-5-7-33 were found to have seedling stage drought stress tolerance. High PCV and GCV were observed for the characters such as root length, shoot length, root shot ratio, germination stress tolerance index, dry weight stress tolerance index and seedling vigour index. Mean germination time showed a high PCV and a moderate GCV. The characters such as number of seeds germinated, germination per cent and germination index showed a moderate PCV and GCV. The characters viz. root length, shoot length, germination stress tolerance index, fresh weight stress tolerance index, dry weight stress tolerance index and seedling vigour index showed a high heritability along with high genetic advance, which indicated that selection based on these traits would be effective. Correlation analysis identified a significant positive genotypic and phenotypic correlation between root length, shoot length and fresh weight stress tolerance index with seedling vigour index. Path analysis showed that shoot length had a positive high direct effect on seedling vigour index and a high indirect effect on seedling vigour index through root length.Among the selected lines, MIB-29-2-3-1 and MIB-29-8-5-35 had higher yield, superior performance for biochemical and physiological character under field study and better seedling stage growth traits under PEG induced drought stress. Hence, these lines can be advanced to further generations through pedigree method of breeding for developing high yielding drought tolerant varieties. These lines can also be further advanced through backcross to develop bold red kernel rice varieties.Item Optimization of biopolymers for seed biopriming in rice (Oryza sativa L.)(Department of Agricultural Microbiology, College of Agriculture, Vellanikkara, 2025-01-24) Deepna, E P.; Panchami, P SSeed biopriming is a novel, cost-effective method that applies beneficial microbial inoculants directly to the seed surface, enhancing seed growth and overall agricultural production. The technique of incorporating biopolymers as a thin, protective film around the seed without altering its size or shape has emerged as a recent trend.These biopolymers help to maintain microbial stability and activity, providing a favorable environment for the inoculants. The present study entitled “Optimization of biopolymers for seed biopriming in rice (Oryza sativa L.)” aimed to develop rice seeds coated with biopolymers and beneficial microbes to enhance growth and yield in rice, as well as to improve seed quality and longevity of bioprimed seeds. The study focused on standardization of the concentrations and imbibition times of biopolymers and bioagents for effective biopriming and evaluation of their effect on plant growth. The study evaluated five biopolymers viz., chitosan, sodium alginate, lignosulfonate, guar gum, and maltodextrin combined with Bacillus subtilis and Azospirillum zeae for seed biopriming in rice. Bioagents compatibility studies confirmed that B. subtilis and A. zeae were compatible, with no inhibition in their growth. Biopolymer and seed compatibility was assessed by imbibing rice seeds in 0.5%, 1%, and 2% biopolymer solutions for 1 h and 24 h, with 1 h imbibition yielding better results than 24 h. Among the different biopolymers used, 0.5% sodium alginate was the most effective, with highest germination rate (83.3%), seedling length (5.98 cm), and seedling vigor index (498) in rice. The incubation of bioagents in biopolymer solutions showed no inhibition in their growth, confirming the compatibility between all the biopolymers and bioagents tested. Based on the compatibility studies, the biopolymer concentrations standardized for seed biopriming in rice were 1% chitosan, 0.5% sodium alginate, 1% lignosulfonate, 0.5% guar gum, and 0.5% maltodextrin, along with a 1 h imbibition time. The coating efficiency of biopolymer with bioagent consortia (Bacillus subtilis + Azospirillum zeae) showed that rice seeds coated with 0.5% sodium alginate maintained the highest population of Bacillus subtilis (42.8 × 10⁸ cfu/g), followed by seeds coated with lignosulfonate (38.12 × 10⁸ cfu/g) after 1h of coating. Similarly, the population of Azospirillum zeae was higher in seeds coated with bioagent consortia and lignosulfonate (27.76 × 10⁸ cfu/g), followed by sodium alginate-coated seeds (26.03 × 10⁸ cfu/g) after 1h. Scanning electron microscopy confirmed the presence of bioagents on the seed surface, while stereozoom microscopy showed no significant changes in seed size or shape. The effect of seed biopriming on plant growth revealed that rice seeds primed with bioagent consortia and 0.5 % sodium alginate achieved the highest germination rate (100%), while those with lignosulfonate showed the longest seedling length (25.78 cm) and highest seedling vigor index (2487). Additionally, a slight increase in seed weight and volume were observed after biopriming. The bioprimed seeds were stored at room temperature for 6 months, with weekly observations recorded for bioagent survival and germination percentage. After three months, a significant decline in both germination percentage and bioagent survivability were observed. However, seeds coated with bioagent consortia and 1% lignosulfonate maintained bioagent populations up to six months. Seeds coated with bioagent consortia and lignosulfonate also maintained a higher germination percentage (82.66%) even after five months of storage. In contrast, chitosan treated seeds did not showed germination after two months of storage, and bioagent population was declined after three months.The two biopolymer-based bioagent consortia formulations, bioagent consortia + 0.5% sodium alginate and bioagent consortia + 1% lignosulfonate were tested to assess their potential for enhancing the plant growth and yield in rice. The experiment was first conducted in sterile soil and then in non-sterile soil to evaluate the effectiveness of biopriming. Under sterile and non-sterile conditions, plant growth parameters such as plant height and the number of tillers per plant were on par for seeds bioprimed with sodium alginate and lignosulfonate. However, the number of grains per panicle and grain yield per plant were higher in seeds treated with bioagent consortia and lignosulfonate in both sterile and non-sterile conditions. Additionally, the seed treatment with bioagent consortia and biopolymers led to an increase in soil nutrient content, further highlighting the beneficial effects of biopriming. The present study highlights the efficacy of biopolymer-based priming in enhancing plant growth in rice, with 0.5% sodium alginate and 1% lignosulfonate, combined with bioagent consortia, showing promising results. Notably, seeds primed with 1% lignosulfonate exhibited the highest performance, significantly improving plant growth and seed viability, while also offering a cost-effective solution. Furthermore, bioprimed seeds retained viability up to six months. However, field trials are essential tovalidate these findings.Item Crop lodging management in rice (Oryza sativa L.)(Department of Agronomy, College of Agriculture, Vellanikkara, 2022-09-13) Oormila, T P; Anitha, SThe research programme entitled “Crop lodging management in rice (Oryza sativa L.)” was conducted with the objective of standardizing the agronomic practices for crop lodging management in upland rice. The experiment was carried out in the Agronomy farm of the College of Agriculture, Vellanikkara during the period from June 2020 to September 2020. The upland variety used was Vaishak. The experiment was laid out in Randomized Block Design (factorial) and replicated thrice. The treatment consisted of two levels of growth regulator application viz., 50 ppm paclobutrazol and control, three levels of planting method viz., dibbling at 15 × 10 cm, dibbling at 20 × 15 cm and broadcasting and three levels of nutrient application viz., soil-test based N: P2O5: K2O, 75% N, 100% P2O5, 125% K2O, 20 kg/ha Si and 50% N, 100% P2O5, 150% K2O, 20 kg/ha Si. Biometric parameters like plant height, culm length and leaf area of rice were significantly reduced by the foliar spray of 50 ppm paclobutrazol. But the effect was significant only up to 60 DAS indicating the low persistence of the chemical in the plant. Dibbling resulted in the overall improvement of biometric parameters compared to broadcasting. The plant height and number of tillers per hill were high from dibbling at 20×15 cm spacing at 30 and 90 DAS. The number of tillers per hill was on par with dibbling at 15 × 10 cm spacing. Even with a lower plant population than broadcasting, the dry matter production from dibbling at 20×15 cm spacing was on par with broadcasting. The plants which got soil-test-based N: P2O5: K2O had taller plants at 60 and 90 DAS as well as high dry matter production at harvest due to the effect of high N. The number of tillers per hill was also higher from this treatment and on par with 75% N, 100% P2O5 125% K2O, 20 kg/ha Si level. The plants which received 75% N, 100% P2O5 125% K2O, and 20 kg/ha Si recorded the thickest culms at 60 DAS and the plants which received 50% N, 100% P2O5, 150% K2O and 20 kg/ha Si application recorded the thickest culms at 60 and 90 DAS. The Si control had lower culm thickness at all the stages. Application of soil-test-based N: P2O5: K2O resulted in the highest culm length at 90 DAS. At 60 DAS, the lodging index was significantly influenced by the planting method and at 90 DAS by nutrient management. The lodging index from dibbling at 15 × 10 cm was high and on par with broadcasting at 60 DAS. The lodging index was low from dibbling at 20×15 cm spacing at all the stages. The application of soil-test-based N: P2O5: K2O resulted in the highest lodging index. The highest number of panicles per square meter was obtained from 50 ppm paclobutrazol foliar spray, dibbling at 15 × 10 cm spacing and the application of 75% N, 100% P2O5, 125% K2O and 20 kg/ha Si. The number of grains per panicle was high from dibbling at 20×15 cm spacing. The other yield attributing parameters did not register any significant variation among treatments. The grain yield was not influenced by paclobutrazol application. However, the straw yield was significantly reduced and hence harvest index was increased from the treatment. Dibbling at 20×15 cm spacing resulted in the highest grain yield and the highest harvest index due to reduced lodging. Straw yield was highest from dibbling at 15 × 10 cm due to the high plant population compared to dibbling at 20×15 cm spacing. Application of 75% N, 100% P2O5 125% K2O and 20 kg/ha Si recorded the highest grain yield and harvest index. The straw yield was highest from soil-test based recommendation N: P2O5: K2O. When N dose was reduced to half, even though lodging was less, grain yield was significantly affected. Hence a nutrient level of 75% N, 100% P2O5 125% K2O of soil-test-based recommendation and 20 kg/ha Si can be considered optimum both in terms of lodging and grain yield. The application of different N: P2O5: K2O: Si levels had a significant influence on the uptake of N and Si at harvest. The highest and superior nitrogen uptake was recorded in the plants that got 100 % N: P2O5: K2O of soil-test based recommendation. The Si uptake from the nutrient level 75% N, 100% P2O5, 125% K2O, 20 kg/ha Si was higher and on par with that from 50% N, 100% P2O5, 150% K2O and 20 kg/ha Si level and was 56 % higher compared to Si control. The gross return from rice cultivation recorded no significant variation among paclobutrazol treated and control plants because the treatment had no significant impact on grain yield. Hence, the net return and B:C ratio were significantly higher in the control. Dibbling at 20cm × 15cm spacing and application of 75% N, 100% P2O5, 125% K2O and 20 kg/ha Si resulted in the highest gross return, net return and B:C ratio. Planting of rice at 20cm × 15cm spacing and application of 75% N, 100% P2O5, 125% K2O of soil test-based recommendation and 20 kg/ha Si resulted in reduced lodging, increased yield and net return of upland rice variety VaishakItem Development of breeding lines in rice(Oryza sativa L.) Pyramided with R genese for resistance to brown plant hopper (BPH) by marker assisted selection.(Department of plant breeding and genetics, college of agriculture, Vellayani, 2023-07-21) Arun Chacko; Jayalekshmy, V GThe present study ‘Development of breeding lines in rice (Oryza sativa L.) pyramided with R genes for resistance to Brown Plant Hopper (BPH) by markerassisted selection’ was conducted in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani and Regional Agricultural Research Station, Pattambi, during the year 2019-2022, with an objective to introgress R genes for resistance to BPH in the background of the elite variety Jyothi using marker-assisted selection. The study comprised of two main experiments. Experiment-I aimed at the BPH bioassay, assessment of morphological and biochemical characters linked to BPH resistance in the donor and recipient parents followed by the validation of the presence of genes for resistance using specific molecular markers. Recipient parent (Jyothi) and probable donors for BPH resistance from the results of a concluded project in the Department of Plant Breeding and Genetics, COA, Vellayani, and other R gene introgressed lines from IRRI were selected for screening. The BPH bioassay was done using the modified seedbox screening test (MSST) developed by Velusamy (1986). BPH-affected seedling survival rate was calculated based on the Standard Evaluation System (SES) scale of 0-9 (IRRI, 2013). Among the twelve rice genotypes screened, PTB-33, PTB-21, and IR7103-121-15-B were classified as highly resistant and the genotypes IR65482-7-216-1-2 and RP2068-18-3-5 were classified as resistant to BPH infestation. The japonica variety Kinandang Patong was moderately resistant to BPH. The recipient parent Jyothi and five other genotypes viz., Manu Ratna, White Ponni, Wayrarem, Vandana, and APO were classified as highly susceptible to BPH infestation. Five genotypes, Jyothi (recipient parent), PTB-33, IR7103-121-15-B, IR65482-7-216-1-2, and RP2068-18-3-5 were forwarded for studying the BPH resistance reaction. The antibiosis and tolerance mechanisms of BPH resistance were explored in terms of nymphal survival rate, honey-dew test, functional plant loss index (FPLI), and tolerance index (TI). The recipient parent, ‘Jyothi’ turned out to be highly susceptible, and ‘PTB-33’ showed high resistance to BPH feeding among the rice genotypes screened. Other genotypes, IR65482-7-216-1-2 RP206818-3-5, and IR7103-121-15-B showed intermediate values compared to PTB-33 and the highly susceptible variety ‘Jyothi’. The morphological characters and biochemical parameters linked with BPH resistance of five genotypes were assessed in a completely randomized design (CRD) with four replications. The results revealed that BPH feeding, survival, functional plant loss index, and disease score were positively correlated with protein content and negatively correlated with phenol and ascorbic acid content. Reducing sugar content in plants did not show much effect on BPH resistance. The genetic parameters, phenotypic and genotypic coefficient of variation were higher in seven characters, and moderate in six characters indicating high variability among the parents. High heritability and genetic advance in the characters except for the number of productive tillers, and culm thickness and grain length respectively indicated the presence of additive gene action. The characters, culm thickness, 1000 grain weight, and protein content showed a significant positive correlation with the functional plant loss index (FPLI). Path analysis of morphological and biochemical characters with FPLI as the dependent variable showed the direct positive effect of the number of productive tillers, panicle length, number of grains per panicle, grain breadth, LB ratio, and phenol content on FPLI. The validation of the presence or absence of genes for BPH resistance in donor and recipient parents was done using SSR markers RM589 for the Bph-3 gene, RM3331 for Bph-18, RM8213 for Bph-20, and RM28561 for Bph-21. Distinguishable polymorphic bands were obtained in SSR markers RM589 (200 bp for resistance and 180 bp for susceptibility) and RM3331 (110 bp for resistance and 130 bp for susceptibility). Based on BPH screening, resistant reaction study, and gene validation, the KAU released variety ‘PTB-33’ and IRRI introgression line IR65482-7-216-1-2 were selected as the donors for Bph-3 and Bph-18 gene respectively in the marker-assisted breeding program. The second experiment was marker-assisted backcrossing to introgress the R genes (Bph-3 and Bph-18) into the background of elite high-yielding but susceptible variety Jyothi. The donors PTB-33 and IR65482-7-216-1-2 were crossed independently with Jyothi to obtain the F1 generation followed by backcrossing with Jyothi to develop the BC1F1 generation. Phenotyping for ten morphological characters and genotyping using gene-specific SSR markers were carried out in all the backcross generations. Genotyping of 63 BC1F1 lines derived from the PTB-33 donor parent with RM589 marker identified 28 plants with the Bph-3 gene in heterozygous condition. Genotyping of 78 BC1F1 lines derived from the IR65482-7-216-1-2 donor parent with RM3331 marker identified 36 plants with Bph-18 gene in heterozygous condition. The goodness of fit test (χ2 test) in BC1F1 lines with genotypic data showed that the genes Bph-3 and Bph-18 followed the ratio of simple dominance. Intercrossing of BC1F1 lines involved two crosses viz., the PTB-33 derived BC1F1 lines with Bph-3 in heterozygous condition as the female parent and IR65482-7-216-1-2 derived BC1F1 lines with Bph-18 in heterozygous condition as male parent denoted as ‘ICAB’ and the reciprocal cross denoted as ‘ICBA’. Among the twenty-two ICAB progenies, three plants showed both genes (Bph-3 and Bph18) in heterozygous condition, and among the eighteen ICBA progenies, five plants were obtained with both genes (Bph-3 and Bph-18) in heterozygous condition. The Euclidean Distance of intercrossed BC1F1 lines from the recipient parent Jyothi using proximity dissimilarity matrix analysis was calculated to select the intercrossed BC1F1 lines more similar to the recipient parent. Eight intercrossed BC1F1 lines with Jyothi-specific characters and both genes in heterozygous condition were backcrossed with Jyothi to develop BC2F1 lines. In the genotypic evaluation of twenty-six BC2F1 lines, five lines showed the presence of both genes (Bph-3 and Bph-18) in heterozygous condition. The five BC2F1 lines with maximum similarity in proximity dissimilarity matrix analysis were selfed and three-hundred and twenty BC2F2 lines were forwarded to BPH bioassay in the seedling stage at RARS, Pattambi, and COA, Vellayani. Eighty-nine BC2F2 lines showed different levels of resistance in the BPH bioassay. Genotyping of these lines showed the presence of both genes (Bph-3 and Bph-18) in homozygous resistant condition in four lines namely, ICAB-1/3/6, ICAB-1/3/7, ICAB-1/6/2, and ICAB-1/6/10. The similarity percentage of these four lines with the recipient parent in proximity dissimilarity matrix analysis was obtained as 84.51 per cent in ICAB-1/3/6, 89.27 per cent in ICAB-1/6/10, 91.15 per cent in ICAB-1/6/2, and 91.6 per cent in ICAB-1/3/7. The developed breeding lines, possessing pyramided R genes for BPH resistance in the background of Jyothi, can be used to develop essentially derived varieties from Jyothi with BPH resistance. This will offer an improved and sustainable solution for combating BPH infestations, reducing reliance on chemical insecticides, and enhancing the stability of rice production.Item Bio recycling for nutrient management and yield enhancement of rice (Oryza sativa L.)(Department of Agronomy, College of Agriculture, Vellayani, 2023-02-17) Anjali, S; Sudha, BThe research work entitled “Bio recycling for nutrient management and yield enhancement of rice (Oryza sativa L.)” was conducted at College of Agriculture, Vellayani during 2020-2022 with the objective to identify a suitable crop nutrition package integrating bio resources and inorganic fertilizers for yield enhancement in rice. The study was carried out as two experiments at the Integrated Farming System Research Station (IFSRS), Karamana. The first experiment included production of composts using different organic substrates viz., rice chaff, water hyacinth, salvinia and wild taro found associated with rice-based cropping systems. The experiment was carried out from September to December, 2021. The statistical design followed was Completely Randomized Design (CRD) with eight treatments and three replications. From treatments T1 to T4, different substrates (rice chaff, water hyacinth, salvinia and wild taro) were co-composted using cow dung and poultry manure in the ratio 4:1:1 (v/v). The substrates were co-composted using cow dung and goat manure in T5 to T8. The time taken for compost maturation, percentage recovery of composts and quality parameters of different composts were found to vary significantly with different co-composting methods. Co-composting of wild taro with cow dung and goat manure (T8) recorded significant earliness in maturity of compost (64 days) and was comparable to T6 (water hyacinth + cow dung + goat manure). Rice chaff co-composted with cow dung and poultry manure (T1) recorded highest recovery of compost (29.85%). Treatment T8 recorded a narrow C:N ratio (12.33) and was comparable to T6 (12.58). The different composts varied in their nutrient contents also. Compost generated from T6 recorded higher N (2.28 %), P (1.08 %) and K (2.7 %) contents. T2 (co-composting water hyacinth with cow dung and poultry manure) recorded significantly higher micro nutrient contents and was comparable to T6. Co-composting of salvinia with cow dung and goat manure (T8) recorded the highest boron content. The content of silicon was significantly higher in T5 (rice chaff + cow dung + goat manure) and was comparable to T6. Content of plant nutrients was the lowest in T5. Different composts generated from Experiment I were used for crop nutrition of rice var. Uma. The field experiment was conducted from last week of January to first week of June, 2022 and was laid out in Randomized Block Design with 9 treatments and three replications. Following the recommended dose of nutrients (90:45:45 kg ha-1 ) for rice and based on soil test data, the NPK dose decided for the experimental field was 70.2: 16.6: 42.3 kg ha-1 . For treatment T1 (control), the KAU Package of Practices Recommendation for crop nutrition was followed on soil test data basis. From treatments T2 to T9, respective composts generated under Experiment I were provided as basal dose @ 2.5 t ha-1 . This was followed by 75 per cent of the recommended nutrients as chemical fertilizers and 25 per cent through respective composts, on N equivalent basis. Full phosphorus was given as basal; whereas N and K were provided in equal splits as basal and at PI stage. The results revealed that treatments had significant influence on the growth, yield and physiological parameters of rice. Basal application of compost 6 @ 2.5 t ha-1 followed by 25 per cent of the recommended nutrients through compost and the rest through chemical fertilizers (T7) recorded taller plants at PI and harvest, tiller count at all the growth stages and dry matter production at harvest. Physiological parameters like leaf area index and SPAD Chlorophyll Meter Reading were also the highest with T7. Application of different composts significantly influenced the weed dry weight at 20 and 40 DAT and significantly lower weed dry weights were recorded with T6. Grain yield (2933 kg ha-1 ) as well as yield attributes were significantly higher with T7. Soil nutrient status after crop harvest was significantly influenced by different treatments. The P and K status of soil was significantly higher in T7 (35 and 167 kg ha-1 ) and was comparable to T1. Different treatments could not significantly influence the soil pH, EC, soil organic carbon and available nitrogen after the experiment. Nutrient uptake by crop was significantly higher in T7 and remained comparable with T8 and T1. Regarding economics, T7 recorded the highest net income (₹ 67, 476 ha-1 ) and B:C ratio (1.59). This was followed by T1 with net returns ₹ 55, 837 ha-1 and B:C ratio 1.58. The present study revealed that bio resources like aquatic weeds and rice chaff associated with rice-based system could be value added through co-composting using locally available organic manures to generate quality composts. Application of water hyacinth compost (water hyacinth + cow dung + goat manure in 4:1:1 ratio v/v) @ 2.5 t ha-1 as basal dose followed by 75 per cent of RDN as inorganic and 25 per cent as water hyacinth compost on N equivalent basis could be recommended as a prospective bio recycling option for higher yield and economics of rice during the summer season.Item Agronomic effectiveness of rice husk and coconut shell biochar -based fertilizers in aerobic rice (Oryza Sativa L.)(Department of Agronomy, College of Agriculture ,Vellayani, 2024-02-19) Parvathy Sasikumar; Nishan, M AThe present study entitled “Agronomic effectiveness of rice husk and coconut shell biochar-based fertilizers in aerobic rice (Oryza sativa L.)” was undertaken at the Department of Agronomy, College of Agriculture, Vellayani during 2021-2023. The objectives of the study were to assess the nutrient release pattern of rice husk and coconut shell biochar-based fertilizers and to evaluate its effects on growth, yield and nutrient use efficiency of aerobic rice. The study was undertaken in three parts. The first part of the study was conducted at the Department of Agronomy, College of Agriculture, Vellayani during October 2022 to March 2023. Rice husk biochar based fertilizer (BCF 1) was prepared by mixing rice husk biochar (40 per cent), vermicompost (17 per cent), urea (17 per cent), NPK (12-32-16) mix (16 per cent), MOP (3 per cent), ayar (1 per cent), bentonite clay (2 per cent) and humic acid (4 per cent) and coconut shell biochar-based fertilizer (BCF 2) was prepared by mixing coconut shell biochar (40 per cent), vermicompost (18 per cent), urea (16 per cent), NPK (12 32-16) mix (16 per cent), MOP (3 per cent), ayar (1 per cent), bentonite clay (2 per cent) and humic acid (4 per cent) on percentage weight basis followed by pelletization. The initial N, P, and K content of BCF varied from 8.63 per cent to 8.82 per cent, 4.49 per cent to 4.51 per cent and 4.60 per cent to 4.72 per cent, respectively. The storage studies revealed that the N, P and K content of BCF was reduced by 6.83 per cent to 8.04 per cent, 0.89 per cent to 1.33 per cent and 0.65 per cent to 1.05 per cent, respectively at six months after storage. Pelleted BCF retained its shape and no fungal growth was observed during six months of storage. In second part, incubation studies were conducted at the Department of Agronomy, College of Agriculture, Vellayani during October 2022 to January 2023 to study the nutrient release pattern of BCF. The experiment was laid out in completely randomized design with four treatments and four replications. The treatments were T1: 100 per cent recommended dose of nutrients (RDN) as BCF 1, T2: 100 per cent RDN as BCF 2, T3: 100 per cent RDN as KAU POP, T4: Control (No application). BCF 1 and BCF 2 were applied on N equivalent basis for supplying recommended dose of 70:35:35 kg NPK ha-1 for aerobic rice. The results of the study showed that conventional fertilizer treatment (T3) exhibited significantly higher nutrient release, with 96.99 per cent of applied nitrogen, 98 per cent of phosphorus, and 92.65 per cent of potassium released at 20 days after incubation, in contrast to the biochar-based fertilizer treatments (T1 and T2) which showed slower release rates, ranging from 58.27-58.39 per cent for nitrogen, 67.92-69.81 per cent for phosphorus, and 44.99-45.19 per cent for potassium. At 40 DAI, 60 DAI, 80 DAI and 100 DAI, the NPK release rate was higher in biochar-based fertilizers compared to conventional fertilizers. The crop response study (part III) was conducted at farmer’s field located at Kakkamoola, Thiruvananthapuram during January 2023 to May 2023 to evaluate the effect of BCF on growth, yield and nutrient use efficiency of aerobic rice. The experiment was laid out in randomized block design with eight treatments and three replications with the rice variety Prathyasa. The treatments were T1: 100 per cent RDN as BCF 1 (basal); T2: 100 per cent RDN as BCF 2 (basal); T3: 75 per cent RDN as BCF 1 (basal); T4: 75 per cent RDN as BCF 2 (basal); T5: 50 per cent RDN as BCF 1 (basal); T6: 50 per cent RDN as BCF 2 (basal); T7: 100 per cent RDN as KAU POP; T8: control (no fertilizers). BCFs were applied on N equivalent basis for supplying recommended dose of 70:35:35 kg NPK ha-1 for aerobic rice. Basal dose of FYM @ 5 t ha-1 was applied to all plots except T8. Lime was applied to T7 @ 600 kg ha-1. Basal application of 100 per cent RDN as BCF 1 (T1) resulted in taller plants at active tillering (62.01 cm) and panicle initiation stages (89.70 cm) and were comparable with T2. The treatment, T1 also recorded significantly taller plants at flowering (108.72 cm) and harvest stages (109.34 cm). The highest number of tillers per square metre, leaf area and leaf area index were observed in T1 at active tillering (753.33, 691.63 cm2, 4.61 respectively), panicle initiation (763.33, 1014.50 cm2, 6.76 respectively) and flowering stages (710.66, 1179.27 cm2, 7.86 respectively) followed by T2. The treatment, T1 also resulted in higher flag leaf area per hill (143.62 cm2) and dry matter production (10311 kg ha-1) and was comparable with T2. All the growth attributes recorded in T3, T4 and T7 were statistically comparable. The number of productive tillers per square metre was higher in T1 (545.33) and was comparable with T2. The treatment, T1 produced longer panicle (24.38 cm), more number of grains per panicle (161.27), higher panicle weight (3.48 g), grain yield (5859 kg ha-1), straw yield (7083 kg ha-1) and harvest index (0.453) and was statistically similar to T2, T3, T4 and T7. Basal application of 100 per cent RDN as BCF 1 (T1) resulted in higher total chlorophyll content at active tillering (1.89 mg g-1 of fresh weight) and flowering stages (2.11 mg g-1 of fresh weight) and was comparable with T2. The treatment, T1 showed higher nitrogen uptake (153.59 kg ha-1) and was comparable with T2 and T3. The phosphorus uptake was higher in T1 (26.92 kg ha-1) and was comparable with T2. The treatment, T2 exhibited higher potassium uptake (130.23 kg ha-1) and was on par with T1. Basal application of 75 per cent RDN as BCF 1 (T3) showed higher agronomic efficiency and partial factor productivity for N (58.41 kg kg-1, 105.68 kg kg-1 respectively), P (116.81 kg kg-1, 211.37 kg kg-1 respectively) and K (116.81 kg kg-1, 211.37 kg kg-1 respectively) and was comparable with T4. The treatment, T7 showed higher physiological efficiency for N (40.45 kg kg-1) and was comparable with T1, T2, T3 and T4. The physiological efficiency of P (231.07 kg kg-1) and K (49.35 kg kg-1) were higher in T3 and were on par with T1, T2, T4 and T7. The treatment, T3 exhibited higher apparent recovery efficiency for N (1.55 kg kg-1) and was comparable with T1, T2 and T4. The apparent recovery efficiency for P (0.50 kg kg-1) and K (2.36 kg kg-1) was higher in T3 and was comparable with T4. The soil available N was higher in T1 (338.69 kg ha-1) and was on par with T2, T3 and T4. The soil available P was higher in T1 (72.91 kg ha-1) and was on par with T2. The soil available K was higher in T2 (291.24 kg ha-1) and was comparable with T1, T3 and T4. The treatment, T2 exhibited higher dehydrogenase activity at 30 DAS (25.97 g TPF g-1 soil d-1), 50 DAS (23.16 g TPF g-1 soil d-1) and 80 DAS (18.55 g TPF g-1 soil d-1) and was comparable with T1. The highest actual gain of N (75.27 kg ha-1) and P (31.30 kg ha-1) was observed in T1 and the highest actual balance of K was observed in T2 (30.10 kg ha-1). Basal application of 100 per cent RDN as BCF 1 (T1) resulted in higher gross income (₹ 192394 ha-1), net income (₹ 51669 ha-1) and BC ratio (1.37) and was statistically comparable with T2, T3 and T4. Thus from the study, it could be concluded that conventional fertilizers demonstrated higher nutrient release, releasing 96.99 per cent of applied nitrogen, 98 per cent of phosphorus, and 92.65 per cent of potassium at 20 days after incubation, while biochar-based fertilizer treatments displayed slower release rates, ranging from 58.27-58.39 per cent for nitrogen, 67.92-69.81 per cent for phosphorus, and 44.99-45.19 per cent for potassium. Basal application of 100 per cent and 75 per cent RDN as BCF resulted in comparable yield and profit. Thus, basal application of FYM @ 5 t ha-1 + either rice husk or coconut shell BCF @ 600 kg ha-1 (equivalent to 75 per cent recommended dose of NPK of aerobic rice (i.e. 52.5: 26.25: 26.25 kg NPK ha-1) could be recommended as the productive, profitable and more efficient nutrient schedule for cultivating aerobic rice.Item Elucidating the role of growth promoting endophytic fungus Piriformospora indica for water stress tolerance in rice (Oryza sativa L.)(Department of Plant Physiology, College of Agriculture ,Vellayani, 2022-03-10) Lekshmi, Mohan S; Beena, RThe research work titled “Elucidating the role of growth promoting endophytic fungus Piriformospora indica for water stress tolerance in rice (Oryza sativa L.)” carried out at Department of Plant Physiology, College of Agriculture, Vellayani during 2020-2021 with the objective to elucidate the changes in morphological, physiological, biochemical and molecular mechanisms associated with water stress tolerance in Piriformospora indica-colonised rice. The roots of Ptb 23, Ptb 24, Ptb 29 and Ptb 30 varieties’ seedlings were appraised microscopically for root colonisation after germinating in trays containing P. indica-infused composted coir pith- cow dung (1:1) mixture maintained in temperature and humidity-controlled conditions. Isolated or chains of double walled pear shaped chlamydospores were observed in the root sections of seedlings in trays with P. indica after seven days of cocultivation. On treatment with Poly Ethylene Glycol (PEG) 6000 at concentrations of 0, 5,10, 15, and 20 per cent, the varieties on root colonisation with P. indica showed higher water stress tolerance while the water stress tolerant varieties Ptb 29 and Ptb 30 showed tolerance to water stress even in the absence of P. indica. Shoot length, shoot and root dry weight, number of root branches, SVI 1 and SVI 2 increased in P. indica-colonised plants than non-colonised plants under water stressed condition, while the root length decreased. Based on the observations on different parameters, Ptb 29 was considered as the best water stress tolerant variety and as Ptb 23 performed better than Ptb 24 under water stress condition, the former was selected as the best water-stress susceptible variety. The P. indica-colonised and non-colonised rice seedlings of Ptb 23 and Ptb 29 were the evaluated for water stress tolerance during the different growth stages by studying the morphological, physiological, biochemical, yield parameters and molecular aspects. P. indica-colonised plants under water stress exhibited higher shoot and root length, shoot and root dry weight, root-shoot ratio and root volume, however, it was more conspicuous in the water stress susceptible variety. The enhanced plant shoot-root growth and biomass production as well as other changes in plant morphology after P. indica-colonisation can be related to the plant response to increase auxin level in roots either produced by the fungus or by the plant due to stimulation by the endophyte. Relative water content was found to be higher in water stressed P. indica-colonised plants in both Ptb 23 and Ptb 29, although the effect of colonisation was more visible in Ptb 23. There was significant increase in the specific leaf area in P. indica-colonised plants of both varieties than non-colonised plants. In the current study, rice plants of Ptb 29 under water stressed condition had higher cell membrane stability index than Ptb 23. Plants in the presence of P. indica showed significantly reduced MDA content which indicates that P. indica lowers the adverse consequences of drought. Ptb 29 had lower MDA content than Ptb 23, which further established that Ptb 29 is more tolerant to water stress. Gas exchange parameters like stomatal conductance, transpiration rate and photosynthetic rate showed increase in P. indica-colonised plants than in non-colonsed plants. Retention of chlorophyll was significantly higher in water stressed plants of Ptb 29 than Ptb 23. The increased activity of antioxidant enzymes such as superoxide dismutase and catalase in P. indica-colonised plants during stressed condition reduced ROS levels in cells and thereby minimizing or preventing damage to cellular components. P. indica-colonised plants showed a reduced invertase activity than non-colonised plants. P. indica-colonisation improved the number of tillers, productive tillers as well the panicle length in plants under water stressed condition. The spikelet sterility was higher in non-colonised and water stressed plants. P. indica-colonisation contributed to a considerable increase in grain weight in Ptb 23. All these factors contributed to the final yield of the plant and unsurprisingly, P. indica-colonised plant sets produced more yield than non-colonised plant sets under water stressed conditions. Even though Ptb 29 produced more yield., P. indica-colonisation was more noticeable and effective in the water stress susceptible variety- Ptb 23. Keeping in view of our results, it can be emphasised that P. indica can mitigate the ill effects of water stress. The findings obtained from this study can be used as a foundation for future lines of research related to rational improvement of rice plants against water stress using endophytes.Item Bridging productivity loss in aerobic rice (Oryza sativa L.) through land configuration and intercropping(Department of Agronomy ,College of Agriculture,Vellayani, 2023-03-10) Shahana Begum.; Shalini Pillai, PItem Elucidating the role of growth promoting endophytic fungus Piriformospora indica for water stress tolerance in rice (Oryza sativa L.)(Department of Plant Physiology, College of Agriculture, Vellayani, 2022-10-03) Lekshmi Mohan S; Beena RThe research work titled “Elucidating the role of growth promoting endophytic fungus Piriformospora indica for water stress tolerance in rice (Oryza sativa L.)” carried out at Department of Plant Physiology, College of Agriculture, Vellayani during 2020-2021 with the objective to elucidate the changes in morphological, physiological, biochemical and molecular mechanisms associated with water stress tolerance in Piriformospora indica-colonised rice. The roots of Ptb 23, Ptb 24, Ptb 29 and Ptb 30 varieties’ seedlings were appraised microscopically for root colonisation after germinating in trays containing P. indica-infused composted coir pith- cow dung (1:1) mixture maintained in temperature and humidity-controlled conditions. Isolated or chains of double walled pear shaped chlamydospores were observed in the root sections of seedlings in trays with P. indica after seven days of cocultivation. On treatment with Poly Ethylene Glycol (PEG) 6000 at concentrations of 0, 5,10, 15, and 20 per cent, the varieties on root colonisation with P. indica showed higher water stress tolerance while the water stress tolerant varieties Ptb 29 and Ptb 30 showed tolerance to water stress even in the absence of P. indica. Shoot length, shoot and root dry weight, number of root branches, SVI 1 and SVI 2 increased in P. indica-colonised plants than non-colonised plants under water stressed condition, while the root length decreased. Based on the observations on different parameters, Ptb 29 was considered as the best water stress tolerant variety and as Ptb 23 performed better than Ptb 24 under water stress condition, the former was selected as the best water-stress susceptible variety. The P. indica-colonised and non-colonised rice seedlings of Ptb 23 and Ptb 29 were the evaluated for water stress tolerance during the different growth stages by studying the morphological, physiological, biochemical, yield parameters and molecular aspects. P. indica-colonised plants under water stress exhibited higher shoot and root length, shoot and root dry weight, root-shoot ratio and root volume, however, it was more conspicuous in the water stress susceptible variety. The enhanced plant shoot-root growth and biomass production as well as other changes in plant morphology after P. indica-colonisation can be related to the plant response to increase auxin level in roots either produced by the fungus or by the plant due to stimulation by the endophyte. Relative water content was found to be higher in water stressed P. indica-colonised plants in both Ptb 23 and Ptb 29, although the effect of colonisation was more visible in Ptb 23. There was significant increase in the specific leaf area in P. indica-colonised plants of both varieties than non-colonised plants. In the current study, rice plants of Ptb 29 under water stressed condition had higher cell membrane stability index than Ptb 23. Plants in the presence of P. indica showed significantly reduced MDA content which indicates that P. indica lowers the adverse consequences of drought. Ptb 29 had lower MDA content than Ptb 23, which further established that Ptb 29 is more tolerant to water stress. Gas exchange parameters like stomatal conductance, transpiration rate and photosynthetic rate showed increase in P. indica-colonised plants than in non-colonsed plants. Retention of chlorophyll was significantly higher in water stressed plants of Ptb 29 than Ptb 23. The increased activity of antioxidant enzymes such as superoxide dismutase and catalase in P. indica-colonised plants during stressed condition reduced ROS levels in cells and thereby minimizing or preventing damage to cellular components. P. indica-colonised plants showed a reduced invertase activity than non-colonised plants. P. indica-colonisation improved the number of tillers, productive tillers as well the panicle length in plants under water stressed condition. The spikelet sterility was higher in non-colonised and water stressed plants. P. indica-colonisation contributed to a considerable increase in grain weight in Ptb 23. All these factors contributed to the final yield of the plant and unsurprisingly, P. indica-colonised plant sets produced more yield than non-colonised plant sets under water stressed conditions. Even though Ptb 29 produced more yield., P. indica-colonisation was more noticeable and effective in the water stress susceptible variety- Ptb 23. Keeping in view of our results, it can be emphasised that P. indica can mitigate the ill effects of water stress. The findings obtained from this study can be used as a foundation for future lines of research related to rational improvement of rice plants against water stress using endophytes.