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Item Enhancing grain yield and quality through soil amelioration and foliar nutrition in rice (Oryza sativa L.) in Vaikom kari soils(Department of Agronomy, College of Agriculture, Padannakkad, 2022-04-03) Sreelekshmi, S; Devi, V SA field experiment entitled “Enhancing grain yield and quality through soil amelioration and foliar nutrition in rice (Oryza sativa L.) in Vaikom Kari soils” was conducted in a farmer's field at Vechoor, during puncha season of 2020. The objectives were to augment the yield and quality of rice in Vaikom Kari soils through soil amelioration practices for managing soil acidity, and to supplement nutrition at panicle initiation stage through foliar application of K and micronutrients. The field experiment was laid out in Randomized Block Design. The effect of soil amelioration on soil parameters and growth characters was assessed in simple RBD with three treatments and fifteen replications. The treatments were: no dolomite (T1), application of ordinary dolomite basally and at 30 DAS (T2) and application of granulated dolomite basally and at 30 DAS (T3). The effect of soil amelioration and foliar nutrition on yield and yield attributes, and plant nutrient content and uptake were analysed in factorial RBD with two factors. Factor A consisted of three levels of dolomite application, D0, D1 and D2, similar to treatments mentioned above (T1, T2, and T3), and factor B consisted of five levels of foliar nutrition at PI stage: without foliar application (N0), foliar spray of 1% KNO3 (N1), foliar spray of 1% K2SiO3 (N2), foliar spray of 1% KNO3 + 0.5% micronutrient solution (N3) and foliar spray of 1% K2SiO3 + 0.5% micronutrient solution (N4). The medium duration rice variety Uma (Mo 16) was used for the study. Analysis of experimental results indicated that treatments had significant effect on growth characters, yield and yield attributes, soil nutrient content, and plant nutrient content and uptake in grain and straw as compared to control. Application of granulated dolomite (D2) produced taller plants with higher LAI at PI and harvest stages, and the highest number of tillers at both maximum tillering and PI stages. The same treatment recorded the highest grain yield (6.79 t ha-1), straw yield (8.78 t ha-1), total dry matter production (15.05 kg ha-1), productive tillers (564.38 m-2), total grains per panicle (85.93), thousand grain weight (28.35 g), and percentage of filled grains (89.32%). Application of 1% KNO3 + 0.5% micronutrient solution at PI stage (N3) resulted in the highest grain yield (6.76 t ha-1) which was on par with all other treatments except the treatment without foliar nutrition, and the highest straw yield (8.91 t ha-1) and thousand grain weight (28.56 g) were obtained with application of 1% KNO3 alone at PI stage (N1). The interaction of soil amelioration and foliar nutrition did not show any influence on yield and yield attributes. Soil analysis was carried out at PI and harvest, and soil amelioration practices had significant effect on pH, EC, OC and all available macro and micronutrient contents in the soil except Zn and Cu. Available N and P contents in the soil at harvest stage were also not influenced by the treatments. Addition of granulated dolomite (D2) significantly increased available Ca and Mg contents and reduced S and Fe contents in the soil. Among various treatments D2 recorded the highest soil pH, OC, available K, available Ca, available Mg and available B at both PI and harvest stages and the highest N content at PI stage and the lowest S and Na contents at harvest stages were observed in the same treatment. Treatment without dolomite application recorded the highest EC, available S, Na, and available Fe at both PI and harvest stages. Plant nutrient contents and uptake were significantly influenced by soil amelioration practices, foliar nutrition and by their interaction effects. Higher uptake of nutrients such as N, P, K, Ca, Mg and S was observed on dolomite application along with foliar nutrition. Plant nutrient content and uptake of nutrients varied among different treatments. The results obtained from the experiment revealed the significant influence of soil amelioration practices, foliar nutrition and their interaction effect on growth and yield attributes, soil pH, EC, OC, available nutrients and plant nutrient uptake in rice as compared to control. Application of granulated dolomite basally and at 30 DAS was effective in reducing soil acidity, thereby increasing the available nutrient content in soil, which resulted in increased grain yield and quality. Foliar nutrition of 1% KNO3 or combined spray of 1% KNO3 with 0.5% micronutrients at PI stage were found to be more effective in enhancing grain yield and quality in rice in Vaikom Kari soils.Item Impact of biofertilizers on iron homeostasis under elevated CO2 condition in rice, Oryza sativa(Department of Plant Physiology, College of Agriculture , Vellayani, 2023-01-25) Musti Sri Phani Bhavya; Manju, R VThe study entitled “Impact of biofertilizers on iron homeostasis under elevated CO2 condition in rice, Oryza sativa” was proposed with an objective of assessing the impact of biofertilizers on iron uptake, translocation and grain iron content in rice variety Uma, under CO2 enriched condition. The experiment was conducted using open top chamber (OTC) facility at the Department of Plant Physiology, College of Agriculture, Vellayani, during the period 2021-2022. In this experiment, growth, yield, quality and iron uptake characteristics of rice variety Uma under elevated CO2 condition as influenced by the application of different biofertilizers were evaluated. The experiment was laid out in CRD with 4 treatments [(KAU-POP (control), POP+Azolla, POP+PGPR and POP+AMF)] under 2 conditions [(Ambient CO2 (aCO2) and Elevated CO2 (eCO2)-500 ppm)] with 3 replications. The experiment results revealed that elevated CO2 had a significant positive influence on growth of the plants which was further enhanced by biofertilizer application. When yield parameters were considered, increased CO2 was found to have an adverse effect. There was 58 per cent and 39.28 per cent reduction in filled grains per panicle and grain yield when plants were grown under eCO2 condition. The increase in temperature associated with CO2 enhancement can affect the pollen viability resulting in increased grain chaffiness and yield reduction. Application of biofertilizers had significantly increased grain yield, among which AMF treatment had shown highest impact under both the CO2 conditions. Among the physiological parameters, total chlorophyll content, total reducing sugars and photosynthetic rate increased in the plants grown inside OTC. However, a reduction was noted in total soluble proteins and transpiration rate under elevated CO2 condition. In all these physiological parameters, the biofertilizers treated plants showed higher response when compared to control plants. Grain carbohydrate content was significantly increased by 10.6 per cent in control plants under eCO2 while protein and amylose contents of grains decreased by 14 per cent and 13 per cent indicating reduced grain quality under eCO2. Even under eCO2 condition, the protein content in PGPR treated plants increased by 7.1 per cent and amylose content in AMF treated plants increased by 4.86 per cent when compared to control plants (aCO2). 115 CO2 enrichment and biofertilizers application were found to influence iron uptake and translocation significantly. The pre-anthesis Fe uptake in control plants was dropped by 11.76 per cent and Fe-accumulation by 4.4 per cent under eCO2 condition. But application of PGPR could bring 57.89 per cent increase in iron uptake under ambient condition and 64.7 per cent increase under eCO2 condition. During post-anthesis stage, Fe-uptake was found to increase compared to pre-anthesis stage. Fe-accumulation in the shoot decreased during post-anthesis stage due to re-mobilization of accumulated Fe into grains. There was a drop in Fe-uptake in control plants under eCO2 by 12.5 per cent at post-anthesis stage. At pre-anthesis and post-anthesis stages, plants treated with PGPR (eCO2) have shown increase in Fe uptake by 47.36 per cent and 40.7 per cent, respectively, than control plants. All the biofertilizers including Azolla, PGPR and AMF had significant impact on grain Fe-content under both the CO2 conditions. The Fe content of grains in control plants was dropped by 21 per cent under eCO2 condition. Application of PGPR was found to be most effective resulting in 80.5per cent and by 72.8 per cent increase in Fe-content under eCO2 and aCO2 conditions, respectively. The Fe content in grains was partitioned more into bran than into the polished rice. Control plants when exposed to eCO2 reduced Fe-content in bran and polished rice by 12 per cent and 23.4 per cent, respectively. PGPR treatment increased the Fe-content by 28.6 per cent and 61.7 per cent in bran and polished rice under elevated CO2 condition and by 22.3 per cent and 46.2 per cent under ambient condition when compared to control plants. Diminishing quality of rice with the increasing concentration of CO2 is a global concern today. Elevated CO2 had a positive impact on growth but negatively influenced grain yield due to eCO2 associated high temperature. By the response of experimental plants to AMF and PGPR treatments, these bio-fertilizers can be recommended in overcoming the impacts of elevated CO2 associated high temperature and thereby improving the plant performance. In the present programme, iron uptake and translocation were found to be modified in an unfavourable manner under eCO2 which reflected in the lower iron content of rice grains. The response of iron homeostasis of the experimental plants to the application of biofertilizers, especially PGPR, under eCO2 strongly suggests the possibility of utilizing them for designing iron management strategies to achieve higher yield and quality in rice.Item Identification of superior genotypes for water stress tolerance in rice (Oryza sativa L.) for south central laterites of Kerala(Department of Plant Breeding and Genetics, College of Agriculture,Vellayani, 2022-02-18) Aravind Krishna; Bindu, M RHe present investigation entitled “Identification of superior genotypes for water stress tolerance in rice (Oryza sativa L.) for south central laterites of Kerala” was conducted at Farming Systems Research Station, Sadanandapuram, Kottarakkara during 2019-21 with an objective to identify and characterize the traditional as well as released rice genotypes of Kerala for water stress tolerance using phenotypic and biochemical markers, suitable for south central laterites of Kerala. The study comprised of thirty genotypes collected from RARS, Pattambi, Department of Seed Science and Technology, College of Agriculture, Vellanikkara, KAU, Thrissur and ICAR- NBPGR, New Delhi. Study was conducted in two experiments viz. laboratory and field study. In the first experiment (Experiment-I), thirty genotypes were evaluated for moisture stress tolerance at seedling stage for seven different morpho-physiological characters viz. Germination percentage, speed of germination, root length, shoot length, seedling dry weight, seedling vigor index 1 and seedling vigor index 2 in laboratory using PEG 6000 (Polyethylene Glycol- 6000) at five different concentrations of 0, 5, 10, 15, 20 percentage (%). The study was conducted in factorial completely randomized design, replicated thrice and the twenty-one tolerant genotypes were selected for field study. In the second experiment (Experiment-II), twenty-one best performing genotypes including the high performing standard check variety Apo in randomized block design were selected and evaluated in the field where irrigation was withheld for 10 days at critical growth stages. The seeds were sown on raised beds of 4 m2 size at a spacing of 20 cm х 20 cm and cultural operations were adopted as per the “Package of Practices (2016)” of Kerala Agricultural University. Genotypes were evaluated for twenty-four characters which included different biometric, physiological and biochemical observations. Significant difference was observed among genotypes for all the characters studied in both field and laboratory experiments. Genetic parameter analysis was performed for 21 characters and for all the characters PCV values were higher than GCV values indicating the influence of environment. The phenotypic and genotypic coefficient of variation were maximum for recovery after stress release and minimum for days to 50 % flowering. Heritability was high for all the characters except leaf rolling score and genetic gain was high for all the selected characters. Correlation studies revealed significant positive correlation for all the selected characters except spikelet sterility, which exhibited significant negative correlation with grain yield. Path analysis conducted for eleven characters showed significant correlation with grain yield and also revealed that relative water content recorded high positive direct effect on grain yield. High positive indirect effect on grain yield was recorded by grain weight per panicle via spikelet sterility. GeneticItem Application of response surface methodology for optimal yield of transplanted rice Oryza sativa L(Department of Agricultural Statistics, College of Agriculture,Vellayani, 2022-02-05) Anjana R Pillai; Brigit JosephThe research work entitled “Application of response surface methodology for optimal yield of transplanted rice (Oryza Sativa L.)” was carried out at Cheruniyoor panchayat of Varkala in Tiruvananthapuram district and College of Agriculture, Vellayani during 2019-2021. The objective was to the development of response surface model using Central Composite Design (CCD) to optimize N, P and K of transplanted rice and to develop a web based application for Response Surface Methodology (RSM). A CCD experiment was conducted with 15 treatment combinations in 3 replications using the rice variety (Uma (MO16)) during the mundakan season as second crop. The grain yield and straw yield data were as the source of primary data which was used for analysis. The analysis was initiated by finding the high and low levels of the central value taken for the studies which was 90:45:45 NPK kg ha-1. The levels were selected on the basis of previous studies and soil tests conducted. Since three factors were chosen for the experiment, α value of ±1.682 was considered. The experiment was conducted using these and observations were found for grain yield and straw yield. The average grain yield, straw yield and harvest index were found to be 5792 kg ha-1, 7578 kg ha-1 and 0.43 respectively with a standard deviation of 934.63 for N, 749.98 for P and 0.026 for K. From analysis, it was found that the multiple R2 for grain yield was 0.89 which was closer to 1 indicating that there is a high correlation between the response variable and the predictor variables while the adjusted R2 was 0.80 representing that the model fitting was good. The predicted R2 was 0.69 i.e., it can predict 69% of new observations for the regression model. The predicted R² of was in reasonable agreement with the adjusted R²; i.e., the difference is less than 0.2. In the case of straw yield (Y2), it was found that there were no significant and the lack of fit value of 0.1046 implied that the model fitting was not good enough. The response model was estimated using R for grain yield. The best model Y was selected based on the lack of fit and R2 values. 𝑌̂ = 6281.62 + 462.271N*+ 546.27P* + 636.12K* + 66.75N*P* + 98.25N*K* + 285.75P*K* -109.08N*2 -331.20P*2-281.88K*2 Where N*, P* and K* are the coded variables and N*= (N-90)/18 115 P* = (P-45)/18 K* = (K-45)/18 From the model it was found that N*, P*, K*, P*², K*² were significant model terms. The model in overall is a significant one with a lack of fit of 0.59 (>0.05). The stationary points for grain yield were determined which is the point of determination of maximum, minimum or saddle points. In this experiment, the optimum levels were found to be beyond our range of interest i.e., outside the fixed domain of -α and +α. Hence, the ridge analysis was performed where the optimal solutions are found within a particular radius of the stationary points. They were 94 N, 62 P and 65 K; 101 N, 65 P and 69 K and 109 N, 69 P and 73 K for 7295 kg ha-1, 7630 kg ha-1 and 7930 kg ha-1 respectively. Among these the most feasible solution both physically and economically were 109 N, 63 P and 73 K i.e., in terms of maximisation of yield and cost. In order to develop the RSM for CCD, a web application for experimental runs required for Circumscribed CCD and Inscribed CCD with 2, 3 and 4 factors were developed initially. The application was developed using the R codes and the server used was R Shiny. In addition, the method of estimating the Response surface models and optimum levels of factors were involved. The stationary points are also generated for the factors and ridge analysis when required. The results of the RSM analysis using CCD concluded that the optimum doses of N, P and K for transplanted rice for variety Uma (MO16) was 93.690, 62.388 and 65.178 Kg ha-1 respectively. A web application for RSM with CCD for factors ranging from 2 to 4 was also developed using R.Item Enhancing grain yield and quality through soil amelioration and foliar nutrition in rice (Oryza sativa L.) in Vaikom kari soils(Department of Agronomy, College of Agriculture, Padanakkad, 2022) Sreelekshmi, S; Devi, V SA field experiment entitled “Enhancing grain yield and quality through soil amelioration and foliar nutrition in rice (Oryza sativa L.) in Vaikom Kari soils” was conducted in a farmer's field at Vechoor, during puncha season of 2020. The objectives were to augment the yield and quality of rice in Vaikom Kari soils through soil amelioration practices for managing soil acidity, and to supplement nutrition at panicle initiation stage through foliar application of K and micronutrients. The field experiment was laid out in Randomized Block Design. The effect of soil amelioration on soil parameters and growth characters was assessed in simple RBD with three treatments and fifteen replications. The treatments were: no dolomite (T1), application of ordinary dolomite basally and at 30 DAS (T2) and application of granulated dolomite basally and at 30 DAS (T3). The effect of soil amelioration and foliar nutrition on yield and yield attributes, and plant nutrient content and uptake were analysed in factorial RBD with two factors. Factor A consisted of three levels of dolomite application, D0, D1 and D2, similar to treatments mentioned above (T1, T2, and T3), and factor B consisted of five levels of foliar nutrition at PI stage: without foliar application (N0), foliar spray of 1% KNO3 (N1), foliar spray of 1% K2SiO3 (N2), foliar spray of 1% KNO3 + 0.5% micronutrient solution (N3) and foliar spray of 1% K2SiO3 + 0.5% micronutrient solution (N4). The medium duration rice variety Uma (Mo 16) was used for the study. Analysis of experimental results indicated that treatments had significant effect on growth characters, yield and yield attributes, soil nutrient content, and plant nutrient content and uptake in grain and straw as compared to control. Application of granulated dolomite (D2) produced taller plants with higher LAI at PI and harvest stages, and the highest number of tillers at both maximum tillering and PI stages. The same treatment recorded the highest grain yield (6.79 t ha-1 ), straw yield (8.78 t ha-1 ), total dry matter production (15.05 kg ha-1 ), productive tillers (564.38 m-2 ), total grains per panicle (85.93), thousand grain weight (28.35 g), and percentage of filled grains (89.32%). Application of 1% KNO3 + 0.5% micronutrient solution at PI stage (N3) resulted in the highest grain yield (6.76 t ha-1 ) which was on par with all other treatments except the treatment without foliar nutrition, and the highest straw yield (8.91 t ha-1 ) and thousand grain weight (28.56 g) were 116 obtained with application of 1% KNO3 alone at PI stage (N1). The interaction of soil amelioration and foliar nutrition did not show any influence on yield and yield attributes. Soil analysis was carried out at PI and harvest, and soil amelioration practices had significant effect on pH, EC, OC and all available macro and micronutrient contents in the soil except Zn and Cu. Available N and P contents in the soil at harvest stage were also not influenced by the treatments. Addition of granulated dolomite (D2) significantly increased available Ca and Mg contents and reduced S and Fe contents in the soil. Among various treatments D2 recorded the highest soil pH, OC, available K, available Ca, available Mg and available B at both PI and harvest stages and the highest N content at PI stage and the lowest S and Na contents at harvest stages were observed in the same treatment. Treatment without dolomite application recorded the highest EC, available S, Na, and available Fe at both PI and harvest stages. Plant nutrient contents and uptake were significantly influenced by soil amelioration practices, foliar nutrition and by their interaction effects. Higher uptake of nutrients such as N, P, K, Ca, Mg and S was observed on dolomite application along with foliar nutrition. Plant nutrient content and uptake of nutrients varied among different treatments. The results obtained from the experiment revealed the significant influence of soil amelioration practices, foliar nutrition and their interaction effect on growth and yield attributes, soil pH, EC, OC, available nutrients and plant nutrient uptake in rice as compared to control. Application of granulated dolomite basally and at 30 DAS was effective in reducing soil acidity, thereby increasing the available nutrient content in soil, which resulted in increased grain yield and quality. Foliar nutrition of 1% KNO3 or combined spray of 1% KNO3 with 0.5% micronutrients at PI stage were found to be more effective in enhancing grain yield and quality in rice in Vaikom Kari soils.Item Physiological and anatomical plasticity of root traits under water stress and molecular characterization using root specific genes in rice(Department of Plant Pathology, College of Agriculture, Vellayani, 2019) Lakshmi Naga Manikanda Chennamsetti; Beena, RThe study entitled “Physiological and anatomical plasticity of root traits under water stress and molecular characterization using root specific genes in rice (Oryza sativa L.)” was conducted in the Department of Plant Physiology, College of Agriculture, Vellayani during October – January, 2017-19 with the objective to quantify the adaptive plasticity in root-shoot morphology, physiology and root anatomical plasticity under water stress in selected rice genotypes and molecular characterization using root specific genes. The extent of variation for various physiological, biochemical and anatomical characters were assessed as an indicator of water stress from six selected genotypes collected from RARS Pattambi and N-22 from IIRR, Hyderabad. Plants were maintained under 100% and 50% field capacity (FC) soil moisture in a rain out shelter. A set of five replications were maintained and observations were made at booting stage on root, physiological, biochemical and anatomical parameters and significant variations for these traits were noticed for tolerant and susceptible genotypes. The study revealed that parameters such as relative water content (RWC) (%), specific leaf area (cm2 g-1), and cell membrane stability index (%) were found to be decreasing but not significant under stress condition whereas root parameters, biochemical and biomass partitioning were found to be increasing among the tolerant and susceptible genotypes. The highest RWC was recorded from N-22 (85.37%) under stress condition whereas least from Ptb 35 (71.96%). N-22 showed the highest reduction in specific leaf area with 219.9 cm2 g-1 whereas Ptb 39 showed an increasing trend in specific leaf area by 1.5% with 183.73 cm2 g-1 under stress. Cell membrane stability index (%) was highest in Ptb 30 (97.10%) under stress whereas least was recorded from Ptb 39 (83.11%). Carbon isotope discrimination (Δ13C)(mil-1) was least for N-22 (21.84) (Δ13C)(mil-1) and highest in Ptb 39 (23.49) (Δ13C)(mil-1) at panicle initiation. Study on root parameters of tolerant and susceptible genotypes at two FC levels exhibited significant variation among root parameters. Root length was highest in Ptb 29 (38.46 cm) and least in Ptb 35 (20.66 cm) under water stress. Among the genotypes Ptb 29 was found to be performing better for other root characters viz., root volume, root dry weight, root/shoot ratio and specific root length whereas least performance was noticed from susceptible genotypes Ptb 35 and Ptb 39. A significant differences in biomass partitioning was noticed among the genotypes, for characters such as leaf weight ratio, stem weight ratio and root weight ratio. Under stress root weight ratio was highest in Ptb 29 (0.21) and lowest in Ptb 35 (0.106). Anatomical studies revealed significant effects at both genotype and treatment levels. Tolerant genotypes were found to be more responsive under water stress for anatomical traits. N-22 and Ptb 29 exhibited an increase in root diameter (1.55mm and 1.796 mm), stele diameter (0.49 and 0.31 mm), late metaxylem number and late metaxylem diameter (5.6, 0.069 mm and 5.6, 0.076 mm respectively. Early metaxylem number found to be increasing in tolerant genotypes N-22 (30.66) whereas susceptible genotypes exhibited declining trend. Sclerenchymatous tissue was found to be highest in N-22 (0.024mm) whereas Ptb 35 a susceptible genotype exhibited lowest value for sclerenchyma with 0.012 mm. Yield attributes were found to vary significantly among genotypes. Spikelet fertility percentage and yield per plant was highest in N-22 with 85.66% and 24.66 g respectively. 1000 grain weight was highest in Ptb 30 (27.23 g) and lowest in Ptb 39 (22.5 g). Genotyping of the selected tolerant and susceptible rice genotypes using available DEEPER ROOTING QTL specific primers and other available drought specific SSR primers was done from seedlings raised in a petri dish. It was found that DRO1 specific microsatellite markers did not exhibited polymorphism among tolerant and susceptible genotypes but another drought related SSR primer RM 518 showed polymorphism for tolerant and susceptible genotypes. Expression studies were done between one tolerant and one susceptible genotypes i.e., Ptb 29 and Ptb 35 with DEEPER ROOTING QTL specific primers and EST- SSR RM 518. Results of expression studies using RM 518 exhibited differential expression under 100% FC and 50% FC condition and also among the genotypes Ptb 29 and Ptb 35. Significant variation was observed for physio-morphological and yield components among rice genotypes under 100% FC and water 50% FC conditions. Genotypes with better root traits such as root length, root shoot ratio and root anatomical plasticity exhibited more tolerance towards drought. The tolerant genotypes i.e., N-22. Ptb 29 and Ptb 30 can be used as donor plants in breeding programs for trait introgression for developing drought tolerant cultivars. Microsatellite marker RM 518 which could distinguish drought tolerant and susceptible genotype can be used for marker assisted selection for drought tolerance in rice. A differential expression of drought related genes was seen in tolerant and susceptible genotypes under water stress condition.Item Crops weather relationship in rice(Department of Agricultural Meteorology, College of Horticulture,Vellanikkara, 2000) Sunil, K M; Kesava Rao, A V RAn experiment was conducted in the Agricultural research Station, Mannuthy during first, second and third crop seasons of 1998-99 to study the crop weather relationship in rice variety 'Kanchana'. The experiment was laid out in randomised block design with three replications. The treatment consisted of three dates of planting in each season i.e., 1 s\ i s" and 30th of June, 1 st 15th and 30th of October and 1 st, 15th and 30th of January. Observations on morphological and yield attributes were recorded during the course of investigation. The daily values of weather elements viz., maximum and minimum surface air temperature, bright sunshine, morning and afternoon relative humidity and wind speed were collected from the Principle Agro Meteorological Station, College of Horticulture, Vellanikkara, to work out the crop weather relationships in rice. . Crops transplanted on 1 st is" and 30tl) of October and 1 st 15th of June were significantly superior in terms of grain yield, panicle number, number of filled grains/panicle, number of leaves, plant biomass, number of tillers and leaf area index. The crop weather relationship studies showed that the wind speed, minimum temperature and mean temperature during flowering to maturity had a significant negative correlation with grain yield. But morning relative humidity and mean relative humidity during transplanting to panicle initiation stage had a significant positive influence on ultimate grain yield. The wind speed, mean temperature, temperature range, RH1-RH2 and solar radiation during vegetative stage were negatively correlated with the straw yield. Maximum temperature during beginning of grain filling to maturity stage also had a negative correlation. But increase in mimmum temperature, mean relative humidity, morning and afternoon relative humidities during transplanting to flowering stage was significantly increase the straw yield as there was a positive correlation. The regression equations developed in the study predicted the grain yield, straw yield, duration of vegetative phase and maximum leaf area index well and a close relation existed between observed and estimated yield. Based on the experimental data, minimum data set for the validation of rice model of the IBSNAT has been generated.Item Bio fortification of rice (Oryza sativa) with zinc under organic and integrated nutrient management practices(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Padannakkad, 2019) Wayoolang Talang; Suresh, P RAn investigation entitled “Biofortification of rice (Oryza sativa) with zinc under organic and integrated nutrient management practices” was carried out in Regional Agricultural Research Station (RARS), Pilicode during June to October 2018. The study was conducted in rice variety Uma (MO 16). The main objective of this research was to check the zinc nutrient content under organic and integrated nutrient management practices (INM). The field experiment was laid out under Randomized Block Design (RBD) with nine treatments and one control each replicated three times. The treatments consisted of soil application of Zn and combined soil and foliar application of Zn under organic (Organic Package Of Practice) and INM practices (Package Of Practice Kerala Agricultural University). Zn was applied as zinc sulphate (ZnSO4) at the rate of 1 per cent and 20 kg ha-1 as foliar application and soil application respectively. Foliar application of ZnSO4 was done at three growth stages of rice viz tillering, panicle initiation and flowering stage. Single foliar application of Zn was done at only tillering stage. Double foliar application of Zn was done at tillering and panicle initiation stages and triple foliar application of Zn was done at all the three growth stages. The effect of different treatments significantly influenced plant growth attributes like plant height, number of tillers per hill and panicles per hill. At harvest stage, the highest plant height (99.9 cm) was recorded in T8 (POP KAU + soil application of Zn + triple foliar spray of Zn) which was on par with T7. The minimum plant height was recorded in control (92.3 cm). Similarly, the maximum number of tillers per hill (15.5) and maximum number of panicles per hill (15.5) was recorded in T8 at harvest stage. Soil and foliar application of Zn along with soil application of NPK fertilizers as per POP KAU significantly improved the grain yield and other crop yield attributes. The treatment that recorded the highest grain yield was T8 (6.7 t ha-1) which was superior as compared to other treatments. The treatments that recorded the highest straw yield (6.5 t ha-1) and highest 1000 grain weight (27.1g) was with treatment T7. 127 The nutrient content in the plant samples (shoot and straw) analyzed at different growth stages of paddy was studied. The results revealed that nutrient content of N, K and Zn was highly improved in treatments under INM practices. At the harvest stage, treatments T7 recorded the highest N (0.62 %) and K (1.9 %) whereas Zn (85.7 mg kg-1) content in straw was highest with treatment T8. However, the nutrient content of P in plant samples declined with the increase in the number of foliar application of Zn. The treatment that recorded the lowest P content (0.19 %) in the straw at harvest was T5 (Organic POP + soil application of Zn + triple foliar application of Zn). The effect of treatments on Zn and P content in rice grains were also studied. Grain analysis results revealed that the treatment that recorded the highest Zn content (55.8 mg kg-1) was in T8 and the lowest Zn content (18.2 mg kg-1) was recorded in T10 (control). Similarly, P content was also analyzed in rice grains to study the interaction between Zn and P. The treatment that recorded the highest P content (0.61 %) in the grain was T2 and lowest P content (0.44%) was recorded in T5.Item Marker assisted backcrops breeding in rice for drought tolerance(Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Vellanikkara, 2019) Athulya S Nair; Abida, P SRice {0ryza sativa L.) is one of the most important food crop grown across the globe. The crop is cultivated in diverse environments ranging from uplands to deep water ecosystems. Drought is one of the major constraints for rice production in rainfed lowlands. In the present scenario of climate change, the frequency of drought is more likely to increase in the future, making drought resistance in rice varieties indispensable. During the era of post-green revolution, many locally adapted traditional rice varieties (TRVs) were replaced by high yielding varieties (HYVs) that thrive best in the irrigated ecosystem. Most of these HYVs sutTer heavy yield loss even under mild water deficit conditions. Hence, improving drought tolerance of high yielding varieties is imperative. Considering this, the study 'Marker assisted backcross breeding in rice for drought tolerance,' was executed with an objective to improve drought tolerance in high yielding rice variety Ptb 39 (Jyothi; J) using Ptb 30 (Chuvannamodan; Ch) as donor parent, through marker assisted backcross breeding. Jyothi is a popular high yielding rice variety of Kerala derived from the cross between Ptb 10 and IR 8. Chuvannamodan is an improved landrace, recommended for ''Modan^ i.e., upland cultivation owing to its drought tolerance ability. Morphological characterisation of both the varieties was done at Regional Agricultural Research Station, Pattambi, during 2018. Chuvannamodan registered a higher vegetative growth than variety Jyothi. The plant height and the number of productive tillers were 141 cm and 33 respectively in Chuvannamodan, while, in comparison, it was 91 cm and 17 in Jyothi. It was also observed that Chuvannamodan flowered earlier (Days to 50% flowering: 76 days) than variety Jyothi (Days to 50% flowering: 93 days). However, Jyothi out-performed Chuvannamodan with respect to the yield traits like number of filled grains per panicle (Ch: 71 and J: 104), iOOO-grain weight (Ch: 27.00 g and J: 28.30 g), and grain density (Ch: 1.09 g/cm^ and J: 1.11 g/cm^). The sterility in Chuvannamodan and Jyothi was 11.40 per cent and 18.40 per cent respectively. The water mining traits like root length, root volume, root dry weight and root to shoot ratio were higher in variety Chuvannamodan. The root length, root volume, root dry weight and root to shoot ratio of Chuvannamodan was respectively 109cm, 96cm"\ 31.60g and 0.31, while, it was 68cm. 32cm^,14.40g and 0.24 respectively in variety Jyothi. The genetic polymorphism study between Jyothi and Chuvannamodan was I studied using 120 SSR markers. Forty-seven markers were found to be n, polymorphic between the two genotypes. Among these polymorphic markers, 24 are reported to be linked to drought tolerance traits. Forty five F1 seeds were obtained by hybridizing variety Jyothi (as female parent) and Chuvannamodan (as male parent). Staggered sowing of the two varieties was done at weekly intervals for this purpose. Only six Fj seeds germinated. The test for confirmation of hybridity was conducted in these plants along with the parents. The polymorphic markers RM3825 and RM263, which are reported to be linked to drought traits were used for hybridity testing. Two plants, P5 (Plant No.5) and P6 (Plant No.6), were confirmed to be true hybrids as they were found to be heterozygous for the parental alleles. The hybrids (P5 and P6), were then backcrossed to the recurrent parent Jyothi to produce BCiFi seeds (15 Nos.). Simultaneously, selfing of the Fis to generate F2S (300 Nos.) was also done. In order to advance further the marker assisted backcross breeding programme aimed at imparting drought tolerance to Jyothi, the BC1F1s produced need to be genotyped further to identify progenies with resistant alleles for drought tolerance. The F? population can be forwarded to develop RJLs (Recombinant inbred lines) that would enable mapping of qualitative traits and quantitative trait loci related to drought tolerance. The F2S can also serve as the base population for the development of advanced breeding lines through pedigree selection.Item Marker assisted selection for heat tolerance in rice (Oryza sativa L.)(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2019) Silpa, V; Sindhumole, PRice is highly susceptible to heat stress, particularly during the reproductive and ripening stages. In the major rice growing tracts of Kerala viz., at Palakkad, Kole and Kuttanad, the temperature tends to rise up to 40 ºC or more during the second/third crop. Consequently, high temperature induced sterility has become a serious problem. To tackle this, high yielding varieties coupled with heat stress need to be developed. As most of the prevalent high yielding rice varieties in Kerala including Uma are highly susceptible to heat stress. It is therefore, essential to impart heat tolerance to such varieties which are cultivated to a very large extent. Marker assisted selection (MAS) has been identified as a dependable, reproducible and time saving strategy to confirm the presence of desirable gene and to quicken the breeding cycle. A study conducted for the identification of SSR markers linked to the genes for heat tolerance in rice through bulked segregant analysis approach using F3 population of the cross Uma x N22 revealed that microsatellite marker, RM5749 was tightly linked to spikelet fertility trait under heat stress. The F4 population (59 nos.) raised from seven F3 lines that were found tolerant to heat stress comprised the base population for the present study. They were characterised morphologically and heat tolerance was scored under natural heat stress in the field conditions based on IRRI spikelet fertility classification. In the 26 F4 lines that registered more than 75 per cent spikelet fertility, foreground selection was done using RM5749. All the 26 F4 plants registered an amplicon corresponding to the heat tolerant parent N22. Background selection of these 26 lines was done using 35 markers found polymorphic between the parents Uma and N22. Seventy five F5 plants were evaluated for morphological characters. Among these, nine F5 plants (Plant nos.16.1.4, 16.1.5, 16.1.6, 31.2.3, 31.2.4, 31.2.5, 31.5.1, 31.6.6, and 31.6.9) with high spikelet fertility (60-70 %) were selected and genotyped using RM5749. These lines were further genotyped using the 35 polymorphic background markers. All the nine F5 plants recorded 54-64 % similarity to Uma genome. The highest spikelet fertility percentage was observed in plant no.16.1.5 (70.78 %) while the highest recovery of the parental genome of Uma was found in plant no. 31.2.5 (64.28 %). Backcrossing of the seven selected heat tolerant lines of F4 (lines 12, 13, 15, 16, 31, 41, and 45) with Uma as male parent resulted in production of BC1F1 seeds. However, the seedlings raised from these seeds did not survive under field conditions. The results obtained thus indicated that the nine lines selected in the present study are to be evaluated in further generations morphologically inorder to isolate genotypes with tolerance to heat stress.
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