1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Crop weather relationship of rice varieties under different growing environments(Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, 2019) Haritharaj, S; Ajithkumar, BItem Modeling rice production in kole lands and its vulnerability to climate change(Academy of Climate Change Education and Research Vellanikkara, 2018) Surabhi, S R; Sandeep, SRice is the most important staple food crop for more than 2/3rd of India’s population, and is the primary source of food for more than three billion people globally. Hence rice production plays a significant role in food security under a changing climate. The Kole lands is a multiple use wetland ecosystem covering an area of 13,632 ha spread over Thrissur and Malappuram districts, and form one of the rice granaries of Kerala. It is a part of the unique Vembanad-Kole wetland ecosystem. The objectives of the study were to develop crop weather relationship for the predominant rice varieties and assess possible changes in yield due to climate change and to study the impact of abiotic factors and farming practices on rice production using simulation model. Daily weather data for the period 1998-2016 were collected from the India Meteorological Department, Thiruvananthapuram. Information on area, production and productivity of rice in Kole lands was collected from Agriculture Statistics Report - Department of Economics and Statistics, Kerala. The weather data from General Circulation Models based on RCP 4.5 and 8.5 were used for the analysis and projections were made up to 2050. Weather cock v.1.5 was used for converting the daily weather data into standard week, month and seasonal formats. The rainfall parameters or indices like seasonal and monthly rainfall, rainy days and high rainfall events were calculated. It is also used to compute PET and Thornthwaite water balances. The crop simulation model DSSAT –developed by IBSNAT was used for studying the impact of climate change on these ecosystems. The monthly rainfall of Kole lands indicates that there was an increase in rainfall during the months of June, July and August as per RCP 4.5 and 8.5. According to RCP 4.5 and 8.5 an increasing trend in number of seasonal rainy days was observed during the monsoon seasons. The maximum amount of potential evapotranspiration was observed during the month of May, whereas the minimum in, November December, and January. The months of January, February, March, April, November and December were found to have no surplus. Whereas water deficit is projected to happen during the month of march. The maximum amount of surplus was found to occur in July and the yearly value shows an increase from the current condition. The area under rice production has shown a declining in Kole lands over a period of 2008 – 2017. Results indicates that the productivity of rice in Kole lands during the first cropping season was 2.08 t/ha. By 2030, the second cropping season was projected to have a yield of 3.124 t/ha. By 2050, the third cropping season would surpass the productivity of first two seasons with productivity of 3.424 t/ha.Item Assessment of rice (oryza sativa L.) production under climate change scenarios(Department of Agricultural Meteorology Vellanikkara, 2017) Jasti Venkata Satish; Ajithkumar, BAgriculture is sensitive to short term changes in weather and to seasonal, annual and long term variations in climate. Climate change will have decisive impact on crop production and the prediction of this climate change emerged as a major research priority during the past decade. Numerous estimates for the impending decade projects that continuous rise of anthropogenic forcing leads to increase in greenhouse gas (GHG) atmospheric concentrations, is expected to alter regional temperature and precipitation patterns, also contributing to higher risk of extreme weather events and climate irregularity (IPCC, 2013), with obvious implications on crops (Porter and Semenov, 2005). Rice (Oryza sativa L.) is vulnerable to unfavourable weather events and climate conditions. Despite technological advances such as improved crop varieties and irrigation systems, weather and climate play significant roles in rice production. The present investigation “Assessment of rice (Oryza sativa L.) production under climate change scenarios” was carried out in the Department of Agricultural Meteorology, College of Horticulture, Vellanikkara during 2016-17, to determine the crop weather relationship, to validate the CERES (Crop Environment Resource Synthesis) -Rice model for the varieties Jyothi and Kanchana and to project the changes of rice yield and growth under climate change scenarios. The field experiment was conducted at Agricultural Research Station, Mannuthy during the kharif season of 2016. Split plot design was adopted with five dates of planting viz., 5th June, 20th June, 5th July, 20th July and 5th August as the main plot treatments and two varieties viz., Jyothi and Kanchana as the sub plot treatments. The number of replications for the experiment was four. Analysis of weather with crop duration and yield showed that maximum and minimum temperatures showed increasing trend towards late plantings, whereas the relative humidity, rainfall and rainy days were found to be low in late planting than during early plantings. To determine the critical weather elements affecting the crop duration, correlation analysis was performed. Number of days for panicle initiation to booting stage, decreased with increase in maximum and minimum temperature, whereas, the reverse was observed with afternoon relative humidity, afternoon vapour pressure deficit and rainfall in Jyothi. In case of Kanchana, days for transplanting to active tillering decreased with increase in maximum, minimum temperatures and bright sunshine hours, whereas relative humidity, afternoon vapour pressure deficit, rainfall and 159 number of rainy days showed a positive influence. The mean yield of Jyothi and Kanchana on June 5th planting found to be on par with June 20th planting. The correlation analysis showed that with increase in maximum and minimum temperature during transplanting to Active tillering will reduce the yield for both Jyothi and Kanchana The crop genetic coefficients that influence the occurrence of developmental stages in the CERES-Rice models were validated, to achieve the best possible agreement between the simulated and observed values. Predicted yield and phenology of both rice varieties, Jyothi and Kanchana under different planting dates were reasonably close to the observed values. Analysis of yield and growth phases of rice under different climate change scenarios ( Representative Concentration Pathways (RCP) 4.5 and 8.5) for the time periods 2050s and 2080s showed that, days taken to panicle initiation, anthesis and physiological maturity decreases for all the five different dates of planting. This may be due to increase in maximum and minimum temperatures during the future scenarios. The predicted values of rice yield for the climate change scenarios during first and second plantings for the time periods 2050s and 2080s showed a low yield whereas increase in yield was observed in third, fourth and fifth plantings compared with 2016. This increase in yield is may be due to combined effect of increase in CO2 (538 and 936ppm) and solar radiation during the panicle initiation, anthesis and physiological maturity for the delayed plantings. These findings suggests that, planting date need to be shifted to late July and early August in case of kharif crop in the central zone of Kerala in future.