EFFECT OF CO2 ENRICHMENT AND CLIMATE CHANGE ON RICE CROP THROUGH FIELD AND SIMULATION STUDY

Abstract

This study is directed to identify the probable effect of increased atmospheric CO2 concentrations and changing climate on rice crop yields in Haridwar Uttarakhand. Fine rice particularly the Basmati contributes substantially into the economy of the state. Rice in Haridwar district is grown in 12300 ha with a low recording productivity of only 2227 kgs/ha which requires improvement under the changing climate. Keeping the aforesaid points in view the study entitled “Effect of CO2 Enrichment and Climate Change on Rice Crop through Field and Simulation Study” has been undertaken with the under mentioned objectives: 1. To conduct field experiment with periodical enrichment of CO2 on rice crop for recording its effect on growth, development, yield and quality. 2. To calibrate DSSAT-CERES Rice model using data recorded from the field experiment. 3. To simulate rice yield under different CO2 treatments using DSSAT CERES –Rice model. 4. To assess climate change pattern of Haridwar district upto 2090 using PRECIS RCM data. 5. To study the impact of climate change and CO2 enrichment on rice yields for the future scenario. 6. To suggest ways and means to improve rice productivity for CO2 enriched crops. Field experiment with different CO2 treatments was conducted at Demonstration Farm, Water Resources Development and Management Department, Indian Institute of Technology Roorkee, Uttarakhand during the year 2011 and 2012. Plants were enriched with CO2 through use of CO2 cylinders that were used for fire extinguishing. Data recorded from field experiment were statistically analyzed using ANOVA analysis along with Tukey Kramer’s PostHoc test. For calibrating DSSAT CERES Rice model field experiment with four dates of planting (on 7th July, 2013 ; 15th July, 2013 ; 22nd July, 2013 and 31st July, 2013) with recommended package of practices was conducted during Kharif season 2013–14. Data recorded was used for calibrating the CERES rice model. To validate the CERES Rice model the crop data from the ii 2011 and 2012 experiments was used. Genetic coefficient generated in the calibration process was used to run the model. The effect of CO2 enrichment on the growth, development and yield parameters was simulated. The simulated values were compared with the observed values by employing statistical evaluation measures such as FB (fractional bias), NMSE (Normalized Root Mean Squared Error), percent deviation and index of agreement (d). The future rice yield predictions were done using A2 and B2 IPCC scenarios and PRECIS climate data of rainfall, maximum temperature and minimum temperature for Haridwar district for the period 2020 – 2090. PRECIS RCM was collected from IITM, Pune. The data pertaining to maximum temperature, minimum temperature and rainfall was extracted, bias corrected and validated for its use in crop simulation. Mann Kendall Trend test was applied to study the trend of climatic parameters for the coming years. PRECIS RCM corrected data was used to simulate grain yield of rice crop cv Sharbhati for the forthcoming decades 2020 – 2090. CO2 enrichment effect in rice crop can be improved by adjusting sowing dates, irrigation management, nutrient management and adopting high yielding heat resistant cultivars. Therefore yields were simulated under three different planting dates, three different plant spacing’s and three different levels of nitrogen fertilizer along with CO2 enrichment treatments for the future (2020 – 2090).  In general plant growth was improved with CO2 enrichment treatments recording increased tillers/hill, leaves/hill, plant height, leaf length and width, plant dry matter/hill and Leaf Area Index. Yield attributes viz. panicles/m2, filled grains/m2, grain weight as well as grain length and width were improved with periodical enrichment of CO2. Negative impact of CO2 enrichment was recorded with increased broken grain and chalkiness percentage.  Calibration and validation of DSSAT model using the experimental data showed that the deviation percentage of observed and simulated values was within the acceptable range of +/- 15%.  Trend analysis of the period showed that the annual rainfall would increase @ 5.8 mm/yr but Kharif rainfall would increase @ 11.6 mm/yr. The annual maximum and minimum temperature would increase @ 0.0460C/yr and 0.0390C/yr. iii  DSSAT CERES rice simulations under A2 and B2 scenarios showed that the yields will decline with the advancing climate change but CO2 intervention will compensate the loss in yield occurred due to higher temperatures and erratic rainfall pattern (climate change).  The DSSAT was used to develop adaptation strategies for the future under the climate change and higher CO2 scenarios. The results showed that the better yields can be obtained by transplanting the crop in the second week of July, adapting the spacing of 20 cm * 15 cm and nitrogen fertilizer application of 90 kgs N/ha.