Chilling Damage Sensitivity Simulation Of Rice In Hetao Irrigation Area

According to IPCC 5th assessment report, global average surface temperature was on the rise with 0.05 ℃/10a in 1998～2012. In context of global warming, the rate is 0.22 ℃/10a, significantly higher in global, significantly higher in North and Qinghai-Tibet Plateau than other areas nearly 50 in China. Climate warming made heat resource in crop growth period, resulting in a drop of defense against chilling damage; crop boundaries movement northward and eastward, early maturing crop varieties gradually be replaced in late maturing varieties; regional made chilling damage occurs increasing, loss of chilling damage increases; drought increased, chilling damage increasing caused by artificial irrigation, increased incidence of chilling damage. Rice is the most important crop in China, its production is related to food security of country. Its cultivation had a long history in Ningxia Hetao Irrigation area, one of high quality and yield rice area. Late maturing was main grown varieties in Hetao Irrigation area, chilling damage occurs frequently in main growing critical period, makes a serious formation impact on growth. Therefore, study of chilling damage on growth and development of rice has a great significance.This study is based on CERES-Rice model of DSSAT system, combined with data of weather, soil, field observations, experimental and production information, localized genetic parameters of typical cultivation methods, simulate chilling damage, determine the impact of chilling damage on growth process in different stages, provide reliable technical support for decision management and climate change management in Ningxia Hetao Irrigation area. The main conclusions as follows:1. The crop growth model validation:Used field test data in Zhongwei to verify time defender of CERES-Rice model. The ability of simulate yield and number at maturity of rice with CERES-Rice model was good, description days from planting to anthesis and days from planting to maturity had good analog capability. Used rice test data of 10 sites in Hetao Irrigation area to verify space simulation, simulation and observation between yield and number at maturity had small analog, description CERES-Rice model also had the ability to simulate in space.2. Climate change analysis from 1960～2013 in Hetao Irrigation area: Temperature changes from 1960 to 2013 in Hetao Irrigation area showed, annual average maximum temperature rise minimum, annual average minimum temperature rose maximum. Average temperature nearly 30a(9.64℃) rose 0.44℃ from 1974 to 2003, description temperature continued warming. In background of warming temperature continued, there were still significantly lower than average temperatures in many years, chilling damage frequently. Annual precipitation declined of 3.93mm/10a from 1960～2013. Average sunshine hours was 2969h from 1960 to 2012, with 65h/10a tendency rate. Trend of sunshine hours particularly significantly reduced since the 21st century. Average maximum and minimum temperature had mutation, was in 1995 and 1988.2-4a periodic changed in annual average maximum temperature, annual temperature, annual precipitation and annual sunshine hours was more significant. There was significant period of change in 2.5-3a in annual average minimum temperature. Annual average temperature had 2-4a and 3-4a significant changes. Annual precipitation had significant 4-8a and 4-7a changes.3. Simulation and verification of chilling damage with CERES-Rice model:By the simulation results of rice chilling damage in Hetao Irrigation area from 1981 to 2012 showed that most of the rate of change in the yield between-10%～+10%, average RMSE was 526.03 kg/hm2, overall error was small; each growth stage E value was smaller, the degress of deviation was smaller; EF values were less than 0.75, lower compound between simulation and observation values; D values were greater than 0.85, higher consistency. Description CERES-Rice model also had the ability to simulation to simulate the rice chilling damage.4. Sensitivity simulation study of rice chilling damage in Hetao Irrigation area: 1) Reduced temperature, temperature and radiation degrees in various stages caused days from planting to anthesis and days from planting to maturity increased; reduced radiation in seedling stage had impact. Seedling stage affected by delayed chilling damage maximum, heeding flowering period minimum. Temperature effected large and small with radiation, comprehensive greater impact on rice growth period. Model of seedling stage, simulation of reducing temperature and solar radiation had the largest sensitivity, reduce solar radiation had minimum sensitivity; model of booting stage and heading flowering period, reduced the temperature sensitive, reduce solar radiation was not sensitive; model of filling stage, had the largest sensitivity of temperature, minimum sensitivity of temperature and solar radiation, had no sensitive of reduce solar radiation alone.2) Lower temperature, radiation, temperature and radiation in every growth stage coused varying degrees of yield, longer duration under the same condition, the rate of yield increased. Reduced temperature made more impact on yield reduction rate than radiation, changed temperature and radiation caused the greatest yield reduction rate. Delayed chilling damage made the greatest yield reduction rate in filling stage; disturbance type chilling damage in booting stage obtaina minimum yield reduction rate. Filling stage suffered delayed chilling damage made the highest yield reduction rate, indicting filling stage more vulnerable to impact of chilling damage; booting stage suffer disturbance type chilling damage made the lowest yield reduction rate, indicat booting stage uncomfortable chilling damage. Delayed chilling damage, reduced temperature got 26.5% average maximum yield reduction rate, reduced radiation was 14.25%, reducd temperature and radiation got 31.25% average maximum yield reduction rate. In disturbance type chilling damage, reduced temperature got 2.1% maximum yield reduction rate, reduced radiation got yield reduction rate of 6.9%, reducing temperature and radiation resulting 5.85% average maximum yield reduction rate. Model of seedling stage, booting stage, heading flowering period and filling stage, reduced temperature and solar radiation had maximum sensitivity, reduced solar radiation had minimum sensitivity. Model of delayed chilling damage and low levels of disturbance type chilling damage was better; when temperature was below 14℃, the simulation of disturbance type chilling damage was less effective; taken together, simulation of rice chilling damage was good.