| Hubei province is one of the main production areas of rice, mid-season rice cultivation occupies a great proportion. In the background of the current climate change, impacts of climate change on mid-season rice production can’t be ignored. To definite the spatial and temporal evolution characteristics of potential productivity of mid-season rice plays an important role in assessing possible impacts of climate change on production and guaranteeing food security.This study used computer numerical simulation to establish growth period model of mid-season rice and simulation mode of occurrence probability of heat injury and chilling injury varies with time, the suitable sowing date and suitable growth season of mid-season rice suffered low risk of heat injury and chilling injury were ensured. When referencing the relevant computing model about potential productivity, an innovative design of the radiation distribution and leaf area index changes with the growth stage in rice canopy for photosynthetic active radiation conversion and utilization module was been made to improve calculation mode, then estimated potential productivity under suitable sowing date of mid-season rice in regions of the province, finally studied the characteristics of time and spatial from the points of view of regional distribution and decadal trend for potential productivity. The main contents and conclusions are as follows:Based on the theory of physiological development time constant, this study established a comprehensive growth period model of mid-season rice considered the effects of temperature and photoperiod by using the growing period in different sowing date of mid-season and the climate data at same time. And the Marquardt algorithm was used to determine the relevant model parameters. The prediction error(root mean squared error) between the simulated and the observed was 1.4d at heading stage, 1.4d at mature stage.From the perspective of reducing the risk of heat injury and chilling injury of mid-season rice, combined with the historical climate data during 1961~2010, the change with time of heat injury and chilling injury risk probability in mid-season rice’s growth season were simulated. A safe period of mid-season rice suffered low risk of heat injury and chilling injury was ensured, namely appropriate heading period, the results showed that the duration of most of sites are more than 15 d, the longest duration reached 30 d except that the appropriate heading duration of the few sites were less than 10 d within the province. In the geographical distribution, in Jianghan plain area the duration was the longest, in the northwest of Hubei province, the duration was shortest.Based on the purpose to let the heading and flowering stage was filled as complete as possible in the heading appropriate period and drop the probability of victimization, according to the established model and the duration of the appropriate heading period, determined the appropriate sowing date of each area, and simulated suitable growth season of mid-season rice, it showed that the suitable sowing date of a few sites in the west of Hubei Province were in mid to late April and mainly distributed in the mid to late May in the province’s other site area.Through the simulation of Gauss integral five points hierarchical method and leaf area index changes with the growth stage, the use of photosynthetic active radiation in internal canopy of rice was calculated and analyzed, based on this the calculation model of photosynthetic potential productivity was improved. Based on the climate data from 1960 to 2010, used mechanism analysis to calculate potential productivity in mid-season rice growth period, used the linear trend line and drew geographic distribution in Surfer and so on, analyzed on the characteristics of time and spatial for potential productivity. |
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