Research On The Characteristics Of Heat Resources And Rice Chilling Injury In The Three Provinces In Northeast China

The Three Northeast Provinces is the important grain production base of our country. Rice is one of the important grain crop in Northeast China which is subject to climate change and chilling injury. Thus, the study on the temporal and spatial variation characteristics of climate heat resources and its influence on the occurrence and development of rice chilling injury has carried an important practical significance for reducing the agricultural economic loss and ensuring the safety of food production.This paper, by using 1961-2014 average daily temperature data from 83 meteorological stations in the three northeast provinces, has obtained the date, duration and accumulated temperature where the temperature exceeds 0℃ and 10℃, by virtue of the 5-day moving average method and further used various statistical analysis methods to analyze the heat resources changes in the three northeastern provinces. Taking the percentage of unfilled grains during 1961 and 2008 calculated from rice growth and yield meteorological effect mode as the basic information to judge sterile-type chilling injury, analyze the spatial distribution characteristics and temporal variation law of sterile-type chilling injury during rice booting stage by cumulative curve anomaly and wavelet analysis; calculate the rice filling degree from 1961 to 2008 by adopting rice growth and yield meteorological effect mode as well as analyze the spatial distribution characteristics and temporal variation law of delaying type chilling injury in Northeast China.The main results are as follows:First, the heat resources as a whole is still showing an increasing trend in Northeast China in the past 54 years, however, there comes the turning point in the year of 2005 when the annual average temperature, the accumulated temperature that has surpassed 0℃ and 10℃ as well as its duration are all converted to a decreasing trend, for the start date is relatively delayed; The end date is relatively ahead of schedule and the overall heat resource is entering a slow reduction phase.Second, sterile-type chilling injury during rice booting stage in Northeast China mainly occurs in the northeast of Jilin Province and the southeast of Heilongjiang Province. In the past 50 years, the phasic variation of chilling injury in Jilin Province is similar to Heilongjiang Province; the phasic variation of chilling injury in Liaoning Province appears no obvious change. As for the chilling injury in Jilin Province and Heilongjiang Province, there is a quasi-periodic variation at 24a、16a and 24a、8a respectively whereas there is no significant quasi period in Liaoning Province. With the advent of 21 st century, sterile-type chilling injury during rice booting stage in Northeast China has significantly increased.Third, the delaying type chilling injury in Northeast China mainly occurs in Northeast and Southeast of Heilongjiang Province and Northeast of Jilin Province which has shown an overall decreasing trend; the chilling injury mainly occurred in 1996 and decreased significantly after 1997.In conclusion, this research reveals the characteristics of temporal and spatial variation of the heat resources in Northeast China in the past 54 years and clearly points out that there appears a turning point around the year 2005 so that the overall heat resources of Northeast China has entered into a slow reduction stage. Most especially, this paper adopts the two indexes such as the percentage of unfilled grains and filling degree to completely separate the sterile-type chilling injury and delaying chilling injury, which has set a good foundation for the quantitative definition and in-depth study of rice chilling injury.