Chinese Journal of Agrometeorology

Analysis of Annual Climate Types and Its Impact on Summer Maize in the North China Plain over the Period 1961-2015

MA Xue-qing, HU Qi, PAN Xue-biao, WANG Jing, HU Li-ting, LI E, HUANG Bin-xiang,

2019, 40(02): 65-75. doi:10.3969/j.issn.1000-6362.2019.02.001

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Based on the 1961-2015 ground surface data from 55 meteorological stations in the summer maize plating area of the North China Plain, annual climate types and its impact on potential summer maize yield were analyzed. Ten annual climate types were determined by calculating the abnormality of mean temperature, precipitation and solar radiation in summer maize growing season. In the past 55 years, the drought year showed the greatest frequencies with the average value of 15.8, followed by the rainy year and the cloudy year, and the least frequencies were the warm and rainy year, as well as the high temperature year. The drought year and the wet year both most occurred in the middle east of Hebei and the middle east of Shandong, and the warm and dry year was mainly found in the northern North China Plain. The cloudy year showed least variations among different regions. Both the normal year and the rainy year showed significant decreasing trends, while significant increasing trends were found for the frequencies of the warm and dry year, the warm and wet year, the high temperature year, and the cloudy year (P<0.05）. Precipitation and solar radiation are the main limiting factors for the potential yield of summer maize in the North China Plain. Compared with the normal year, the potential maize yield in the less rainy year (including the drought year, the warm and dry year and the cold and dry year） reduced by more than 15%, and the warm and dry year type had the greatest influence on the potential yield. The cloudy year showed 12.5% lower potential maize yield than the normal year, and significant differences were found among regions.

Applicability Evaluation of Snow Depth Reanalysis Data in Xilinhot and its Surrounding Areas

WANG Fei, ZHU Zhong-yuan, HAO Xiang-yun, SONG Hai-qing, HAN Dong-dong

2019, 40(02): 76-85. doi:10.3969/j.issn.1000-6362.2019.02.002

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The snow cover data from 1981 to 2010 in the ERA-Interim global reanalysis and the ERA Interim/Land model (ERA-Land) were provided by the European Mid-term Forecasting Center (ECMWF). The observing datasets from 8 national meteorological stations surrounded by Xilinhot (including Xilinhaote, Dongwuzhumuqi, Xiwuzhumuqi, Zhenglanqi, Duolun County, Narenbaolig, and Keshiketengqi) were taken as a standard to calculate the correlation coefficient, average deviation, standard deviation ratio and other statistical parameters of the reanalysis data, which were combined with the linear change comparison and the quality index and the Brunke ranking method. The applicability of the snow depth reanalysis was comprehensively evaluated in Xilinhaote area. The results showed that both the ERA-Interirn and ERA-Land data performed the seasonal variation trend of snow depth in the study area well, however, the latter one gained better simulation results and good stability. Xilinhot and its east site were more reproducible than the western site; ERA-Land data had better simulation effect and good stability, and the northern stations had better consistency than the southern stations; ERA-Land data in most of Xilinhot area had a good quality trend, Naren Station was the most obvious, in Zhenglanqi Station south of Xilinhot, Duolun County Station showed a trend of variation, but the variation rate was very small; The ranking results were the best in east Wuzhuqinqi station and the worst in Zhenglan banner.

Characteristics of Grassland Degradation in the Qinghai Tibetan Plateau, Based on NDVI3g Data

CAO Xu-juan，HASBAGAN Ganjurjav，HU Guo-zheng，GAO Qing-zhu

2019, 40(02): 86-95. doi:10.3969/j.issn.1000-6362.2019.02.003

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The Qinghai-Tibetan Plateau is an important ecological security barrier and animal husbandry base in China. Alpine grassland is the largest ecosystem in the Qinghai-Tibetan Plateau, accounting for more than 60% of the total area of the plateau. In recent years, the alpine grasslands in the Qinghai-Tibetan Plateau are experienced large area of degradation, which is restricting the ecological services of the plateau and the sustainable development of animal husbandry. To date, however, it is remaining unclear in the status of grassland degradation on the Qinghai-Tibetan Plateau. In this study, the degradation status was presented by the grassland degradation index, which was retrieved from vegetation coverage, based on NDVI3g data. The results showed that the current situation (2011-2013) of average grassland degradation index in the Qinghai-Tibetan Plateau was 1.76, which indicated light degradation level. The area of degraded grassland reached 41% and has no change compared with the historical average (1986-2010), but the areas of moderate, severe, and extra severe degradation has been increased in the Qinghai-Tibetan Plateau. The areas of slight, moderate, severe, and extra severe degraded grassland were 22%, 8%, 6% and 5%, respectively during 2011 to 2013, while they reached 28% (slight), 7% (moderate), 4% (severe) and 1% (extra severe) during 1986 to 2010. The degradation index in alpine desert was 3.23 during 2011 to 2013, which reached an extremely degradation level. The degradation index in the alpine meadow and alpine grassland steppe were 1.49 and 1.57, respectively during 2011 to 2013, which were characterized as light degradation level. In the Qinghai-Tibetan Plateau, the degraded area of grassland in Xinjiang reached 71%, higher than that in Qinghai and Tibet, which reached 42% and 41%, respectively. The degraded area of grassland in Gansu, Sichuan and Yunnan were relatively small, reached 25%, 10% and 12%, respectively, in the Qinghai-Tibetan Plateau. In summary, there exist spatiotemporal variations in grassland degradation in the Qinghai-Tibetan Plateau. There is no significant change in current grassland degradation status compared with the historical average. However, in some regions on the plateau, i.e. alpine region, the grasslands showed a continuously degrading trend.

Human-grain Relationship and Its Future Change in Yunnan Based on Climatic Potential Productivity

LI Meng, ZHU Yong, ZHOU Jian-qin, MA Si-yuan

2019, 40(02): 96-104. doi:10.3969/j.issn.1000-6362.2019.02.004

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In order to analyze and compare population carrying capacity and human-grain relationship based on food supply and climatic potential productivity (Tspv) in Yunnan, population carrying capacity and human-grain relationship under future climate change were predicted. In this study, using average temperature and annual precipitation observed by 117 meteorological stations in Yunnan in 1961?2015 and simulated by the global climate model in 2016-2055, the temporal-spatial changing characteristics of Tspv in various regions of Yunnan were calculated and analyzed by the Thornthwaite Memorial model, and Tspv -population carrying capacity and climate carrying capacity were constructed and calculated. The results showed that: (1) Tspv in Yunnan presented obvious zonal and vertical distribution. Overall, Tspv was higher in the south than that in the north, and higher in areas at low altitude than that in areas at high altitude. Precipitation is the main limiting factor of Tspv in Yunnan. (2)In 1961-2015, Tspv only significantly increased in partial areas of western Yunnan, significantly decreased in local areas of central Yunnan, and showed no obvious change in other areas. Average Tspv in Yunnan presented large inter-annual fluctuations and a significant change around 2009. (3)In 2006-2015, per capita grain supply in Yunnan grew steadily, approaching or exceeding the demand of well-off grain. Cultivated land-population carrying capacity increased year by year, but was far lower than Tspv-population carrying capacity. Although during year with a sharp yield reduction, Tspv-population carrying capacity could still meet the demand of affluent grain under current population and cultivated land scale, with a surplus human-grain relationship. (4)With current stable amplitude of population, cultivated land and productivity, Tspv and Tspv-population carrying capacity in Yunnan will increase stably, and human-grain relationship will mainly be grain surplus under different emissions in the future. The carrying capacity and human-grain relationship under high emission will be superior to low emission.

Method to Characterize the Degree of Chilling Injury with the Cloudy-Cold Index

CHEN Hui-lin, HUO Zhi-guo, TIAN Guang-hui, TONG Jin-he

2019, 40(02): 105-113. doi:10.3969/j.issn.1000-6362.2019.02.005

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In view of the problem that the existing chilling injure analysis lacked the representation of the overcast and rainy condition, the cloudy-cold index model was proposed in this article. Based on the ranking of the degrees of cloudy and cold of each city and county in Hainan by the experts of agriculture and meteorology, and daily meteorological data from 1971 to 2010 in each city and county in Hainan, the cloudy-cold index model which could reflect the combined effect of low temperature intensity and rainy-sunless was constructed by using the Uniform Experiment Design method. Based on the relationship in the cloudy-cold index model, the cloudy-cold index of each cloudy-cold event in cities and counties in Hainan during the period from 1971 to 2010 was calculated. Severe, moderate and mild chilling injures and their indicators were divided by 10%, 30% and 60% of the cloudy-cold index sequence. The distribution and changes of the chilling injure in Hainan were further analyzed, and the geographical distribution characteristics of the cold disaster were consistent with the actual service of the chilling injure in practice. The yearly change of the cold disaster was well confirmed in the record of the chilling injure in the Chinese Meteorological Disaster Ceremony which showed that the model had a certain practical application, which can provide a new technical method for the monitoring, early warning and evaluation of chilling injure.

Characteristics of Low Temperature in Spring and its Effect on Crops Seeding Dates in 2013 in Heilongjiang Province

JIANG Li-xia, WANG Ping, WANG Dong-dong, LIAN Ping, WU Shuang, ZHANG Xue-mei,YAN Ping, LI Xiu-fen

2019, 40(02): 114-125. doi:10.3969/j.issn.1000-6362.2019.02.006

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Based on the spring meteorological observation data from 28 agro-meteorological stations in very cold region, Heilongjiang province during 1971 to 2016, by introducing the daily average air temperature, minimum air temperature and maximum air temperature and using mathematical statistics method, characteristics of typical low temperature of three spring temperature factors was investigated in 2013, and the correlation between temperature and seeding dates of soybean, maize and rice was analyzed. The results showed that the spring temperature in 2013 was generally lower than the temperature in the same period of each year during 1971 to 2016 in the research area, the years which ΔT was below 0℃ were dense after the early 1990s, and its number of years of the maximum air temperature was most, but the number of years of the minimum air temperature is least. At the same time, ΔT of the three temperature factors all showed a declining trend. ΔTof the minimum air temperature declined significantly, and it changed dramatically, however change trend of ΔT of the maximum air temperature was not significant, and this indicated that ΔT of minimum air temperature and maximum air temperature reduced non-symmetrically. The daily spring temperature in 2013 was generally lower than the perennial temperature in the research area, duration of the low temperature was long and days of ΔTD＜0℃ exceeded 50% of the total spring days. The maximum continuous days of the low temperature accounted for more than 20% of the total spring days, and the days of the daily maximum temperature is most, 61% of the stations reached 35 days or more, and the low temperature lasted for more than one month. Compared with the historical seeding dates in each year, the seeding dates of soybean, maize and rice in 2013 were mainly delayed. Correlation between ΔTof the spring temperature and ΔD of crops seeding dates was significant in 53% stations, which showed that the spring temperature reduced and the seeding dates would be late. ΔTof each temperature factor decreased 1℃, and ΔDof seeding dates increased about 0.9?6.3 days. In particular, the impact of minimum air temperature was most significant. The combination of waterlogging and low temperature was more likely to cause late sowing of crops.

Effects of Shading and Light Restoration on Photosynthetic Characteristics of Tomato Leaves during Flowering and Fruit Period

ZHU Yu-qing, XUE Xiao-ping

2019, 40(02): 126-134. doi:10.3969/j.issn.1000-6362.2019.02.007

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In order to reveal the changes of photosynthetic parameters of tomato leaves under different shading days and the recovery ability of leaf photosynthetic parameters after light restoration, the shading and light restoration experiment on potatoes with solar greenhouse was conducted, taking the infinite-growth-typed tomato “Power Corolla (Lycopersicon esculentum?Mill) ” as material, putting tomatoes in greenhouse during the flowering and fruiting period, and 5 different shading days treatments were designed: T1 (3 days shading), T2 (6 days shading), T3 (9 days shading), T4 (12 days shading) and T5 (15 days shading). The natural light in the greenhouse was used as the control (CK). The results showed that shading decreased the light saturation point and increased the light compensation point of tomato leaves comparing with CK. Net photosynthetic rate of tomato leaf after shading 15 days decreased by 49.0%, and intercellular carbon dioxide concentration increased by 68.3%. With shading days growing, stomatal conductance and transpiration rate decreased quickly after a short increasing, which decreased by 32.9% and 1.60% respectively after shading 15 days. The content of chlorophyll a, chlorophyll b and carotenoids increased by 125.2%, 182.6% and 115.4% respectively when the shading days growing, and the change of chlorophyll b content was significant (P<0.05). Among the fluorescence parameters in tomato leaves, F0 increased with shading days growing, and increased by 30.87% after shading 15 days, while ΦPSⅡ, qP and ETR decreased with the shading days growing, and they decreased by 32.4%, 29.8% and 36.7% respectively after shading 15 days. Nonetheless, the response of Fv/Fm to shading environment was not significant. The shading days had different effects on the recovery ability of different leaf parameters, shading more than 12 days made leaf net photosynthetic rate and intercellular carbon dioxide concentration unable to restore to original state. The chlorophyll content in leaves could not be recovered when shading more than 9 days, the recovery capability of chlorophyll a and carotenoids was better than that of the chlorophyll b. When shading period was less than 9 days, the photosynthetic parameters and chlorophyll content of tomato leaves could be restored to the initial state after the recovery process.

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