Table of Content

10 June 1997, Volume 18 Issue 03

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Analysis and Forecast of ≥10℃ Effective Accumulated Temperature (EAT) in Northeast China

Wang Yongguang Ai Wanxiu (National Climate Centre, Beijing 100081)

1997, 18(03):  . 

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In this paper, the basis and reason for the use of the temperature 10℃ as the critical temperature of the effective accumulated temperature (EAT) in Northeast China were discussed. From the point of EAT forecast, the EAT anomaly was redefined with 40% sample size. The relationship between the 500 hPa circulation and ≥10℃ EAT, as well as the mechanism of the influence of the 500 hPa circulation upon EAT were analysed using the methods of composite height anomaly chart and analogue index. By calculating the 500 hPa analogue index of each area, it was found that the feature of three areas is very useful for EAT forecast, especialy for forecast of anomalous lower EAT.

A Comparison of Growth and Development Characters of Wheat Sown in Latesummer and Early Autumn with Those Sown in Winter in Guizhou Plateau

Zhao Zhi Li Jiaxiu Yang Changda Zhang Chengqi (Dept. of Agronomy, Guizhou Agric. Coll., Guiyang 550025)

1997, 18(03):  . 

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The experiment conducted showed that, because of the acceleration of higher temperature to growth and development of spring wheat cultivars, the vegetative growth of late summer and early autumn sowing wheat finished rapidly. They produced fewer tillers and smaller leaf area, accumulated less dry matter and had shorter period of duration and lower grain yield as compared with winter sowing wheat . The number of spikes per mu was found to be the main limiting factor to high grain yield of late summer and early autumn sowing wheat. In most of the years, the number of grains and 1000 grain weigh of late summer and early autumn sowing wheat were less than those of winter sowing wheat. Eco climatic conditions were considered as the main factors determining both of the traits.

Studies on The Resistance of Rice to Low Temperature in Cold Region Ⅰ. The Quantitative Relationship of Seed Water Absorption and Germination to Temperature

Wang Lianmin Wang Lizhi Zhang Guomin (Crop Cultivation Research Institute of Heilongjiang Academy of Agricultural Sciences, Haerbin 150086)

1997, 18(03):  . 

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Based on the results of water absorption and germination of 8 rice cultivars (lines) under different temperature regimes, we determined their threshold low temperature and effective accumulated temperature required for 50% seeds germination by using growth curve model. The results showed that the threshold low temperature and effective accumulated temperature for 50% seeds germination of H35013 were low, indicating that its low temperature tolerance is stronger at germinating stage. The effects of temperature on water absorption by rice seeds were also elucidated.

The Development and Application of Thermal Methods for Measuring Sap Flow

Luo Zhongling (Institute of Agrometeorology, Chinese Academy of Agricultural Sciences, Beijing 100081)

1997, 18(03):  . 

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The historical development of thermal methods and techniques for the measurement of stem sap flow is described briefly in this paper. Thermal technique has been used as a tracer to measure the velocity of sap flow since 1932. In the heat pulse velocities (HPV) method, the timed transport of a temperature pulse over the distance from the source to a given point downstream yields an estimate of the velocity of the sap flow. The quantity of sap flow is calculated from flow geometry, cross sectional area and flow velocity. In another development, stead state thermal heat balance (THB) method was proposed in the 1980’s. The theory of THB is based on the pattern of diffusion within the flow medium. Actual flow is calculated by determining the amount of heat taken away by the flow. Use of this method does not alter any of the environmental or physiological factors affecting the transpiration process. THB was mainly used in field crops or horticulture plants. Both HPV and THB techniques require relatively more complex instumentations, they are only suitable for scientific use in the near future.

Correlation Analysis of Air Temperature and Humidity in the Inside and Outside of Tea Garden with Plastic Shed

Chen Haisheng Huang Shoubo Yu Zhongwei Fan Xinghai Xu Yamei (Zhejiang Agricultural University, Hangzhou 310029) Xu Yuwen Han Wenyan Wang Guoqing (Tea Research Institute, Chinese Academy of Agricultural Sciences)

1997, 18(03):  . 

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Correlation analysis and curve fitting were conducted for the following variables recorded from the inside and outside of tea garden with plastic shed: daily average temperature, average temperature at 2:00 PM, lowest temperature, average air relative humidity and lowest air relative humidity, and corresponding regreesion equations were established. The equations could be used to estimate the increases in temperature, humidity and cold resistance in the arch plastic shed.

Estmation of Production Potential of Wheat in Nanjing as Influenced by Future Climatic Changes

Zheng Youfei Wan Changjian Xu Weixin (Nanjing Institute of Meteorology, Nanjing 210044)

1997, 18(03):  . 

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Change in sloar UV radiation and its effect on wheat growth have not received adequate attention in studies investigating the changing trend of climate resulting from CO 2 doubling and its influence on wheat. Our experiments showed that enhanced solar UV radiation could produce negative effects on wheat, leading to shortened plants, poor growth, inhibition of normal physiological activites and decrease in yield. Based on the overall evaluation of climatic changes, including solar UV radiation, on wheat production, estimates of climatic production potential were obtained for winter wheat grown in Nanjing under doubling CO 2 concentration.

Meteorological Disasters for Fruit Trees and Their Prevention System in China

Huang Shoubo Shen Chaodong Shen ShuguangShao Naner Cai Jian(Zhejiang Agricultural University, Hangzhou 310029)(Jiangshan meteorological bureau)

1997, 18(03):  . 

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Injury to fruit trees, from hazardous weather, is the major natural calamity of fruit trees growing regions in China. It affects the normal development of fruit trees and their yield. Based on the geographic distribution of fruit trees and the types of meteorological disasters in fruit tree growing regions in China, an integrated system against these disasters was proposed which consists of 8 sub systems. Losses of fruit production due to these disasters could be minimized by adopting this system.