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20 May 2017, Volume 38 Issue 05

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Spatiotemporal Variation and Causes Analysis of Dry-wet Climate at Different Time Scales in North China Plain

HU Qi, DONG Bei, PAN Xue-biao, WANG Xiao-xiao, WEI Pei, ZHAO Hai-han, ZHANG Xu-ting

2017, 38(05):  267-277.  doi:10.3969/j.issn.1000-6362.2017.05.001

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Global warming has caused non-uniform changes in precipitation intensity and distribution, which will inevitable impact on the wet and dry climate. In order to make clear the distribution of dry-wet climate zone and changes have occurred in recent 54 years, authors analyzed the temporal and spatial variation characteristics of dry and wet climate in North China Plain over the period 1961 to 2014 in this paper. The influence of main meteorological factors on ET0 was also been studied by using the sensitivity and contribution rate method, as well as the causes for dry-wet climate variation. In this study, 62 meteorological stations each with 54-year data record （from 1961 to 2012） were selected in China （including Beijing, Tianjin, Shandong, Henan and Hebei）, ET0 was then calculated by using Penman-Monteith method. The results showed that the area of semi-arid area was expanding continuously since the dividing line for semi-arid area and semi-humid area extended eastward and southward in three periods （period 1:1961-1980; period 2:1981-2000; period 3:2001-2014）. However, the humid area did not show significant changing trend. Precipitation showed non-significant trend over the period 1961 to 2014, while ET0 showed a significant decreasing trend with large spatial differences. In most parts of Henan and Shandong, the climate became wet because that the negative trend for ET0 is larger than the decreasing trend for precipitation. On the contrast, most of Tianjin and Hebei regions showed significant dry trend rates with the decreasing precipitation and increasing ET0. As for the main contribution factor to ET0 changes in each month, wind speed was the dominant factor in November to the following January, temperature in February, and sunshine hours in June to September. The main contribution factors to ET0 in other months were result from the combined effects of relative humidity and wind speed.

Evaluation of 16 Models for Reference Crop Evapotranspiration (ET0) Based on Daily Values of Weighing Lysimeter Measurements

LIU Xiao-ying, LI Yu-zhong, ZHONG Xiu-li, CAO Jin-feng, YUAN Xiao-huan

2017, 38(05):  278-291.  doi:10.3969/j.issn.1000-6362.2017.05.002

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Accurate estimation of reference crop evapotranspiration (ET0) is essential due to its critical role in determining crop water use and regional assessment of water supply and demand. Though numerous models have been developed, their rigorous test with measured data is lacking. In this paper daily estimates of 16 ET0 models, including five combination-, six radiation- and five temperature-based ones, were evaluated with measurements from April through October in 2012 at a semiarid site of Xiaotangshan, Beijing, China. Daily ET0 was measured by two weighing lysimeters （length×width×depth =1.3m×1.3m×2.3m） located in a fescue grass （Festuca arundinacea Schreb） plot surrounded by a 167ha crop. On basis of root mean square error （RMSE） we found the performance ranking: FAO79 Penman =1963 Peman＞1996 Kimberly Penman＞FAO24 Penman＞FAO56 Penman-Monteith（PM）＞Turc＞FAO24 Blaney-Criddle（BC）＞DeBruin-Keijman＞Jensen-Haise>Priestley-Taylor （PT）＞FAO24 Radiation＞Hargreaves＞Makkink＞Hamon＞Mcloud＞Blaney-Criddle（BC）. Overall, the combination models performed best with RMSE of 1.33-1.47mm?d-1, followed by the radiation models with RMSE of 1.48-1.77mm?d-1 and the temperature models with RMSE of 1.50-2.68mm?d-1. The best FAO79 Penman and 1963 Penman were respectively 10% and 13% more accurate than the best radiation （Turc） and temperature （FAO24 Blaney-Criddle） models. Better performance of the combination and radiation models was due to that they explicitly contain dominant factors（radiation or vapor pressure deficit（VPD））influencing ET0. All models tended to overestimate at low evaporative rate while underestimate at high rate the measured values, exhibiting threshold feature, but on average the combination and radiation methods respectively underestimated by 0.14mm?d-1 and 0.33mm?d-1, whereas the temperature method overestimated by 0.52mm?d-1. The former two had relatively lower threshold ET0 than the latter, and they were thus more applicable to low evaporative condition, and vice versa for the latter. All combination and radiation models, and the Hargreaves and FAO24 BC in temperature method captured measurement trend and showed robust structure. To improve them future efforts should be on local calibration, but for temperature models not capturing measurement trend future focus should be on structure optimization. VPD and maximum humidity RHx were two main factors affecting deviation of combination and radiation methods. The former affected models with underestimation in a positive manner, and the latter affected those with overestimation （1963 Penman、FAO79 Penman） in a negative manner. The calibrated coefficients of the PT （1.38）, Makkink （0.83）, Turc （0.014） and Hamon （1.248） were higher while those of the Hargreaves （0.0019） and BC （0.192） were lower than the original ones. Coefficients of PT and Hamon can also be best estimated with minimum humidity, and those of Turc and Makkink with VPD, and Hargreaves and BC with radiation or sunshine hours. The degree of climate dryness of the study site and the lower relative weight to the aerodynamic component were responsible for poor behavior （RMSE=1.47mm?d-1） of the FAO56 PM. Later modifications to wind function of original Penman appeared fruitless, and therefore we suggest continued use of the older Penman equations in climate similar to our site in China. Meanwhile, more tests of the FAO56 PM against measurements would be valuable to answer questions like “Is the FAO56 PM really superior to the older Penman equations solely in terms of accuracy”, “in what climate it performs better” and “Is it common that it underestimates in high evaporative condition”.

Effects of Total Solids Content and Inoculation Ratio on Anaerobic Digestion of Swine Manure

XU Wen-qian, DONG Hong-min, CHEN Yong-xing, SHANG Bin, TAO Xiu-ping, ZHANG Wan-qin

2017, 38(05):  292-300.  doi:10.3969/j.issn.1000-6362.2017.05.003

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In order to investigate the effects of different total solids content（4%, 6%, 8%）and inoculation ratio （rI/S=1.5, 2.0, 3.0）on the mesophilic anaerobic digestion of swine manure, batch experiments were conducted using the Automatic Methane Potential Test System. Results showed that total solids content and inoculation ratio had a significant effect on daily and accumulated biogas production, and total solids content played a much more role than inoculation ratio. On the basis of the experimental parameters, the cumulative methane yield increases with the increase of the inoculation ratio, while with the increase of total solids content decreases after increasing first. The highest cumulative biogas yield and methane yield (469.1mL·g-1VS and 333.2mL·g-1VS) was achieved with total solids content of 6% and rI/S of 3.0. In addition, the kinetic model shows that the lower total solids content and the higher inoculation ratio increased the average daily methane production rate and shortened the lag phase of methanogenesis. The first-order kinetic model showed a better fit to the experimental results than the modified Gompertz model, and to a certain extent, the fit accuracy was improved with the increase in total solids content and inoculum rate.

Effects of Far-red Light on the Growth and Qualities of Lettuce in Plant Factory

MA Tai-guang,CHEN Xiao-li,GUO Wen-zhong,LI Ling-zhi,LI Hai-ping

2017, 38(05):  301-307.  doi:10.3969/j.issn.1000-6362.2017.05.004

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The experiment was carried out in a closed plant factory, where white light irradiation for 12h (0：00-12：00) was used as the basal light to ensure the normal growth of lettuce. Two kinds of LED far-red light (peak at 850nm and 930nm) were used as supplemental light. Three modes of far-red light that were respectively semi-overlapped(S), overlapped(O) and non-overlapped(N) relative to the basal white light were applied by adjusting the on and off time of far-red light. That was, six treatments which were respectively Fr930S, Fr850S, Fr930O, Fr850O, Fr930N, and Fr850N had been examined in the study. The light intensity, lighting period as well as the electric energy consumption were the same among treatments. The growth and nutritional qualities of lettuce were measured in order to analyze the effects of different?far-red light as well as to determine the best supply mode of far-red light. The results showed that: (1) different modes of far-red light with the same peak wavelength resulted in various influence on the growth and quality of lettuce. Meanwhile, different peak wavelengths of far-red light with the same supply mode also caused discrepancies in the growth and quality of lettuce. (2) Among the six light treatments, the fresh weight of shoot was the highest under 850nm far-red light with non-overlapped mode; The crude protein and soluble sugar content were both the highest under 850nm far-red light with semi-overlapped mode; The highest vitamin C content as well as the lowest nitrate content were both detected under 930nm far-red with non-overlapped mode. Therefore, during the practical production, based on the same energy consumption, people can choose and adjust the wavelength and supply modes of far-red light according to different productive purposes.

Climatic Suitability Assessment of Dangshansu Pear in the Area along the Abandoned Channel of the Yellow River Based on Cloud Model

LI De, ZHOU Wen-lin,SUN Yi, SUN Hui-he

2017, 38(05):  308-320.  doi:10.3969/j.issn.1000-6362.2017.05.005

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The impact of climate conditions on the growth and development of Dangshansu pear is evaluated. It is great significance in coping with climate change, regional climate resources development and utilization. In this paper, the representative origin named Dangshan County of Dangshansu pear in the area along the abandoned channel of the Yellow River is selected as the sampling point. Based on the cloud model theory, the climatic suitability of light, temperature and water were established by using long-term observation data and meteorological monitoring data in the phenophase of Dangshansu pear. The climatic suitability of different phenological periods and interannual ages were determined by weighted combination method and geometric mean method. The results showed that the sunshine suitability could be described by the left half cloud model and the temperature and precipitation suitability could be described by trapezoidal cloud. The correlation coefficients of integrated climatic suitability with actual yield, climate yield and yield per plant were 0.4452 (P＜0.05), 0.3734 and 0.5620 (P＜0.01), respectively. From 1961 to 2015, the variation trend of climate suitability of Dangshansu pear is not obvious, but in 1961-1989 and 1990-2010, it is the higher and lower period of climate suitability respectively. In 1987, the accumulated anomaly of climate suitability is the largest. During the study period, the temperature suitability increased remarkably, increasing by 0.0274·10y-1. The suitability of sunshine and precipitation has no obvious variation trend. The average of precipitation suitability is lower than that of sunshine and temperature, and the coefficient of variation is four times of that of sunshine and temperature suitability. The climatic suitability of each phenological period did not show a trend change, but the climatic suitability of sprouting stage and flowering stage was low (between 0.50 and 0.53), and the coefficient of variation was large (between 45.0 and 57.0).The climatic suitability and coefficient of variation of other phenological periods were relatively small. In the background of climate change, the increase of temperature is beneficial to the growth of pear. The management of germination and flowering period should be strengthened in the production of Dangshansu pear to enhance the climate suitability of pear trees.

Effects of Lodging at the Late Growth Stage on Dry Matter Distribution and Yield of Winter Wheat

LIU Zhong-yang, CHEN Huai-liang, HU Cheng-da, GUO Peng

2017, 38(05):  321-329.  doi:10.3969/j.issn.1000-6362.2017.05.006

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Winter wheat lodging experiment was conducted during 2014-2015 by artificial stimulation. Three lodging treatments of 30o(T1), 60o(T2), 90o(T3) angle with the vertical direction were applied during heading stage, the early filling stage, and the middle and late filling stage. No lodging treatment was taken as control(CK). Dry matter (DM) distribution and yield components of winter wheat were investigated. The results indicated that DM distribution was altered due to lodging extend and lodging stage. Lodging at heading stage and the early filling stage decreasedDM accumulation rate, and accelerated DM translocation to panicle from stem and sheath. Leaf DM was altered later. By the corporate effect of insufficient solar radiation and altered transition rate, DM distribution in each organ varied rapidly and the growth rate of stem, leaf and sheath had no significant variation. The lodging at middle and late filling stage led a significant decrease of DM in all organs, and the decrease extent reduced to growth stages.The lodging treatment at heading stage and early filling stage decreased grain yield mainly due to the kernel number and 1000-kernel weight reduction, while middle and late lodging treatment decreased grain yield primarily due to the 1000-kernel weight reduction with a normally kernel number. The extent of yield reduction rate due to lodging was early filling stage > heading stage > middle and late filling stage.