Chinese Journal of Agrometeorology

Spatiotemporal Variation of Heat and Solar Resources and Its Impact on Summer Maize in the North China Plain over the Period 1961-2015

YANG Peng-yu, HU Qi, MA Xue-qing, HU Li-ting, REN Fei-yang, YAN Meng-ling,

2018, 39(07): 431-441. doi:10.3969/j.issn.1000-6362.2018.07.001

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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, spatiotemporal distribution and variation of heat and solar resources in annual scale and in different periods were analyzed. In this study, active accumulated temperature over 10℃(DT10) and solar radiation were used as the indices of heat resources and solar resources, respectively, and the impact of the changes in heat resources and solar resources on maize potential yield was also calculated. In the past 55 years, DT10 in the maize growing season has significantly increased by 75.4℃·d, and all the contour lines of accumulated temperature have obviously shifted toward north. As for the solar radiation in maize growing season, a significant decreasing trend was found for each station. In the last 15 years, the DT10 increased by 8% while solar radiation reduced by 16.2% compared to that in 1961?1980. Overall, climate change increased heat resources and reduced solar resources in the North China Plain, which had positive and negative effects on the maize production in the North China Plain. In recent 55 years, photosynthesis-temperature potential productivity of maize showed significant decreasing trend with trend value ?28.3kg·667m?2·10y?1(P<0.05). The area of high photosynthesis-temperature potential yield has also decreased in different period, indicating that the negative effect of the reducing radiation resources on photosynthesis-temperature potential productivity was greater than the positive one due to the increase in heat resources. There is still a lot promoting room for maize productivity in the study area, for the maize yield per unit area only reaches 27.5% of the photosynthesis-temperature potential yield. Further research is needed by comprehensively considering the influence of other climatic factors like precipitation, as well as social factors like agronomic measures.

Nitrification and Denitrification and its Response to Biochar Addition in Agricultural Soil：A Review

ZHAO Guang-xin, ZHANG Qing-wen, LIU Xing-ren, TIAN Xiu-ping

2018, 39(07): 442-452. doi:10.3969/j.issn.1000-6362.2018.07.002

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Nitrous oxide (N2O) is one of the most important greenhouse gases, and agriculture soils are the main emission sources. Nitrification and denitrification, which are dominated by microbes, are the most important emission pathways. Therefore, the soil nitrification and denitrification have been paid much attention by scientists. Based on a large quantity of literatures, this paper summarizes the methods of distinguishing the contribution of nitrification and denitrification to N2O emission, soil N2O production pathway and its influencing factors, and mechanism of the effects of biochar on N2O emission. The results showed that the response of nitrification and denitrification to biochar was different, and there was still a lot of uncertainty in the effect of biochar on N2O emission reduction. The underlying mechanism was not yet clear. As such, this paper proposed the best research method to distinguish the contribution of nitrification and denitrification to N2O emission. Finally, the research prospect of the influencing factors of nitrification and denitrification and the response mechanism of biochar in farmland soil were also proposed.

Effect of Continuous Light with Blue and Red LED on Growth and Quality of Different Lettuce Cultivars

ZHA Ling-yan, LIU Wen-ke

2018, 39(07): 453-461. doi:10.3969/j.issn.1000-6362.2018.07.003

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In order to explore lettuce responses to whole growth period continuous light and diverse responses among cultivars, an experiment was conducted in an environmentally-controlled plant factory equipped with red plus blue LED lamps to investigate the effects of normal lighting (12h/12h, 6：00?18：00, NL) and continuous lighting (24h/0h, 6：00?6：00, CL) on the yield and quality of five hydroponic lettuce cultivars. The results showed that the shoot fresh weights of five lettuce cultivars except ‘Dawei’ cultivar were significantly improved under CL treatments compared with NL treatment. ‘Lvluo’ cultivar showed the greatest amplification among five cultivars. At early growth stage, the leaf chlorophyll contents of five cultivars grown under CL were significantly higher than those grown under NL. While no significant difference of five cultivars’ leaf chlorophyll contents was observed between NL and CL treatments at harvest. Compared to NL treatment, CL treatment significantly increased the soluble sugar, total phenolic and flavonoid contents of five cultivars and anthocyanin contents of two purple cultivars.CL treatment slightly or significantly increased total ascorbic acid content of all lettuce cultivars except ‘Lvluo’ cultivar, and mainly increased in reduction state. CL had no significant effect on dehydroascorbic acid of five cultivars. In short, CL could significantly enhance the yield and biosynthesis of soluble sugar and antioxidant substance. The adaptability of five lettuce cultivars to CL was different, and ‘Lvluo’ cultivar was the most adaptable cultivar. CL during whole growth period has the potential to enhance yield and quality of lettuce in plant factory production.

Relationships between Diffuse Radiation Fraction and Light Use Efficiency and Gross Primary Productivity of Winter Wheat

YANG Xiao-ya, LI Jun, JIANG Xiao-dong, TONG Xiao-juan, YU Qiang

2018, 39(07): 462-467. doi:10.3969/j.issn.1000-6362.2018.07.004

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The quantitative relationships between the diffuse radiation fraction (DF) and light use efficiency (LUE) and gross primary productivity (GPP) from jointing to milky maturity of winter wheat (from April 1, 2004 to May 20 and from April 10, 2005 to May 31) were analyzed in this research on the basis of field CO2 flux observation. The research results can improve the simulation accuracy of LUE model and crop model. The results indicated that the relationship between DF and LUE was significantly positive linear (P＜0.001), and the relationship between DF and GPP was significantly parabolic curve (P＜0.001). LUE increased linearly with the increasing of DF, while GPP increased first and then decreased. Observational experiments on 2004 and 2005 showed that the GPP of winter wheat reached the highest under the condition of moderate solar radiation, with the average values of DF and photosynthetic active radiation (PAR) were 0.57, 27.7molm?2d?1, respectively. The quantitative equations between DF and LUE and GPP in two years were different. The differences were mainly attributed to the different PAR level and the distribution frequency of DF from jointing to milky maturity of winter wheat during the two years.

Analysis on the Temporal and Spatial Changes of Frost Date in the Huaihe River Basin from 1960 to 2015

MA Shang-qian, ZHANG Bo, TANG Min, MA Bin, YANG Mei, LIANG Jing-jing, ZHANG Jia-qi,

2018, 39(07): 468-478. doi:10.3969/j.issn.1000-6362.2018.07.005

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Ground 0cm daily minimum temperature collected at 61 meteorological stations were used to identify the first and last frost dates. Linear trend estimation was used to describe the trends in the first frost date, last frost date and the length of the frost-free period. The Mann-Kendall mutation test, the sliding T-test and the IDW method were used to analyze the mutation year and spatial variations of the first frost date, last frost date and the frost-free period in the Huaihe River Basin. The results showed that: (1) with the speed of 2.15, 2.49, 4.38d·10y?1 (P＜0.01) of the first frost date, the last frost date and the frost-free period, respectively, showing the trends in delaying, advance and extension. The rates of change in the three groups were the most significant in the 1990s, at 16.38, 5.34 and 20.6d·10y-1 (P＜0.01), respectively. (2) The first frost date was spatially late in the south, early in the north, early in the mountain and late in the plain. There were 86.9% of the stations postponing significantly (P＜0.05). The last frost date was early in the southwest, late in northeast, early in the plain and late in the mountain, 83.6% stations showed an early trend with the rate of 3.44-5.92d·10y-1 (P＜0.05). The frost-free period decreased with the increase of latitude and altitude. 93.4% stations passed the 0.05 significant level test, and the extension rate of change was 3.56-7.59d·10y-1 (P＜0.05). (3) The locations of the contour lines of 8 November, 1 April and 220 days were slightly northerly about 1° and 2° than the other climate reference periods and the decadal, with the most obvious trend being around 32°N and 34°N, which corroborated the 2nd conclusion. (4) Mutations of first frost date, last frost date and the frost-free period occurred in 2002, 1995 and 1998, respectively.

Effects of Spraying Foliar Fertilizer in Advance on Cold Dew Wind Resistance of Super Hybrid Late Rice

CAO Na，XIONG Qiang-qiang，CHEN Xiao-rong，HE Hao-hua，ZHU Chang-lan，FU Jun-ru，

2018, 39(07): 479-489. doi:10.3969/j.issn.1000-6362.2018.07.006

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Super hybrid late rice variety WufengyouT025 was used as test material as well as the treatments of spraying foliar fertilizers for 3 concentrations of potassium dihydrogen phosphate (KH2PO4) with 0.1% (P1), 0.3% （P3), 0.5% (P5) and the control for clear water (CK) were set. The effects of spraying P and K fertilizers on the leaf temperature, yield and physiological characteristics in double-season late rice under low temperature conditions during heading and flowering stage were studied. The results showed that rice leaf temperature under the different foliar fertilizer application treatments was higher than that of CK, and the warming effect of treatment P3 was the best during the low temperature period. Leaf chlorophyll content and net photosynthetic rate (Pn) of rice plants decreased gradually with the treatments under low temperature, while the reduction range was the smallest in treatment P3, variation of the different treatments on transpiration rate (Tr), stomatal conductance (Cs), and intercellular CO2 concentration (Ci) presented the same character. The activities of the antioxidative enzymes varied in different degrees and the activities of superoxide dismutase (SOD) and peroxidase (POD) in CK was the highest and P3 was the lowest, while the activity of catalase (CAT) was opposite in the mass that CK was the lowest and P3 was the highest after low temperature advance. Malondialdehyde (MDA) content for the different treatments increased in different degrees after low temperature advance, and that in P3 was the lowest. Under low temperature, foliar spraying potassium dihydrogen phosphate and potash could improve dry matter accumulation to varying degrees during yellow ripening stage, especially panicle dry matter accumulation and achieve the purpose of slowing down the yield decrease, among which treatment P3 was the best. Yield of P3 at the second sowing date (sowing in July 1st) in 2015 encountering low temperature obviously increased by 14.04% compared to CK. It could be found from the yield components that effective panicles per plant, the total grains per panicle, seed setting rate were significantly improved for the all treatments compared to CK. The application of foliar spraying of 0.3% potassium dihydrogen phosphate was the most effective agronomic measure to enhance the resistance to low temperature during heading and flowering stage for double-season super hybrid late rice.

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