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Hong B.,Shaanxi Institute of Zoology | Zhang F.,Shaanxi Institute of Zoology | Li Y.,Shaanxi Institute of Zoology | Zhang S.,Shaanxi Institute of Zoology | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Southern root-knot nematode, Meloidogyne incognita, is an important pathogen of vegetables, and was first observed in South China. With the development of indoor agricultural facilities, it was found for the first time in Shaanxi in 2000, and now is widely distributed through different ecological vegetable growing zones in Northern and Southern Shaanxi, and the Guanzhong area. M. incognita has become a devastating soil-borne disease, causing great economic losses in vegetable production. It survives at soil depths of 5 to 15 cm, and overwinters in the soil as eggs or second instar larvae. Soil temperature is an important factor affecting its overwintering, and this is dependent on climate and plant conditions. Air and soil temperature data for open fields can be obtained from meteorological stations, but soil temperature data for indoor agricultural facilities is not available, and thus mathematical models need to be established to simulate soil temperatures under different cultivation conditions. Each winter (November to the following March) from 2009 to 2012, air and soil temperatures in four agricultural systems in four ecological regions (Yanan, Shangluo, Yangling, and Dali) in Shaanxi Province were automatically recorded. Mathematical models relating air temperature to soil temperature were then developed, and air temperatures from 96 meteorological stations were converted to soil temperatures. Based on the lowest survival temperature of M. incognita measured in the laboratory, a regional map of nematode overwintering was developed, and analyzed for different planting conditions using the Kriging Interpolation of GIS. We found the following: (1) Overwintering of M. incognita was significantly restricted below 1°C. If the temperature was less than-1°C over 32 days, the nematode was not able to overwinter. (2) The relationship between soil temperature and air temperature is linear. We used the following relationship equations between soil temperature (Y) and air temperature (X) in four planting conditions: Y =0.8125X+1.9325, R =0.934 (open field); Y = 0.7943X+1.8563, R = 0.918 (mulched field); Y = 0.7046X+6.2685, R =0.907 (plastic tunnel house); Y = 0. 302X +14. 519, R = 0. 597 (greenhouse). (3) The areas where P values are between 70% and 80% (probability of the average soil temperature of the coldest month being less than-1°C) could be considered the overwintering boundary line for M. incognita. The order of different planting conditions from south to north is: open field, mulched field, and plastic tunnel house. In open fields, the north boundary is through Linyou-Yongshou-Chunhua-Yaozhou-Tongchuan-Baishui-Chengcheng-Hancheng; in mulched fields, the boundary is through Binxian-Xunyi-Yijun-Luochuan-Huanglong-Yichuan; and in plastic tunnel houses is Zhidan-Ganquan-Ansai-Yanan-Yanchuan-Qingjian. However, in greenhouse conditions the nematode can overwinter throughout the whole province. Using GIS and geostatistics methods, we have analyzed the northern boundaries of M. incognita overwintering sites and provided regional classification for open fields, mulched fields, plastic tunnel houses, and greenhouses. Our work makes clear the response of the nematode to low temperature stress, so that rapid and effective monitoring as well as theoretical and technical support for prevention and control can be developed in Shaanxi Province. © 2014, Science Press. All rights reserved. Source


Qu Z.-J.,Shaanxi Meteorological Service Station for Economic Crops | Zhang Y.,Shaanxi Meteorological Service Station for Economic Crops | Wang J.-H.,Shaanxi Meteorological Service Station for Economic Crops | Zhang T.,Shaanxi Meteorological Service Station for Economic Crops | And 2 more authors.
Chinese Journal of Ecology | Year: 2015

An automatic measurement system of microclimate gradients was employed to observe photosynthetically active radiation (PAR), air temperature, tree body temperature, relative humidity at different heights of 6, 3 and 1. 5 meters, and total radiation atop the canopy and soil temperature and humidity from 10 to 60 cm with intervals of 10 cm in an apple orchard on the Loess Plateau from January 2011 to December 2013. The microclimate characteristics of the apple orchard at different growth stages were investigated. The results showed that the total radiation, PAR, air temperature and tree body temperature all presented an obvious diurnal variation with one peak. The total radiation and PAR peaked at 12:50, air temperature and tree body temperature peaked around 16: 00. The total radiation and PAR reached maximum at vigorous growth stage and second at initial growth stage. The air temperature, tree body temperature and soil temperature reached maximum at vigorous growth stage, and came second at initial growth stage. PAR atop the canopy was greater than that beneath the canopy at vigorous growth and dormant stages. The vertical variation of air temperature was greatest at dormant stage, and next at vigorous growth stage. Except at the surface, soil temperatures increased with the depth, accompanying a smaller diurnal variation. Humidity was maximum at vigorous growth stage, and next at dormant stage, and its maximum daily difference occurred at initial growth stage and came second at vigorous period. Humidity was higher beneath canopy than atop canopy during night, especially at vigorous growth stage. Soil moisture was highest at initial growth stage and next at vigorous growth stage. It was lower in the surface and deep layers, and reached maximum at 20 cm depth with a great variation. © 2015, editorial Board of Chinese Journal of Ecology. All rights reserved. Source


Qu Z.-J.,Shaanxi Meteorological Service Station for Economic Crops | Shang X.-N.,Xianyang Meteorological Bureau | Wang J.-H.,Shaanxi Meteorological Service Station for Economic Crops | Liang Y.,Shaanxi Meteorological Service Station for Economic Crops | And 2 more authors.
Chinese Journal of Applied Ecology | Year: 2015

Temperature is the most sensitive environment factor for the blooming period of apple. Temperatures at different levels were measured by automatic micro-climatic gradient system in the blooming periods from 2011 to 2014, in two Fuji apple orchards with two different tree ages and structures [small canopy open center shape (SMCOCS) and freedom spindle shape (FSS)], respectively, which were typical in the Loess Plateau. Variations of the temperature gradient in both canopy and tree body were analyzed in sunny, overcast, cloudy, and rainy weather conditions, and a predicting model was established that could predict the temperature of the canopy (TL) according to the temperature observed in nearby meteorological station (TM). The results showed that the vertical distribution of canopy temperature and its difference to the outside of orchard was mainly due to the tree structure, rather than the weather condition. The average temperature and daily minimum temperature increased while the daily maximum temperature and the diurnal temperature range decreased from the bottom to the upper of the canopy. For SMCOCS, the diurnal temperature range reached its peak under the canopy in the clear days, and the diurnal temperature range was less than that for FSS in the middle and upper canopy in cloudy or overcast conditions. The daily variation of temperature difference between inside and outside the orchard behaved as a single peak-valley-peak for FSS but as a single peak for SMCOCS. The minimum temperature outside the orchard was closer to that in the middle of canopy, but higher than that in the bottom of the canopy. For SMCOCS, the minimum temperature in the bottom of its canopy was rather lower than that in the orchard outside, especially in cloudy or overcast day, while in the middle or upper canopy, the minimum temperature difference with the orchard outside was smaller than that for the FSS. The linear model was found to be able to predict the TL with absolute errors below 1℃, and the best prediction was found for the FSS in rainy days. © 2015, Editorial Board of Chinese Journal of Applied Ecology. All right reserved. Source

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