| Baishui County,Weinan City,Shaanxi Province,is located in the transitional zone between the Guanzhong Plain and the Loess Plateau in northern Shaanxi.The mountains and plateaus are crisscrossed,and the elevation difference is 446 – 1568 m.Affected by complex topography and local microclimate,flowering disaster is the main factor affecting the yield and quality of apple.Due to the unstable temperature in early spring,flowering disasters occur frequently.Studies have shown that the main meteorological conditions affecting the flowering of white water apples are heat factors,and the temperature is the most important factor.Therefore,based on the analysis of local meteorological data over the same period for many years,it is of great significance to understand the spatial variation characteristics of the initial flowering period of apples in the region,and to take effective measures to deal with flowering disasters and ensure high yield and quality of apples.Based on the daily temperature data of 19 meteorological stations in Baishui County and adjacent areas from January 1 to April 15,2008 to 2016,this paper systematically analyzed the distribution characteristics of heat resources before apple blossom in Baishui County.The average annual mean effective accumulated temperature of ≥ 5 °C before flowering was used as an index to estimate the average initial flowering period of apple in Baishui county.The average initial flowering period of apple in Baishui county was determined by correlation and regression analysis.Finally,Arcgis software was used to draw the initial distribution maps of 0 °C,3 °C and 5 °C stably passing through Baishui County,the accumulated temperature of ≥ 0 °C,≥ 5 °C and effective accumulated temperature of ≥ 5 °C in early spring of Baishui County,and the refined spatial distribution map of multi-year average initial flowering period of Baishui apple.The main results are as follows :(1)The initial date of the first flowering stage of Baishui apple appeared from March31 to April 15,and the time variation of the initial date of the first flowering stage of apple in each township was large.The general rule of the average flowering time distribution in the county is that the east is earlier than the west,and the south is earlier than the north.Early at low altitude,late at high altitude.The flat area is early,and the gully area is late.The earliest flowering period of apples appeared on March 31,from Fenglei Town,Xigu Town and other flat areas in the southeast of Baishui County gradually recursive to the west and north,at the latest in the mountainous area of Yuntai Town in the west of Baishui County,April 15.(2)According to the accumulated temperature index of apple ’s average initial flowering period,the township meteorological station data and DEM data were selected,and the ARCGIS software was used to simulate the average initial flowering period in mountainous areas with complex terrain and invert the spatial distribution of initial flowering period.The inversion results show that the distribution of the average initial flowering period of Baishui apple is greatly affected by altitude and topography.The initial flowering period is recursive from east to west and from south to north.The high altitude area is later than the low altitude area,and the gully area is later than the flat area.Apples in most areas of white water bloom from March 31 to mid-April on average.Therefore,cold air activity in April is a key factor affecting apple production safety,which needs special attention in agricultural meteorological services.(3)In recent years,due to the influence of warm winter climate,the temperature in early spring has rebounded rapidly.In general,in the early and middle April,if the apple flowering period encounters abnormal weather such as northwest cold flow,cold air intrusion or long-term rain,wind and sand continuous cold high pressure control,strong radiation cooling at sunny night,and the temperature is-2 °C for more than half an hour,frost will occur.The later the low temperature occurs,the greater the harm to fruit trees.At the same latitude,the damage in the west is more serious than that in the east under the same climatic conditions.The higher the altitude is,the heavier the frost damage is.The frost damage of shady slope,tuyere,channel,low-lying terrain and lower part of trees is particularly serious.The damage of contiguous orchards was severe,and the damage of single small-area orchards was light.Backwind sunny,where the soil moisture is lighter frost damage,open terrain,where the terrain is dry,the better ventilation,flowering damage lighter or not.(4)It is recommended that departments at all levels and fruit growers pay high attention to weather and frost warning information issued by local governments and meteorological departments in order to take timely and effective measures to strengthen the prevention of flowering frost.Can take orchard irrigation,delay flowering.Use smoke or heater to raise orchard temperature and improve microclimate.Orchard spray nutrient solution to enhance the cold resistance of trees.Irrigation and fertilizer,enhance resistance.Stop thinning and delay fruiting.Artificial pollination,improve fruit setting.Measures such as ensuring fruit setting and precise fruit setting will minimize the loss of frost damage during flowering.In summary,The study shows that the early April of each year is a critical period for the flowering of white water apples.According to the white water heat distribution map and the distribution map of the initial flowering period studied in this paper,the flowering period of apples is accurately determined after the effective accumulated temperature is reached.Combined with the early spring weather conditions,it provides the basis for the prediction of frost damage at flowering stage and the meteorological support for the efficient and orderly development of frost damage prevention.And put forward the prevention and control measures of flowering frost damage,for apple quality and high yield escort. |
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