Spatial-temporal Variation and Zoning of Rain-washing Damage to Early Rice Pollen in Jiangxi Province

Rain-washing damage to pollen is one of the main agrometeorological disasters of early rice in Jiangxi. Meanwhile, the rice cropping areas in Jiangxi have very complex terrains, and the agroclimatic conditions are variable, and therefore the coincidence period of flowering period and wet season vary in different regions. Considering those above, based on observations of 81 meteorological stations and 14 rice stations in the early rice planting areas of Jiangxi from 1981 to 2017, the spatial-temporal variation and zoning of rain-washing damage to early rice pollen in Jiangxi are analyzed by empirical orthogonal function(EOF) rotated empirical orthogonal function(REOF).Results show that the occurrence frequency of rain-washing damage to early rice pollen in Jiangxi is generally high in northeast and low in southwest, while in northern Jiangxi, it is high along the south part and low on both sides. The high value area is in northern Pingxiang, southern Yichun, Xinyu, Nanchang, northern Fuzhou and northeastern Jiangxi, with the occurrence frequency more than 60%. The low value area is in Ganzhou and southwestern Ji'an, with the occurrence frequency less than 40%. Mild disasters occur all over the Province, and its frequency and range are increasing since 1992. Severe disasters mainly occur in northeastern Jiangxi, and there are two active periods and two inactive periods. According to results of EOF and REOF analysis, the high value areas (the absolute value is not less than 0.5) of the first five rotated principal components cover almost the whole planting area of the early rice in Jiangxi, and high value areas of five components are in the south part of northern Jiangxi, central Jiangxi, northeastern Jiangxi, southern Jiangxi and the north part of northern Jiangxi in turn, which means that the rain-washing damage to early rice pollen in Jiangxi can be divided into five subareas as above. Among those subregions, northeastern Jiangxi is in the high-risk area of severe rain-washing damage to pollen, the south part of northern Jiangxi is in the high-risk area of mild rain washing-damage to pollen, central Jiangxi and the north part of northern Jiangxi are the sub-high risk area, and southern Jiangxi is the low risk area.