SPATIAL CORRELATION OF SOYBEAN PRODUCTIVITY, ENHANCED VEGETATION INDEX (EVI) AND AGROMETEOROLOGICAL VARIABLES

ABSTRACT The survey information from growing regions, the interaction with the vegetation index and climatic variables is of great importance in the search for soybean productivity increase. Paraná is the second largest soybean producer in Brazil and presents great spatial variability, both in periods of the crop cycle as in soil and climate. The objective of this study was to analyze the spatial correlation of soybean productivity, the enhanced vegetation index (EVI) and agrometeorological variables (water balance, global radiation and average temperature) in the state of Paraná, on a decendial scale, using the Moran global autocorrelation index between the 2010/2011 and 2012/2013 crop years. Similarity was found in the average productivities in 2010/2011 and 2012/2013. In 2011/2012 the state average was 2.38 t ha−1 lower in 10.19% compared to the national average, caused by the water deficit in flowering and grain filling phases. As a consequence, spatial autocorrelation indicated a higher similarity in productivity among municipalities with a Moran index of 0.735. The use of vegetation indices and agrometeorological variables allowed the identification of different sowing periods between regions and great climatic variability, influencing the soybean productivity.摘要 获取大豆种植区域的调研数据，并探究其与植被指数、气候变量间的交互作用，对提升大豆单产的相关研究具有重要意义。巴拉那州（Paraná）是巴西第二大大豆生产州，其作物周期内的各阶段、土壤与气候条件均存在显著的空间异质性。本研究旨在以2010/2011至2012/2013作物年度为研究时段，采用全局莫兰自相关指数（Moran global autocorrelation index），在十年尺度下分析巴拉那州内大豆单产、增强型植被指数（EVI）以及农业气象变量（包括水分平衡、全球辐射与平均气温）的空间相关性。2010/2011与2012/2013年度的大豆平均单产表现出较高相似性。2011/2012年度，巴拉那州大豆平均单产较全国平均水平低10.19%，单产值为2.38吨/公顷，该现象由开花期与籽粒灌浆阶段的水分亏缺所导致。在此背景下，空间自相关分析结果显示，各市政辖区间的大豆单产存在高度相似性，全局莫兰指数达0.735。通过结合植被指数与农业气象变量，本研究得以识别出不同区域间的播种期差异与显著的气候异质性，上述因素均会对大豆单产产生影响。