作 者 ：闫峰,史培军,武建军,王艳姣,李春强
期 刊 ：生态学报 2008年 28卷 9期 页码：4381~4387
关键词：冬小麦；生育期；MODIS- EVI；河北；
Keywords:winter wheat, phenology, MODIS- EVI, Hebei Province,
摘 要 ：生育期信息对作物生长发育的动态监测、田间精细管理以及产量预测等具有重要意义。采用NASA提供的2005年1~7月8d合成的MYD09数据产品计算出的EVI(增强型植被指数)时间序列图像，对河北省冬小麦的返青期、抽穗期和成熟期等3个关键生育期的时空分布特征进行了研究。结果表明：冬小麦生育期在空间分布上，由南向北随着纬度的增加，其返青期、抽穗期和成熟期依次推迟；不同纬度地区冬小麦的返青期、抽穗期和成熟期时间间隔基本一致，河北省南部地区冬小麦的3个主要生育期比北部地区约提前8d以上；在东西向分布上，生长条件存在异质性差异的冬小麦，其返青期相对一致，但生长条件较好冬小麦的抽穗期和成熟期比普通冬小麦提前4d左右。
Abstract:As an important factor during crop growing period, phenology is widely used in growing monitoring, field management and output forecasting. Winter wheat is one of the most important crops in Heibei China and its phenology will be affected by not only climate but also farmers′ planting habit and so on In this paper, temporal series MYD09A1, the 8-day reflectivity composite productions provided by NASA, which derived from AQUA-MODIS (Moderate Resolution Imaging Spectroradiometer) images from January to July in 2005 were used to calculate enhanced vegetation index (EVI). Based on winter wheat′s whole growing stages, three key phenologies were defined from temporal series EVI as following: greenup begins with the second continually increasing in EVI, heading stage begins with the maximum of EVI and maturity begins with the second decreasing of EVI before the minimum. Winter wheat flourishes in the first ten days in May generally, so the 16th 8- day EVI image which is relatively cloud-free was used to density sliced to show different growing conditions. From the south part of winter wheat area to the north in Hebei China, temporal series images of five areas of interesting (AOI) with the same EVI level (0.3-0.4) were analyzed, and greenup, heading stage and maturity were abstracted from the images. Results show that EVI could be used to estimate crop phenology successfully. From the south to the north, with the increasing of latitude, greenup, heading stage and maturity of winter wheat in Hebei China became later and later. Winter wheat in the south of Hebei turned green at the 8th 8-day in 2005 (about the first ten days in March), the middle part of winter wheat turned green about in the second ten days in March, which was 8 days later than that in the south, and the north part of winter wheat′s greenup was deferred about 8 days than the middle part to the last ten days in March. Periods among the three key phenologies of winter wheat were almost stationary, and phenology of wheat in the south of Hebei could be 8-16 days earlier than that in the north. From the east to the west in the middle part of winter wheat in Hebei Province, three AOIs with about the same latitude but different EVI value (0.3-0.4, 0.4-0.5, 0.5-0.6) were used to analyze phenology spatial character. On the condition that different EVI level could instead different growing conditions and managements of crop, we could get conclusions that from the east to the west, winter wheat with different growing conditions turned green at about the same period; heading stage and maturity of winter wheat with the best growing condition came at the 15.5th 8-day and the 20.5th 8-day, respectively, which could be about 4 days earlier than those of wheat with common growing conditions.
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