不同株型夏玉米群体冠层反射光谱特征及其应用研究

比较不同株型夏玉米在不同时期的反射光谱差异性,研究分析了红边位置(λred)、红边振幅(Dλred)、最小振幅(Dλmin)及Dλred/Dλmin与叶片全氮含量(LTN),叶绿素含量(Chl)及叶面积指数(LAI)间的相关性,并建立预测模型。结果表明,光谱差异随生育进程呈不同程度的规律性变化。在全生育期,用Dλred/Dλmin能更好地推算LTN,尤其在吐丝期,在开花前用Dλred也佳,在拔节期和喇叭口期用λred也有较高的精度。估算Chl时,在开花前用Dλred较可靠,在喇叭口期和抽雄期用λred也可考虑。估算LAI时,抽雄期后用Dλred推算有较高的可信度,在抽雄期用λred较好,在开花期和吐丝期用Dλred/Dλmin推算更为可靠。

Canopy Reflectance Characteristics of Different Plant Types and It''''s Application in Summer Maize

In the paper, by means of statisticalFtest, reflectance spectra characteristics were compared andanalyzed synthetically among different varieties at different growth stages of summer maize, and statisticalmodels were established between red edge position (λred), red edge swing (Dλred), minimal swing230　　　　　(Dλmin),Dλred/Dλmin and Leaf total nitrogen (LTN), Chlorophyll content (Chl), Leaf area index(LAI). The results of study indicated: along with the growth, spectral discrepancy took on disciplinarychang, namely, the discrepancy gradually increased from jointing stage to tasseling stage, thereafter, thediscrepancy gradually decreased at anthesis and silking stage, but the discrepancy was bigger at anthesisthan that at anthesis, and yet the discrepancy surprisingly increased at milking stage.Dλred/Dλmin wasadded to simulate LTN more accurately thanDλmin during the growth, especially at silking stage,Dλredbefore anthesis,λred at jointing stage and bell stage. The result of utilizingDλred for estimating Chl wasencouraging before anthesis,λred at bell stage and tasseling stage. It was feasible to estimate LAI withDλred after tasseling stage or withλred andDλmin at tasseling stage, furthermore, usingDλred/Dλminwas more reliable than the others at anthesis and silking stage. Therefore, the proper red edge parameterswere so sensitive to corresponding agronomy index that they could be considered as responsive indicator ofthe agronomy indices of summer maize.