title: [Monitoring winter wheat population dynamics using an active crop sensor].
abstract: Tiller density plays an important role in attaining optimum grain yield and applying topdressing N in winter wheat. However, the traditional approach based on determining tiller density is time-consuming and labor-intensive. As technology advances, remote sensing might provide an opportunity in eliminating this7 problem. In the present paper, an N rate experiment and a variety-seeding and sowing dates experiment were conducted in Quzhou County, Hebei Province in 2008/2009 to develop the models to predict the amount of winter wheat tillers. Positive linear relationships between vegetation indices and tillers were observed across growth stages (R2, 0.25-0.64 for NDVI; 0.26-0.65 for RVI). The validation results indicated that the prediction using NDVI had the higher coefficient of determination (R2, 0.54-0.64), the lower root mean square error (RMSE, 260-350 tillers m(-2)) and relative error (RE, 16.3%-23.0%) at early growth stages of winter wheat. We conclude that active GreenSeeker sensor is a promising tool for timely monitoring of winter wheat tiller density.
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Jun-Hua
authors.initials: JH
authors.lastname: Wu
authors.forename: Shan-Chao
authors.initials: SC
authors.lastname: Yue
authors.forename: Peng
authors.initials: P
authors.lastname: Hou
authors.forename: Qing-Feng
authors.initials: QF
authors.lastname: Meng
authors.forename: Zhen-Ling
authors.initials: ZL
authors.lastname: Cui
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.forename: Xin-Ping
authors.initials: XP
authors.lastname: Chen
mesh_terms: D018533:Biomass; D012621:Seasons; D013057:Spectrum Analysis / Q000295:instrumentation*; D013686:Telemetry; D014908:Triticum / Q000254:growth & development*