被撤回的出版物: Use of digital photography from unmanned aerial vehicles for estimation of leaf area index in onion (Allium cepa L.) (Retracted article. See vol. 51, pg. 140, 2013)

Canopy cover and structure, which have considerable effects on the interaction between vegetation and the environment, especially in the case of crops, can be represented by a few parameters, which are based on the calculation of different vegetation indexes. One of the most common indexes in agronomy is the leaf area index, which is a parameter associated with agronomic, biologic, environmental, and physiologic processes. The aim of this study is to evaluate a non-destructive method to measure canopy cover in an onion crop by means of aerial digital photography from unmanned aerial vehicles, and to determine the relationship with leaf area index obtained by using an automated infrared imaging system. The field experiment was conducted in a 4.75 ha commercial onion plot irrigated with a centre pivot system during the 2010 irrigation season. To determine the leaf area in the laboratory during crop development, data were sampled on three. At each sampling event, eight experimental plots of 1 m(2) were used. In each one of them, aerials photographies were taken by using a vertical take-off and landing quadracopter aircraft. Software for leaf area index calculation was developed to obtain canopy cover. Three models have been used to analyze the relationship between leaf area index and canopy cover. According to this, the model which best fits the relationship between leaf area index and canopy cover is the linear model. The relationship between both parameters was closer in the first stages than in more advanced stages. (c) 2012 Elsevier B.V. All rights reserved.