Detection of target spot and bacterial spot diseases in tomato using UAV-based and benchtop-based hyperspectral imaging techniques     

Abdulridha  Jaafar  Ampatzidis  Yiannis  Kakarla  Sri Charan  Roberts  Pamela 《Precision Agriculture》2020,21(5):955-978

Early and accurate diagnosis is a critical first step in mitigating losses caused by plant diseases. An incorrect diagnosis can lead to improper management decisions, such as selection of the wrong chemical application that could potentially result in further reduced crop health and yield. In tomato, initial disease symptoms may be similar even if caused by different pathogens, for example early lesions of target spot (TS) caused by the fungus Corynespora cassicola and bacterial spot (BS) caused by Xanthomonas perforans. In this study, hyperspectral imaging (380–1020 nm) was utilized in laboratory and field (collected by an unmanned aerial vehicle; UAV) settings to detect both diseases. Tomato leaves were classified into four categories: healthy, asymptomatic, early and late disease development stages. Thirty-five spectral vegetation indices (VIs) were calculated to select an optimum set of indices for disease detection and identification. Two classification methods were utilized: (i) multilayer perceptron neural network (MLP), and (ii) stepwise discriminant analysis (STDA). Best wavebands selection was considered in blue (408–420 nm), red (630–650 nm) and red edge (730–750 nm). The most significant VIs that could distinguish between healthy leaves and diseased leaves were the photochemical reflectance index (PRI) for both diseases, the normalized difference vegetation index (NDVI850) for BS in all stages, and the triangular vegetation index (TVI), NDVI850 and chlorophyll index green (Chl green) for TS asymptomatic, TS early and TS late disease stage respectively. The MLP classification method had an accuracy of 99%, for both BS and TS, under field (UAV-based) and laboratory conditions.

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Veterinary antibiotics influence trigonelline biosynthesis and plant growth in Arachis hypogaea L.     

Amith R. Devireddy  Madhuri A. Inupakutika  David Willmon  Prathusha Kakarla  Naveen Puppala 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2017,67(3):245-251

Antibiotics from various sources such as livestock waste are being accumulated in the soil. The excessive uptake of antimicrobial agents by plants has been a major concern as it is currently unknown how plants respond to the presence of antibiotics in agricultural lands. The objectives were to analyze the alteration of trigonelline (TRG) biosynthesized by plants in response to various antibiotic stresses and to evaluate the ability of peanut (Arachis hypogaea L.) plants to resist the deleterious impacts of antibiotic uptake. Three veterinary antibiotics used in this study were tetracycline, streptomycin sulfate, and chloramphenicol in the concentrations of 2.5 and 5 mg L^?1. Mean TRG amounts were 53.4 ± 1.6 and 59.9 ± 1.1 μg·g^?1 dry weight (DW) in Spanish as treated with growth chloramphenicol and streptomycin at 2.5 mg·L^?1, respectively, and were significantly (p ≤ .05) different compared to the control (40.4 ± 1.6 μg·g^?1 DW) of Spanish. Spanish genotype treated with chloramphenicol at 5 mg·L^?1 had a mean TRG amount of 41.0 ± 1.0 μg·g^?1 DW and improved yield, with the average pod number of 29.6 ± 7.6 and pod weight of 20.1 ± 6.1 g. TRG was continuously biosynthesized and increased under antibiotic stress up to 12.7% at full pod (R4 growth stage) and 139.1% at beginning maturity (R7), but declined 20.2% at the harvest stage (R8) in all combined genotypes when compared with TRG amounts (21.7 ± 0.6 μg·g^?1 DW) at the flowering R1 stage.  相似文献