•Detection and discrimination of plant stress origin using hyperspectral imaging.•Nematode infestation can be reliably differentiated from the water deficiency.•Abiotic drought resulted in the most ...obvious differences in the light spectrum.•Identification of nematode infestation possible with specific spectral regions.•Reliable prediction of nematode infestation even in early stages of infestation.
Crop plants are subjected to various biotic and abiotic stresses. Both root-knot nematodes (biotic stress) and water deficiency (abiotic stress) lead to similar drought symptoms in the plant canopy. In this work, hyperspectral imaging was used for early detection of nematode infestation and water deficiency (drought) stress in tomato plants. Hyperspectral data in the range from 400 to 2500 nm of plants subjected to different watering regimes and nematode infestation levels were analysed by partial least squares – discriminant analysis (PLS-DA) and partial least squares – support vector machine (PLS-SVM) classification. PLS-SVM classification achieved up to 100% accuracy differentiating between well-watered and water-deficient plants, and between 90 and 100% when identifying nematode-infested plants. Grouping the data according to the time of imaging increased the accuracy of classification. Shortwave infrared spectral regions associated with the OH and CH stretches were most relevant for the identification of nematode infested plants and severity of infestation. This study demonstrates the capability of hyperspectral imaging to identify and discriminate between biotic and abiotic plant stresses.
The objective of our research was to test hyperspectral imaging as a method for early detection and discrimination of biotic and abiotic stress in maize. We investigated the individual and combined ...effects of wireworm feeding and drought stress on leaf spectral responses and on various morphological and physiological traits of maize plants, selecting two hybrids with different tolerance to drought. Physiological parameters were determined at three time points (14, 21 and 28 days after adding wireworms and changing watering regime), along with hyperspectral imaging. Most of the differences in physiological characteristics between treatments were detected on day 21, when drought was the main cause of the negative physiological outcome, while the presence of wireworms only caused lower relative chlorophyll content, resulting in lower combined stress damage in some treatments. The morphological data showed greater wireworm damage to hybrid ZP341 and a greater negative effect of combined stress on hybrid FuturiXX. Hyperspectral imaging detected pest infestation and drought stress before they were detected by classical methods, with the highest overall accuracy on day 14 (84.7%) and the lowest on day 28 (67%). It can therefore be used as a method for early detection of wireworm infestation and/or drought in maize.
Root-knot nematodes are considered the most important group of plant-parasitic nematodes due to their wide range of plant hosts and subsequent role in yield losses in agricultural production systems. ...Chemical nematicides are the primary control method, but ecotoxicity issues with some compounds has led to their phasing-out and consequential development of new control strategies, including biological control. We evaluated the nematicidal activity of
I-1582 in pot and microplot experiments against
. I-1582 reduced nematode counts by 51% and 53% compared to the untreated control in pot and microplot experiments, respectively. I-1582 presence in the rhizosphere had concurrent nematicidal and plant growth-promoting effects, measured using plant morphology, relative chlorophyll content, elemental composition and hyperspectral imaging. Hyperspectral imaging in the 400-2500 nm spectral range and supervised classification using partial least squares support vector machines successfully differentiated
-treated and untreated plants, with 97.4% and 96.3% accuracy in pot and microplot experiments, respectively. Visible and shortwave infrared spectral regions associated with chlorophyll, N-H and C-N stretches in proteins were most relevant for treatment discrimination. This study shows the ability of hyperspectral imaging to rapidly assess the success of biological measures for pest control.
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Crop infestation with root-knot nematodes (RKN) and water deficiency lead to similar visible symptoms in the plant canopy. Identification of biotic or abiotic stress origin is ...therefore a problem, and currently the only reliable methods for determination of RKN infestation are invasive and applicable only for point-searches. In this study the applicability of hyperspectral remote sensing for early identification of drought stress and RKN infestations in tomato plants was tested. A four-stage image and data management pipeline was established: (1) image acquisition, (2) data extraction, (3) pre-processing, and (4) processing.
•This pipeline reduces atmospheric impacts, facilitates data extraction (by using specially designed spectral libraries and supervised classification procedures), diminishes the impact of viewing geometry, and emphasized small spectral variations not apparent in the raw data.•By combining partial least squares – discriminant analysis and support vector machines with time series analysis, we achieved up to 100% classification success when determining watering regime and infestation, and their severity.•This pipeline could be at least partially automated, thus facilitating high throughput identification of stress origin in plants. Furthermore, the same pipeline could be applied to hyperspectral phenotyping procedures, which are gaining importance in breeding programs.
Frequent fires on drought-prone grasslands, such as pastures in the sub-Mediterranean region, can induce large post-fire variations of CO2 fluxes between the ecosystem and the atmosphere. ...Consequently, substantial changes in the C-cycle can be expected. In our research, we studied post-fire carbon fluxes (net canopy CO2 exchange (NE) and canopy respiration) on calcareous karst grassland after two spring fire events, a natural one in 2010 and a man-induced (anthropogenic) one in 2011. Canopy chamber measurements performed at short regular time intervals throughout the season revealed the rapid recovery of NE after the initial loss of C-sink strength. The long-term effects of the natural fire were largely masked by an early-season drought. In contrast, the burned areas did not reach the productivity of non-disturbed sites until the end of the season after the anthropogenic fire in 2011, when the post-burning period was characterised by favourable growing conditions. The similar NE values could be explained by a significant reduction of respiration at burned areas. Our research showed that C-sink strength of grassland after a fire disturbance can be re-established quite rapidly, after a month, although a full recovery (regeneration of plant cover, C fluxes) can take more time. The re-establishment is largely dependent on environmental conditions (soil water availability).
Sheep's wool and leather shavings tanned without chromium (III) salts would be suitable for fertilization in organic farming, where is the lack of easily accessible fertilizer nitrogen. This ...hypothesis was tested in a two-year field experiment growing asparagus at Rogelj organic farm in Kranj (Slovenia). The block designed experiment with three replicates comprised fertilization treatments with sheep's wool (W), leather shavings (L), cattle manure (FYM) and unfertilized (Ø). Doses of fertilizers were relevant to 0 (Ø), 140 (W1, L1), 280 (W2, L2, FYM) and 560 kg (W3, L3) N/ha. Fertilizers were dosed the first year before the start of the vegetation. Within the next year we followed their subsequent effect. The highest soil mineral N was found in the W2, which produced also the highest asparagus yield (nonsignificant) in the first year. On contrary, NO3-N content in the asparagus crop was small what reflects the good synchrony of N mineralization and consumption of N at W2. Treatments W and L released significantly more N in the next year than the same dose of nitrogen from FYM. The experiment showed that mainly sheep wool represents a quality alternative organic fertilizer.
Sheep's wool and leather shavings tanned without chromium (III) salts would be suitable for fertilization in organic farming, where is the lack of easily accessible fertilizer nitrogen. This ...hypothesis was tested in a two-year field experiment growing asparagus at Rogelj organic farm in Kranj (Slovenia). The block designed experiment with three replicates comprised fertilization treatments with sheep's wool (W), leather shavings (L), cattle manure (FYM) and unfertilized (Ø). Doses of fertilizers were relevant to 0 (Ø), 140 (W1, L1), 280 (W2, L2, FYM) and 560 kg (W3, L3) N/ha. Fertilizers were dosed the first year before the start of the vegetation. Within the next year we followed their subsequent effect. The highest soil mineral N was found in the W2, which produced also the highest asparagus yield (nonsignificant) in the first year. On contrary, NO₃-N content in the asparagus crop was small what reflects the good synchrony of N mineralization and consumption of N at W2. Treatments W and L released significantly more N in the next year than the same dose of nitrogen from FYM. The experiment showed that mainly sheep wool represents a quality alternative organic fertilizer.
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