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Agriculture, Volume 4, Issue 2 (June 2014), Pages 58-216

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Research

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Open AccessArticle Fluorescence Indices for the Proximal Sensing of Powdery Mildew, Nitrogen Supply and Water Deficit in Sugar Beet Leaves
Agriculture 2014, 4(2), 58-78; doi:10.3390/agriculture4020058
Received: 15 January 2014 / Revised: 12 February 2014 / Accepted: 13 March 2014 / Published: 28 March 2014
Cited by 5 | PDF Full-text (935 KB) | HTML Full-text | XML Full-text
Abstract
Using potted sugar beet plants we aimed to investigate the suitability of four fluorescence indices to detect and differentiate the impact of nitrogen supply, water deficit and powdery mildew in two sugar beet cultivars (Beta vulgaris L.). Plants were grown inside [...] Read more.
Using potted sugar beet plants we aimed to investigate the suitability of four fluorescence indices to detect and differentiate the impact of nitrogen supply, water deficit and powdery mildew in two sugar beet cultivars (Beta vulgaris L.). Plants were grown inside a polytunnel under two nitrogen levels combined with water deficit or full irrigation. Changes in plant physiology were recorded at two physiological stages with a multiparametric handheld fluorescence sensor and a fluorescence imaging system. The analysis of chlorophyll content and osmotic potential served as reference. Based on our results, the fluorescence indices “Nitrogen Balance Index” and “Simple Fluorescence Ratio” responded quite sensitively to drought stress and mildew infection. Moreover, the blue-to-far-red fluorescence ratio revealed significant stress-induced alterations in the plant physiology. In all, fluorescence indices might be used as single or combined indices for successful stress sensing. However, a robust stress differentiation by using only one fluorescence ratio could not be accomplished. Full article
Open AccessArticle Advanced Multi-Color Fluorescence Imaging System for Detection of Biotic and Abiotic Stresses in Leaves
Agriculture 2014, 4(2), 79-95; doi:10.3390/agriculture4020079
Received: 30 January 2014 / Revised: 20 March 2014 / Accepted: 25 March 2014 / Published: 4 April 2014
Cited by 6 | PDF Full-text (2210 KB) | HTML Full-text | XML Full-text
Abstract
The autofluorescence of a sample is a highly sensitive and selective optical property and gives the possibility to establish non-destructive techniques of the investigation of plants, like detecting the chlorophyll fluorescence related to stress phenomena. In this study, an advanced multi-color fluorescence [...] Read more.
The autofluorescence of a sample is a highly sensitive and selective optical property and gives the possibility to establish non-destructive techniques of the investigation of plants, like detecting the chlorophyll fluorescence related to stress phenomena. In this study, an advanced multi-color fluorescence imaging system and data analysis were presented. The advantage of an imaging system is the additional receiving of spatial information over a sample area, this is a strong improvement compared to spot measurements commonly used. The purpose was to demonstrate the possibility of the detection and characterization of stress symptoms using this system. Specific fluorescence ratios were identified to characterize the stress status over the whole leaf, here shown on barley grown under different nitrogen supply (abiotic stress). Due to the changes, it is possible to make conclusions about leaf pigments (chlorophylls and phenolics) related to stress response. The second aim was to use the shape of local symptoms (biotic stress) as a criterion. For this purpose, three structural different kinds of fungal symptoms were analyzed using shape descriptors. It shows that an additional image shape analysis can be very useful for extracting further information, in this case the successful discrimination of fungal infections. Full article
Open AccessArticle Evaluation of Spring Wheat (20 Varieties) Adaptation to Soil Drought during Seedlings Growth Stage
Agriculture 2014, 4(2), 96-112; doi:10.3390/agriculture4020096
Received: 22 January 2014 / Revised: 22 March 2014 / Accepted: 26 March 2014 / Published: 4 April 2014
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Abstract
The effect of soil drought (10 days) on the growth of plants, the accumulation of water and leakage of electrolytes, gas exchange, the contents of chl a + b and carotenoids in leaves and photochemical activity of photosystem II was studied at [...] Read more.
The effect of soil drought (10 days) on the growth of plants, the accumulation of water and leakage of electrolytes, gas exchange, the contents of chl a + b and carotenoids in leaves and photochemical activity of photosystem II was studied at the seedling stage by transient fluorescent analysis in 20 of the popular varieties of polish spring wheat. Drought caused a particularly strong reduction in vigor of growth of seedlings, net photosynthesis rate and triggered an increase in electrolyte leakage from the leaves. Certain varieties during the drought demonstrated relatively intense CO2 assimilation at low water loss through transpiration. The varieties tested were significantly different in terms of tolerance to drought of the processes of gas exchange and seedlings development. Photochemical processes in PSII showed high tolerance to drought and at the same time low differentiation among varieties. The results obtained suggested that tolerance of growth parameters to drought and CO2 assimilation at the seedling stage may alleviate consequent depression of final yield of the grain. Full article
Open AccessArticle Crop Dominance Mapping with IRS-P6 and MODIS 250-m Time Series Data
Agriculture 2014, 4(2), 113-131; doi:10.3390/agriculture4020113
Received: 6 January 2014 / Revised: 19 March 2014 / Accepted: 14 April 2014 / Published: 25 April 2014
Cited by 3 | PDF Full-text (1704 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes an approach to accurately separate out and quantify crop dominance areas in the major command area in the Krishna River Basin. Classification was performed using IRS-P6 (Indian Remote Sensing Satellite, series P6) and MODIS eight-day time series remote sensing [...] Read more.
This paper describes an approach to accurately separate out and quantify crop dominance areas in the major command area in the Krishna River Basin. Classification was performed using IRS-P6 (Indian Remote Sensing Satellite, series P6) and MODIS eight-day time series remote sensing images with a spatial resolution of 23.6 m, 250 m for the year 2005. Temporal variations in the NDVI (Normalized Difference Vegetation Index) pattern obtained in crop dominance classes enables a demarcation between long duration crops and short duration crops. The NDVI pattern was found to be more consistent in long duration crops than in short duration crops due to the continuity of the water supply. Surface water availability, on the other hand, was dependent on canal water release, which affected the time of crop sowing and growth stages, which was, in turn, reflected in the NDVI pattern. The identified crop-wise classes were tested and verified using ground-truth data and state-level census data. The accuracy assessment was performed based on ground-truth data through the error matrix method, with accuracies from 67% to 100% for individual crop dominance classes, with an overall accuracy of 79% for all classes. The derived major crop land areas were highly correlated with the sub-national statistics with R2 values of 87% at the mandal (sub-district) level for 2005–2006. These results suggest that the methods, approaches, algorithms and datasets used in this study are ideal for rapid, accurate and large-scale mapping of paddy rice, as well as for generating their statistics over large areas. This study demonstrates that IRS-P6 23.6-m one-time data fusion with MODIS 250-m time series data is very useful for identifying crop type, the source of irrigation water and, in the case of surface water irrigation, the way in which it is applied. The results from this study have assisted in improving surface water and groundwater irrigated areas of the command area and also provide the basis for better water resource assessments at the basin scale. Full article
Open AccessArticle Salinity-Induced Changes of Multiparametric Fluorescence Indices of Tomato Leaves
Agriculture 2014, 4(2), 132-146; doi:10.3390/agriculture4020132
Received: 11 January 2014 / Revised: 22 April 2014 / Accepted: 22 April 2014 / Published: 30 April 2014
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Abstract
The aim of our study was to identify appropriate multiparametric fluorescence ratios to evaluate the response of tomato (Solanum lycopersicum) genotypes to salinity. In this context, we hypothesized that the fluorescence indices BFRR_UV, FLAV, NBI and SFR provided by the [...] Read more.
The aim of our study was to identify appropriate multiparametric fluorescence ratios to evaluate the response of tomato (Solanum lycopersicum) genotypes to salinity. In this context, we hypothesized that the fluorescence indices BFRR_UV, FLAV, NBI and SFR provided by the multiparametric fluorescence technique reveal the impact of salinity on tomato leaves. For this purpose, the tomato genotypes H-2274, Harzfeuer and Rio Grande were grown in the greenhouse under standard or saline conditions. As reference measurements, we recorded the maximum photochemical efficiency of photosystem II (Fv/Fm) via pulse-amplitude-modulated (PAM) chlorophyll fluorescence (ChlF) and analyzed the concentrations of sodium (Na), potassium (K), magnesium (Mg), proline and chlorophyll (Chl). In general, “Harzfeuer” showed a more pronounced response to salinity, as revealed by the increase in Na and proline as well as the decrease in K concentration. Significant differences between the control and the salt treatment were also assessed with Fv/Fm. The ratios BFRR_UV, FLAV, SFR_G and NBI_G increased significantly in the salinity-exposed plants. These ratios, compared with Fv/Fm, also provide precise but more rapid information about the impact of salinity on tomato leaves. On this basis, we demonstrate that the multiparametric fluorescence indices provide a valuable, rapid and practical tool for the in situ monitoring of the physiological status of plants exposed to salinity. Full article
Open AccessArticle Non-Invasive Spectral Phenotyping Methods can Improve and Accelerate Cercospora Disease Scoring in Sugar Beet Breeding
Agriculture 2014, 4(2), 147-158; doi:10.3390/agriculture4020147
Received: 27 March 2014 / Revised: 25 April 2014 / Accepted: 29 April 2014 / Published: 8 May 2014
Cited by 4 | PDF Full-text (615 KB) | HTML Full-text | XML Full-text
Abstract
Breeding for Cercospora resistant sugar beet cultivars requires field experiments for testing resistance levels of candidate genotypes in conditions that are close to agricultural cultivation. Non-invasive spectral phenotyping methods can support and accelerate resistance rating and thereby speed up breeding process. In [...] Read more.
Breeding for Cercospora resistant sugar beet cultivars requires field experiments for testing resistance levels of candidate genotypes in conditions that are close to agricultural cultivation. Non-invasive spectral phenotyping methods can support and accelerate resistance rating and thereby speed up breeding process. In a case study, experimental field plots with strongly infected beet genotypes of different resistance levels were measured with two different spectrometers. Vegetation indices were calculated from measured wavelength signature to determine leaf physiological status, e.g., greenness with the Normalized Differenced Vegetation Index (NDVI), leaf water content with the Leaf Water Index (LWI) and Cercospora disease severity with the Cercospora Leaf Spot Index (CLSI). Indices values correlated significantly with visually scored disease severity, thus connecting the classical breeders’ scoring approach with advanced non-invasive technology. Full article
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Open AccessArticle Field Observations with Laser-Induced Fluorescence Transient (LIFT) Method in Barley and Sugar Beet
Agriculture 2014, 4(2), 159-169; doi:10.3390/agriculture4020159
Received: 13 February 2014 / Revised: 18 April 2014 / Accepted: 12 May 2014 / Published: 22 May 2014
Cited by 2 | PDF Full-text (573 KB) | HTML Full-text | XML Full-text
Abstract
The laser-induced fluorescence transient (LIFT) method is a non-invasive remote sensing technique for measurement of photosynthetic performance of plants under laboratory and field conditions. We report here a long-term comparative study to monitor the performance of different cultivars of barley and sugar [...] Read more.
The laser-induced fluorescence transient (LIFT) method is a non-invasive remote sensing technique for measurement of photosynthetic performance of plants under laboratory and field conditions. We report here a long-term comparative study to monitor the performance of different cultivars of barley and sugar beet during the growth season of these crops. The LIFT measurements provided useful results about photosynthetic light use efficiency on selected leaves in the canopy of the studied crops. The different canopy architectures, with different optical properties, influenced the LIFT measurements. Full article
Open AccessArticle Rapid Development of Microsatellite Markers for Plantago ovata Forsk.: Using Next Generation Sequencing and Their Cross-Species Transferability
Agriculture 2014, 4(2), 199-216; doi:10.3390/agriculture4020199
Received: 7 February 2014 / Revised: 6 May 2014 / Accepted: 6 June 2014 / Published: 20 June 2014
Cited by 1 | PDF Full-text (729 KB) | HTML Full-text | XML Full-text
Abstract
Isabgol (Plantago ovata Forsk.) is an important medicinal plant having high pharmacological activity in its seed husk, which is substantially used in the food, beverages and packaging industries. Nevertheless, isabgol lags behind in research, particularly for genomic resources, like molecular markers, [...] Read more.
Isabgol (Plantago ovata Forsk.) is an important medicinal plant having high pharmacological activity in its seed husk, which is substantially used in the food, beverages and packaging industries. Nevertheless, isabgol lags behind in research, particularly for genomic resources, like molecular markers, genetic maps, etc. Presently, molecular markers can be easily developed through next generation sequencing technologies, more efficiently, cost effectively and in less time than ever before. This study was framed keeping in view the need to develop molecular markers for this economically important crop by employing a microsatellite enrichment protocol using a next generation sequencing platform (ion torrent PGM™) to obtain simple sequence repeats (SSRs) for Plantago ovata for the very first time. A total of 3447 contigs were assembled, which contained 249 SSRs. Thirty seven loci were randomly selected for primer development; of which, 30 loci were successfully amplified. The developed microsatellite markers showed the amplification of the expected size and cross-amplification in another six species of Plantago. The SSR markers were unable to show polymorphism within P. ovata, suggesting that low variability exists within genotypes of P. ovata. This study suggests that PGM™ sequencing is a rapid and cost-effective tool for developing SSR markers for non-model species, and the markers so-observed could be useful in the molecular breeding of P. ovata. Full article

Review

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Open AccessReview Olive Cultivation, its Impact on Soil Erosion and its Progression into Yield Impacts in Southern Spain in the Past as a Key to a Future of Increasing Climate Uncertainty
Agriculture 2014, 4(2), 170-198; doi:10.3390/agriculture4020170
Received: 30 December 2013 / Revised: 15 May 2014 / Accepted: 29 May 2014 / Published: 11 June 2014
Cited by 3 | PDF Full-text (2827 KB) | HTML Full-text | XML Full-text
Abstract
This article is intended as a review of the current situation regarding the impact of olive cultivation in Southern Spain (Andalusia) on soil degradation processes and its progression into yield impacts, due to diminishing soil profile depth and climate change in the [...] Read more.
This article is intended as a review of the current situation regarding the impact of olive cultivation in Southern Spain (Andalusia) on soil degradation processes and its progression into yield impacts, due to diminishing soil profile depth and climate change in the sloping areas where it is usually cultivated. Finally, it explores the possible implications in the regional agricultural policy these results might have. It tries to show how the expansion and intensification of olive cultivation in Andalusia, especially since the late 18th century, had as a consequence an acceleration of erosion processes that can be identified by several indicators and techniques. Experimental and model analysis indicates that the rate of soil erosion accelerated since the expansion of mechanization in the late 1950s. In addition, that unsustainable erosion rates have prevailed in the region since the shift to a more intense olive cultivation systems by the end of the 17th Century. Although agroenvironmental measures implemented since the early 2000s have reduced erosion rates, they are still unsustainably high in a large fraction of the olive area in the region. In the case of olive orchards located in steeper areas with soils of lower water-holding capacity (due to coarse texture and stone content), cumulative erosion has already had a high impact on reducing their potential productivity. This is one of the factors that contributes towards increasing the gap between these less intensified orchards in the mountainous areas and those in the hilly areas with more gentle slopes, such as for instance the lower stretches of the Guadalquivir River Valley. In the case of olive orchards in the hilly areas with better soils, easier access to irrigation and lower production costs per unit, the efforts on soil conservation should be oriented towards limiting off-site damage, since the soil water-storage function of these soils may be preserved in the medium term even at the current soil erosion rates. The assessment made in this manuscript should be regarded as an initial approximation, since additional efforts in terms of increasing experimental records (for current or historical erosion) and of improving model analysis, with more comprehensive studies and more robust calibration and validation processes, are required. Full article
(This article belongs to the Special Issue Soil Erosion: A Major Threat to Food Production and the Environment)
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