Sorting biotic and abiotic stresses on wild rocket by leaf-image hyperspectral data mining with an artificial intelligence model.

BACKGROUND: Wild rocket (Diplotaxis tenuifolia) is prone to soil-borne stresses under intensive cultivation systems devoted to ready-to-eat salad chain, increasing needs for external inputs. Early detection of the abiotic and biotic stresses by using digital reflectance-based probes may allow optimization and enhance performances of the mitigation strategies. METHODS: Hyperspectral image analysis was applied to D. tenuifolia potted plants subjected, in a greenhouse experiment, to five treatments for one week: a control treatment watered to 100% water holding capacity, two biotic stresses: Fusarium wilting and Rhizoctonia rotting, and two abiotic stresses: water deficit and salinity. Leaf hyperspectral fingerprints were submitted to an artificial intelligence pipeline for training and validating image-based classification models able to work in the stress range. Spectral investigation was corroborated by pertaining physiological parameters. RESULTS: Water status was mainly affected by water deficit treatment, followed by fungal diseases, while salinity did not change water relations of wild rocket plants compared to control treatment. Biotic stresses triggered discoloration in plants just in a week after application of the treatments, as evidenced by the colour space coordinates and pigment contents values. Some vegetation indices, calculated on the bases of the reflectance data, targeted on plant vitality and chlorophyll content, healthiness, and carotenoid content, agreed with the patterns of variations observed for the physiological parameters. Artificial neural network helped selection of VIS (492-504, 540-568 and 712-720 nm) and NIR (855, 900-908 and 970 nm) bands, whose read reflectance contributed to discriminate stresses by imaging. CONCLUSIONS: This study provided significative spectral information linked to the assessed stresses, allowing the identification of narrowed spectral regions and single wavelengths due to changes in photosynthetically active pigments and in water status revealing the etiological cause.

Surveying soil-borne disease development on wild rocket salad crop by proximal sensing based on high-resolution hyperspectral features.

Wild rocket (Diplotaxis tenuifolia, Brassicaceae) is a baby-leaf vegetable crop of high economic interest, used in ready-to-eat minimally processed salads, with an appreciated taste and nutraceutical features. Disease management is key to achieving the sustainability of the entire production chain in intensive systems, where synthetic fungicides are limited or not permitted. In this context, soil-borne pathologies, much feared by growers, are becoming a real emergency. Digital screening of green beds can be implemented in order to optimize the use of sustainable means. The current study used a high-resolution hyperspectral array (spectroscopy at 350-2500 nm) to attempt to follow the progression of symptoms of Rhizoctonia, Sclerotinia, and Sclerotium disease across four different severity levels. A Random Forest machine learning model reduced dimensions of the training big dataset allowing to compute de novo vegetation indices specifically informative about canopy decay caused by all basal pathogenic attacks. Their transferability was also tested on the canopy dataset, which was useful for assessing the health status of wild rocket plants. Indeed, the progression of symptoms associated with soil-borne pathogens is closely related to the reduction of leaf absorbance of the canopy in certain ranges of visible and shortwave infrared spectral regions sensitive to reduction of chlorophyll and other pigments as well as to modifications of water content and turgor.

Can Microbial Consortium Applications Affect Yield and Quality of Conventionally Managed Processing Tomato?

Three commercial microbial-based biostimulants containing fungi (arbuscular mycorrhizae and Trichoderma spp.) and other microrganisms (plant growth-promoting bacteria and yeasts) were applied on a processing tomato crop in a two-year field experiment in southern Italy. The effects of the growing season and the microorganism-based treatments on the yield, technological traits and functional quality of the tomato fruits were assessed. The year of cultivation affected yield (with a lower fruit weight, higher marketable to total yield ratio and higher percentage of total defective fruits in 2020) and technological components (higher dry matter, titratable acidity, total soluble solids content in 2020). During the first year of the trial, the consortia-based treatments enhanced the soluble solids content (+10.02%) compared to the untreated tomato plants. The sucrose and lycopene content were affected both by the microbial treatments and the growing season (greater values found in 2021 with respect to 2020). The year factor also significantly affected the metabolite content, except for tyrosine, essential (EAA) and branched-chain amino acids (BCAAs). Over the two years of the field trial, FID-consortium enhanced the content of proteins (+53.71%), alanine (+16.55%), aspartic acid (+31.13%), γ-aminobutyric acid (GABA) (+76.51%), glutamine (+55.17%), glycine (+28.13%), monoethanolamine (MEA) (+19.57%), total amino acids (TAA) (+33.55), EAA (+32.56%) and BCAAs (+45.10%) compared to the control. Our findings highlighted the valuable effect of the FID microbial inoculant in boosting several primary metabolites (proteins and amino acids) in the fruits of the processing tomato crop grown under southern Italian environmental conditions, although no effect on the yield and its components was appreciated.

Optimizing N Fertilization to Improve Yield, Technological and Nutritional Quality of Tomato Grown in High Fertility Soil Conditions.

Processing tomato is the second most important worldwide cash crop, generally produced in high-input systems. However, fruit yield and quality are affected by agronomic management, particularly nitrogen (N) fertilization, whose application to indeterminate growth genotypes for canning has yet to be investigated in depth. Hence, the objective of this work was to assess the effects of different N rates (0, 50, 125, 200, 275, and 350 kg ha-1) on fruit yield and quality characteristics of processing tomato 'San Marzano' landrace. The results of our study showed that 125 and 200 kg of N ha-1 are the most appropriate rates in soil with high fertility, ensuring the highest values of marketable yield and brix yield. However, plants fertilized with 125 kg of N ha-1 attained higher values of N efficiency and fruit K and P concentrations than plants fertilized with 200 kg of N ha-1. Our results suggest that overdoses of N supplies negatively affected fruit yield and quality of San Marzano landrace grown in high soil fertility conditions, also reducing the agricultural sustainability. Hence, specific agronomic protocol and extension services are required to optimally manage tomato crop systems.

Leaf Metabolic, Genetic, and Morphophysiological Profiles of Cultivated and Wild Rocket Salad (Eruca and Diplotaxis Spp.).

Rocket salad (Diplotaxis spp., Eruca spp.) is a leafy vegetable rich in health-promoting compounds and widely consumed. In the present study, metabolic profiles of 40 rocket accessions mainly retrieved from gene banks were assessed. Seven glucosinolates (GLSs) and 15 flavonol compounds were detected across genotypes. Dimeric 4-mercaptobutyl-GLS and 4-(ß-d-glucopyranosyldisulfanyl)butyl-GLS were the major components of the total glucosinolate content. Flavonols were different between genera, with the exception of isorhamnetin 3,4'-diglucoside. Morphoagronomic traits and color coordinates were also scored. Results showed a negative correlation between color and GLSs, indicating these last as responsible for the increase of the intensity of green and yellow pigments as well as for the darkness of the leaf, whereas agronomic traits showed positive correlation with GLSs. Genetic diversity was assessed using inter simple sequence repeat (ISSR) markers, allowing separation of the accessions on the basis of the species and elucidating the observations made by means of phenotypic data.

Characterization of bean (Phaseolus vulgaris L.) ecotype "Fagiolo occhio nero di Oliveto Citra" using agronomic, biochemical and molecular approaches.

Common bean (Phaseolus vulgaris) is the most important grain legume and plays a significant role in human nutrition being a major source of dietary protein and representing a rich source of minerals and certain vitamins. Several large germplasm collections have been established, which contain large amounts of genetic diversity, including wild and domesticated species. In this study agronomic, biochemical and molecular characterization of landrace bean named "Fagiolo occhio nero di Oliveto Citra" (Phaseolus vulgaris L.), is described. Seeds were obtained by local farmers and field trials were carried out during years 2009-2010, in the typical cultivation site (Oliveto Citra, Salerno Province), using two different densities of investment. During 2011, in order to evaluate the performance in different environments, field trials were conducted in three localities (Battipaglia, Oliveto Citra and Controne). Data analysis shows good adaptability across locations and similar grain yield using two spacing's of seeds. Morphological characterization and molecular analysis, using AFLP and Minisatellite molecular markers, were performed on ten "biotypes" collected from local farmers. Seeds characterization showed variability on the violet area surrounding the hilum (named as eye) while markers have provided useful information on relationships between biotypes. Biochemical analysis, which includes the contents of protein, minerals and antioxidants, shows how the composition is consistent with respect to other landraces and commercial cultivars. The landrace under study revealed genetic stability and good adaptation to cultivated environment with best performance in the native area. In addition, the bio-agronomic characteristics are in accord with studies reported in literature.

DNA fingerprinting and quality traits of Corbarino cherry-like tomato landraces.

Twenty-five landraces of the cherry-like tomato named Corbarino, a typical niche product grown in the Sarno valley of the Campania region, have been characterized. The landraces used have been compared to eight cultivars widely spread in the same area of cultivation. The genetic diversity within and between landraces was evaluated through the comparison of DNA fingerprints obtained with (GATA)(4) probe hybridized to TaqI digested genomic DNA. Twenty-two of the Corbarino landraces were homogeneous and were unequivocally characterized by their DNA fingerprints. The others are probably "population varieties" in that within each of them polymorphic DNA fragments were identified. According to the characterization of fruit shapes, four groups were identified. One landrace from each group, harvested at the same ripening degree, was further characterized for yield, fruit quality components, antioxidant activities, and carotenoid contents and compared to Faino F(1) and Tomito F(1) hybrids. The Corbarino landraces were all characterized by high yield, a high level of carbohydrates, and high levels of soluble and total solids. Interestingly, the biotype named ISCI 05 was the most suitable for canning. Landraces ISCI 07 and ISCI 05 gave the highest value of antioxidant activities and carotenoid content. These data, together with previously published results, suggested that ISCI 05 should be proposed for the institution of a Label of Origin.