Search

The aim of this research was to test the viability of short wave near infrared spectroscopy (SW-NIRS) for the monitoring of fruit quality and ripening evolution in Algarve Citrus orchards ( Citrus sinensis L. Osbeck ‘Newhall’). Specifically, we have investigated the robustness of SW-NIRS calibration models in real conditions, that is: i) measurements were performed on tree, at a single location in the fruit equator, in the sunlight and with no temperature equilibration; and ii) with validation through independent data obtained in different years and/or orchards. Calibration models for soluble solids content (SSC), juice pH, titratable acidity (TA), firmness and maturation index (MI = SSC/TA) were built from the spectral data obtained in two orchards with different edaphoclimatic conditions, and in two consecutive years, corresponding to four independent datasets. We propose a method to assess model robustness through the comparison of internal validation (IV: calibration and validation data sets homogeneously sampled from the whole data set) and external validation (EV: calibration and validation data sets corresponding to different orchards and/or years). The method is based on the statistics of the results obtained by either IV and EV when applied to all the possible combinations of the four datasets. The results show that IV overestimates the models’ performance relatively to the realistic exercise of EV. Globally, SSC and juice pH were the best performing models, with fair performances in IV and poor performances in EV (example for SSC: (IV/EV): rmsep = 1.00/1.15%, SDR = 1.40/1.13, R 2  = 0.49/0.34). Firmness yielded the worse models, while TA and MI yielded intermediate performances. However, the plots derived from the comparison method suggest a convergence of IV and EV performances for larger numbers of samples, and thus the potential for future continuous model improvement. [ABSTRACT FROM AUTHOR]

• SW-NIRS was used to build PLS calibration models for 'Ortanique' quality attributes. • The best calibration models were obtained for MI and TA and the worse for glucose. • Coarse predictive models were obtained for ascorbic acid, sucrose and total sugars. • Models' robustness was tested externally with datasets from two orchards. • Model updating was implemented through bias correction and spiking. The aim of this study was the non-destructive assessment of 'Ortanique' (Citrus reticulata Blanco x Citrus sinensis (L) Osbeck) ripening, based on the prediction of internal quality attributes (IQA) by short-wave near-infrared reflectance spectroscopy (SW-NIRS) calibration models. Spectra from fruit of 50 trees located in two different orchards, were acquired on tree using a customized portable visible near-infrared (vis-NIR) system. Partial least squares (PLS) was used to build the various IQA calibration models. The models were tested through internal validation (IV) and external validation (EV). Generally, the IV results were always superior to those of EV: regarding IV, a high regression coefficient (R2) and low root mean square error of prediction (RMSEP) were achieved, revealing a good predictive performance for juice pH (R2 = 0.80; RMSEP = 0.10; SDR = 2.23), soluble solids content (SSC) (R2 = 0.79; RMSEP = 0.75 %; SDR = 2.27), titratable acidity (TA) (R² = 0.73; RMSEP = 0.24 % citric acid; SDR = 1.94) and the maturation index (MI) (R2 = 0.80; RMSEP = 1.38; SDR = 2.2). The best EV predictions were obtained for TA (R2 = 0.69; RMSEP = 0.38 % citric acid; SDR = 1.24), and MI (R2 = 0.69; RMSEP = 2.07; SDR = 1.49). Calibration models for glucose, fructose and sucrose showed medium-coarse predictions for both validation strategies. A detailed investigation of MI models was performed, to understand the causes of their poor EV results. In the context of EV, model updating strategies were explored by using some validation samples to improve the calibration model. The methods of bias correction and spiking were tested, showing a clear improvement in the predictions. [ABSTRACT FROM AUTHOR]

Halting biodiversity loss is one of the major conservation challenges of our time and science-based conservation actions are required to safeguard the survival of endangered species. However the establishment of effective conservation strategies may be hampered by inherent difficulties of studying elusive animals. We used analysis of control region sequences to obtain baseline information on the genetic diversity and population structure and history of the elusive and critically endangered Mediterranean monk seal that will help define an effective conservation strategy for the species. We analyzed 165 samples collected throughout the entire extant range of the species and identified 5 haplotypes. Based on levels of genetic diversity (haplotypic diversity: 0.03; variable sites: 0.6%) the Mediterranean monk seal appears to be one of the most genetically depauperate mammals on Earth. We identified three genetically distinct monk seal subpopulations: one in the north Atlantic [Cabo Blanco vs. Aegean Sea ( F ST = 0.733; P = 0.000); Cabo Blanco vs. Ionian Sea ( F ST = 0.925; P = 0.000)] and two in the Mediterranean, one in the Ionian and another one in the Aegean Sea (Ionian vs. Aegean Sea F ST = 0.577; P = 0.000). Results indicate a recent divergence and short evolutionary history of the extant Mediterranean monk seal subpopulations. Based on the results we recommend continuation of the monitoring efforts for the species and systematic collection of genetic samples and storage in dedicated sample banks. On a management level we argue that, based on genetic evidence, it is justified to manage the Atlantic and Mediterranean monk seal subpopulations as two separate management units. In Greece, the existence of two subpopulations should guide efforts for the establishment of a network of protected areas and identify the monitoring of habitat availability and suitability as an important conservation priority. [ABSTRACT FROM AUTHOR]

• Tree georeferencing allowed assessing the spatiotemporal ripening trend of cultivars. • Maps showed a large variability in the fruit internal quality attributes. • The optimal harvest date (OHD) of both cultivars varied within and between orchards. • OHD occurred two months earlier in the coastal than in the mountainous area orchards. • Maps allowed detecting the differential decrease of juice content in both cultivars. "Algarve Citrus" are non-climacteric Protected Geographical Indication (PGI) commodities. They are harvested with minimal levels of juice content (≥35 %), soluble solids content (SSC) (≥10 %) and maturation index (MI) (≥8), as required by the respective PGI normative reference. These internal quality attributes (IQA) are usually determined in small samples of fruit collected from the orchards close to harvest. This study aimed to use geostatistics to help predict the optimal harvest date (OHD) of two sweet orange (Citrus sinensis (L.) Osbeck) cultivars, namely, 'Newhall', and 'Valencia Late', at two different edaphoclimatic conditions observed in the locations of Quarteira, at the coast, and Paderne, near a mountainous area. Two orchards of 0.5-0.7 ha per cultivar were chosen and a total of 25 trees were georeferenced within each orchard, comprising 100 sampling points/trees. Firmness, juice content, SSC and MI of fruit were determined through time. In general, the fruit grown in Quarteira showed higher SSC and MI and lower firmness values, ripening two months earlier than those grown in Paderne, although the full effect of the various edaphoclimatic factors on these results are not fully understood. However, geospatial modelling of ripening has shown a large variability within the orchards, with some IQA evolution patterns observed in some orchards and/or cultivars but not in the others. Specifically, 1) a negative correlation between the firmness and MI spatial patterns; 2) a variable decay rate of firmness, much faster in Paderne for 'Valencia Late'; 3) local minima in juice content, below 35 %, observed in restricted spatial areas and in specific time periods, and which were clearer in 'Newhall'. These local variations highlight the need for an optimized management based on geospatial modelling. For example, the variable decay rate of firmness must be taken into account during fruit harvest and postharvest handling. On the other side, the observation of localized plots with juice content below 35 % must be contextualized in the broader picture of the entire orchard which, in the present study, always had consistent temporal average level above 35 %. This study has provided evidence that fruit ripening variability should be considered in the site-specific orchard management of citrus to optimize their harvest date. [ABSTRACT FROM AUTHOR]