A Novel Vegetation Index for Coffee Ripeness Monitoring Using Aerial Imagery

Coffee ripeness monitoring is a key indicator for defining the moment of starting the harvest, especially because the coffee quality is related to the fruit ripeness degree. The most used method to define the start of harvesting is by visual inspection, which is time-consuming, labor-intensive, and does not provide information on the entire area. There is a lack of new techniques or alternative methodologies to provide faster measurements that can support harvest planning. Based on that, this study aimed at developing a vegetation index (VI) for coffee ripeness monitoring using aerial imagery. For this, an experiment was set up in five arabica coffee fields in Minas Gerais State, Brazil. During the coffee ripeness stage, four flights were carried out to acquire spectral information on the crop canopy using two quadcopters, one equipped with a five-band multispectral camera and another with an RGB (Red, Green, Blue) camera. Prior to the flights, manual counts of the percentage of unripe fruits were carried out using irregular sampling grids on each day for validation purposes. After image acquisition, the coffee ripeness index (CRI) and other five VIs were obtained. The CRI was developed combining reflectance from the red band and from a ground-based red target placed on the study area. The effectiveness of the CRI was compared under different analyses with traditional VIs. The CRI showed a higher sensitivity to discriminate coffee plants ready for harvest from not-ready for harvest in all coffee fields. Furthermore, the highest R2 and lowest RMSE values for estimating the coffee ripeness were also presented by the CRI (R2: 0.70; 12.42%), whereas the other VIs showed R2 and RMSE values ranging from 0.22 to 0.67 and from 13.28 to 16.50, respectively. Finally, the study demonstrated that the time-consuming fieldwork can be replaced by the methodology based on VIs.

Spatial distribution of Crimean agroecological resources as a factor of variability of the main and secondary metabolites of grapes

The work is aimed at identifying the relationship between agroecological conditions and the formation of carbohydrate-acid and phenolic grape complexes. The agro-climatic parameters of 14 cv. ‘Cabernet Sauvignon’ industrial vineyards located in five wine-growing regions of Crimea have been determined using the methods of geoinformation and mathematical modeling. According to the similarity of 9 agro-climatic characteristics, the vineyards are united into 6 clusters, significantly different from each other. The dispersion of the main and secondary metabolites of grapes, as well as technological indicators based on them in the harvest from the selected clusters, has been established. According to the combined mass concentration of anthocyanins in berries, potential amount of extractable anthocyanins, anthocyanin extractability, monophenolmonooxygenase activity, glucoacidimetric index and grape ripeness index the selected vineyard clusters are discriminated with Wilks L. = 0.09 at α<0.00001. Sugar content, active acidity index, glucoacidimetric index, and grape ripeness index were found to correlate inversely with the amount of precipitation during the growing season; anthocyanin extractability correlates directly with the Huglin and Winkler indices; monophenolmonooxygenase activity with the sum of active temperatures above 10 °C, Huglin index, total precipitation per year and growing season.

Comprehensive ripeness-index for prediction of ripening level in mangoes by multivariate modelling of ripening behaviour

Prediction of ripeness level in climacteric fruits is essential for post-harvest handling. An index capable of predicting ripening level with minimum inputs would be highly beneficial to the handlers, processors and researchers in fruit industry. A study was conducted with Indian mango cultivars to develop a ripeness index and associated model. Changes in physicochemical, colour and textural properties were measured throughout the ripening period and the period was classified into five stages (unripe, early ripe, partially ripe, ripe and over ripe). Multivariate regression techniques like partial least square regression, principal component regression and multi linear regression were compared and evaluated for its prediction. Multi linear regression model with 12 parameters was found more suitable in ripening prediction. Scientific variable reduction method was adopted to simplify the developed model. Better prediction was achieved with either 2 or 3 variables (total soluble solids, colour and acidity). Cross validation was done to increase the robustness and it was found that proposed ripening index was more effective in prediction of ripening stages. Three-variable model would be suitable for commercial applications where reasonable accuracies are sufficient. However, 12-variable model can be used to obtain more precise results in research and development applications.

Effect of Loosening Agent Sprays on the Efficiency of the Mechanical Harvesting of ‘Arbequina’ Olives

The aim of this work was to evaluate the effect of ethephon (2-chloroethylphosponic acid), applied either alone or in combination with phosphorus compounds, on olive trees (Olea europaea L.) to improve the efficiency of mechanical harvesting. The trial was carried out in mature ‘Arbequina’ olive trees located in northeast Spain during the 2007 and 2008 olive crop seasons. In 2007, the olive trees were sprayed with 300 or 500 mg·L−1 of ethephon combined with two phosphoric formulations: monopotassium phosphate (MKP), at 15 g·L−1 or 30 g·L−1 and monoammonium phosphate at 15 g·L−1. In 2008 olive trees were sprayed with two ethephon concentrations (150 or 300 mg·L−1) in combination with 15 g·L−1 or 30 g·L−1 MKP or alone. Harvesting was performed with a commercial trunk shaker. Data were analyzed as a randomized complete block design with eight replications. Fruit removal force (FRF), ripeness index, fruit weight, natural drop, shaking efficiency (SE), leaf drop (LD), oil content, and bloom intensity of the next year’s bloom were measured. The trial treatments did not significantly affect ripeness index or oil content. Ethephon reduced FRF and increased shaking efficiency with significant differences. P compounds did not seem to affect FRF and LD. Small amounts of ethephon (150 mg·L−1) caused a large degree of fruit loosening (a 77% reduction in FRF at 11 days), which was sufficient to improve the efficiency of mechanical harvesting with minimal leaf drop.

Note. The ripening of Prunus persica fruits with a dominant flat allele Nota. Maduración de frutos de Prunus persica con un alelo dominante de la forma achatada

The changes of peaches ( Prunus persica, L.) with a predominant flat allele were studied during their ripening on the tree. Physicochemical and physiological parameters were analyzed between days 101 and 121 after fruit set. During this period, the weight ranged from 65 g (corresponding to fruit growth stage III) up to a stabilized weight of 90 g when the fruit was ripe. The color changes that characterized fruit ripening began to appear on day 112 after fruit set, with a decrease in the hue angle value both in the skin and pulp. Firmness diminished along the experience from 6.75 to 3.03 Monet units in ripe state. Ripened fruit was also characterized by a soluble solid content of 13.43 °Brix and 0.178% malic acid as titratable acidity. The ripeness index increased throughout maturation from 25.41 at the outset to 44.42 on day 112 after fruit set, and 75.45 at the end of the experiment. The fruit showed a clear climacteric behavior with increased ethylene production and respiration rate. The onset in both processes started on day 112 after fruit set, reached a maximum on day 116, and decreased thereafter. Changes in the content of free and conjugated 1-aminocyclopropane-1-carboxy lic acid (ACC) were coincident with those of ethylene evolution throughout ripening. In regard to polyamine levels, putrescine showed a peak slightly later than that of ethylene and ACC.

Influencia de la época de cosecha sobre las características de la granadilla morada (Passiflora edulis Sims) y su jugo/Influence of harvest season on the characteristics of purple passion fruit (Passiflora edulis Sims) and its juice

The effect of two different harvest seasons (winter and summer) on some characteristics of passion fruit and juice was studied. Three different harvests were made during the two seasons every 15-20 days. The soluble solids/acid ratio was used as a ripeness index. The weight, diameter, peel thickness and yield of juice and seeds were determined in the fruit. Soluble solids, pH, acidity, total and reduced sugars, starch, pectin and pectinesterase activity were determined in the juice. A sensory evaluation of the quality and intensity of aroma was made. Influence of the date of harvest on the technological characteristics of the fruit and juice were observed. Winter fruits showed higher weight, diameter and peel thickness and lower juice yield than those from the summer harvest. The juice from the summer harvest showed a higher content of soluble solids, less acidity, and a higher content in starch, pectin and sugars than that of the summer harvest. The sensory evaluation showed that the aroma of the juice from the summer harvest was better in intensity and quality than that of the winter fruit.

Changes in Susceptibility to Brown Rot with Ripening in Three Clingstone Peach Genotypes

Susceptibility to brown rot, caused by Monilinia fructicola (Wint.) Honey, changed with fruit ripening in the susceptible clingstone peach [Prunus persica (L.) Batsch] cultivar Corona and two moderately resistant genotypes. Nonwounded fruit were more resistant before epidermis color break from green to yellow. Susceptibility increased from color break to the period when the epidermis had acquired a uniformly yellow ground color. With continued ripening, susceptibility remained constant or decreased, depending on genotype. A ripeness index based on fruit color permitted objective within and between genotype comparisons of susceptibility. The genetic selection for precociously developing high yellow-orange flesh color has resulted in a clingstone peach selection possessing a flesh quality suitable for processing and with high levels of brown-rot resistance at the mature-green fruit development stage.