Biometric evaluation of twelve olive cultivars under rainfed conditions in the region of Calabria, South Italy

R E G U L A R A R T I C L E *Corresponding author: Dr. Angelo M. Giuffrè, Università degli Studi “Mediterranea” di Reggio Calabria. Dipartimento AGRARIA, Contrada Melissari, 89124 (Reggio Calabria), Italia. Phone +39 (0) 965.1694362, E.mail: amgiuffre@unirc.it. Received: 19 May 2017; Revised: 23 August 2017; Accepted: 25 September 2017; Published Online: 15 October 2017 Giuffrè: Biometrics of olive cultivars from Calabria (Italy) Emir. J. Food Agric ● Vol 29 ● Issue 9 ● 2017 697 Giuffrè et al., 2012; Giuffrè and Louadj, 2013), wax esters (Giuffrè 2013a; Giuffrè, 2014a), fatty alcohols (Giuffrè, 2013b; Giuffrè, 2014b; Giuffrè, 2014c), triglycerides (Giuffrè, 2013c; Giuffrè, 2014d), fatty acid methyl esters (Piscopo et al., 2016), prediction olive ripening (Benalia et al., 2017) these results have to be associated to the biometrics to implement the information on each cultivar and on its possible use in relation to the production geographical area. The aim of this work was to describe the biometrics of fruits from 12 of the main olive cultivars growing in the Calabria and to study the influence of cultivar and harvest year on biometrics, also in relation to fruit use. MATERIALS AND METHODS Cassanese, Coratina, Frantoio, Itrana, Leccino, Nocellara Messinese, Nociara, Ottobratica, Pendolino, Picholine, Roggianella and Sinopolese were the cultivars chosen for this experiment. All cultivars grown in the same geographical area of the Gioia Tauro Plan at 115 m on the sea level (South-West Calabria, Italy). The maximum temperature of this geographical area is 42-43 °C on August (in the morning) and the minimum is -1.5 °C on January/ February (in the night). The rain fell per year (mean between 2014-2015-2016) was 575 mm. Calabria is the second Italian region for olive oil production: 755,032 tons on 2016 (Istat. it, 2017). Ottobratica and Sinopolese are autochthonous for this area, Cassanese originates from Nord-East Calabria and all other cultivars were allochthonous for this geographical area and for this region. Ten 25-30 year-old trees were randomly selected for each cultivar. Plants were chosen along an oblique line between two opposite corners of the orchard. Trees of all cultivars were own-rooted and the same fertilisation program was applied each year with N, P and K in a ratio 20/10/10. Pruning was conducted every two years, deadwood was removed each year. The ground is flat, alluvial, with silt and sand. The environment is humid and temperate. Olive trees were not irrigated. The antiparasitic treatments were mainly against: Bactrocera oleae, Spilocaea oleaginea and Colletotricum gloeosporioides. Fruits (3 kg per tree) were manually and randomly collected in the 2014, 2015 and 2016 harvest years when the maturity index was 3 (IOC, 2011). Each cultivar grown in a specific and unirrigated orchard. Plants were healthy and uniform in size. Biometric data were determined within 6 hours of olive picking. Oil was extracted by a Soxhlet apparatus as follows: the dried olive flesh was weighed and packaged with filter paper before being placed overnight in the Soxhlet in a petroleum ether bath at room temperature, thereafter the temperature was increased up to the petroleum ether boiling point and the oil extraction was conducted with the continuous method for 6 hours. Moisture content was calculated as a percentage of weight of the pitted fruit. Statistical analysis Means and standard deviations were statistically analysed by Excel 2010 software. The SPSS version 17.0 was used for correlations (T-test at p < 0.05), one-way ANOVA (Tukey’s test at p < 0.05), two-way ANOVA (with p < 0.05) and hierarchical cluster analysis (HCA, Euclidean distance as similarity measurement and furthest neighbour method as amalgamation rule). Principal component analysis (PCA) was conducted by the XLSTAT (2016). A 12 x 3 factorial design (12 olive cultivars x 3 harvest years) was applied. Seven samples (n=7) for each cultivar and for each harvest year were prepared, each sample was analysed in triplicate. RESULTS AND DISCUSSION Production Nociara cv shows the most pronounced alternate bearing and the dupes’ production is concentrated in the on-crop year whereas almost no production there is the off-crop year. However, Nociara cv is also the most producing among the cultivars studied in this work, 13 tons per hectare as mean of two harvest years (on-crop and off-crop years). Ottobratica and Sinopolese shown the highest production per tree (100 kg as a mean of two harvest years), (Table 1). Fruit weight Fruit weight is one of the most important parameters and it is mainly considered when fruits are bought for a table olive use. It is correlated with the ovary weight at olive bloom (Rosati et al., 2009). The IOC (2004) size-graded the fruits with relation to their number per kilogramme or hectogramme (Table 2). In table olive processing size homogeneity is fundamental, for this reason, within each size as defined in table 2, it is stipulated that after removing from a 100 olives aliquot, the olive having the largest horizontal diameter and the olive having the smallest Table 1: Olive production per tree and per hectare, data are the mean of two years production (on‐crop and off‐crop years) Cultivar Production per tree (kg) Production per Ha (tons) Tendency to alternate bearing Cassanese 60 12 High Coratina 60 12 High Frantoio 65 13 High Itrana 10 2 High Leccino 70 11 High Nocellara Messinese 30 5 High Nociara 70 13 Very high Ottobratica 110 10 High Pendolino 70 11 High Picholine 30 6 Medium Roggianella 55 11 High Sinopolese 100 8 High Giuffrè: Biometrics of olive cultivars from Calabria (Italy) 698 Emir. J. Food Agric ● Vol 29 ● Issue 9 ● 2017 horizontal diameter, the difference between the horizontal diameters of the remaining olives may not exceed 4 mm. The IOC classifies olives in three main categories: smallsized (less than 3 g), medium-sized (3-5 g), and largesized (> 5 g). By the IOC classification, only Nocellara Messinese was constantly in the large-sized category and produced the heaviest drupes. Cassanese and Picholine produced medium-sized fruits (more than 4 g) in all the three studied years, i.e. drupes more heavy than drupes from Sayali cv obtained in North Tunisia (Hannachi, et al., 2008). Itrana produced medium-sized olives in two out of the three considered harvest years (Fig. 1). Ottobratica produced the smallest fruits in all the harvest years, always less than 1.5 g, i.e. less than 1/3 weight of the fruits from the cultivars producing the heaviest drupes. In traditional home olive table preparation in Calabria, all the 12 studied cultivars are used for both table olives preparing and for oil extraction, but in a industrial process, Nocellara Messinese, Cassanese, Picholine and Itrana are preferred. Cultivar very highly significantly influenced fruit weight (p< 0.001); harvest year influenced less this parameter (p< 0.05), (Table 3). Aganchich et al (2008) studied olive trees (Moroccan Picholine cv) and found that plants irrigated with 100% of the crop evapotranspiration on the two sides of the root system produced drupes having a significant lower weight if compared with plants submitted to partial rootzone drying. Hannachi et al. (2008) examined the fresh weight of drupes from cultivars and from oleaster in Tunisia and verified the influence of the geographical area on this parameter, in addition drupes from cultivars were found to be more heavy than drupes from oleaster. Flesh weight Many aspects are related to the flesh weight. Fruit size and consequently flesh weight influence parasitic attacks: Psyttalia concolor having a relatively short ovipositor prefers fruits with a thin mesocarp whereas the Bacrocera oleae larva prefers to feed deep inside the mesocarp (Wang et al., 2009). From the point of view of table olive processing the flesh weight and consequently the flesh thickness is one of the parameters influencing the time of brine (NaCl in a aqueous solution) and/or lye (NaOH in a aqueous solution) diffusion into the flesh (Garrido-Fernández et al., 1997). In the present work the flesh weight was found to be in accordance to the fruit weight, in fact Nocellara Messinese had the highest absolute flesh content, being in the 4.0-4.5 g range. Cassanese and Picholine were in the 3.0-4.0 g range. All other cultivars had a flesh weight lower than 3 g (Fig. 2). A very high correlation was found between the fruit weight and the flesh weight (0.978, p < 0.001) whereas pit weight was less correlated with fruit weight (0.743, p < 0.001), meaning that the pit had a lesser influence on total fruit weight (Table 4). Ebiad and Abou-Qaoud (2014), studied three cultivars (Nabali Baladi, Nabali Moassan and Souri) growing in a semi-coastal location in Palestina, they found cultivar to significantly influence the flesh weight with the cv Nabali Mohassan to produce drupes having more than twice the flesh weight (2.94 g) if compared with cv Souri (1.22 g). The latter cultivar showed a flesh weight similar to our Frantoio cv which ranged between 1.20 g and 1.37 g from 2014 to 2016 harvest year. Pit weight A low pit weight is preferred in both the table processing and the oil extraction industries. Nocellara Messinese showed the highest value in all the three studied years 1.02 g, 1.12 g and 1.12 g for 2014, 2015 and 2016 respectively and it was the only cultivar producing olive pits with a mean fresh weight higher than 1 g. Cassanese, Coratina, Leccino, Nociara and Picholine ranged between 0.6 g and 0.9 g (Fig. 3). The lowest values were always found in Ottobratica, Pendolino and Roggianella. In our work the pit weight was the only parameter not significantly influenced by harvest year (Table 3). All the studied cultivars presented a pit weight higher than the one of Chemlali cv grown in the site of Rouhia in North Tunisia (0.17 g) whereas Leccino and Table 2: Size scale as number of fruits per kilogramme, above 410, the interval is 50 fr