Andrea Paoletti

Qualitative evaluation of olive oils from new olive selections and effects of genotype and environment on oil quality

In the dynamically changing olive oil industry, new cultivars with greateradaptability to modern cul - tivation techniques and with high quality oils are needed. In this paper, oil quality, in terms of fatty acid compo - sition and content in phenolic compounds, was analysed for many new genotypes previously selected in a bree- ding program and cultivated in three different locations of central and southern Italy. Data on some cultivars commonly grown in each area were included for comparison. The availability of data from many genotypes cul - tivated in all three locations allowed quantitative analyses of the genetic and environmental effects on the oil qua - lity traits studied. The acidic composition varied greatly both with genotype and with environment and so did the concentration in phenols, though the effect of genotype on phenols was not significant (P=0.09). The fatty acid composition, particularly the oleic/(palmitic+linoleic) ratio, appeared predominantly under genetic control, with a broad sense heritability of 0.58 while the environmental effect explained 0.31 of the total variance. The oil con - tent in phenolic compounds, instead, had lower heritability (0.29) and was more affected by the environment, which explained 0.50 of the total variance. Few genotypes were selected as the best for each location, but none performed best in all locations. This suggests that, in olive, the highest oil quality is difficult to achieve with a sin - gle genotype in different environments, due to a strong or even predominant effect of the environment on some quality traits. More likely, combinations of genotypes and territories can produce oils with high and typical qua - lity. In this paper, we provide information on potential new genotypes with promising performances in different Italian regions. Further testing of oil quality, together with agronomic performance, is necessary prior to any release of new cultivars.

Effect of agronomical practices on carpology, fruit and oil composition, and oil sensory properties, in olive (Olea europaea L.)

We examined whether some agronomical practices (i.e. organic vs. conventional) affect olive fruit and oil composition, and oil sensory properties. Fruit characteristics (i.e. fresh and dry weight of pulp and pit, oil content on a fresh and dry weight basis) did not differ. Oil chemical traits did not differ except for increased content of polyphenols in the organic treatments, and some changes in the acidic composition. Sensory analysis revealed increased bitterness (both cultivars) and pungency (Frantoio) and decreased sweetness (Frantoio) in the organic treatment. Fruit metabolomic analysis with HRMAS-NMR indicated significant changes in some compounds including glycocholate, fatty acids, NADPH, NADP+, some amino acids, thymidine, trigonelline, nicotinic acid, 5,6-dihydrouracil, hesanal, cis-olefin, β-D-glucose, propanal and some unassigned species. The results suggest that agronomical practices may have effects on fruit composition that may be difficult to detect unless a broad-spectrum analysis is used.

Tissue size and cell number in the olive (Olea europaea) ovary determine tissue growth and partitioning in the fruit

The relationship between tissue size and cell number in the ovary and tissue size in the fruit, was studied in eight olive (Olea europaea L.) cultivars with different fruit and ovary size. All tissues in the ovary increased in size with increasing ovary size. Tissue size in the fruits correlated with tissue size in the ovary for both mesocarp and endocarp, but with different correlations: the mesocarp grew about twice as much per unit of initial volume in the ovary. Tissue size in the fruit also correlated with tissue cell number in the ovary. In this case, a single regression fitted all data pooled for both endocarp and mesocarp, implying that a similar tissue mass was obtained in the fruit per initial cell in the ovary, independent of tissues and cultivars. Tissue relative growth from bloom to harvest (i.e. the ratio between final and initial tissue size) differed among cultivars and tissues, but correlated with tissue cell size at bloom, across cultivars and tissues. These results suggest that in olive, tissue growth and partitioning in the fruit is largely determined by the characteristics of the ovary tissues at bloom, providing important information for plant breeding and crop management.

Floral Biology: Implications for Fruit Characteristics and Yield

Floral biology has important practical implications, in addition to its scientific relevance, given that flower characteristics and bloom affect fruit characteristics and yield. Yield derives from fruit quality (e.g. weight) and quantity (i.e. number), which, in turns, depend on flower quantity and quality: flowers must be suitable to become fruits, and then must be pollinated and fertilized, and must set fruits, which must then grow. Not all flowers can do all of this: some flowers, for instance, have aborted ovaries which are partially developed or absent at bloom, depending on when the abortion occurred. Even when still present, these aborted ovaries are not capable of becoming fruits. Normal pistils, may not be pollinated or fertilized, but also fertilized ovaries may drop after some growth, resulting in fruit drop. From 100 flowers, in olive, all the above phenomena result in one to few fruits (Hartmann, 1950). Because of this low fruit set, it is often believed that cultural practices aimed at improving pollination, increasing fruit set or reducing ovary abortion or fruit drop, may lead to increased olive yields.