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During the last decade, several nanoparticles have been synthesized such as nano-silver, nano-silica, nano-aluminum, nano-zinc oxide, nano-copper, carbon nanotubes, and nano-titanium dioxide. The u...

A sufficient and mature vegetative growth is an essential condition for production in the following season and consequently affects the alternate bearing (AB) behavior. However, little is known about its interaction with the crop load and water supply. Herein, we studied the effect of different water regimes and bearing status on the vegetative intensity and flush and its consequence on the flowering parameters of the following season. Rainfed (RF) and fully irrigated (FI) treatments were applied for bearing (ON) and non-bearing (OFF) trees of the ‘Zalmati’ olive orchard in south Tunisia during 2018. The water deficit condition (RF) and the high crop load (ON) have caused a similar decrease in the total node number and shoots length by about 65%. Furthermore, the flowering parameters in 2019, especially the percentage of floral buds (i.e., floral induction intensity), were differentially affected by water supply according to the bearing status of the previous season. FI reduced the percentage of floral buds in 2019 by about 37% for OFF trees, while it increased it by more than four times for the ON trees. Concerning the growth flush, the second (i.e., autumnal) flush seems to respond better to water supply than the first (i.e., spring) one, for both vegetative and flowering parameters. The second flush of growth provided 28% of the total vegetative growth but contributed about 35% to the total number of floral buds for RF OFF trees. Besides, FI makes the first and the second flushes contribute equally to total vegetative growth and to the flowering parameters of the following season. On the other hand, the bearing status of the trees does not affect the contribution of each flush to the total vegetative growth.

The date palm, a central plant in the fragile oasis ecosystem, is considered one of the fruit species most tolerant to salt stress. However, the tolerance mechanisms involved are yet to be addressed and their evaluation until now was mainly based on heterogenous plant material such as seedlings or limited to in vitro experiment conditions. For these reasons, we propose to deepen our knowledge of the morphological and physiological responses to salt stress using acclimated ex vitro plants resulting from the propagation of a single genotype. The plants were irrigated with 0, 150, 300, or 450 mM NaCl solutions for four months. Our results showed that the influence of water salinity on growth and ion-homeostasis regulation was very dependent on stress levels. The 150 mM NaCl concentration was found to improve dry biomass by about 35%, but at higher salt concentrations (300 and 450 mM) it decreased by 40–65%. The shoot:root dry mass ratio decreased significantly at the 150 mM NaCl water concentration and then increased with increasing water salt concentration. The leaf:root ratio for Na+ and Cl− decreased significantly with increasing water salinity up to a concentration of 300 mM NaCl, and then stabilized with similar values for 300 mM and 450 mM NaCl. In contrast to Na+ and Cl−, leaf K+ content was significantly higher in the leaf than in the root for all salt treatments. Unlike Na+ and K+, Cl− was expelled to the surface of leaves in response to increased water salinity. Overall, date palm plants appear to be more capable of excluding Cl− than Na+ and of changing biomass allocation according to salt-stress level, and their leaves and roots both appear to play an important role in this tolerance strategy., All authors are funded through the Small Research group project from the Deanship of Scientific Research at King Khalid University under research grant number (R.G.P.1/295/43).

Cakile maritima is a halophytic plant model that is well known by its ability to tolerate high salt concentrations. Salinity was reported to improve the tolerance of halophytes to several abiotic stresses; however, the involvement of salt in the tolerance to biotic stress is still scant. In the present work, the effect of salt on C. maritima responses towards the pathogenic Alternaria alternata was investigated. For that, C. maritima seeds were germinated for four weeks. Plants were then divided into four groups: i) Plants irrigated with salt (200mM NaCl); ii) Plants infested by fungus; iii) Plants irrigated with salt and infested by fungus and finally control plants (0mM NaCl, without inoculation). Our results showed that upon salt stress or fungal attack, plants reduced biomass production, hydration status and photosynthetic performance which were associated with a decrease in the gas exchange and chlorophyll fluorescence parameters, with a more pronounced effect upon fungal attack. However, under combined stress, a significant increase of these parameters was noticed, with a level close to that of control. Concerning nutrient contents, K, Zn, Fe, Cu and Mg decreased in the C. maritima leaves exposed to both stresses applied individually. In contrast, all these nutrients were increased in plants grown under combined stress. Taken together, we can conclude that plants grown under combined stresses had better growth rate and physiological performance compared to all other treated plants, and that salt may be the key in improving the C. maritima ability to tolerate fungal attack.

The purpose of this study was to evaluate the relationship between two types of vigor and architectural parameters (quantitative and qualitative) and the duration of juvenile period in olive and to test the effectiveness of three different strategies for an early elimination of seedlings with long juvenile period. Architectural parameters were evaluated in 794 one-year-old olive seedlings, and first flowering time for each seedling was then recorded the following three years. Among the quantitative parameters, ‘Plant height’ and ‘Secondary shoots insertion angle’ were those most correlated with the juvenile period duration. Among the qualitative parameters, ‘Main vertical axis’, ‘Branching system’, ‘Preferential distribution of long shoots’, ‘Extreme leaf size’, ‘Branch orientation’ and ‘Branch bending’ were also able to distinguish seedlings with different juvenile period duration. Four architectural types (defined on the basis of the qualitative parameters evaluated) were found in higher percentages in seedlings with short juvenile period. Finally, three new selection strategies based on the ‘Branch orientation’ (strategy I), the established architectural types (strategy II), and the association of ‘Plant height’ with architectural type (strategy III) all provided greater capacity for discarding seedlings with long juvenile period than did using only ‘Plant height’ method, the early selection criterion currently used for that purpose in breeding programs. The strategy based on combining a quantitative criterion (i.e. ‘Plant height’) and the qualitative architectural types, provided the most promising results from a practical point of view considering both ease of measurement and selection effectiveness.

The relationship between tissue (mesocarp and endocarp) growth and either tissue initial (i.e. in the ovary at bloom) size or cell number was studied using the olive cultivar Leccino (L) and its mutated clone (LC), which produces tetraploid fruits. LC ovaries were 2.7 times the volume of L ovaries, but contained an overall similar number of much larger cells. This allowed decoupling cell number and ovary size, which are normally closely correlated. With this decoupling, cell number in the ovary correlated with tissue growth in the fruit while tissue size in the ovary did not. Cell size in the ovary was inversely correlated with the tissue relative growth from bloom to harvest (i.e. the ratio between final and initial tissue size). These results support the hypothesis that cell number and not tissue size are related to fruit growth and sink strength, and that cell size in the ovary tissues is a good predictor of tissue growth, across cultivars and tissues, even when cell size is strongly affected by ploidy.

Unlike orthodox species, seed recalcitrance is poorly understood, especially at the molecular level. In this regard, seed maturation and germination were studied in the non-orthodox Quercus ilex by using a proteomics strategy based on two-dimensional gel electrophoresis coupled to matrix-assisted laser desorption ionization/time of flight (2-DE-MALDI-TOF).Cotyledons and embryo/radicle were sampled at different developmental stages, including early (M1–M3), middle (M4–M7), and late (M8–M9) seed maturation, and early (G1–G3) and late (G4–G5) germination. Samples corresponding to non-germinating, inviable, seeds were also included. Protein extracts were subjected to 2-dimensional gel electrophoresis (2-DE) and changes in the protein profiles were analyzed. Identified variable proteins were grouped according to their function, being the energy, carbohydrate, lipid, and amino acid metabolisms, together with protein fate, redox homeostasis, and response to stress are the most represented groups. Beyond the visual aspect, morphometry, weight, and water content, each stage had a specific protein signature. Clear tendencies for the different protein groups throughout the maturation and germination stages were observed for, respectively, cotyledon and the embryo axis. Proteins related to metabolism, translation, legumins, proteases, proteasome, and those stress related were less abundant in non-germinating seeds, it related to the loss of viability. Cotyledons were enriched with reserve proteins and protein-degrading enzymes, while the embryo axis was enriched with proteins of cell defense and rescue, including heat-shock proteins (HSPs) and antioxidants. The peaks of enzyme proteins occurred at the middle stages (M6–M7) in cotyledons and at late ones (M8–M9) in the embryo axis. Unlike orthodox seeds, proteins associated with glycolysis, tricarboxylic acid cycle, carbohydrate, amino acid and lipid metabolism are present at high levels in the mature seed and were maintained throughout the germination stages. The lack of desiccation tolerance in Q. ilex seeds may be associated with the repression of some genes, late embryogenesis abundant proteins being one of the candidates.

ISHS Acta Horticulturae 1177: International Symposium on Physiological Principles and Their Application to Fruit Production., The physiology of fruit development is closely related to the cellular processes in the fruit tissues-cell division, expansion and differentiation. We have been carrying out microscopy and image analysis studies on olives to quantify these processes and provide a more comprehensive view of their role, timing, interaction, and the influencing factors. Ovary size and cell number at bloom are highly correlated with cultivar fruit size at maturity. The highest rate and amount of mesocarp cell division occurs immediately following bloom, and it continues throughout fruit development, although at a reduced rate. The differences in fruit size among cultivars are due to cell number and water status tends to impact cell size rather than number. Pit hardening requires the initiation and completion of individual cell sclerification, which is composed of a series of processes, which vary among cells but are coordinated for the endocarp tissue. Endocarp sclerification is affected by both water and assimilate availability, and it seems to drive the end of endocarp expansion rather than vice versa. These results provide new information for interpreting and managing olive fruit growth, and for choosing breeding criteria., This research was supported by a number of Spanish and Italian research grants and cooperative funds, most recently by Spanish Junta de Andalucia - European Regional Development Fund (ERDF) co-financed Project PO11-AGR-7835.

Unlike orthodox species, seed recalcitrance is poorly understood, especially at the molecular level. In this regard, seed maturation and germination were studied in the non-orthodox Quercus ilex by using a proteomics strategy based on two-dimensional gel electrophoresis coupled to matrix-assisted laser desorption ionization/time of flight (2-DE-MALDI-TOF).Cotyledons and embryo/radicle were sampled at different developmental stages, including early (M1&ndash, M3), middle (M4&ndash, M7), and late (M8&ndash, M9) seed maturation, and early (G1&ndash, G3) and late (G4&ndash, G5) germination. Samples corresponding to non-germinating, inviable, seeds were also included. Protein extracts were subjected to 2-dimensional gel electrophoresis (2-DE) and changes in the protein profiles were analyzed. Identified variable proteins were grouped according to their function, being the energy, carbohydrate, lipid, and amino acid metabolisms, together with protein fate, redox homeostasis, and response to stress are the most represented groups. Beyond the visual aspect, morphometry, weight, and water content, each stage had a specific protein signature. Clear tendencies for the different protein groups throughout the maturation and germination stages were observed for, respectively, cotyledon and the embryo axis. Proteins related to metabolism, translation, legumins, proteases, proteasome, and those stress related were less abundant in non-germinating seeds, it related to the loss of viability. Cotyledons were enriched with reserve proteins and protein-degrading enzymes, while the embryo axis was enriched with proteins of cell defense and rescue, including heat-shock proteins (HSPs) and antioxidants. The peaks of enzyme proteins occurred at the middle stages (M6&ndash, M7) in cotyledons and at late ones (M8&ndash, M9) in the embryo axis. Unlike orthodox seeds, proteins associated with glycolysis, tricarboxylic acid cycle, carbohydrate, amino acid and lipid metabolism are present at high levels in the mature seed and were maintained throughout the germination stages. The lack of desiccation tolerance in Q. ilex seeds may be associated with the repression of some genes, late embryogenesis abundant proteins being one of the candidates.

The annual fluctuations in olive crop load due to alternate bearing and other factors often lead to large differences in fruit size and oil content between years at harvest. A better understanding of how fruit parameters respond to the different leaf: fruit (i.e., source: sink) ratios that occur with contrasting crop loads would provide important information for crop management. Thus, the primary objectives of this study conducted with the cv. Arauco in three growing seasons were to: 1) determine the weight and size responses of the fruit and its main tissues, mesocarp (pulp) and endocarp (pit), to crop load; and 2) obtain relationships between different estimates of the source: sink ratio versus various fruit and oil parameters. Fruit thinning was performed by hand on uniform trees with high initial crop loads four weeks after full bloom the first season to obtain different crop loads at harvest. The thinning percentages the first season were 24%, 48% and 87%, along with an unthinned control. The same trees were then monitored the following two seasons without any further thinning. Fruit were sampled at harvest each season to determine fruit and tissue weights and diameters, oil weight per fruit, and oil concentration (%). Fruit weight was reduced 30–40% by high crop loads in each growing season with the mesocarp being much more affected than the endocarp. Oil weight per fruit (−50%) showed a somewhat greater reduction than fruit weight to crop load due to both fruit diameters and fruit oil concentration being decreased at high crop loads. Fruit and tissue weights and oil weight per fruit all displayed bilinear functions versus source: sink ratio when the source was expressed as canopy volume (a surrogate for leaf area) and sink on both a fruit number and glucose equivalent (GE) basis. Source limited fruit growth at both medium and high crop loads due to limited photoassimilate availability based on the bilinear functions, and the slope of the endocarp response to source: sink ratio was 15 times less than that of the mesocarp when expressed on a GE basis. A quantitative comparison with previously published studies indicated that maximum fruit weight appears to be obtained in olive between 1–2 m of leaf area per kg of GE. The bilinear relationships of source: sink ratio versus fruit weight observed in this study could contribute to crop modelling, and further research concerning how and when the mesocarp and endocarp respond to crop load is needed to aid crop management in obtaining sufficient fruit size and quality for table olive cultivars., This study was partially supported by grants from the Instituto Nacional de Tecnología Agropecuaria (Projects 2006-09) to the Catamarca-La Rioja Region, the Agencia Nacional de Promoción Científica y Tecnología (PICT2008 0884) to P.S. Searles, and the Spanish Ministry of Science and Innovation (AGL2009-07248) to H.F. Rapoport. We thank Huaco SA for use of their orchard, Enrique Ríos for technical support in the field, and Diana Ovejero for statistical advice. M. Cecilia Rousseaux provided critical comments on an earlier version of the manuscript.

In drupe-type fruits, pit hardening, resulting from sclerification of the fruit endocarp, is widely used as a phenological marker for both physiological studies and orchard management. In spite of the importance of pit hardening for understanding fruit development processes and for agricultural practices, however, its quantification has remained obscure and precision has been lost with time and lax usage. In this study, we used a mechanical device to measure the physical pressure required to break the olive pit in order to define the timing of pit hardening more precisely and to permit closer observation of its relationship to fruit and endocarp growth and development. Over 4 years we found that pit-hardening pressure increased following a sigmoid pattern, at first gradually but then with a large and rapid increment of change in a relatively short period of time. The rapid acceleration of hardening began at the time when pit longitudinal and transverse diameters attained their maximum size. That timing is consistent with the anatomical differentiation of the sclerified endocarp cells which can no longer expand nor divide. The results improve our knowledge of pit hardening and provide a more precise context for evaluating the metabolic costs, physiological interactions and genetic controls of stone fruit endocarp development. On a practical level, the association of the intensification of pit-breaking pressure with the cessation of pit expansion indicates that pit diameters can be useful morphological markers to identify the onset of this period.

Definitions of the cells that constitute the exocarp or exterior tissue of fleshy fruits are often vague, sometimes providing contradictory descriptions of the epidermis plus none or varying numbers of underlying cell layers for the same species. This study uses a morphometric approach to investigate how cell dimensions, cell number, and their relation with genetically based fruit size differences can contribute to a characterization of tissue organization in the external fruit region, using the olive drupe as an example.We determined cell area, radial and tangential widths, and cell number in the epidermis and 20 subepidermal cell layers of mature fruits of four olive cultivars that range in fruit size. Variation of these measurements among cell layers and the implied cellular contributions to fruit expansion revealed two different subepidermal regions, but with constant widths and layer numbers for all cultivars: (1) the first four cell layers (1-4), which have similar behavior to the epidermis; and (2) the following five cell layers (5-9), which are more similar to the mesocarp. The results provide new insights about cell patterns in the external region of the olive fruit and suggest that layers 1-4 together with the epidermis may act as a multiseriate exocarp and layers 5-9 may act as an outer mesocarp. © 2012 by The University of Chicago. All rights reserved., The study was funded by the Ministry of Science and Innovation of Spain and European Research and Development Funds (grant AGL2009-07248).

Resumen del trabajo presentado en el VI International Symposium on Olive Growing, celebrado en Évora (Portugal) del 09 al 13 de septiembre de 2008., One of the main drawbacks in olive breeding is the lengthy juvenile period which must be overcome in order to evaluate flowering and fruiting characteristics. In the framework of an olive breeding program, we are attempting to overcome this problem following two strategies. The first one is to use cultural practices aimed at increasing the number of olive seedlings with early flowering and, therefore, able to be evaluated. In this sense, the optimum height for transplanting to the field seems to be 100 cm. Also, characterization of the juvenility cone in olive seedlings has shown that 100 cm is the optimum height to form the canopy. The second strategy to overcome juvenility is that of developing early selection criteria for the length of the juvenile period. Plant height and the number of lateral shoots, measured in the greenhouse, seem to be good criteria to eliminate plants with long juvenile period later in the field. Additionally, other markers of the phase change apart from the onset of flowering are under study. On one hand, leaves from juvenile and adult shoots appear to differ in their histological organization. On another, a gene called JAT showed an expression in juvenile tissue much higher than that in adult tissue.

Sufficient flower number and quality is a prerequisite for subsequent fruit set, and, in the case of commercial fruit crops, for fruit production. In the olive tree, Olea europaea L., flower development constitutes an extensive process which requires two to three months and includes the elongation and branching of the inflorescence axis and the formation of the individual flowers. We applied controlled water deficit to young olive trees in successive periods from winter dormancy until flowering and initial fruit set, and determined inflorescence, flower, ovary and ovule development and final fruit yield at both morphological and histological levels. Water deficit during winter dormancy had no effect on either flowering or fruiting parameters. Fruit production was reduced in all other treatments, but due to different timing-related causes. Deficit during inflorescence development reduced many different flowering parameters, including inflorescence number, flower number, perfect flower number and percentage, and ovule development. When applied two weeks prior to bloom little change was noted in floral development, but ovary and ovule starch content were reduced as was fruit set. Finally, deficit during bloom-initial fruit set produced a drastic effect in which many flowers remained closed and fertilization was prevented. Overall the results indicated developmental plasticity and compensation among flowering and fruiting parameters, and high sink priority for the ovary tissues. © 2011 Elsevier B.V., This study was financed by ERDF co-financed Spanish Ministry of Science and Innovation grants AGL2008-02570 and AGL2009-07248, and Andalusian Excellence grantPO6-AGR-01791.

Differences in mature fruit size among olive cultivars are related to differences in ovary size at bloom, but it is not known whether cell number or size determines the variation in ovary size. In this study we measured cell size and number in equatorial cross-sectional areas of the principal ovary tissues (mesocarp and endocarp) in eight cultivars with very different fruit and ovary size. The results showed that cell number explained most of the differences in ovary size, while cell size was not related to ovary size, except for a weak (R2=0.33) correlation in the endocarp. Since sink strength is thought to be related to cell number, this finding supports the hypothesis that larger ovaries represent stronger sinks. The implications of greater sink strength with bigger ovaries are discussed. Within cultivars, while the cross-sectional areas of mesocarp and endocarp were similar, cell number was higher in the mesocarp but cell size was smaller compared to the endocarp. © 2011 Elsevier B.V., The study was funded by the Italian Ministry for Agricultural, Food and Forestry Politics (MiPAAF) RIOM project, and Spanish Ministry of Science and Innovation Grant AGL2009-07248.

Fruit size at harvest is an important parameter of table olive yield and quality, and is a function of the growth of both major tissues, the fleshy mesocarp (pulp) and the endocarp (pit). High crop loads most often reduce both fruit size and the mesocarp-to-endocarp ratio and delay fruit maturity. Less is known quantitatively, however, about the relationships between olive fruit size and source:sink ratios. Thus, the objectives of the present study were to assess the responses of fruit size and tissue parameters to crop load and to obtain source:sink relationships for these parameters. Fruit samples were taken from low, medium, and high crop load treatments in a commercial orchard (cultivar 'Arauco') located in Bañado de los Pantanos, Argentina, at harvest for green table olives in March 2009. Fruit fresh and dry weight, mesocarp weight, and mesocarp-to-endocarp ratio were at least 35% less in trees with high crop load than those with low crop load. The endocarp showed less response with only a modest reduction of 15%. At the cellular level, mesocarp cell number decreased with increasing crop load, while cell size was not affected. Additionally, a bilinear relationship was found between individual fruit dry weight and the source:sink ratio (canopy volume:fruit dry weight) with fruit weight increasing linearly up to a threshold of about 0.8 m3 of canopy volume per kg of fruit dry weight, above which no further increase occurred. Similar relationships were also obtained for mesocarp and endocarp dry weights versus source:sink ratio. These results provide original quantitative estimates of olive source:sink relationships and indicate the close integration between fruit developmental processes and whole tree phenomena.

The timing, duration, and intensity of summer water restrictions differentially affect overall olive fruit growth and production, based on the underlying fruit developmental processes. For that, the fruit component and tissue morphogenetic response to different irrigation strategies during summer was examined in a hedgerow olive orchard cv. Arbequina. Control trees (CON) were irrigated to maintain the root zone close to field capacity throughout fruit growth. From budburst to 4 weeks after full bloom (WAFB) (Period 1) and from 14 WAFB to harvest (at 23 WAFB) (Period 4) trees of all treatments were irrigated as CON. Two severe water deficit treatments were applied during summer by irrigating 30% CON from 4 to 9 WAFB (Period 2) in DI-P2 or from 9 to 14 WAFB (Period 3) in DI-P3. Moderate water deficit was applied in Periods 2 and 3 by irrigating 50% CON in DI-P2&3. Growth and development of the fruit and its component tissues (exocarp, mesocarp and endocarp), fruit composition, mesocarp cell area and cell number, and epidermal characteristics at the end of each period were evaluated. Water deficits significantly reduced fruit volume at the time when they were applied. Mesocarp size was more sensitive to water deficit than endocarp size and showed a high recovery capacity after rewatering. Although the majority of cells were developed in Period 1, a substantial number of mesocarp cells were also formed later. While mesocarp cell number was unaffected by water reduction in any of the deficit periods, cell size was highly affected but with high recoverability. Endocarp size was reduced when water restriction was applied in DI-P2 and its effect continued until harvest. Fruit oil content at harvest was not significantly affected by the applied water restrictions, whereas water was the fruit component which most responded to both the increases and decreases in irrigation. Cuticle thickness, epidermal cell size and number at harvest appeared to respond to both irrigation regime and fruit expansion pressures. © 2014 Elsevier B.V., This study was partially supported by the Office of International Relations of the Polytechnical University of Madrid (Proyect AL10-PID-20) and by Spanish Ministry of Science and Innovation ERDF co-financed grant AGL2009-07248.

Floral biology and fruit development were studied in Leccino Compact (LC), a polyploid olive mutant of cultivar Leccino (L). This mutant, considered a mixoploid with both diploid and tetraploid cells, has thicker leaves and fruit size similar to the diploid cultivar. So far, no information is available on its floral biology. In this study, the ploidy level of the LC fruit epicarp, analyzed by flow cytometry, was determined to be tetraploid. Pollen size distribution confirmed that most flowers were tetraploid. Morphological and histological measurements of various floral structures and fruits were carried out on the two genotypes, and LC showed larger floral structures (i.e. rachis, flower and ovary) and slightly higher pistil abortion rates. The total number of flowers per inflorescence was not significantly different between L and LC. The large difference (about 2 fold) in ovary cross sectional area between LC and L ovaries was mainly due to increased cell size. LC had slightly larger fruit cross-sectional area (but not greater fruit volume, since LC fruits were less elongated), with much larger cells. Therefore tetraploidy resulted in larger floral structures, as normally occurs in tetraploid plants, but had little effect on fruit size, despite much larger cell size., The study was funded by the Italian Ministry for Agricultural, Food and Forestry Politics (MiPAAF), BIODATI Project (Ob. Fu. 2.01.99.09.02) and by Spanish Junta de Andalucia—European Regional Development Fund (ERDF) co-financed Project PO11- AGR-7835.

The in vitro germination of excised embryos can break dormancy rapidly and shorten the time required to produce seedlings, speeding up olive breeding programmes as well as rootstock production. In this study, the in vitro germination potential of four Sicilian olive cultivars was evaluated during two years of experiments, using explants with three different morphological configurations that represent three different degrees of embryo exposure: (1) intact stoneless seeds containing the embryo, the endosperm and the seed coat (Emb+En+SC), (2) seeds without the seed coat (Emb+En) and (3) naked, isolated embryos (seed coat and endosperm both removed: Emb). Differences were found in the germination percentages and timing due to both genotype and explant type. The root and shoot meristems, the radicle-hypocotyl axis, the provascular tissues and embryo storage reserves were identified as embryo anatomical structures which could influence germination capacity. Observation of these structures, however, indicated similar germination potential among cultivars, suggesting possible differences in other dormancy factors. In spite of variation in cultivar performance, after 60 days of in vitro culture all cultivars demonstrated the highest germination of naked embryos (explant type 3) and lowest for stoneless seeds (explant type 1); stoneless seeds without the seedcoat (explant type 2) showed intermediate germination percentages., This work was partially supported by the CORI (International Cooperation) 2006 program and by the project ‘‘Innovative Methods of propagation and Conservation of Mediterranean Trees’’, FFR 2012–2013, provided by the University of Palermo to Maria Antonietta Germana`.

Endocarp developmental timing in drupe-type fruits, involving tissue expansion and sclerification processes, is increasingly used as marker for biological studies and crop management. In spite of its wide application, however, little is known regarding how these morphogenetic processes unfold or the factors that modify it. This study evaluates endocarp expansion and sclerification of olive (Olea europaea) fruits, used as an example of drupe-type fruits, from trees growing under different water regimes: full irrigated, deficit irrigated (moderate reduction of water availability) and rainfed (severe reduction of water availability). Fruits were sampled weekly until pit hardening, and fruit and endocarp areas were evaluated in histological preparations. An image analysis process was tested and adjusted to quantify sclerified area and distribution within the endocarp. Individual stone cells differentiated independently but distribution and timing indicated the overall coordination of endocarp tissue sclerification. Increase in sclerified area was initially gradual, accelerated abruptly the week prior to the end of endocarp expansion and then continued at an intermediate rate. These results suggest that the end of the expansion period is driven by sclerification and the morphogenetic signals involved act first on sclerification rather than endocarp size. Intensification of sclerification and the end of expansive growth occurred first with lowest water supply. Moderate and severe reductions in water availability proportionately decreased endocarp expansion and prolonged the sclerification, delaying the date of physically perceived hardening but not affecting the final degree of endocarp sclerification. © 2013 Scandinavian Plant Physiology Society., The work was supported by Spanish Ministry of Science and Innovation and accompanying European Funds for Regional Development (AGL2009-07248 to H. F. R.).

Architectural characteristics play an important role in the agronomic performance of fruit tree genotypes. However quantifying such traits in large numbers of individuals represents an important challenge, and little is known regarding their diversity and inheritance. This study evaluates the occurrence, variability, relevance and robustness of visual descriptors, which we propose and test for assessing ten major plant architectural traits in a large number of young olive seedlings and their parents. Our results revealed high phenotypic plant architecture diversity in the studied 825 seedlings from directed crosses, as well as significant parent genotype influence. From ten initially proposed traits, five ('Main vertical axis', 'Preferential distribution of lateral shoots', 'Dominant length of lateral shoots', 'Branch orientation' and 'Branch bending') were found to have the most relevant descriptors for olive seedling architecture based on the high capacity to indicate diversity, strong influence of parent genotype, lack of correlation with each other, and demonstrated value for agronomical performance. All of the descriptors of these five most relevant traits were then combined to generate 105 plant phenotypes, eight of which predominated and showed a clear dependence on parental characteristics. Validity of the results obtained from visual evaluation was verified by their correspondence to quantitative measurements at different stages of analysis. The synthetic characterization of plant-form provides new insights regarding olive seedling description, variability, and parent genotype influence, and represents a significant advance for measuring complex plant architectural traits. © 2012 Elsevier B.V., The work was partly funded by project RTA2008-00033-C02-01, National Institute of Agricultural Research, Spain partially funded by European Regional Development Funds (ERDF).

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. © 2012 CSIRO., The study was funded by the Italian Ministry for Agricultural, Food and Forestry Policies (MiPAAF), RIOM project, Progetto Strategico OLEA–Genomica e Miglioramento Genetico dell’Olivo’, D.M. 27011/7643/10 and by the Spanish Ministry of Science and Innovation ERDF co-financed funds project AGL2009–07248.

In drupe fruits, in addition to fruit size, the proportions of mesocarp and endocarp tissues are critical objectives for fruit quality, crop production and management. The olive fruit is a typical drupe, with cultivars which show a wide range in both fruit size and the proportions of mesocarp and endocarp. Characterizing the roles of tissue and cellular processes in producing genetically based fruit size variability is necessary for crop improvement, as well as deepening our understanding of fruit developmental physiology. This study used microscope image analysis to evaluate cell number and size, the growth of mesocarp and endocarp tissues, and their developmental timing in producing fruit size among six olive cultivars with a large range of fruit size. We found that cultivar mesocarp and endocarp size increased linearly with fruit size, with larger sizes favoring an increasingly greater mesocarp/endocarp ratio. Within the mesocarp, cultivar-based fruit size related directly to cell number and was established soon after bloom by cell division rate. In spite of different cell division rates, all cultivars showed similar timing of cell division activity, with the majority of cells produced in the two months after bloom but, surprisingly, a substantial number of cells formed during the following 6 months. Cell expansion was high throughout fruit growth and an important factor in achieving final fruit size, but cell size did not differ among cultivars at any time. We can conclude that fruit size differences among olive cultivars are due at the tissue level to both mesocarp and endocarp sizes and at the cellular level to cell division throughout fruit growth. Furthermore, since cell size is consistent among cultivars in spite of variable cell division, it is likely that cultivar differences in cell expansion accompany those in cell division. © 2011 Elsevier B.V., This work was supported by Spanish Ministry of Science and Innovation ERDF co-financed funds [grant number AGL2009-07248].