Floral analysis cannot be considered as an alternative to the foliar diagnosis in the olive

Correlations between macro and micronutrient concentration of olive leaves and those obtained in floral buds at five development stages, were studied in order to evaluate the utility of floral analysis for the diagnosis of the nutritional status of olive orchards. Olive leaves from ‘Arbequina’, ‘Frantoio’, ‘Hojiblanca’, ‘Bella de España’ and ‘Picual’ cultivars were taken during July of 2002 and 2003. Samples of floral buds were collected at five development stages: closed bud (E), petal fall (G), G + 15 days, G + 30 days and pit hardening (H). Results showed a lack of signification of the correlation coefficients between leaf and floral analysis for N, P, K, Ca, Mg, B, Zn, Mn, Fe, Cu and Na in both years of the experiment. The few significant correlations obtained were not repeated in both years. Therefore, the results indicate that floral bud mineral analyses cannot substitute the foliar diagnosis to establish the nutritional status of the olive orchards.     

Inflorescence architecture of olive

The influence of flower position on the inflorescence on opening day, gender, and petal persistence was studied in three olive cultivars: Manzanillo, Mission, and Frantoio. In each cultivar, 45 inflorescences were checked every morning from flower opening to petal fall. Perfect flowers opened mainly in the beginning of the flower opening period, and staminate flowers opened later. Flower position on the inflorescence had a highly significant effect on the opening day in all cultivars. Terminal flowers and the flowers located on the primary branches opened earlier than the flowers located on the secondary branches. Flower position had also a highly significant effect on gender in Manzanillo and Mission. In Manzanillo, the secondary branches had fewer perfect flowers than the primary branches. In Mission, the secondary branches had no perfect flowers at all. Among the primary branches, the branch arising immediately next to the terminal flower had the latest flowers to open and the lowest percent of perfect flowers. In Manzanillo, perfect flowers had significantly longer petal persistence than staminate flowers. To study flower competition within the inflorescence, the distal half of 120 inflorescences, on which the flowers tend to be perfect, in three trees of Manzanillo were removed about 1 month before full bloom. There was a highly significant effect on the percent of perfect flowers that opened on the proximal half. Flower competition may be a reason for pistil abortion in flowers located on secondary branches.     

Plant water stress and K starvation reduce absorption of foliar applied K by olive leaves

Three-month-old mist-rooted ‘Picual’ olive cuttings were transplanted into 2-l plastics pots containing perlite as substrate and fertigated with a complete nutrient solution containing 0.05, 0.1 or 2.5 mM KCl depending on the experiment. In the first experiment, plants were sprayed with RbCl (Rb⁺ is a K⁺ analog) at a rate of 4% at 63 days after transplanting (DAT). Foliar Rb⁺ uptake through leaves increased with K⁺ concentration in the nutrient solution, indicating that foliar Rb⁺ uptake was lower when plants were K⁺ deficient than when they were adequate. On the contrary, it was observed that translocation of Rb⁺ from leaves to other organs of the plant was higher under K⁺ deficiency conditions. In the second and third experiments, when differences appeared on shoot length due to K⁺ nutritional status (0.05 or 2.5 mM KCl) at 63 DAT, a group of plants were subjected to water stress during 7 weeks. On the other hand, another group of plants (control plants) did not receive any water stress treatment during the experiments. After this period of 7 weeks, all plants were sprayed with RbCl at 4%. Leaf K⁺ concentration diminished in water-stressed plants independently of plants nutritional status. Foliar Rb⁺ uptake through leaves was restricted by water stress either in plants with low K⁺ (0.05 mM KCl) or plants with high K⁺ (2.5 mM KCl). Translocation of Rb⁺ from leaves was greater under water stress conditions in both K⁺ nutritional statuses. In conclusion, the results obtained could explain the irregular response in olive trees to foliar K⁺ sprays, particularly, when they grow in rainfed orchards.     

Effect of alleviating products with different mode of action on physiology and yield of olive under drought

Two years old self-rooted Koroneiki olive trees (Olea europaea L.) were subjected to two irrigation regimes, i.e. the fully irrigated and the severely water stressed trees, while they were treated with three alleviating products of different mode of action. The products used were the osmolyte glycine betaine, the antioxidant Ambiol and the heat and irradiance reflecting kaolin clay particles. The effects of product application and water regime on leaf characteristics, shoot and root growth, photosynthesis, leaf compatible solids (carbohydrates) concentration and yield were evaluated. All products applied, exhibited significant alleviating action, based on the relative alleviation index. Irrigated trees exhibited greater growth than drought stressed ones, while the ameliorating products maintained the water content of the leaves under drought conditions and resulted in lower leaf tissue density. On the other hand carbon assimilation rate, stomatal conductance and intrinsic water use efficiency were significantly reduced under drought stress, while the opposite stood for intercellular CO₂. Drought stress resulted in elevated sucrose leaf concentration, while the application of Ambiol increased stachyose concentration and that of glycine betaine did the same with the mannitol concentration. Among the alleviating products tested in this experiment Ambiol and glycine betaine had a significant positive effect on leaf water content, photosynthesis and yield under both drought and well irrigated conditions.     

Calcium increases sodium exclusion in olive plants

‘Picual’ olive cuttings were grown in a greenhouse under saline conditions in 2 L plastic pots containing perlite. Plants were irrigated with a nutrient solution plus 75 mM NaCl and 0, 2.5, 10 or 40 mM CaCl₂. Vegetative growth, leaf and root Na⁺ and Ca²⁺ concentrations were measured. Na⁺ toxicity symptoms were observed in plants non-treated with Ca²⁺. Shoot length was higher in Ca²⁺ treated plants, although shoot growth was reduced at 40 mM CaCl₂, probably due to the high total ion concentration reached in the external solution. Ca²⁺ supply linearly increased leaf and root Ca²⁺ concentration and decreased leaf Na⁺ concentration. However, there were no differences in root Na⁺ concentration. Results indicate Ca²⁺ may take part in the Na⁺ exclusion mechanism, mainly preventing Na⁺ transport to the shoot, that may be an important ability for survival under saline conditions.     

Identifying the location of olive fruit abscission

For high quality oil, table olive characteristics, and reduction of alternate bearing tendencies, it is often desirable to harvest olive fruits prior to full physiological maturity, that is, before the natural separation zone has differentiated. Olive fruit abscission can occur at different positions, mainly fruit-pedicel, pedicel rachis and peduncle-branch, apparently varying according to cultivar, fruit weight, and fruit maturation. Precisely identifying the location of separation is critical for studying the differentiation of the abscission zone or zones and testing the effectiveness of harvest procedures, including the mode of action of different fruit-loosening chemicals. We determined the olive fruit abscission zone position under natural conditions, throughout the complete fruit maturation period, for two cultivars differing in fruit size. The major separation zone for the cultivars studied was between the fruit and pedicel. For cv. Picual, abscission in zones other that fruit-pedicel occurred in less than 15% of the fruit at all dates throughout the maturation period, whereas in cv. Hojiblanca, the percentages of fruits detached at peduncle-shoot (27%) and pedicel-rachis (19%) were initially substantial, and then decreased progressively during fruit maturation. Our data clearly indicate both varietal and temporal differences which should be taken into account not only when testing fruit-loosening compounds but in extrapolating test results to different varieties or dates. Fruit weight did not appear affect the abscission location. The method we used, of counting the different detached units, is simple and effective for determining the position of fruit abscission.     

Potassium fertilization of rainfed olive orchards

Experiments under both greenhouse and field conditions were performed to study the influence of the type of salt applied (KCl or K₂SO₄) and to compare the effectiveness of their method of application (soil versus foliar) on leaf K concentration and yield in olive trees established under rainfed conditions. In the experiment performed in the greenhouse, mist-rooted 3-month-old ‘Picual’ olive plants growing in 2-l pots containing perlite were irrigated with a complete nutrient solution containing either 0.05 or 2.5 mM KCl during 128 days after transplanting (DAT). A group of plants received one K soil application at a dose equivalent to 1 kg of K per tree at 63 DAT. Another group received four foliar applications at 63, 78, 93 and 108 DAT with a K concentration of 10.5 g/l. The experiment under field conditions was developed with 80-year-old ‘Hojiblanca’ olive trees. Soil application was performed in March every year at a rate of 1 kg K/tree by injecting K fertilizer around the trees. Foliar sprays were carried out in April, March, June and July every year with the same K concentration used for the greenhouse experiment. The results showed that, under both field and greenhouse conditions, either KCl or K₂SO₄ increased K concentration in leaves. Also, both K salts had a positive effect in increasing K content in fruits under field conditions, although the intensity of the increase varied among years. Tree water stress and low K status seemed to influence K uptake. The method of K application, soil or foliar, did not affect the effectiveness of K fertilization.     

油橄榄叶片营养诊断研究

【目的】针对目前国内油橄榄产区施肥带有盲目性、树体营养容易失衡问题,研究建立叶片营养诊断标准,旨在为油橄榄营养诊断和平衡施肥提供参考依据。【方法】以白龙江干热河谷区66个盛果期(15～18 a)代表性油橄榄园为研究对象,应用诊断施肥综合法(DRIS),建立油橄榄叶片诊断标准,并应用其对供试果园营养进行诊断。【结果】油橄榄叶片最适宜值:N为1.6%～1.9%,P为0.10%～0.14%,K为0.6%～0.8%,Ca为1.1%～1.22%,Mg为0.08%～0.10%。高产组和低产组P/N、K/N、Ca/N、Mg/N、Ca/p、k/Ca、Mg/k和Mg/Ca差异显著,确定为油橄榄叶片指数计算的DRIS参数。营养平衡指数(NBI)低产组大于高产组。【结论】两组橄榄园都存在养分过量和不足并存现象,高产组油橄榄园树体的养分状况比低产组果园平衡,营养失衡是低产的主要因素。高产组大多数果园需补充P和Mg,而低产组则需补充N肥。     

Impacts of water stress on gas exchange,water relations,chlorophyll content and leaf structure in the two main Tunisian olive (Olea europaea L.) cultivars

Leaf structural adaptations for the reduction of water loss were examined in two olive (Olea europaea L.) cultivars (Chemlali and Chétoui) growing under water stress conditions. Leaf measurements included leaf tissue thickness, stomatal density, trichome density, specific leaf area, leaf density, water relations, and gas exchange. We found considerable genotypic differences between the two cultivars. Chemlali exhibited more tolerance to water stress, with a thicker palisade parenchyma, and a higher stomatal and trichome density. Chemlali leaves also revealed lower specific leaf area and had higher density of foliar tissue and lower reduction in net CO₂ assimilation rate. The mechanisms employed by these two cultivars to cope with water deficit are discussed at the morpho-structural level. The morphological and structural characteristics of the leaves are in accordance with physiological observations and contribute to the interpretation of why the olive cv. Chemlali is more drought-tolerant than cv. Chetoui. Furthermore, from the behaviour of Chemlali plants we consider this cultivar very promising for cultivation in semi-arid areas.     

Anatomy of the olive inflorescence axis at flowering and fruiting

In spite of the importance of the peduncle and pedicel in supporting and connecting flowers and fruits to the mother plant, these structures are little known in the olive, and more detailed information can be instrumental in studies of fruit development, ripening and abscission. The structure of pedicel and peduncle was studied at flowering and at fruit maturation for the Spanish olive cultivar “Picual”. Both organs have a stem-like structure. At flowering the pedicel is less developed as the transport requirements to individual flowers are minimal compared to that of the complete inflorescence, and the structure has high chances of being shed in the heavy flower abscission in this species. The peduncle is thicker, due to a ridged cortex, and has larger xylem vessel size. By fruit maturation in November, the overall diameter of both pedicel and peduncle increases, due to both conducting tissues and support tissues: in the pedicel the xylem increases 6-fold, in the peduncle 3-fold, while the phloem undergoes smaller increases. An important developmental feature of pedicel and peduncle is the increase in their capacity to mechanically support the growing fruit. To this end both organs, in addition to the increased thickness of the conducting tissues, produce a lignified sclerenchyma ring. Unlike the stem, however, which produces numerous sclereids, the sclerenchymatous ring only consists of fibres, which offer greater flexibility and make the structure less prone to breaking.     

Genetic diversity in Tunisian olive accessions and their relatedness with other Mediterranean olive genotypes

Eighty-four olive accessions obtained from the National Conservatory of Boughrara-Sfax (Tunisia), previously evaluated for morphological traits, were analysed with 47 random amplified polymorphic DNA (RAPD) markers. They were compared with other olive genotypes originated from Eastern or Western Mediterranean. The highest and lowest similarities between genotypes, estimated by simple matching algorithm, were 0.98 and 0.40, respectively. A dendrogram based on Ward's method and a factorial correspondence analysis (FCA) showed that most of Tunisian accessions are closely related to olive genotypes originating from the Eastern Mediterranean and some are clustering with genotypes originated from the Western Mediterranean. These findings suggested multiple and complex origin of Tunisian olive. A comparative study between a previous morphological analysis and current RAPD assay was carried out and discussed.     

DNA fingerprinting of olive varieties in Istria (Croatia) by microsatellite markers

The Istria region, where olives have been cultivated for many centuries, is characterized by a considerable variety of microclimates. The study of varieties traditionally cultivated in Croatian Istria and their relationships with varieties in historically and geographically connected regions is very important in order to identify native olive germplasm, well adapted to local conditions, and to characterize the oil of regional origin. Twelve olive microsatellite markers were used for identification and differentiation of a set of 27 olive accessions grown in Istria (Croatia). Among the 27 accessions, 18 different SSR profiles were discriminated. All 12 microsatellite markers analysed were polymorphic, revealing a total of 81 alleles. The number of alleles per locus ranged from four to nine. This is the first molecular characterization of olive germplasm in Croatian Istria. The analysis clarified the genetic relationships of varieties native to Croatian Istria with introduced olive varieties, as well as with varieties in the neighbouring Slovene Istria region. Numerous varieties in neighbouring regions showed high similarity and a few cases of synonymy (‘Bilica’-‘Bjankera’; ‘Buga’-‘?rna’) and one Croatian-Slovenian homonymy (‘Bu?a’-‘Buga’) were observed. The results provide useful information for a native germplasm survey and can be used for the construction of a unique database comprising all olive varieties in the Istrian region of Croatia and Slovenia.     

Intra-cultivar variability of three major olive cultivars grown in different areas of central-southern Italy and studied using microsatellite markers

A collection of 70 olive samples, originating from diverse areas in central-southern Italy (Abruzzo, Apulia, Calabria, and Umbria) and corresponding to 3 major cultivars denominations (‘Carolea’, ‘Coratina’ and ‘Frantoio’), was genotyped at 10 microsatellite loci. In total, 44 alleles with a mean number of 4.4 alleles per locus were detected. The molecular analysis, allowed the study to show a clear genetic diversity between the three cultivars ‘Carolea’, ‘Coratina’ and ‘Frantoio’ and to state that ‘Carolea’ is a polyclonal cultivar, while ‘Coratina’ and ‘Frantoio’, are probably monoclonal ones. The analysis of intra-varietal polymorphism, through the SSR analysis, proved to be very useful both for varietal identification and for intra-varietal ones. Our work shows that the current designations of olive cultivars fall short of describing the genetic variability among economically important plant material. A thorough investigation of the existing variability will prove of major importance for both management and economic production of olive trees.     

SSR markers reveal the uniqueness of olive cultivars from the Italian region of Liguria

Twenty-three important Ligurian olive accessions corresponding to 16 cultivars were studied using 12 SSR markers and 40 Mediterranean cultivars were included in the study in order to investigate the relationships between Ligurian and Mediterranean germplasm. All SSRs produced polymorphic amplifications. One hundred and forty-nine alleles were found in the 63 accessions analysed. Twenty-two alleles were specific to germplasm from Liguria and of these 12 were unique to single cultivars. Heterozygosity and discriminating power calculated in this regional germplasm were high on average (0.70 and 0.74) and not so much lower than the values in the total sample that includes cultivars from different Mediterranean countries (0.77 and 0.88 respectively). No cases of genetic identities were found between Ligurian and Mediterranean accessions. Several cases of homonyms and synonyms within the Ligurian germplasm were explained. Cluster analysis generally revealed a clear discrimination of the profiles from Liguria and Italy with respect to the cultivars from other Mediterranean countries. Only one Ligurian cultivar, “Negrea”, appeared to have a different origin, grouping with the Mediterranean cultivars.     

Encapsulation of in vitro-derived explants of olive (Olea europaea L. cv. Moraiolo): II. Effects of storage on capsule and derived shoots performance

The experiments described in this paper were designed to examine the effect of storage at different temperatures for various periods on regrowth and proliferation ability of encapsulated olive microcuttings (capsules). The proliferation and rooting ability of the shoots derived from the capsules were compared with those maintained in normal proliferation by 45 days period of subculturing. A simple method of encapsulated microcuttings storage in plastic cuvettes was used. Interesting feature was the ability of the capsules to retain their viability and regrowth after storage at room temperature as well as at 4 °C for 15 and 30 days and both axillary buds on the nodes of almost all capsules sprouted successfully. Improvement in proliferation and rooting abilities were found in subsequent culturing of the shoots developed from the capsules. The study indicates bright prospects of commercial application of alginate nutrient capsule technology in various situations like supply of certified plant material from both official or private organizations to the plant nurseries and/or exchange of germplasm at international level without refrigerated containers just in plastic cuvettes.     

The effect of waste water irrigation on the extra virgin olive oil quality from the Tunisian cultivar Chemlali

The availability of fresh water is very scarce in the Middle East and North Africa. Yet consequently, brackish water or recycled wastewater can be used for irrigation, minimising the exploitation of natural water resources. The aim of this work was to study how irrigation with treated wastewater (TWW) over 4 years affects some parameters of “Chemlali” olive oil quality. Two treatments were considered: trees irrigated with treated wastewater and others cultivated in rain-fed conditions. Results showed that irrigation with TWW over 4 years did not affect free acidity, and specific ultraviolet absorbance at K₂₃₂ and K₂₇₀. For both the crop seasons the mean values of these parameters were lower than the upper limits established for “extra virgin” olive oil. However, irrigation with TWW cumulatively increased palmitic, palmitoleic, linoleic and linolenic acid contents and decreased oleic acid rates. A significant decrease of total phenol contents was also observed at the end of experimental period.     

Early growth habit and vigour parameters in olive seedlings

Fruit tree growth habit and vigour are important traits for orchard management and production, yet are difficult to select for in breeding programs because the parameters for their evaluation are complex, and their expression often requires sufficient plant size and development, entailing valuable time. Thus, in olive (Olea europaea L.) breeding, as for other fruit crops, it is critical to define growth habit and vigour parameters with selection potential, and to determine the earliest age at which they can be measured. Furthermore seedling growth habit traits are important in themselves, particularly in their relation to juvenile period length and management. To explore these issues we evaluated a series of new and standard growth habit parameters during the first year of growth in a population of unpruned olive seedlings originating from six different crosses. The influence of plant age on growth habit traits was determined by comparing measurements at two or three different times. Both parent genotype and plant age significantly affected the vigour and growth habit of the olive seedlings, and 9 months was the most appropriate age for evaluating seedling growth parameters. ‘Picual’, ‘Arbosana’ and ‘Sikitita’ were shown to be promising cultivars for use as genitors, because of their tendency to produce offspring with desirable growth habit traits such as high vigour, weeping habit and low lateral shoot number. From among the 17 parameters studied, based on parent influence and the absence of correlation among parameters, five were identified which best described olive seedling growth habit: Primary Shoot Top Diameter, Primary Shoot Conicity, Secondary Shoot Number, Secondary Shoot Insertion Angle and Longest Secondary Shoot Internode Length.     

Genetic diversity and relationships of wild and cultivated olives at regional level in Spain

Genetic diversity and relationships between local cultivars and wild olive trees from three important Spanish olive-growing regions, Andalusia (South), Catalonia and Valencia (from Eastern Mediterranean Coastal area), were studied by means of eight SSR loci. Distinct allelic composition and heterozygosity levels were found in wild olive populations and cultivars. The observed patterns of genetic variation revealed: a) the independent clustering of Andalusian wild olives in a separate gene pool, b) the belonging of wild populations and most cultivars from Catalonia to another gene pool, c) the joined clustering of Andalusian and a set of Valencian cultivars in a third gene pool, and d) clustering of wild individuals from Valencia to the three different gene pools. These results suggest that wild populations of Andalusia may represent true oleasters, the ones from Catalonia may be feral forms derived from cultivar seed spreading, while the population of Valencia seems to be the most admixed one. The significant differentiation between Andalusian and most Catalonian cultivars is indicating an independent selection of olive cultivars in the two regions. The detection of a certain wild genetic background in some Catalonian and Valencian cultivars and the similarity found between wild and cultivated forms may suggest the use of local wild trees in olive domestication. The proposed scenario for the development of olive cultivars in Andalusia includes an empirical selection of outstanding local wild genotypes followed by various generations of crosses and various replanting campaigns, as well as possible introductions of ancestral cultivars. Therefore, our findings would lead us to support the hypothesis that the current diversity found in Spanish olive cultivars may be regionally differentiated and due to both, autochthonous and allochthonous origin. The information obtained in this work gives insights into the genetic resources of the main olive producing country, demonstrating that wild olive populations and local cultivars both represent potential sources of useful variability for olive breeding programs.     

Cultivar-based fruit size in olive depends on different tissue and cellular processes throughout growth

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.     

Gas exchange and antioxidant response of sweet pepper to foliar urea spray as affected by ambient temperature

This paper analyses the effect of different air temperatures (10, 20 and 30 °C) on the response of sweet pepper plants (Capsicum annuum L. cv. Herminio) to foliar urea applications after growing plants for 20 day with and without nitrogen (N) applied to the growing substrate. Leaf CO₂ assimilation, chlorophyll fluorescence, root respiration, lipid peroxidation and antioxidative enzymes were analysed. Spraying plants with urea increased leaf CO₂ assimilation of N-deficient plants when applied at 20 or 30 °C, compared with non-sprayed plants. When plants were sprayed with urea at 10 °C chlorophyll fluorescence of leaves was similar to that of plants that were supplied with full N in the nutrient solution. Root respiration was not affected by urea sprays whilst leaf NO₃⁻ concentration was increased by urea but only when it was sprayed at 10 or 20 °C. Lipid peroxidation and ascorbate peroxidase in N-deficient plants were reduced significantly by urea sprays, especially when plants were sprayed at 20 °C with N-limitation in the growing substrate. This study shows that N-limitation in the growing substrate induces a temperature-dependant increase in the activities of antioxidant enzymes in leaves of pepper and applications of foliar urea can be optimised, when applied at the appropriate temperature, to partly replace the N supplied to the roots of sweet pepper.