Olive Seedlings Research Articles

Olive seedlings growth as affected by humic and amino acids, macro and trace elements applications

Spraying Chemlali olive seedlings with humic and amino acids, macro and trace elements, as a single or in different were evaluated during two successive seasons 2008 and 2009. Each treatment was sprayed three times (March, July and September). Shoot and root characteristics also leaf macro and trace elements were discussed. The obtained results indicated that treatment of (Humic acid +amino acids+ macro elements+ trace elements) was the most effective one compared with the other treatment since this treatments gave the best results concerning plant height, brunch numbers, leaf numbers, also it increased plant diameter and leaves area comparing with control. On the other hand, this treatment raised root length and root weight than the control plant.

Response of olive seedlings to foliar sprays with amino acids and some micro elements

Kronaki olive seedlings were sprayed with Pepton (the commercial form of amino acids mixture) at 0.5 and 1% alone or in combination with mixture of some chelated micro elements (Zn + Mn + Fe) at 0.25 and 0.5%. Each treatment was sprayed three times through the growing seasons. The obtained results indicated that, treatment No. 4 (Pepton 0.5% + micro elements at 0.25%) was the most effective one comparing with the other treatments. Since this treatments gave the best results concerning height and diameter of the plant, branches number, leaves number and leaves area comparing with the control.

Variability of first flower to ground distance in olive seedlings and its relationship with the length of the juvenile period and the parent genotype

During development, most woody plants that develop from seeds undergo a juvenile phase before transitioning to adulthood. The first flowering indicates the end of the juvenile period and can be used as a marker to discriminate between phases. In this study we analyzed the distance of the first flower from the ground, measured along the trunk and supportive branches, in 385 olive seedlings coming from eight different crosses. We found that for tree canopy base heights of 1.5 and 1.0 m the average distance at which the first flower appeared was 2.41 or 2.07 m, respectively. Moreover, we observed for the first time that the first flower to ground distance was significantly correlated with the juvenile period length and the olive seedling parent genotype. In fact, a particular cultivar demonstrated a consistent influence on the location of the progeny first flower, irrespective of being used as female or male parent. This implies that the first flower to ground distance may not be constant within the olive species. A juvenile cone and its measurement was recently described in olive trees. In this study we similarly find a negative relationship between branch insertion height and the distance from the branch insertion in the trunk to the nearest inflorescence. This observation confirms the cone-shape transition from juvenile to adult phases, although it implies that the specific characteristics of the juvenile cone ultimately depend on the length of the juvenile period. Trees with longer juvenile periods tended to flower for the first time at a greater total distance from the ground. This increase in the first flower to ground distance was due to an increase in the distance from the branch insertion in the trunk to the nearest inflorescence on the branch, whereas the branch insertion height decreased.

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.

Optimizing Early Flowering and Pre-selection for Short Juvenile Period in Olive Seedlings

In recent years, the juvenile period of olive seedlings has been reduced by diverse forcing and pruning-formation techniques, but it is still a major drawback for breeding. Plant height at the time when seedlings are transplanted to the field has been found effective for obtaining earlier flowering, but the value of this parameter varies widely among olive breeding programs. We evaluated different transplant dates, taking into account mean plant height and age, with the aim of determining the optimum parameters for achieving early flowering and easy plant management and, at the same time, for the early elimination of genotypes with a long juvenile period. A mean seedling height of ≈100 cm at the time of planting in the field provided the best results in terms of shortening the juvenile period and facilitating handling of the seedlings. For all dates tested, seedling height at transplanting was effective as a pre-selection criterion for the early elimination of genotypes with long juvenile periods, with slight improvement in effectiveness with advancing transplant date.

Olive seedling first-flowering position and management

The prolonged length of the juvenile period represents a substantial obstacle in olive ( Olea europaea) breeding programs, delaying both the possibility for analyzing the fruit, the harvest unit, and the capacity for sexual recombination. In both olive and other fruit tree species, the juvenile–adult transition has been successfully hastened by forcing and formation procedures designed to rapidly achieve a minimum height. Precise knowledge of the position within the tree canopy where the juvenile–adult transition occurs, identified by the location of the first flowers, offers further potential for manipulating tree structure in order to hasten that transition. The occurrence of the juvenile–adult transition has been described spatially within the canopy as the formation of a juvenility cone, which we report here for olive plants from seed, and for the first time quantitatively describe its position based on the added trunk and branch distances from the soil. In canopies of seedlings from open pollination of cv. Arbequina olive the first-flowering position was consistently located, in our conditions, at an average distance of 200 cm from the trunk base. Based on that evidence, that first flowering can occur at lower positions, and on the values we obtained, three canopy-formation heights (100–130 cm, 130–160 cm and >160 cm) were compared for their effect on the length of the juvenile period and the vigour of olive seedlings. Canopy heights of 100–130 cm, much lower than the 160 cm previously reported by the olive tree breeding program of Córdoba, produced the highest number of flowering plants in the first two flowering years and also provided easier management.

Effects of Seed Scarification on Seed Germination and Early Growth of Olive Seedlings

Effects of Seed Scarification on Seed Germination and Early Growth of Olive Seedlings

IN VITRO GERMINATION OF STONELESS SEEDS AND ISOLATED EMBRYOS OF 14 SICILIAN CULTIVARS OF OLEA EUROPAEA L.

Olive seeds are characterized by an orthodox behaviour and exhibit a state of dormancy caused by different factors such as the hard covering structures (sclerified endocarp) and the inhibitory germination substances contained both in the teguments and in the endosperm and within the embryo. For these reasons, olive seed germination percentages and rates are usually low. To speed up olive seedling development can be very advantageous in breeding programmes as well as in rootstock production for grafting of hard-to-root cultivars. In this study, the in vitro germination potential of stoneless seeds (seeds without the sclerified endocarp) without teguments and of excised embryos of fourteen Sicilian olive cultivars was evaluated. For the in vitro germination of excised embryos, three different media (presence/absence of plant growth regulators, different carbon source concentrations) have been evaluated. Differences in the seed and in isolated embryo germination percentages due to culture media were recorded. In vitro germination of isolated embryos can be a useful method for increasing the efficiency of germination. In fact, according to these results, embryo culture can increase the efficiency and shorten the time for starting initial progeny evaluation of olive breeding programmes.

First Report of Root Rot and Twigs Wilting of Olive Trees in Argentina Caused by Phytophthora nicotianae.

In Argentina, olives (Olea europaea) are planted on approximately 90,000 ha located primarily in the northwest continental regions. During a 2005 survey, root rot was recorded at several olive plantations in Catamarca, La Rioja, and San Juan provinces (3). Aboveground symptoms associated with root rot were twigs wilting with or without chlorosis, defoliation, and death. Symptoms were initiated on lateral branches and sometimes affected the entire crown. Even if young (5-year-old) trees displayed root rot, aerial symptoms may or may not be seen until years later. Disease incidence varied from 3 to 30%. Rotted rootlets were associated mainly with the infection of Phytophthora palmivora Butler and less frequently with another Phytophthora species. Isolates of this species were heterothallic, had a fluffy growth on carrot agar, and arachnoid growth on potato dextrose agar. Chlamydospores approximately 36 μm in diameter were also produced. The species developed prominent, papillate, noncaducous sporangia of different shapes ranging from ellipsoid to spherical when submerged in saline solution. Sporangia were 35 to 57 × 25 to 45 μm (average 44 × 33 μm), L:B ratio from 1.1 to 1.7. Isolates formed oogonia and amphyginous antheridia following mating type assays. On the basis of morphological features, these isolates were identified as P. nicotianae Breda de Haan. Identity was confirmed by sequencing the rDNA internal transcribed spacer (GenBank Accession No. FJ746693) (1). One-year-old O. europea seedlings were challenged with P. nicotianae (A1 isolates 306G and 339) through soil infestation assay in a growth chamber at 25°C. Infested and uninfested autoclaved millet grains moistened with V8 juice were used to inoculate 15 olive seedlings per isolate and controls, respectively. Fifty days after inoculation, seedlings showed foliar symptoms similar to those observed in the field and had an average of 50% reduction in the root system. Control plants remained healthy. P. nicotianae was always reisolated from symptomatic roots. P. nicotianae was reported on Citrus aurantium in Argentina in 1947 and is currently associated with several hosts (2). In 2002, the same species was reported associated with olive root rot in southern Italy (4). It is possible that P. nicotianae was recently introduced into Argentina through importation of Mediterranean olive varieties. The demonstrated pathogenicity of P. nicotianae on olive together with the recently reported detection of P. palmivora (3) presents a serious threat to olive cultivation in Argentina.

A New Eriophyid Mite (Acari: Eriophyidae) and A New Record fromOlea europaeaL. (Oleaceae) in Montenegro

A new species of plant-feeding eriophyid mite collected from olive seedlings in Southern Montenegro is described. Shevtchenkella barensis sp. nov. inhabiting olive, Olea europea L. (Oleaceae) was found in an olive nursery attacking seedlings and causing serious damage. Aceria oleae (Nalepa), is herein recorded as new for the fauna of Montenegro.

Salinity Effect on Concentration, Uptake, and Relative Translocation of Mineral Nutrients in Four Olive Cultivars

ABSTRACT The aim of this greenhouse study was to investigate the distribution of some ions in four olive cultivars, (Olea europaea L., cvs. ‘Zard’, ‘Conservolea’, ‘Manzanila’, and ‘Mission’) under saline conditions. One-year old olive seedlings were planted in the plastic pots contained 1:1 sand: perlite medium and irrigated with one-half strength Hoagland's No. 1 nutrient solution. A completely randomized design with factorially arranged treatments and four replications was used. Four salinity treatments [0, 40, 80, and 120 mM sodium chloride (NaCl)] were used during 100 days. At harvest, shoot and root dry matter yield as well as concentration of mineral nutrients was separately determined in root, apical and basal leaves. There was significant (P < 0.05) difference among cultivars in concentration, uptake, and relative translocation of sodium (Na), chloride (Cl), and potassium (K) in different plant tissues. ‘Conservolea’ cultivar had the highest Na and Cl and the lowest K concentration in apical and basal leaves. In all cultivars, with increasing salinity, the tissue concentration of Na and Cl increased while the K concentration decreased. The results showed that under saline conditions, the distribution of mineral nutrients in olive depends on both plant cultivar and the ion of interest.

Leaf gas exchange, water relations, nutrient content and growth in citrus and olive seedlings under salinity

The effects of salinity on growth, leaf nutrient content, water relations, gas exchange parameters and chlorophyll fluorescence were studied in six-month-old seedlings of citrus (Citrus limonia Osbeck) and rooted cuttings of olive (Olea europaea L. cv. Arbequina). Citrus and olive were grown in a greenhouse and watered with half strength Hoagland’s solution plus 0 or 50 mM NaCl for citrus, or plus 0 or 100 mM NaCl for olive. Salinity increased Cl - and Na + content in leaves and roots in both species and reduced total plant dry mass, net photosynthetic rate and stomatal conductance. Decreased growth and gas exchange was apparently due to a toxic effect of Cl - and/or Na + and not due to osmotic stress since both species were able to osmotically adjust to maintain pressure potential higher than in nonsalinized leaves. Internal CO2 concentration in the mesophyll was not reduced in either species. Salinity decreased leaf chlorophyll a content only in citrus.

Analysis of primary and secondary growth and modelling growth dynamics of olive shoots (Olea europaea L.)

SummaryUnderstanding growth rate in woody plants is an essential criterion for the establishment of tree architecture, and therefore of future tree form. Olive seedlings exist as three main tree structures: bushy, mixed, and tree-form. Growth dynamics were observed on different types of shoots of these different forms throughout the growing season. Both primary growth (elongation and developed metamers) and secondary growth (basal diameter increment) were considered. To study the inter-annual pattern of shoot growth, simple linear regressions were performed between shoot properties measured at the beginning and at the end of the vegetative season. Positive correlations were obtained for all growth parameters. Allometric relationships between primary and secondary growth indicated that the increment in basal diameter was related to primary growth. Bud size and the contents of primordia were compared to the structure of the future shoot and leaves produced after the Spring and Autumn growth flushes. Shoots were entirely preformed in the bushy form. Mixed- and tree form-types had a preformed portion, followed by a neoformed portion. Mathematical models on olive growth were developed based on growth dynamic parameters. Elongation and metamer numbers showed a tri-sigmoid evolution (two Spring flushes and an Autumn flush) which was modelled by theoretical equations defined by tri-logistic functions, and characterised by nine parameters. Secondary growth was also represented by three logistic shapes, indicating three phases of girth expansion on all three forms. These results indicate that olive tree growth is rhythmic under the rain-fed conditions of Tunisia.

Possible early selection of short juvenile period olive plants based on seedling traits

The relationship between the length of the juvenile period and nine olive seedling parameters (plant height, diameter, number of nodes, lateral shoots, internode length, leaf length, width, area, and shape index) was explored in 287 plants belonging to four different progeny. The traits were measured at two timepoints: after the plants had completed a forced growth cycle in the greenhouse/shadehouse (15 months after sowing) and after one growing season in the field (27 months after sowing). Strong linear tendencies of most vigour traits (mainly plant height and diameter) with the time of first flowering were observed. Leaf traits measured after one year in the field were also related to the length of the juvenile period, but not the same traits that were measured the previous year. Strong positive correlations were observed between the parameters studied. All results are discussed in terms of selecting the best seedling traits to be used as pre-selection criteria for short juvenile period during early stages.

IN VITRO GERMINATION OF THREE OLIVE CULTIVARS

Olive seedlings are used in breeding programs as well as rootstocks for grafting of hard-to-root cultivars. However, olive seed germination is not easy, low and slow germination rate are some of the persisted problems. In vitro germination of isolated embryos could be a useful method for increasing the efficiency of germination. One of the main following objectives in embryo culture is the isolation of embryo from the endosperm that contains inhibitory germination substances. This results to shortening of reproductive cycle and the necessary time for obtaining seedlings. In this study, the embryo germination potential of three olive cultivars including 'Manzanilla' and two Iranian cultivars i.e. 'Dezful' and 'Zard' was evaluated. Also the effect of three harvesting times (middle of August, September and October) on growth and development of embryos was studied. Aseptically isolated embryos were cultured in MS medium with one third of macro elements and placed in growth chamber at 25°C day, 21°C night with 16-h photoperiod. According to results, some differences were revealed between germination percent of embryos and the following growth of them. The highest germination percent and seedling formation was obtained at the first culture time with means of 86 and 73 percent, respectively. 'Dezful' cultivar with 90% germination and 79% seedling formation showed the highest values.

The Length of the Juvenile Period in Olive as Influenced by Vigor of the Seedlings and the Precocity of the Parents

A first attempt to determine the effect of vigor and parents on the length of the juvenile period of olive seedlings is here reported. Vigor seems to have a significant influence on the percentage of flowering seedlings, especially in the first 2 years of bearing. The different parents used have produced differences in the juvenile period of their descendants. A correspondence between the length of the unproductive period of the parents and the length of the juvenile period that they transmit to their descendants has been observed. The seedling forcing growth protocol described here has been able to produce flowering seedlings 28 months after germination, with &gt;93% of seedlings flowering 65 months after germination.

Nursery and Field Response of Olive Trees Inoculated with Two Arbuscular Mycorrhizal Fungi, Glomus intraradices and Glomus mosseae

This paper reports the effects of inoculation with arbuscular mycorrhizal fungi on early plant development, field establishment, and crop yield of the olive (Olea europaea L.) cultivar Arbequina. The response of olive plants to the fungi Glomus intraradices (Schenck and Smith) and G. mosseae (Nicol.&amp; Gerd.) Gerdemann &amp; Trappe in different potting mixes was studied in two different nursery experiments. Pre-inoculation with selected arbuscular mycorrhizal fungi prior to transplanting in the field improved plant growth and crop yield up to three years after inoculation. G. intraradices was more efficient at promoting plant growth than both G. mosseae and the native endophytes present in the orchard soil. Inoculation at the time of transplanting enhanced early plant growth in all the field situations studied. Diminishing mycorrhizal effects over time resulted from natural colonization of noninoculated seedlings and related to the native arbuscular mycorrhizal (AM) fungal population of the field soil. Early inoculation of olive seedlings enhances early plant development and crop productivity of olive trees.

Evaluation of vegetative growth traits and their relation to time to first flowering of olive seedlings

The aim of this work was to assess growth traits during the initial developmental stages of olive seedlings, which could be correlated to time to first flowering, facilitating fast selection in olive breeding programs. The experimental material consisted of 232 olive seedlings derived from controlled crosses of 'Kalamon' with self (KA × KA), with 'Amphissis' (KA × AM), and with 'Koroneiki' (KA × KO) and from open pollination of 'Kalamon', 'Amphissis', 'Koroneiki', 'Chalkidikis', and 'Manzanillo'. Vegetative traits of the seedlings, including canopy height and diameter, length of lateral vegetation, number of leaves, mean and total leaf area per plant, leaf shape characteristics, and specific leaf area (SLA), were recorded until 15 months after sowing. The first seedlings to initiate flowers, 4 years after sowing, were also recorded. The existence of correlations between the above growth traits and time to first flowering was investigated. In single-branched seedlings 6 months after sowing, height measured at this stage was significantly correlated with the mean and total leaf area per plant, specific leaf area, and other vegetative traits measured 15 months after sowing. Seedlings with high values of these parameters were the first to initiate flowers 33 months later. Our results indicated that pre-selection of olive seedlings for earliness of first flowering is possible, based on vegetative characteristics assessed very early in their development.

PARASITIC NEMATODES ASSOCIATED WITH OLIVE IN COUNTRIES BORDERING THE MEDITERRANEAN SEA

PARASITIC NEMATODES ASSOCIATED WITH OLIVE IN COUNTRIES BORDERING THE MEDITERRANEAN SEA

PARTIAL MOLECULAR CHARACTERIZATION AND RT-PCR DETECTION OF A PUTATIVE CLOSTEROVIRUS ASSOCIATED WITH OLIVE LEAF YELLOWING

SUMMARY Electrophoretic analysis of extracts from cortical tissues of olive trees of cvs ‘Biancolilla’ and ‘Nostrana’ from Sicily (southern Italy) showing bright chrome yellow discolourations of the leaves, consistently revealed a number of double-stranded RNA (dsRNA) bands, the largest of which had a size (ca 15 kbp) similar to that of the full genomic dsRNA of some species of the genus Closterovirus. A segment of 611 nucleotides, showing sequence homology with the HSP70 homologue gene of Closteroviridae was amplified by RT-PCR from symptomatic trees of both cultivars, using degenerated primers designed on the conserved phosphate 1 and 2 motifs of the HSP70 homologue gene sequence. Computer-assisted phylogenetic analysis showed that the 611 nt HSP70 homologue sequence from olive differed from that of other members of the family Closteroviridae, suggesting that it probably belonged to an undescribed closterovirus, for which the tentative name olive leaf yellowing-associated virus (OLYaV) is proposed. A set of OLYaV-specific primers was designed which amplified a 383 nt fragment of the HSP70 homologue. RT-PCR assays with these primers detected OLYaV sequences in olive trees with leaf yellowing from some Italian regions (Calabria and Latium) and Jerusalem, and in individuals of an unidentified pseudococcid mealybug species and of the psyllid Euphyllura olivina that had fed on symptomatic cv. ‘Biancolilla’ trees. No amplification was obtained with extracts from controls (symptomless olives and apparently healthy olive seedlings) or from olive trees from other Italian regions (Sardinia, Tuscany) that showed somewhat differing yellowing symptoms.