Olive Cuttings Research Articles

ROOT ROT DISEASE OF OLIVE TRANSPLANTS AND ITS BIOLOGICAL CONTROL

Several nurseries of olives in Fayoum and Giza were surveyed for root rot incidence during early summer of 2003. In Fayoum, root rot incidence reached 53% while in Giza, disease incidence was 44%. Disease symptoms consist of partial wilting, leaves browning and twig dieback, which was associated with severe root rot and basal stem cankers and followed, in most cases, by plant decline and death. The most frequently isolated fungi from rotted roots were Fusarium oxysporum, F. solani, F. moniliforme, Rhizoctonia solani, Sclerotium rolfsii, Cylindrocarpon sp. and Alternaria alternata. Isolation frequency of different fungi varied among olive cultivars. Generally, Fusarium spp. were the most frequently isolated pathogens and Fusarium oxysporum was the most frequent (35.5%) on all cultivars followed by F. solani (19.3%) R. solani (16.1%). Meanwhile, S. rolfsii, F. moniliforme, Cylindrocarpon sp. and A. alternata occurred at lowfrequencies. Pathogenicity tests showed that all tested isolates caused varied degrees of root rot symptoms on olive transplants, cvs. Manzanillo and Picual. Fusarium oxysporum, F. solani and R. solani caused the highest root rot incidence and severity on both cultivars. There was a positive correlation between disease severity on roots and severity of foliar symptoms. All evaluated olive cultivars were susceptible or extremely susceptible to fungal pathogens. All cultivars showed high disease severity with root rots, especially in response to infection by F. solani, F. oxysporum and S. rolfsii. However, the least foliar symptoms were recorded on cultivar Coratina. Application of two commercial biological control products (Rhizo-Plus and Trichoderma 2000) to soil, 24h before planting olive cuttings in the nursery, significantly reduced incidence of root rot on transplants of cultivars Manzanillo and Picual, up to 28 weeks after planting

FURTHER CHARACTERIZATION OF OLIVE LEAF YELLOWING-ASSOCIATED VIRUS

RACE-PCR using a denatured dsRNA extract from an olive plant infected by Olive leaf yellowing-associated virus (OLYaV), extended a previously sequenced large fragment of the viral genome by 854 nt downstream in the heat shock protein 90 (HSP90). This sequence showed from 45 to 53% identity at the nucleotide level with that of putative HSP90s of different members of the family Closteroviridae. In phylogenetic trees constructed with published HSP90 and RdRp sequences, OLYaV was well separated from other viruses, as was Little cherry virus 1 (LChV-1), another unassigned species in the family Closteroviridae. A polyclonal antiserum was raised to a recombinant protein encoded by the HSP70 gene in fusion with sequence encoding the maltose binding protein. In Western blots of extracts from infected olive tissues, IgGs purified from this antiserum reacted with a polypeptide with a Mr of ca. 65 kDa, which was identified as the putative viral HSP70. Closterovirus-like flexuous particles with distinct cross banding and a maximum length of ca. 2000 nm were seen in extracts from infected roots and leaves of rooted olive cuttings. The cytopathology of infected leaves was similar to that induced by other members of the family Closteroviridae. However, the new information is still insufficient for the ultimate classification of OLYaV.

Influence of arbuscular mycorrhizas on the growth rate of mist-propagated olive plantlets

The aim of this work was to determine the influence of early inoculation of semi-woody olive cuttings (cv. Cornicabra), cultivated under mist propagation conditions, with arbuscular mycorrhizal fungi. A strongly positive response was seen to root inoculation with the three fungal species tested —Glomus mosseae, G. intraradices and G. claroideum— both in nursery phase plantlets, and in older plants grown in 5 L pots.

First report ofMacrophomina phaseolinaon olives (Olea europaea) in Australia

Macrophomina phaseolina was isolated from diseased olive roots. This is the first record on this host in Australia. Infection studies demonstrated that two isolates of the fungus were capable of inducing typical charcoal rot symptoms on rooted olive cuttings.

Growth and Gas Exchange Responses of Olive Tree Cuttings to Elevated CO2 Concentration under Saline Conditions

Physiological responses of olive cuttings of `Koroneiki' and `Picual' (Olea europaea L.) to zero or high salinity (NaCl 100 mmol·L-1) and to ambient CO2 (380 ppm) or elevated (700 ppm) CO2 concentration were studied in sand culture in greenhouses. Growth parameters, net gas exchange of leaves and leaf chloride concentration were measured after two months of treatment. `Koroneiki' had significantly greater shoot growth and net assimilation of CO2 (Ac) at elevated CO2 than at ambient CO2 but this difference disappeared under salt stress. Growth and Ac of `Picual' did not respond to elevated CO2 regardless of salinity treatment. Stomatal conductance and leaf transpiration were lower at elevated CO2 such that leaf water use efficiency increased at elevated CO2 in both cultivars regardless of saline treatment. The saline treatment increased leaf chloride (Cl) concentration and reduced growth and net gas exchange responses in both cultivars. There was no difference in leaf Cl accumulation between the two varieties. At high salinity, elevated CO2 had little effect on leaf Cl implying that at least in `Koroneiki', Cl accumulation was not closely linked to water uptake.

Rooting Response of ‘Nabali’ and ‘Improved Nabali’ Olive Cuttings to Indole Butyric Acid Concentration and Collection Season

Rooting Response of ‘Nabali’ and ‘Improved Nabali’ Olive Cuttings to Indole Butyric Acid Concentration and Collection Season

Seasonal Variation in Rooting of Leafy Olive Cuttings

Seasonal Variation in Rooting of Leafy Olive Cuttings

DEVELOPMENT OF A NESTED PCR PROTOCOL FOR DETECTION OF OLIVE-INFECTING VIRUSES IN CRUDE EXTRACTS

A reverse transcription nested polymerase chain reaction (RT-n-PCR) was developed and applied to the detection of Arabis mosaic virus (ArMV), Cherry leaf roll virus (CLRV), Olive latent virus-1 (OLV-1), Olive latent virus-2 (OLV-2), Olive latent ringspot virus (OLRSV) and Strawberry latent ringspot virus (SLRV) in naturally infected olive cuttings. The method was more sensitive and reliable than conventional RT-PCR. This increased sensitivity allowed virus detection in samples that were negative to the first round of RT-PCR amplification. Coupled with simple sample preparation from cortical scrapings of olive cuttings, this protocol should be useful in routine testing for olive viruses.

Performance of Olive (Olea europaea L.) Cuttings Taken from Different Varieties in the Agro-climatic Conditions of Peshawar

Performance of Olive (Olea europaea L.) Cuttings Taken from Different Varieties in the Agro-climatic Conditions of Peshawar

IBA Promotes Rooting in the Hardwood Cuttings of Olive (Olea europaea L.) Cultivars

IBA Promotes Rooting in the Hardwood Cuttings of Olive (Olea europaea L.) Cultivars

Seasonal dynamics of electrical impedance parameters in shoots and leaves related to rooting ability of olive (Olea europea) cuttings.

Electrical impedance parameters were measured in shoots and leaves of Olea europaea L. for 18 months to determine seasonal variations in intracellular and extracellular resistances and in the state of membranes; these factors were related to rooting ability. Double- and single-DCE (ZARC) models were used as equivalent circuits for shoots and leaves, respectively. Seasonal variations were observed in all of the impedance parameters measured. Intracellular resistance of the shoots increased during the winter resting period, whereas intracellular resistance of the leaves decreased. Relaxation times for both leaves and shoots decreased during the winter. Close relationships were found between rooting ability and intracellular and extracellular resistances and relaxation times of shoots and leaves.

Training Initiation Date Affects Height of Nursery Olive Trees

An experiment was carried out to determine when to initiate training potted rooted cuttings of olive (Olea europaea L.), so that tall and well developed nursery trees could be produced in an 8-month growing season. Initiating training to single shoot when average height of tallest shoots was 38 cm (15.0 inches) produced 1-m (3.28-ft) tall nursery trees in 7.5 months, with training restricted to the last 2.5 months. Taller plants [1.17 m (3.84 ft)] and some lateral shoots growing above 1 m were produced following another 0.5 month of growth. Five training months were needed to produce 1.43-m (4.69-ft) trees if training was initiated when main shoots were only 16 cm (6.3 inches). Initiating training at the beginning of the growing season did not produce significantly taller trees. Untrained plants only reached a height of 69 cm (27.2 inches) at the end of the test period.

First Report of Phytophthora megasperma and Pythium irregulare As Olive Tree Root Pathogens.

Several species of the genus Phytophthora are associated with root rot and trunk cankers in olive trees (Olea europaea L.). Among them, Phytophthora megasperma has been cited as being associated with olive root rots in Greece (1). Unidentified species of Pythium and Phytophthora have also been associated with olive tree root rots in the United States. However, the status of P. megasperma and Pythium spp. as olive tree root pathogens has remained unclear. Following a 5-year period of severe drought in southern Spain, autumn-winter rainfall rates in 1996 to 1997 steadily increased in both quantity and frequency. Under these unusually wet conditions, olive trees remained waterlogged for several months. During this period, we observed foliar wilting, dieback, and death of young trees, and later found extensive root necrosis. In 46 of 49 affected plantations surveyed, P. megasperma was consistently isolated from the rotted rootlets, particularly in young (<1- to 10-year-old trees) plantations. This fungus was not detected on plant material affected by damping-off from several Spanish olive tree nurseries. The opposite situation occurred with P. irregulare. This species was not associated with rotted rootlets in the field. In contrast, it was consistently isolated from necrotic rootlets from young olive plants affected by damping-off. These plants were grown in a sand-lime-peat soil mixture under greenhouse conditions and showed foliar wilting and extensive necrosis of the root systems. Pathogenicity tests were conducted with several isolates of P. megasperma and P. irregulare on 6-month-old rooted cuttings of olive, under both weekly watering and waterlogged conditions. Under waterlogged conditions, both fungal species produced extensive root necrosis 2 weeks after inoculation that resulted in wilting of the aerial parts and rapid plant death. Waterlogged control plants remained without foliar symptoms but a low degree of root necrosis was recorded. In addition, under weekly watering conditions, plants inoculated with either species showed some degree of root rot but foliar symptoms were not evident. No differences in pathogenicity were observed within the Phytophthora or Pythium isolates. Reference: (1) H. Kouyeas and A. Chitzanidis. Ann. Inst. Phytopathol. Benaki 8:175, 1968.

Analysis of leaf water relations in leaves of two olive (Olea europaea) cultivars differing in tolerance to salinity.

One-year-old rooted cuttings of olive (Olea europaea L. cvs. Frantoio and Leccino) were grown either hydroponically or in soil in a greenhouse. Plants were exposed to NaCl treatments (0, 100, and 200 mM) for 35 days, followed by 30 to 34 days of relief from salt stress to determine whether previously demonstrated genotypic differences in tolerance to salinity were related to water relations parameters. Exposure to high salt concentrations resulted in reductions in predawn water potential (Psi(w)), osmotic potential at full turgor (Psi(piFT)), osmotic potential at turgor loss point (Psi(piTLP)), and relative water content (RWC) in both cultivars, regardless of the growth substrate. Leaf Psi(w) and RWC returned to values similar to those of controls by the end of the relief period. The effect of salinity on Psi(pi) appeared earlier in Leccino than in Frantoio. Values for Psi(piFT) were -2.50, -2.87, and -3.16 MPa for the 0, 100, and 200 mM salt-treated Frantoio plants, respectively, and -2.23, -2.87, and -3.37 MPa for the corresponding Leccino plants. Recovery of Psi(pi) was complete for plants in the 100 mM salt treatment, but not for plants in the 200 mM salt treatment, which maintained an increased pressure potential (Psi(pi)) compared to control plants. Net solute accumulation was higher in Leccino, the salt-sensitive cultivar, than in Frantoio. In controls of both cultivars, cations contributed 39.9 to 42.0% of the total Psi(piFT), mannitol and glucose contributed 27.1 to 30.8%, and other soluble carbohydrates contributed 3.1 to 3.6%. The osmotic contribution of Na(+) increased from 0.1-2.1% for non-treated plants to 8.6-15.5% and 15.6-20.0% for the 100 mM and 200 mM salt-treated plants, respectively. The mannitol contribution to Psi(piFT) reached a maximum of 9.1% at the end of the salinization period. We conclude that differences between the two cultivars in leaf water relations reflect differences in the exclusion capacities for Na(+) and Cl(-) ions.

Factors Causing Losses of Rooted Cuttings of Olive Propagated under Mist and Ways of Its Prevention

To study the reasons for the losses of rooted semihardwood cuttings of olive propagated under the mist method, a 2-year experiment was carried out at the Horticulture Dept. of Faculty of Agriculture of the Tehran Univ. In this experiment, semihardwood cuttings of olive (Zard cultivar) in four different media—heavy-(Al), semi-heavy(A2), medium (A3), and light (A4), all disinfected with two different concentrations of Captan—were used. Root growth stages with low, medium, and light densities in spring and fall were evaluated. The results indicate that there are the least losses in semi-heavy (A2) and medium (A3) media. This could be the result of a better ventilation conditions in these media, which activates N and Ca and finally accelerates the better growth conditions in all young rooted cuttings. On the other hand, it was clear that inadequate disinfection will result in losses of rooted cuttings, and using Captan at 2 ppm gives the best result. This research indicate that, with the higher growth rate, the first medium will have the fewer losses. The reason is the higher density and more durability and strength of the root, which control the disease-causing factors; so far that these factors do not influence the young roots. Finally, strong and dense roots show less losses. This experiment was designed in a factorial with randomized complete block and the averages were compared in a Duncan test and the results of abnormally distributed characteristics were shown by using logarithmic and sinus method.

Study of the Effect of Different Media Beds, Time, and Wounding Factors on the Rooting of Semi-hard Cuttings of Olive [Olea europaea (Roghani &amp; Zard Zeitoun C.V.)] under Mist Conditions

To determine the most proper bed, time, and wounding factors on the rooting of semi-hard cuttings of olive (Olea europaea), cuttings were selected and research was conducted at the Faculty of Agriculture of the Tehran Univ. in Karaj. The required cuttings were taken from healthy and similar mother trees at the Roodbar Research Station. Then, semi-hard cuttings of 15 cm in length and 3 to 5 mm in diameter with four terminal leaves were prepared. Then those prepared cuttings were treated with IBA at 4000 ppm and Captan fungicide at 3000 ppm before planting. This experiment was designed in a factorial with a randomized complete block, with four media bed factors for rooting in seven levels (peatmoss + perlite, sawdust + sand, peatmoss + sand, and perlite, sand, and perlite + sand), the time factor for cutting preparation in four levels (May, August, September, and March), cultivars at two levels (Roghani and Zard Zeitoun), and wounding treatment at two levels (unwounded and wounded); there were three replications (20 cuttings per replicate per each unit). The results indicate that, among the selected beds, perlite with 53% of rooting average yield has the highest and peatmoss + perlite with a rooting average of 43.8% has the lowest. As far as time is concerned, those cuttings prepared in March show the highest rooting average of 69.3%, while those prepared in August show the lowest average of 12.7%. The comparison between the two cultivars shows that Roghani, with 60.4% rooting yield, is preferred to Zard Zeitoun, with 48.2% rooting average. There were no significant differences between wounded and unwounded cuttings with regard to rooting.

Screening of olive cultivars for salt tolerance

The tolerance of 26 olive ( Olea europaea L.) cultivars to an excess of Nacl in the growing medium was determined in order to screen genotypes for salt tolerance. Rooted olive cuttings growing in 1 l pots and pruned to a single shoot per plant were used for the experiment. Treated plants were watered with a nutrient solution and once a week with 250 ml of a 100 mM NaCl solution. Control plants received only the nutrient solution. Relative growth, expressed as shoot length of treated plants as a percentage of that of control plants, was the criterion used for screening genotypes. Forty-nine days after the initiation of treatments the relative growth of salt-treated plants ranged from 16 to 70%, and served to rank cultivars for salt tolerance.

Rooting Systems of Semi-hardwood Olive Cuttings of Three Selected Varieties of Manzanilla, Sevillana, and Clonavis

Propagation testing of semi-hardwood olive cuttings was conducted to ensure adequate production to meet Iranian needs. `Clonavis', `Sevillana', and `Manzanilla' were selected to investigate their rooting situations. Three variables (cultivar, differential concentrations of IBA, and vertical cut in the basal end of the cuttings) were considered in a randomized complete-block factorial design test with four replications with 10 cuttings in each treatment. Cuttings 10 to 15 cm long and 0.5 to 1.5 cm in diameter were taken from each cultivar. IBA (0, 2000, 3000, and 4000 ppm) was used in two vertical cuts in basal end of half of the cuttings. Statistical analysis of the rooting capability differed for the three cultivars. `Sevillana' and `Clovanis' rooted better than `Manzanilla'. IBA at 3000 ppm resulted in the highest rooting percentage in all cultivars. The maximum number of roots was obtained with IBA at 4000 ppm in roots that had the basal cuts. Basal end cuts affected considerably the rooting percentage and number of roots, but had no effect on increased root length.

Enhancement of IBA stimulatory effect on rooting of olive cultivar stem cuttings

Three groups of olive cultivars were characterized as showing low, moderate or high rooting percentage after application of indole-3-butyric acid (IBA) treatment. To improve the rooting of olive cuttings, urea-phosphate (UP) and paclobutrazol (PB) were tested in combination with IBA. UP alone did not stimulate rooting of olive cuttings; however, when applied together with IBA it significantly enhanced the rooting of cultivar ‘Manzanillo’ cuttings. PB alone had a weak effect on rooting of cuttings but in combination with IBA it improved the rooting of cultivars ‘Manzanillo’ and ‘Souri’ cuttings. A triple combination of IBA, UP and PB provided the most effective treatment for the improvement of rooting percentage. IBA treatments increased the number of roots per cutting in comparison with the control, but decreased the length of the roots of cultivar ‘Barnea’. IBA plus UP or PB further increased the number of newly formed roots. However, IBA plus UP markedly increased root length. The three compound treatment did not differ from IBA plus PB regarding root number per cutting, but the roots were longer than in IBA treated and control cuttings. The survival of rooted cuttings treated with IBA was relatively low, for all cultivars tested. IBA plus UP plus PB improved the survival of the rooted olive plants compared with IBA alone. Thus UP and PB were shown to enhance the effect of IBA in stimulation of rooting and survival of olive cuttings.

Relationship of Carbohydrate Sources and Indole-3-Butyric Acid in Olive Cuttings

Indole-3-butyric acid (IBA) treatment improves rooting of easy-to-root and moderate-rooting olive cultivars, but does not stimulate root formation in hard-to-root cultivars. The rate of root formation in olive cuttings is slow and a source of carbohydrates is required to maintain and improve the effect of IBA. Sucrose treatment applied together with IBA and several times thereafter improved all rooting parameters: rooting percentage, number of adventitious roots and root length. During rooting, photosynthesis in the cuttings is very low and has almost no effect on the carbohydrate content, so that starch appears to be the major source of carbohydrates. Amyloplast levels decline during rooting and IBA increases the rate of their disappearance. A significant percentage of rooted olive cuttings collapse during their hardening process, when no starch pool is available. Only photosynthesis of fully-expanded leaves can contribute to the source of the carbohydrates needed by the rooted plants. However, when the top growth is reduced, as often occurs in IBA-treated cuttings, the carbohydrate supply may not be enough to keep the rooted plants alive and to support their growth and development. The data suggest that carbohydrates have an important role in rooting and improve the stimulatory effect of IBA in this process. During the stages involved in the formation of adventitious roots the endogenous carbohydrate pool is the main source of carbohydrates, while in young rooted plants the main source comes directly from the photosynthesis.