Olive Cuttings Research Articles

Effects of the root-knot nematodes Meloidogyne incognita and M. javanica on olive plants growth in glasshouse conditions

Abstract The influence of ten initial population levels (0, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 12.8 and 25.6 second stage juveniles/cm3 soil) of Meloidogyne incognita and M. javanica on olive cultivar Zard growth was studied in two pot trials. Ten month old self-rooted olive cuttings were individually transplanted into 2 000 cm3 pot and inoculated with the defined initial populations, of both nematode species. Plants were grown in glasshouse for 13 months, then they were uprooted and plant growth (percent growth increase of main shoot length, number of nodes on main shoot, top and root fresh and dry weights and root length) and nematode parameters (root gall index, J2/g root, final nematode population density and reproduction rate Pf/Pi) were recorded. Results showed that cv. Zard was more susceptible to M. javanica than to M. incognita. A significant reduction of main shoot length growth 37.6 % and 10.7 % was observed at 0.1 and 12.8 juveniles/cm3 soil of M. javanica and M. incognita, respectively, in comparison to uninfested plants. Root systems of olive plants grown in M. incognita or M. javanica infested soils were galled within the gall index range 1.4–6. No significant differences were observed in the number of nodes on main shoot, top and root fresh weights and root dry weight at high levels of M. incognita Pi. A tolerance limit (T) of 0.4 juveniles/cm3 soil was estimated for olive plants cv. Zard to M. javania. The use of resistant olive rootstock or selected cultivars is recommended to minimize or to limit damage of nematode infections in nurseries and to prevent secondary attacks of soil borne plant pathogens especially Verticillium dahliae.

The amount of nitrogen applied and nutritional status of olive plants affect nitrogen uptake efficiency

Mist-rooted ‘Picual’ olive cuttings were used to test the hypothesis that both the amount of nitrogen applied and the nutritional status of olive plants may affect nitrogen uptake efficiency (NUE). Plants were placed in a greenhouse at 30/15°C (day/night) with a 14h photoperiod. Two different experiments were developed. In the first, plants were subjected to the application of 0, 50, 100, 200, 400, 600 or 800ppm N. In the second experiment, the aim was to obtain three groups of plants differentiated by the nutritional status. Each group received 0, 50 or 100ppm N, according to the results obtained in the first experiment. When plants of each group differed in their nitrogen content, they were subjected to additional nitrogen application either via foliar or to the soil. At the end of each experiment, plants were harvested and nitrogen was determined in leaves, stems and roots to obtain the nitrogen uptake by the plants. Nitrogen uptake efficiency (NUE) was estimated as NUE=(N uptake/N applied)×100. Nitrogen content of the plant, vegetative growth and leaf chlorophyll content increased from 0 to 100ppm N applied, decreasing at higher doses of N application. Consequently, NUE exponentially decreases with the amount of N applied above 100ppm, with values ranging from 45.9% at 100ppm to 4.1% at 800ppm N. The method of nitrogen application, foliar or to the soil, does not affect nitrogen uptake, but the contrary occurs with the nutritional status of the plant. Nitrogen deficient plants were able to uptake more fertilizer nitrogen that well-nourished plants, with a significant reduction in NUE. Consequently systematic, annual applications of large amounts of fertilizer nitrogen may cause nitrogen over-fertilization and negative effects in both the plant and the environment.

The Possible Role of Polyamines to the Recalcitrance of “Kalamata” Olive Leafy Cuttings to Root

The objective of this study was to investigate the role of endogenous polyamines (PAs) (the sum of free plus soluble conjugate plus insoluble bound) on rooting potential of leafy cuttings of an easy, that is,“Arbequina” and a difficult-to-root olive cultivar, that is, “Kalamata”. Subsamples of cuttings were taken for PAs analysis before planting in the mist system and during the early phases of rhizogenesis (EPR). “Arbequina” exhibited higher initial free and total PA content than “Kalamata”. Spermidine (Spd) was the predominant PA observed in both cultivars. A low content of free putrescine (Put) and Spd was found in both cultivars, whereas spermine (Spm) was occasionally detected. “Arbequina” as well as “Kalamata” exhibited the highest free Put and free Spd in summer and Put was the predominant PA among the free PAs. “Arbequina” exhibited the highest individual and total PAs in spring, followed by those in summer and autumn. In contrast, “Kalamata” had the maximum PAs in summer and the lowest in autumn. Changes in the endogenous content of individual and total PAs during the EPR were also observed. Treatment of “Kalamata” cuttings in autumn with both indole-3-butyric acid (IBA) and Put increased rooting compared to IBA alone. Among the PAs administered, Put was the most effective, whereas Spd and Spm failed to promote rooting. PAs, especially in their free form, seem to be involved in the rooting process of olive cuttings; Put application enhanced the rooting response of the difficult-to-root “Kalamata” olive cultivar.

Field Resistance to Verticillium Wilt in Selected Olive Cultivars Grown in Two Naturally Infested Soils.

The resistance of 11 olive cultivars to Verticillium dahliae was assessed in two experimental field trials. One-year-old rooted olive cuttings from the World Olive Germplasm Bank (IFAPA research center, Córdoba, Spain) were planted in a heavily infested field in Utrera (Sevilla province) and in a moderately infested field in Andújar (Jaén province) of southern Spain. Plants were assessed for Verticillium wilt resistance during 22 months based on disease severity and tree growth. Severe disease symptoms were observed 6 months after planting in both trials. Twenty months after planting in the heavily infested soil, V. dahliae had killed nearly all of the trees of 'Bodoquera', 'Cornicabra', 'Manzanilla de Sevilla', and 'Picual', demonstrating the elevated risk of planting susceptible cultivars in a soil heavily infested with V. dahliae. 'Arbequina', 'Koroneiki', 'Sevillenca', and especially 'Frantoio', 'Empeltre', and 'Changlot Real' showed a high level of disease resistance. However, all of them were affected by the disease. Although the field results confirmed the level of resistance previously obtained for these olive genotypes under controlled conditions, there were some discrepancies. This information will be useful in managing the disease and also in selecting new cultivars for the breeding of Verticillium wilt resistance.

Alternative rooting induction of semi-hardwood olive cuttings by several auxin-producing bacteria for organic agriculture systems

Southern Spain is the largest olive oil producer region in the world. In recent years organic agriculture systems have grown exponentially so that new alternative systems to produce organic olive cuttings are needed. Several bacterial isolates, namely Pantoea sp. AG9, Chryseobacterium sp. AG13, Chryseobacterium sp. CT348, Pseudomonas sp. CT364 and Azospirillum brasilense Cd (ATCC 29729), have been used to induce rooting in olive semi-hardwood cuttings of Arbequina, Hojiblanca and Picual cultivars of olive (Olea europea L). The first four strains were previously selected as auxin-producing bacteria and by their ability to promote rooting in model plants. They have been classified on the basis of their 16S rDNA gene sequence. The known auxin producer A. brasilense Cd strain has been used as a reference. The inoculation of olive cuttings was performed in two different ways: (i) by dipping cuttings in a liquid bacterial culture or (ii) by immersing them in a paste made of solid bacterial inoculant and sterile water. Under nursery conditions all of the tested bacterial strains were able to induce the rooting of olive cuttings to a similar or greater extent than the control cuttings treated with indole-3-butyric acid (IBA). The olive cultivars responded differently depending on the bacterial strain and the inoculation method. The strain that consistently gave the best results was Pantoea sp. AG9, the only one of the tested bacterial strains to express the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. The results are also discussed in terms of potential commercial interest and nursery feasibility performance of these strains.

Performance of Olive Cuttings (Olea europaea L.) of Different Cultivars Growing in the Agro-climatic Conditions of Al-Jouf (Saudi Arabia)

Performance of Olive Cuttings (Olea europaea L.) of Different Cultivars Growing in the Agro-climatic Conditions of Al-Jouf (Saudi Arabia)

Fungal Diseases of Olive Cuttings in the Rooting Stage in Jordan

Fungal Diseases of Olive Cuttings in the Rooting Stage in Jordan

Involvement of alternative oxidase (AOX) in adventitious rooting of Olea europaea L. microshoots is linked to adaptive phenylpropanoid and lignin metabolism

Alternative oxidase (AOX) has been proposed as a functional marker candidate in a number of events involving cell differentiation, including rooting efficiency in semi-hardwood shoot cuttings of olive (Olea europaea L.). To ascertain the general importance of AOX in olive rooting, the auxin-induced rooting process was studied in an in vitro system for microshoot propagation. Inhibition of AOX by salicylhydroxamic acid (SHAM) significantly reduced rooting efficiency. However, the inhibitor failed to exhibit any effect on the preceding calli stage. This makes the system appropriate for distinguishing dedifferentiation and de novo differentiation during root induction. Metabolite analyses of microshoots showed that total phenolics, total flavonoids and lignin contents were significantly reduced upon SHAM treatment. It was concluded that the influence of alternative respiration on root formation was associated to adaptive phenylpropanoid and lignin metabolism. Transcript profiles of two olive AOX genes (OeAOX1a and OeAOX2) were examined during the process of auxin-induced root induction. Both genes displayed stable transcript accumulation in semi-quantitative RT-PCR analysis during all experimental stages. In contrary, when the reverse primer for OeAOX2 was designed from the 3'-UTR instead of the ORF, differential transcript accumulation was observed suggesting posttranscriptional regulation of OeAOX2 during metabolic acclimation. This result confirms former observations in olive semi-hardwood shoot cuttings on differential OeAOX2 expression during root induction. It further points to the importance of future studies on the functional role of sequence and length polymorphisms in the 3'-UTR of this gene. The manuscript reports the general importance of AOX in olive adventitious rooting and the association of alternative respiration to adaptive phenylpropanoid and lignin metabolism.

The Effects of IBA and H2O2 on Rooting of 2 Olive Cultivars

Two groups of olive cultivars were characterized as showing low (Tokhmkabki) and high (Roghani) rooting percentage after application of IBA treatment. Semi-hard wood cuttings were dipped in H2O2 (0-3.5% w/v) and IBA (4000 mg.l -1 ) and also they were investigated in combination. H2O2 alone did not stimulate rooting of olive cuttings and there were no significant differences between this treatment and control in both cultivars. It was obvious that IBA treatments increased the rooting percentage, number of root cuttings, root length and root fresh\dry weight in 2 olive cultivars but the combination of IBA and H2O2 in some factors was more effective but there were no significant differences when IBA was used instead of in both cultivars.

Rooting of Some Olive (Olea Europaea L.) Cultivars Under Shaded Polyethylene Tunnel at Middle Egypt Region Conditions

The present study was conducted during 2008 and 2009 seasons on fifteen olive cultivars as a source of cuttings and planted in the experimental orchard of Horticultural Research Station, Seds, Beni- Suef Governorate, Egypt. The cultivars namely: Aggizi Aksi, Aggizi Shami, Arbequin, Coratina, Dolce Frantoio, Hamed, Kalamata, Koroneiki, Manzanillo, Maraki, Nabali Mohassan, Picual, Toffahi and Wardan. The cuttings were planted under a white plastic tunnel inside a shaded net house. This study included the two experiments: Experiment (1): The aim of this experiment was to study rooting ability parameters of the fifteen olive cultivars under study, the results showed that, cuttings of Manzanillo, Picual, Aggizi Shami, Aggizi Aksi, Koroneiki and Coratina gave the highest values of most of the studied rooting parameters as, rooting percentage, number of roots and total roots length. Experiment (2): The main objective was to study the effect of time of cutting preparation dates (February, May, August and November) of three olive cultivars (Coratina, Kalamata and Manzanillo) as well as interaction effect of their combinations on rooting ability parameters. Cuttings of Manzanillo cv. had good rooting characters 66.25 & 66.14 followed by Coratina cv. 62.39 & 59.91 then Kalamata cv. 12.52 & 10.81 during 2008 & 2009 seasons. August and November were considered the best date of cutting preparation under the same conditions of this study. Cuttings of Manzanillo prepared at August gave the highest rooting percent .The highest survival percentage after two months from transplanting was recorded from cuttings prepared and planted at August and November in both studied seasons. As a conclusion we can say that rooting of some olive cuttings under shaded Polyethylene tunnel consider the best method compared with the other methods because it do not need a very expensive equipments.

First Report of a Decline and Wilt of Young Olive Trees Caused by Simultaneous Infections of Verticillium dahliae and Phytophthora palmivora in Sicily

In summer 2008, leaf chlorosis, defoliation, exceptional fruit set, twig dieback, and wilt were observed on 4-year-old olive (Olea europea L.) trees cv. Tonda Iblea in a drip-irrigated orchard in eastern Sicily. Rot of fine roots was associated with these symptoms and on ~15% of symptomatic trees rot extended to the crown and basal stem. Trees declined slowly or collapsed suddenly with withered leaves still attached. Incidence of affected trees was ~10%. A fungus identified as Verticillium dahliae Kleb. was isolated from the xylem of main roots and basal stem. An oomycete identified as Phytophthora palmivora (Butler) Butler was isolated from roots and basal trunk bark. Both pathogens were recovered from symptomatic trees with mean frequency of positive isolations per tree of 80 and 30% for V. dahliae and P. palmivora, respectively. To isolate V. dahliae, wood chips were surface disinfested in 0.5% NaOCl for 1 min and plated onto potato dextrose agar (PDA). The fungus was identified on the basis of microsclerotia, verticillate arrangement of phialides on conidiophores, and hyaline single-celled conidia. Ten monoconidial isolates were characterized by PCR using primer pairs INTND2f/INTND2r and DB19/espdef01 (3). Only 824-bp amplicons, diagnostic of the virulent, nondefoliating V. dahliae pathotype, were obtained. P. palmivora was isolated on selective medium (2) and pure cultures were obtained by single-hypha transfers. Colonies grew on PDA between 10 and 35°C (optimum at 27°C). Chlamydospores and elliptical to ovoid, papillate, caducous (mean pedicel length = 5 μm) sporangia (length/breadth ratio of 1.8) were produced on V8 juice agar. All isolates were paired with reference isolates of P. nicotianae and produced gametangia only with isolates of the A2 mating type. PCR amplicons of a representative isolate generated using primers ITS 6 and ITS 4 (1) were sequenced and found to be identical to those of a reference isolate of P. palmivora (GenBank No. AY208126). Pathogenicity of V. dahliae (IMI 397476) and P. palmivora (IMI 397475) was tested on 6-month-old rooted cuttings of olive cv. Tonda Iblea. Ten cuttings were transplanted into pots with steam-sterilized soil and inoculum of P. palmivora (4% vol/vol) produced on wheat kernels. Ten olive cuttings were inoculated with V. dahliae by injecting the stem with 150 μl of a conidial suspension (107 conidia ml-1) and 10 cuttings were stem inoculated with V. dahliae and transplanted into soil infested with P. palmivora. Controls were 10 noninoculated cuttings transplanted into steam-sterilized soil. Pots were kept in a greenhouse (25 ± 3°C) for 4 months. No aerial symptoms were observed on cuttings transplanted into soil infested with P. palmivora. However, root dry weight was reduced by 40% in comparison with the controls. Cuttings inoculated solely with V. dahliae had a 15% reduction in height compared with the controls but only four cuttings wilted. All cuttings inoculated with P. palmivora and V. dahliae wilted, indicating a synergism between the two pathogens. Controls remained healthy. Each pathogen was reisolated solely from inoculated cuttings and both pathogens were reisolated from cuttings with double inoculations. A similar syndrome 'seca' (drying) was reported in Spain (4).

Differential Uptake, Distribution within Tissues, and Use Efficiency of Manganese, Iron, and Zinc by Olive Cultivars Kothreiki and Koroneiki

Three-month-old rooted olive cuttings (Olea europaea L., cvs. Koroneiki and Kothreiki of ≈20 to 25 cm in height) were grown outdoors for 140 days (from 30 May until 17 Oct.) under ambient conditions in black plastic bags containing 3 kg of soil. Three soils from different parent material (Marl, Gneiss schist., and Peridotite) and with different physicochemical properties were chosen. In all the soils, ‘Kothreiki’ produced significantly greater total plant biomass compared with ‘Koroneiki’. Furthermore, between the two cultivars studied, ‘Kothreiki’ absorbed significantly greater quantity of manganese (Mn), iron (Fe), and zinc (Zn) per plant compared with ‘Koroneiki’. In all the soils, significantly greater concentrations of Mn, Fe, and Zn were recorded in the root system of both cultivars compared with those of leaves and stems. Between the two cultivars studied, ‘Kothreiki’ had greater percentage of the total Mn content distributed in the root system (74% to 80%) than ‘Koroneiki’ (44% to 56%). That high ability of ‘Kothreiki’ to accumulate Mn in its root system could possibly be advantageous in soils with high Mn concentrations and could constitute a detoxification mechanism to olive trees, protecting the above-ground part of the tree from Mn toxicity. Furthermore, greater concentrations of magnesium (Mg) were recorded in the root system of the olive plants than in leaves and stems, whereas potassium (K) and calcium (Ca) concentrations were greater in leaves compared with those of other tissues (roots and stems). The total per plant quantity of Ca, Mg, and K was significantly greater in the cultivar Kothreiki than ‘Koroneiki’ in all the soils tested. On the other hand, ‘Kothreiki’ presented significantly lower use efficiency of Mn in Marl and Gneiss schist soils, and that of Fe and Mg in all soils, so ‘Koroneiki’ could be considered as a Mn- and Fe-efficient olive cultivar, whereas ‘Kothreiki’ was Mn- and Fe-inefficient.

Rooting of "Ayvalik" olive cuttings in different media

The "Ayvalik" olive cultivar, the most grown for high quality olive oil in Turkey, is generally regarded as showing very good rooting ability. However, cuttings sometimes show moderate or even poor rooting performances, a problem likely related to the use of inappropriate rooting media. The aim of this work was to determine the most successful media among those traditionally used and to identify promising alternatives. October cuttings were planted in 25 different media in two consecutive years under mist propagation conditions. Substrates such as peat, perlite, bark, pumice, sand, polystyrene beads, phenolic foam, rockwool and vermiculite were used pure or in mixtures. In the first year the highest rooting percentage (100%) and visual rating scores (5) were obtained with phenolformaldehyde foam. Perlite-vermiculite (1:1 v/v) was associated with a 95% rooting percentage in both years. The highest mean number of roots (10.8), root length (47 mm), root dry (382 mg) and fresh weights (48.3 mg), and number of secondary roots (13) were recorded in the same medium in the second year. Rockwool, peat-polystyrene (2:1 v/v) and sand-perlite (1:2 v/v) also led to more than 90% of cuttings taking root, while pure sand, peat and peat-sand mixtures gave very low (5-28%) rooting percentages. Perlite-vermiculite 1:1 (v/v) and pre-sized rockwool cubes may be appropriate alternatives to traditional sand-perlite mixtures for rooting "Ayvalik" olive cuttings.

Effect of Root-promoting Products in the Propagation of Organic Olive (Olea europaea L. cv. Cornicabra) Nursery Plants

Olive cuttings root well using synthetic auxin indole-3-butyric acid (IBA). However, European and North American regulations do not allow the use of synthetic products to obtain organic vegetative propagation materials. In this work, we evaluated different products that could replace IBA in the propagation of olive cv. Cornicabra leafy-stem cuttings. In 2003, six products with a known auxin effect were assessed: IBA, algae extract, brewer's yeast, a bed of sunflower seed, seaweed dry extract (Sm-6 Organico™), and an extract of macerated seeds (Terrabal Organico™). The basal end of cuttings was treated with one of these products and placed on a mist bed with basal temperature control. After 2 months, rooting percentage, number of roots per cutting, number of cuttings with callus formation, and number of cuttings with basal thickening were determined. No significant differences were found in rooting percentage or number of roots per cutting between IBA and Terrabal Organico™ and Sm-6 Organico™. These last products had significantly higher percentage of rooted cuttings without callus formation than IBA. In 2004, a new trial was conducted in which seven treatments were evaluated: IBA applied for 7 s; Terrabal Organico™ applied for 1, 4, and 8 h; and Sm-6 Organico™ applied for 1, 4, and 8 h. No significant differences in rooting percentage or number of roots per cutting were observed between IBA and Terrabal Organico™ applied for 1 h, whereas all the Sm-6 Organico™ treatments had significantly lower rooting percentages than IBA. Both rooting percentage and the percentage of rooted cuttings without callus development decreased significantly as treatment duration with Terrabal Organico™ increased. Therefore, Terrabal Organico™ could produce a toxic effect on cuttings when treatment duration is increased. Thus, Terrabal Organico™ could be a valid alternative to IBA in the propagation of organic olive plants of cv. Cornicabra when applied to the basal end of cuttings for 1 h.

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.

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.

Effects of IBA , growing Media and Certain Treatments on Rooting of Olive Cuttings Olea europaea L.

Three different experiments were conducted in a certain nursery. The aim of these experiments is to know the effect of the different concentration of the Auxin (IBA) growing media, and treatments of olive cuttings (sliced, normal cuttings and from previously ringed origin). Two cultivars of olive (17 years old) were tested, the first was Manzinello and the second was Ashrasy and cultivated the mid of February 2003 in Baghdad. Results of this study are summarized follows" 1- Ashrasey cultivar gave a significant increase in the rooting percentage (78.56%), the average number of roots in cutting (7.39 root/cutting) and finally the average length of roots (21.97 cm) in comparison with Manzinello cultivar. Also, the percentage of giving roots and average root length sliced cutting and those taken from previously ringed cuttings was (61.05-61.93 %) and (16.08-20.28 cm) respectively compared to the control (normal cuttings). However, the same results were true for the mentioned characters when a combined treatments between sliced and ringed cuttings. 2- The percentage one peat moss: river (1:1) sand that was treated 4000ppm gave the highest rooting percentage (83.73%), average of root number (13.1 root/cutting) and root length (33.65cm). An interacted treatment between rooting media (1:1) and the two cultivars gave a high significant percentage in the three studied characters. The sand media was the weakest in giving roots, then the media of (2:1). The treatment of IBA with 4000ppm gave the highest rooting percentage (70.77%), and the treatment of IBA with 3000ppm gave the highest root length (25.85 cm). The interacted treatments of IBA 3000ppm and Ashrasy cultivar gave the highest rooting percentage (95.43 %). The treatment of IBA 5000ppm the highest root number (11.53 root/cutting). The combined treatment of IBA 4000ppm and the Manzinello cultivars gave the highest average of root length (29.87 cm). Ashrasy cuttings show an optimum way of propagation, rapid and high percentage of giving roots (90%), but Labeeb cv. Show difficulty of giving roots. Khstawi cv. May be motivated by growth regulator or using suitable growing media (80.07%).

Calcium starvation increases salt susceptibility in olive plants but has no effect on susceptibility to water stress

SummaryThe responses of leaf water status, growth, and ion concentrations to water or to saline stresses were compared in olive cuttings of different Ca2+ status. Mist-rooted ‘Picual’ olive cuttings were grown in a greenhouse in 2 l plastic pots containing perlite. A nutrient solution with or without 2.5 mM CaCl2 was initially used to irrigate the plants. When the Ca2+-starved plants differed in height from the Ca2+-treated plants, water or saline stress (i.e., no irrigation or 75 mM NaCl, respectively) were applied. The results indicated that Ca2+ increased growth in saline-treated plants, but not in water-stressed plants. After 98 d growth, the stresses were relieved and the plants were irrigated again with or without Ca2+. Growth increased and leaf water status was increased during this recovery period, but no direct effects of Ca2+ were observed in the response of plants to stress-relief. We suggest that the beneficial effect of Ca2+ on tolerance to salt stress in olive plants was related to protection against Na+ toxicity, because there was no response of water-stressed plants to the supply of Ca2+.

Calcium increases sodium exclusion in olive plants

Abstract ‘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 CaCl 2 . Vegetative growth, leaf and root Na + and Ca 2+ concentrations were measured. Na + toxicity symptoms were observed in plants non-treated with Ca 2+ . Shoot length was higher in Ca 2+ treated plants, although shoot growth was reduced at 40 mM CaCl 2 , probably due to the high total ion concentration reached in the external solution. Ca 2+ supply linearly increased leaf and root Ca 2+ concentration and decreased leaf Na + concentration. However, there were no differences in root Na + concentration. Results indicate Ca 2+ 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.

Potassium Starvation Increases Stomatal Conductance in Olive Trees

The effects of potassium (K) status and water availability in the growth medium on growth, water content, water-use efficiency and stomatal conductance was studied in mist-rooted `Chemlali de Sfax' olive (Olea europaea L.) cuttings grown in a perlite substrate. Potassium starvation produced dehydration of all parts of the plant, reduced shoot growth and water-use efficiency. By contrast, K starvation enhanced stomatal conductance in well-irrigated plants and, even more, in water-stressed plants. These results suggest that moderate K deficiency in olives may impair the plant's ability to regulate stomatal closure; this may account for the dehydration observed in K-starved plants, particularly in situations of water stress. This result is of great importance for agricultural practices of this crop, because K status, which may not be considered deficient, can cause disorders in olive trees.