In vegetables, tolerance to drought can be improved by grafting commercial varieties onto drought tolerant rootstocks. Grafting has emerged as a tool that copes with drought stress. In previous ...results, the A25 pepper rootstock accession showed good tolerance to drought in fruit production terms compared with non-grafted plants and other rootstocks. The aim of this work was to study if short-term exposure to drought in grafted plants using A25 as a rootstock would show tolerance to drought now. To fulfill this objective, some physiological processes involved in roots (rootstock) and leaves (scion) of grafted pepper plants were analyzed. Pepper plants not grafted (A), self-grafted (A/A), and grafted onto a tolerant pepper rootstock A25 (A/A25) were grown under severe water stress induced by PEG addition (-0.55 MPa) or under control conditions for 7 days in hydroponic pure solution. According to our results, water stress severity was alleviated by using the A25 rootstock in grafted plants (A/A25), which indicated that mechanisms stimulated by roots are essential to withstand stress. A/A25 had a bigger root biomass compared with plants A and A/A that resulted in better water absorption, water retention capacity and a sustained CO
assimilation rate. Consequently, plants A/A25 had a better carbon balance, supported by greater nitrate reductase activity located mainly in leaves. In the non-grafted and self-grafted plants, the photosynthesis rate lowered due to stomatal closure, which limited transpiration. Consequently, part of NO
uptake was reduced in roots. This condition limited water uptake and CO
fixation in plants A and A/A under drought stress, and accelerated oxidative damage by producing reactive oxygen species (ROS) and H
O
, which were highest in their leaves, indicating great sensitivity to drought stress and induced membrane lipid peroxidation. However, drought deleterious effects were slightly marked in plants A compared to A/A. To conclude, the A25 rootstock protects the scion against oxidative stress, which is provoked by drought, and shows better C and N balances that enabled the biomass to be maintained under water stress for short-term exposure, with higher yields in the field.
Aims
A potential of rare earth elements (including yttrium) (REY) accumulation in olives is increasing due to enhanced use of REY in human activities. REY transfer to extra virgin olive oil (EVOO) is ...little studied, and characterising the relationships between soil properties and REY concentrations in olive leaves, pomace and EVOO can enhance our understanding of soil-plant interactions.
Methods
Three different soil types (reclaimed karst, rendzina and cambisols), with the sum of REY concentrations (54–364 μg g
−1
) among the highest in European soils, were characterized for their pH, organic carbon, total carbonates and the applied agronomic practice. Aluminium, calcium, iron, phosphorus and REY were determined in soil (total and plant-available), olive leaves, pomace and EVOO.
Results
REY were mainly excluded from plant uptake and only small amounts of REY were transferred to leaves (0.2–652 ng g
−1
), pomace (0.001–10 ng g
−1
) and EVOO (<0.5–33 pg g
−1
). Soil REY availability (0.001–1685 ng g
−1
) and plant uptake increased with increasing soil acidity. Leaf REY concentrations were mainly explained by plant-available REY and pH. There was an indication of enhanced REY plant availability being associated with low available phosphorus and soil ploughing.
Conclusions
Soil properties influence REY uptake and further partitioning to leaves, fruits and EVOO.
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BFBNIB, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NMLJ, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•The efficiency of short- versus long-term ABA exposure was investigated in bell pepper.•Changes in gs and ACO2 were dependent on ABA rate and days of exposure.•Exogenous ABA influenced adaxial and ...abaxial stomata number.•Exogenous ABA promoted growth of thinner roots.•ABA: A tool to ‘imprint plant stress acclimation’ to recurrent stressful events.
Plants perceive environmental stress and use this information to modulate their regular pattern of development. Abscisic acid (ABA) mediates plant responses to many abiotic stresses. This study investigated the efficiency of short- versus long-term ABA exposure on critical morphological and physiological responses linked to functional changes in stomata, stomatal density, plant water status, photosynthetic activity and overall growth in bell pepper (Capsicum annuum L.). ABA was applied to pepper seedlings as foliar at 0, 0.1 or 1.0mM for 5, 10 or 15 consecutive days. A depressive effect of ABA on net photosynthetic rate (ACO2) and stomatal conductance (gs) compared to control was found after 5-day ABA-exposure at 1.0mM, and after 15-day ABA-exposure at 0.1mM and 1.0mM ABA. Plants quickly resumed the photosynthetic activity since no effect of ABA was found after a longer recovery. Temporary higher leaf water potential was observed in seedlings treated with ABA compared to control. At 17days after the beginning of the experiment, the number of stomata at adaxial and abaxial side was reduced at 1.0mM ABA-rate compared to 0.1mM ABA for each ABA-day of exposure. ABA-rate at 1.0mM decreased leaf weight, number and area with a more pronounced effect as ABA-days of exposure increased. Stem dry weight was almost unaffected by ABA-rate at 0.1mM, but 1.0mM decreased stem weight by 30% after 15-day ABA-exposure. The increased specific root length at 1.0mM ABA-rate after 5- or 15-day ABA exposure suggested that ABA induced the growth of thinner roots. The delayed effect of ABA-rate and ABA-days of exposure was measured for plants allowed to recover for 23days after the last application for the longest treatment. Growth parameters were generally affected by ABA after longer recovery. The effect of ABA on modulation of pepper seedlings growth and physiology was dependent on rate and length of exposure but recovery duration was important as well. These results provide new evidences that application of ABA at a specific rate and length of exposure could eliminate the risk of stressing young seedlings to the point of physiological injury as previously reported for some hardening techniques.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Trendy high-density olive fields are often monovarietal orchards, mostly using the cultivar Arbequina. However, Arbequina shows a strong self-incompatibility response, and its yields depend on wind ...cross-pollination, which is not always available. With the aim of finding suitable self-compatible cultivars that can replace Arbequina, we evaluated pollen–pistil interaction, fruit set and seed paternity in Arbosana under different pollination treatments: self-pollination, open-pollination and three cross-pollination treatments: × Arbequina, × Sikitita and × Koroneiki. All these cultivars are low-vigor cultivars suitable for high-density orchards, making them potential pollinizers for Arbosana. The results show that Arbosana is also self-incompatible with a strong reduction in fruit set due to a lower fertilization level caused by a strong inhibition of pollen tube growth in self-pollinated flowers. Seed-paternity analyses confirmed the self-incompatibility response of Arbosana and suggest that some fruit obtained in bagged shoots under self-pollination were, in fact, a product of cross-fertilization. In conclusion, we recommend against the use of Arbosana in large monovarietal orchards. On the contrary, good results were obtained under cross-pollination with Sikitita, Arbequina and Koroneiki pollen, allowing us to recommend them as pollinizers for Arbosana in appropriate pollination designs. This is the first time Arbosana self-incompatibility has been reported.
•Temperature and genotype of pollen affect pollen germination, pollen tube growth, and fertilization percentage in olive.•Increased temperature reduced pollen tube growth and fertilization ...percentage.•Cross-pollination resulted with higher pollen tube growth rate and fertilization percentage than self-pollination.•Temperature and genotype interaction was significant for pollen performance.
The reproductive phase has proven to be one of the most temperature sensitive stages in plants. Relatively high or low temperatures, especially during the progamic phase, are often correlated with low fertilization percentages and low fruit setting in different years and orchards. Here, the olive variety ‘Oblica’ was employed in a two year field experiment to assess the effect of temperature on the duration of the flowering period as well as on pollen germination, pollen tube growth, and fertilization percentage. An increase in temperature in the field was caused by covering trees with polyethylene cages. Cultivars ‘Leccino’ and ‘Levantinka’ were used as pollen donor genotypes in the cross-pollination treatment, and pollen from ‘Oblica’ trees was applied in the self-pollination treatment. Pollen germination in vitro was enhanced when pollen grains were exposed to higher temperatures two days before the start of flowering (29% for covered trees vs. 17% for uncovered trees in 2009; and 12.3% vs. 10% in 2010). Higher temperatures advanced the appearance of full bloom and shortened the duration of flowering period by one day for ‘Oblica’ trees inside the cages. No significant difference in pollen germination on the stigma was observed between the trees exposed to different temperatures. Pollen donor genotype affected pollen germination in vivo. Temperature had significant influence on pollen tube growth in the style and on fertilization percentage, but the reaction was genotype dependent. Higher temperatures reduced pollen tube growth in the style (decrease for 17% in 2009 and for 9% in 2010) and fertilization percentage (decrease for 9% in 2009 and for 8% in 2010) by increasing the time required for pollen tubes to reach the base of the style or the ovule. Due to faster pollen tube growth, the percentages of pollen tube growth and fertilization were significantly higher in cross-pollinated flowers (94.9% in 2009 and 70.9% in 2010 for pollen tube growth; 58.9% in 2009 and 51.4% in 2010 for fertilization) than in self-pollinated flowers (35.4% in 2009 and 59.6% in 2010 for pollen tube growth; 19.3% in 2009 and 39.1% in 2010 for fertilization). The results of our study support the model that the self-incompatibility level in olive is regulated by temperature because differences in self-fertilization percentage were observed between ‘Oblica’ trees outside and inside the polyethylene cages.
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Two bacteria belonging to the Pseudomonas and Pantoea genera were isolated from olive knots. Both bacterial strains were omnipresent in this study’s olive orchard with high susceptibility of the ...autochthonous olive genotypes indicating coevolution of bacteria with host plants. Genomes of two endemic bacteria show conserved core genomes and genome plasticity. The Pseudomonas ST1 genome has conserved virulence-related genes including genes for quorum sensing, pilus, and flagella biosynthesis, two copies of indole acetic acid biosynthesis (IAA) operons, type I-VI secretions systems, and genes for alginate and levan biosynthesis. Development of knots depends only on the presence of the Pseudomonas ST1 strain which then allows Pantoea paga strain co-infection and cohabitation in developed knots. The two bacteria are sensitive to a large number of antimicrobials, antibiotics, H2O2, and Cu (II) salts that can be efficiently used in propagation of bacterial free olive cultivars.
is one of the most devastating pests in tomato greenhouse production. Insecticide resistance management for
requires a novel approach that maximizes non-chemical methods for pest control. The aim of ...this study was to test the effects of rootstocks on
populations in hydroponically grown tomato plants. In order to contribute to the better understanding of the mechanisms defining the attractiveness of plant to the aerial pest, the effects of rootstocks on leaf anatomy and the amino acid composition of phloem sap were assessed. A two-factorial experimental design was adopted using cultivars (rootstock cultivars and Clarabella) grown as either non-grafted or grafted with cultivar Clarabella as a scion. The rootstock cultivars included Arnold, Buffon, Emperador, and Maxifort. A reduction in
density was observed using all rootstock cultivars. The number of adult individuals per leaf was 2.7-5.4 times lower on rootstock cultivars than on Clarabella. The number of large nymphs per square centimeter was at least 24% higher on non-grafted Clarabella compared with all other treatments. The leaf lamina thickness and mesophyll thickness were lower in self-grafted Clarabella than in non-grafted or in one grafted on rootstock cultivars; however, the extent of this reduction depended on the rootstock. The leaves with thinner laminae were generally less attractive to
. Eighteen amino acids were detected in the exudates of phloem sap. In all treatments, the most abundant amino acid was γ-aminobutyric acid (GABA), followed by proline, serine, alanine, and histidine. The scion cultivar Clarabella was the most attractive to
and had a higher content of leucine than did rootstock cultivars, and a higher content of lysine compared to Buffon and Maxifort. The features modified by rootstock such are changes in leaf anatomy can affect the attractiveness of plants to
. Thus, the grafting of tomato could constitute a valuable tool in an integrated management strategy against this aerial pest.
For two years, the tomatoes (cv. ‘Belle’ and ‘Clarabella’), ungrafted, self-grafted and grafted onto the ‘He-man’ rootstock, were grown under two irrigation regimes, i.e., partial-root zone drying ...(PRD) and fully irrigated (FI), to investigate whether grafting can alleviate drought stress and promote water-use efficiency (WUE). The grafted plants under the FI regime had the highest vegetative growth, which was the result of more leaves and greater leaf area and were only significantly different from the PRD grown ungrafted plants. The grafted plants had the highest yield as a result of the greater number of larger fruits and the yield did not differ between the irrigation treatments. No differences were found in the leaf NPK concentrations, while the Ca and Mg were higher under the PRD regime. The ungrafted plants under the PRD regime had the highest total soluble solids and acidity in the fruit juice. The grafted plants had a significantly higher WUE, more pronounced in the PRD regime. The different types of irrigation did not influence the vegetative growth and the yield in the greenhouse grown grafted tomato. The PRD and rootstock effects should be additionally investigated with deficit irrigation.
The olive tree (Olea europaea L.) is a wind-pollinated crop that exhibits an extreme alternate bearing habit. To improve fruit set, several methods have been used to determine the most successful ...compatible combinations of cultivars. In this study, priority is given to seed paternity analysis based on simple sequence repeats (SSRs), microsatellite markers used for the identification of potential pollen donors of cultivar ‘Oblica’ in a mixed olive orchard during two consecutive years. Seven microsatellite primers were successfully used to examine the paternity of olive embryos from ‘Oblica’ mother trees. Embryos were considered as a product of self-fertilization if only maternal alleles were present, but not a single case of self-fertilization was found among all the embryos analyzed. Two dominant pollen donors were not the closest nor the cultivars with the highest number of trees in the orchard, suggesting that cross-compatibility may have a key role in determining pollen donor success. In our earlier studies, pollen tube growth and fertilization success correlated with fruit set when controlled crosses between cultivars were performed; however, some discrepancy might appear compared to paternity analyses when mother trees have a free choice among different pollen sources from cultivars growing in their surroundings.
•Pollen-pistil interaction affects pollen performance in olive.•Cross-pollination resulted with higher pollen tube growth rates than self-pollination.•Earlier and greater amount of fertilization was ...found for cross-pollination than for self-pollination.•Pollen-pistil interaction is early and reliable mode to estimate compatibility in olive.
Most olive cultivars are partially self-incompatible. However, the mechanisms of self-incompatibility are still unclear and the choice of pollinizers for the main olive cultivars becomes difficult especially after the constant introduction of foreign cultivars in new environmental conditions. In order to determine compatibility relationships and to select suitable pollinizers for the main Croatian cultivars, pollen germination, pollen tube growth and fertilization percentage have been assessed in ‘Lastovka’ and ‘Oblica’, as well in the Italian cultivar ‘Leccino’ following self- and cross-pollination treatments in 2009 and 2010 seasons. Massive pollen tube growth, higher pollen tube growth rates, earlier and greater amount of fertilization were found for cross-pollination compared to self-pollination. The flowering periods of the studied cultivars overlapped in a high degree in both years. In ‘Lastovka’, cross-pollination was more efficient than self-pollination regarding pollen germination, tube growth and fertilization. Index of self-incompatibility (ISI), calculated as the ratio of fertilization following self-pollination to that following cross-pollination, was 0.4 and 0.5 in 2009 and 2010, respectively, which categorize this cultivar as partially self-incompatible. Higher ISI was found for ‘Leccino’ (0.7 in 2009; 1.0 in 2010) and ‘Oblica’ (0.5 in 2009; 0.7 in 2010). However, most cross-pollination treatments provided higher fertilization levels than self-pollination, proving that cross-pollination was also beneficial for ‘Leccino’ and ‘Oblica’. Inter-incompatibility reactions between cultivars were not observed.
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