Nitrate photo-assimilation in tomato leaves under short-term exposure to elevated carbon dioxide and low oxygen

The role of photorespiration in the foliar assimilation of nitrate (NO 3 -) and carbon dioxide (CO2) was investigated by measuring net CO2 assimilation, net oxygen (O2) evolution, and chlorophyll fluorescence in tomato leaves (Lycopersicon esculentum). The plants were grown under ambient CO2 with ammonium nitrate (NH4NO3) as the nitrogen source, and then exposed to a CO2 concentration of either 360 or 700 μmol mol -1, an O2 concentration of 21 or 2%, and either NO 3 - or NH4 + as the sole nitrogen source. The elevated CO2 concentration stimulated net CO2 assimilation under 21% O2 for both nitrogen treatments, but not under 2% O2. Under ambient CO2 and O2 conditions (i.e. 360 μmol mol-1 CO2, 21% O 2), plants that received NO3 - had 11-13% higher rates of net O2 evolution and electron transport rate (estimated from chlorophyll fluorescence) than plants that received NH 4 +. Differences in net O2 evolution and electron transport rate due to the nitrogen source were not observed at the elevated CO2 concentration for the 21% O2 treatment or at either CO2 level for the 2% O2 treatment. The assimilatory quotient (AQ) from gas exchange, the ratio of net CO2 assimilation to net O2 evolution, indicated more NO3 - - assimilation under ambient CO2 and O 2 conditions than under the other treatments. When the AQ was derived from gross O2 evolution rates estimated from chlorophyll fluorescence, no differences could be detected between the nitrogen treatments. The results suggest that short-term exposure to elevated atmospheric CO 2 decreases NO3 - assimilation in tomato, and that photorespiration may help to support NO3 - assimilation.Fil: Searles, Peter Stoughton. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Bloom, Arnold J.. University of California at Davis; Estados Unido

Influence of Experimental Warming on the Rate and Duration of Fruit Growth and Oil Accumulation in Young Olive Trees (cvs. Arbequina, Coratina)

Olive tree cultivation in new warmer areas and climate change have increased the global interest in understanding how air temperature affects both fruit growth and oil accumulation. The aims of this study were to evaluate the rate and duration of fruit growth and oil accumulation in response to experimental warming (+3) in a semiarid region of Argentina; and assess how warming affected fatty acid composition. Young, potted olive trees (cvs. Arbequina, Coratina) were warmed (T+) or maintained near ambient temperature (T0) inside open top chambers in the field during oil accumulation in 2014–2015 or 2015–2016 using different trees in each season. Warming reduced the rate of both fruit growth and oil accumulation in T+ compared to T0 in both cultivars. These rate reductions under T+ led to large decreases in final fruit dry weight and oil concentration. In contrast, the durations (i.e., days) of fruit growth and oil accumulation were most often not affected. Cultivar x temperature interactions were observed in 2014–2015 with warming decreasing oleic acid and increasing linoleic acid in cv. Arbequina, while cv. Coratina showed no response to warming. However, no interactions were found in 2015–2016. Studying how fruit growth and oil accumulation respond to adaptation strategies against increasing air temperatures should be a priority in both young and mature olive trees of numerous cultivars given crop expansion to new regions and future climate scenarios.Fil: Miserere, Andrea. Universidad Nacional de La Rioja. Secretaría de Ciencia y Tecnología. Centro de Investigación e Innovación Tecnológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Searles, Peter Stoughton. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Rousseaux, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentin

Light quality environment and photomorphological responses of young olive trees

Tree densities have increased greatly in olive orchards over the last few decades. In many annual crop species, increased density reduces the horizontal red/far-red (R/FR) and blue/green (B/G) ratios during canopy development even before direct shading occurs, and such changes are known to alter plant morphology. This study with olive trees evaluated: (1) whether the leaf area index (LAI) of neighboring trees modifies the light quality environment prior to a tree being directly shaded and (2) the potential morphological responses of three olive cultivars to changes in light quality. Increasing LAI using different spatial arrangements of potted, three-year-old trees reduced the horizontal R/FR ratio more than that of the B/G ratio. Cultivar-specific responses to low R/FR ratio were observed for individual leaf area and aboveground/belowground biomass ratio using laterally positioned FR mirrors or green fences. No statistically significant responses were detected in response to green vegetation fences that reduced both horizontal R/FR and B/G ratios, but a cluster analysis grouped together the overall morphological responses to both FR mirrors and green fences. These results in olive trees suggest that cultivar differences in response to light quality may be relevant for understanding adaptation to dense orchards and identifying cultivars best suited to them.Fil: Ladux, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Trentacoste, Eduardo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Mendoza-san Juan. Estación Experimental Agropecuaria Junin; ArgentinaFil: Searles, Peter Stoughton. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Rousseaux, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina. Universidad Nacional de La Rioja. Departamento de Ciencias Exactas, Físicas y Naturales; Argentin

Plant response to solar ultraviolet-B radiation in a southern South American Sphagnum peatland

1. Plant growth and pigmentation of the moss Sphagnum magellanicum and the vascular plants Empetrum rubrum, Nothofagus antarctica and Tetroncium magellanicum were measured under near-ambient (90% of ambient) and reduced (20%) ultraviolet-B (UV-B) radiation for three growing seasons in a Sphagnum peatland in Tierra del Fuego, Argentina (55°S). 2. Reduction of solar UV-B increased height growth but decreased volumetric density in S. magellanicum so that biomass production was not influenced during the 3 years. The morphology of vascular plants tended not to respond to UV-B reduction. 3. A 10-20% decrease in UV-B-absorbing compounds occurred in T. magellanicum under solar UV-B reduction. No effects were seen on chlorophyll or carotenoids in S. magellanicum, although, for UV-B-absorbing compounds, a significant interaction between UV-B and year suggests some response to solar UV-B reduction. 4. The climate-related growth of the dwarf shrub E. rubrum was assessed retrospectively by correlating an 8-year record of annual stem elongation with macroclimatic factors including solar UV-B and visible radiation, precipitation and temperature. 5. No significant negative correlations were found between annual E. rubrum stem elongation and ambient solar UV-B, the ratio of UV-B: visible radiation, or the 305-nm: 340-nm irradiance ratio for an 8-year record (1990-91 to 1997-98), nor was stem elongation affected by solar UV-B reduction in our experimental field plots after 3 years. 6. The role of solar UV-B radiation on plant growth in Sphagnum peatlands in Tierra del Fuego, Argentina, is likely to depend on the severity of stratospheric ozone depletion over the next several decades. The increases in ambient solar UV-B associated with ozone depletion over the last 20 years are less than the difference between our radiation treatments. Therefore, providing that the ozone layer substantially recovers by the middle of this century, only modest effects of increased solar UV-B on plant growth may be expected.Fil: Searles, Peter Stoughton. State University of Utah; Estados UnidosFil: Flint, Stephan D.. State University of Utah; Estados UnidosFil: Diaz, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Rousseaux, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Ballare, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Caldwell, Martyn M.. State University of Utah; Estados Unido

Impact of simulated mechanical hedge pruning and wood age on new shoot demography and return flowering in olive trees

Key message: More vigorous watersprouts and fewer low vigor shoots form as wood age increases at the cutting points with greater canopy pruning depth in olive trees, which reduces return flowering. Such information is relevant to long-term olive orchard pruning strategies in hedgerows. Abstract: Demographic analysis of growth responses to pruning in fruit trees seeks the quantification of the typology of new shoots originating from the remaining branches. Pruning of hedgerows using mechanical discs is becoming increasingly common in orchards, but little information is available as to how such pruning, which does not discriminate between branch size, wood age at the cutting point, branch type, or position, modifies subsequent new shoot demography. Hence, the experiment described in this study in young olive trees (cv. Arbequina) assessed the following questions: (1) Is the type and growth of new shoots associated with the intensity of mechanical pruning and/or the wood age on which they grow? (2) How many growing seasons does it take for new shoots formed after pruning to flower? The principal hypothesis was that a greater proportion of vigorous watersprouts form compared to low vigor shoots as wood age at the cutting points increases with canopy pruning depth, and that the watersprouts have low flowering potential. Both new shoot growth and return flowering were monitored on exposed supporting wood over several growing seasons after implementing three winter (25W, 50W, and 75W) pruning levels of increasing intensity and one summer pruning (75S) treatment along with an unpruned control (CON). As hypothesized, a greater number and elongation of vigorous watersprouts were found as wood age increased at the cutting points with greater winter pruning intensity, and the watersprouts had low levels of return flowering even 3 full years after pruning compared to the CON. Growth of low vigor shoots was relatively more important than watersprout growth in the severe summer pruning treatment, although 3 years after the summer pruning flowering was not fully recovered. In contrast, the more lightly pruned winter treatments (25W, 50W) did not show significant differences in flowering with the CON at the end of 3 years. Thus, mechanical hedge pruning in olive trees should be light-to-moderate to avoid the formation of watersprouts on older wood, which leads to long-term reductions in flowering.Fil: Albarracin, Valeria Mariel. Centro Regional de Investigaciones Cientificas y TRansferencia Tecnológica La Rioja (CRILAR) - Provincia de La Rioja - UNLaR - SEGEMAR - UNCa - CONICET. ; Argentina. Ministerio de Agroindustria - Subsecretaria de Agricultura, Bs As ; ArgentinaFil: Hall, Antonio Juan. Universidad de Buenos Aires, Facultad de Agronomía (IFEVA), CONICET; ArgentinaFil: Searles, Peter Stoughton. Centro Regional de Investigaciones Cientificas y TRansferencia Tecnológica La Rioja (CRILAR) - Provincia de La Rioja - UNLaR - SEGEMAR - UNCa - CONICET; ArgentinaFil: Rousseaux, Maria Cecilia. Centro Regional de Investigaciones Cientificas y TRansferencia Tecnológica La Rioja (CRILAR) - Provincia de La Rioja - UNLaR - SEGEMAR - UNCa - CONICET; Argentin

Sap Flow Responses to Warming and Fruit Load in Young Olive Trees

Global warming will likely lead to temperature increases in many regions of South America where temperatures are already considered to be high for olive production. Thus, experimental studies are needed to assess how water use in olive trees may be affected by global warming. The objectives of this study were to (i) evaluate the response of olive tree sap flow, stomatal conductance, and xylem anatomy to elevated temperature and (ii) determine whether fruit load may affect the temperature responses. A warming experiment using well-irrigated olive trees (cv. Arbequina) in open-top chambers (OTCs) with two temperature levels was performed from fruit set to the end of fruit growth in two seasons. Temperature levels were a near ambient control (T0) and a treatment 4°C above the control (T+). Trees were in the chambers for either one (2015–2016) or two seasons (2014–2015, 2015–2016) and were evaluated only in the second season when all trees were 3 years old. Whole-tree sap flow on leaf area basis, stomatal conductance, and aspects of xylem anatomy were measured. Sap flow was slightly higher in T+ than T0 trees heated for one season early in fruit development (summer) likely due to the elevated temperature and increase in vapor pressure deficit. Later in fruit development (fall), sap flow was substantially higher in the T+ trees heated for one season. Total vessel number per shoot was greater in the T+ than the T0 trees at this time due to more small-diameter vessels in the T+ trees, but this did not appear to explain the greater sap flow. The T+ trees that were heated for two seasons had less fruit load than the T0 trees due to little flowering. In contrast to trees heated for one season, sap flow was less in T+ than controls late in fruit development the second season, which was likely related to lower fruit load. An independent experiment using untreated trees confirmed that sap flow decreases when fruit load is below a threshold value. The results emphasize that multiple, interacting factors should be considered when predicting warming effects on water use in olive orchards.Fil: Miserere, Andrea. Universidad Nacional de La Rioja; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Searles, Peter Stoughton. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Manchó, Guadalupe. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Maseda, Pablo H.. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Rousseaux, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentin

Influence of deficit irrigation and warming on plant water status during the late winter and spring in young olive trees

Changes in rainfall patterns and increases in ambient air temperature (i.e., warming) are expected with climate change. Yet, little information is available on how plant water status will respond to the combination of water deficit and increased air temperature in fruit tree species. The objective of this study was to evaluate the individual responses of deficit irrigation and warming and their combination on plant water status during the late winter and spring in young olive trees. Two temperature and two irrigation levels were applied in open top chambers during the late winter and spring of 2018 and 2019 to two- or three-year-old, potted trees (cv. Arbequina in 2018; Coratina in 2019). The temperature levels were a near-ambient control and a warming treatment that was 4 °C above the control, while the two irrigation levels were 100% and 50% of irrigation needs. Midday stem water potential (Ψs), stomatal conductance, net leaf photosynthesis, transpiration, and leaf temperature were measured periodically, and the difference between leaf and air temperature (ΔT) was calculated. The Ψs generally decreased due to irrigation deficit and warming when applied individually. When both treatments were combined, an additive response was observed. In contrast, stomatal conductance and net photosynthesis were consistently decreased by deficit irrigation, but were less affected by warming. Irrigation deficit did not affect leaf temperature under our experimental conditions. As was expected, warming most often increased leaf temperature, but it also significantly decreased ΔT early in the season when leaf transpiration appeared to be greater due to warming. The results indicate that modifications in water management with global warming will likely be required given the mostly negative individual or additive effects of irrigation deficit and air temperature on Ψs and other variables.EEA ChilecitoFil: Iglesias, Maria Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Iglesias, Maria Agustina. Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Iglesias, Maria Agustina. Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de la Rioja; ArgentinaFil: Iglesias, Maria Agustina. Secretaria de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Iglesias, Maria Agustina. Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Rousseaux, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Rousseaux, Maria Cecilia. Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Rousseaux, Maria Cecilia. Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de la Rioja; ArgentinaFil: Rousseaux, Maria Cecilia. Secretaria de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Rousseaux, Maria Cecilia. Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Rousseaux, Maria Cecilia. Universidad Nacional de La Rioja. Departamento de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Aguero Alcaras, Luis Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Chilecito. Agencia de Extensión Rural Aimogasta; ArgentinaFil: Hamze, Leila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Hamze, Leila. Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Hamze, Leila. Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de la Rioja; ArgentinaFil: Hamze, Leila. Secretaria de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Hamze, Leila. Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Searles, Peter Stoughton. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Searles, Peter Stoughton. Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Searles, Peter Stoughton. Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de la Rioja; ArgentinaFil: Searles, Peter Stoughton. Secretaria de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Searles, Peter Stoughton. Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentin

How temperatures may affect the synthesis of fatty acids during olive fruit ripening: genes at work in the field

A major concern for olive cultivation in many extra-Mediterranean regions is the adaptation of recently introduced cultivars to environmental conditions different from those prevailing in the original area, such as the Mediterranean basin. Some of these cultivars can easily adapt their physiological and biochemical parameters in new agro-environments, whereas others show unbalanced values of oleic acid content. The objective of this study was to evaluate the effects of the thermal regime during oil synthesis on the expression of fatty acid desaturase genes and on the unsaturated fatty acid contents at the field level. Two cultivars (Arbequina and Coratina) were included in the analysis over a wide latitudinal gradient in Argentina. The results suggest that the thermal regime exerts a regulatory effect at the transcriptional level on both OeSAD2 and OeFAD2-2 genes and that this regulation is cultivar-dependent. It was also observed that the accumulated thermal time affects gene expression and the contents of oleic and linoleic acids in cv. Arbequina more than in Coratina. The fatty acid composition of cv. Arbequina is more influenced by the temperature regime than Coratina, suggesting its greater plasticity. Overall, findings from this study may drive future strategies for olive spreading towards areas with different or extreme thermal regimes serve as guidance for the evaluation olive varietal patrimony.EEA San JuanFil: Contreras Valentín, Ana Cibeles. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Juan; Argentina.Fil: Contreras Valentín, Ana Cibeles. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pierantozzi, Pierluigi. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Juan; Argentina.Fil: Pierantozzi, Pierluigi. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Maestri, Damian. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Maestri, Damian. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tivani, Martín. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Juan; Argentina.Fil: Tivani, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Searles, Peter. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Brizuela, Magdalena. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Fernández, Fabricio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Catamarca; Argentina.Fil: Toro, Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cerro Azul; Argentina.Fil: Puertas, Carlos. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Junin; Argentina.Fil: Trentacoste, Eduardo R. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Junin; Argentina.Fil: Kiessling, Juan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Alto Valle. Agencia de Extensión Rural Centenario; Argentina.Fil: Mariotti, Roberto. National Research Council. Institute of Biosciences and Bioresources; ItaliaFil: Baldoni, Luciana. National Research Council. Institute of Biosciences and Bioresources; ItaliaFil: Mousavi, Soraya. National Research Council. Institute of Biosciences and Bioresources; ItaliaFil: Fernández, Paula. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; ArgentinaFil: Fernández, Paula. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Fernández, Paula. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Moschen, Sebastián. Instituto Nacional de Tecnología Agropecuaria (INTA).Estación Experimental Agropecuaria Famaillá; Argentina.Fil: Moschen, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Torres, Myriam Mariela.Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Juan; Argentina.Fil: Torres, Myriam Mariela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Dynamics of shoot and fruit growth following fruit thinning in olive trees: same season and subsequent season responses

The need to understand how the balance between vegetative and reproductive growth in olive trees is modified by different crop loads has become more important over the last 20 years due to increasing planting densities and the greater use of irrigation. The objectives of this study conducted in a well-irrigated olive orchard were to: (1) evaluate shoot and fruit growth dynamics following fruit thinning during the same growing season in which thinning was applied and during the next growing season; and to (2) determine crop load effects on bloom, fruit set, and fruit yield over three growing seasons. Hand-thinning of fruit 35 days after full bloom on 9-year-old cv. ‘Arauco’ trees in an “on” year led to thinning treatments of 24, 48, and 87% with respect to an unthinned control. Apical and lateral shoot elongation were measured every two weeks throughout the growing season, and fruit were sampled to determine fruit weight at the same interval. Apical shoot elongation occurred only early in the season when crop load was medium or high, while apical elongation continued for most of the season when crop load was low. Elongation of laterals contributed significantly to total shoot elongation on fruit-bearing branches in trees with low crop loads after thinning the first season. Individual fruit dry weight was reduced about 40% by high crop loads in both seasons. Differences in relative growth rates of both the shoots and the fruit due to crop load suggest fruit growth was limited by photoassimilate availability early in the season, but shoot growth was limited most of the season under medium and high crop loads. Inflorescence number per shoot was reduced by crop load in the two seasons following the thinning event. Fresh fruit yield was only reduced in one of the two biennia (i.e., periods of 2 years) in the trees that were heavily thinned (87%) the first season. The trees in which about one-half (48%) of the fruit were thinned the first season did not show biennia yield reductions and maintained a low alternate bearing index over three seasons. Thus, chemical thinning could be applied in growing seasons with high flowering. Further studies are needed to better assess competition for resources between shoots and fruit with the ultimate goal of reducing alternate bearing.Fil: Fernandez, Fabricio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Catamarca; ArgentinaFil: Ladux, Jose Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Chilecito; ArgentinaFil: Searles, Peter Stoughton. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentin

Nutrient Reference Levels for Fertigation Scheduling in Olive Groves of an Arid Region of Argentina (San Juan)

The diagnosis of tree nutritional status in fruit trees by leaf-nutrient analysis allows for fertilization scheduling by fertigation. In olive, a specific equilibrium in leaf nutrient concentration occurs that depends on the dominant edaphic and climatic conditions as well as the time of year. Therefore, the objective of this study was to determine leaf-nutrient reference values in olive in an arid region of Central-western Argentina at two different times of the year. Leaf samples were taken during the winter rest period (July) and summer (January; a month after pit hardening) over three consecutive years in 100 commercial olive orchards from several cultivars in the Tulum Valley of San Juan, Argentina. These periods have been proposed previously in other regions. Leaf nutrient contents were analyzed and the obtained values were compared with those reported elsewhere. Confidence intervals (95%) of nitrogen (N), phosphorus (P) and potassium (K) in the winter were 1.73-1.83%, 0.14-0.16%, and 0.92-0.98%; respectively, while summer values were 1.56-1.70% (N), 0.16-0.18% (P), and 1.14-1.26% (K). The N concentrations were somewhat lower than those reported for the Mediterranean Basin with P and K values in contrast being similar or greater. Values of the remaining nutrients (Ca, Mg, Mn, Na, Cu, Zn, B and Fe) were generally similar to those reported for the Mediterranean. However, boron levels were somewhat high in the winter (25.38 ppm), and magnesium (0.13%) and manganese (33.04 ppm) were low in the summer. Given that the winter period showed narrower confidence intervals than the summer period for N, P, and K, winter sampling could be considered for annual fertilizer scheduling in intensive olive orchards in arid Central-western Argentina. However, sampling during the early summer period may provide critical information just prior to oil accumulation.Fil: Bueno, L. A.. Instituto Nacional de Tecnologia Agropecuaria. Centro Reg.cuyo Mendoza-san Juan. Estacion Exptal.agrop.san Juan; ArgentinaFil: Sánchez, E.. Instituto Nacional de Tecnologia Agropecuaria. Centro Reg.cuyo Mendoza-san Juan. Estacion Exptal.agrop.san Juan; Argentina. Instituto Nacional de Tecnologia Agropecuaria. Centro Reg.patagonia Norte. Estacion Exptal. Agrop. Alto Valle; ArgentinaFil: Searles, Peter Stoughton. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Cientificas y Transferencia Tecnológica de Anillaco; Argentin