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Water potential is considered to be the “gold-standard” measure for plant water status determination. However, there are some discrepancies on how and at what time of the day water potential measurements should be performed in order to obtain meaningful information. The aim of this work is to evaluate the discrimination ability of water potential measurements in grapevines depending on the time of the day and of the measurement procedure (leaf vs. stem). To do so, a meta-analysis was performed using >78,000 measurements of water potential data obtained in field irrigation experiments, provided by 13 research teams working in this subject in Spain. For each measurement day and experiment, Discrimination Ratio (DR) was calculated and used to determine the discrimination ability of each method, and then pooled for comparison. The measurement procedure with the greatest DR can be hypothesised to be the most suitable under the average working conditions. Leaf water potential showed lower DR mean values than predawn or stem water potential. The climatic conditions and the cultivar may affect to the discrimination ability, although the abovementioned trend was always maintained. Leaf water potential in vineyards should therefore be replaced, as a general rule, by either stem or predawn water potential readings, without a clear pre-eminence of the performance of predawn and stem water potential measurements. Building a common dataset and its subsequent meta-analysis has been proved to be an efficient and robust tool to compare plant measurements, and should be implemented for other species and/or measurement procedures.

Viticulture in Southern Europe heads towards a scenario of drier and warmer the growing seasons due to climate change. This decrease in the amount of water available for the vines and increase in evapotranspiration make necessary finding strategies to reduce vineyard water needs. In this context, the effect of severe trimming (40–60% of shoot length), performed at pea-size stage, on plant water status was evaluated in four different vineyards located in North of Spain. Severe trimming improved plant water status clearly only when climate conditions were more demanding, whereas only a slight improvement or no change was observed elsewhere. Lower leaf areas resulted in less water deficit following a logarithmical trend revealing that the effect was more pronounced at low leaf area levels. Severe trimming had non-significant effects on cluster number, yield and cluster weight, but presents a tendency to reduce total soluble solids content and to increase total acidity, consequently delaying ripening.

Background and Aims Vineyards, one of the most widespread agricultural systems, have significant but scarcely evaluated carbon sequestration potential. Allometry is a cost-effective approach to estimate plant biomass, but few studies – focused mainly on permanent structure carbon fixation – have dealt with it in grapevine. This study develops allometric models that accurately estimate grapevine standing biomass (total vine biomass at harvest), using extensive field-collected data sets. Methods and Results Data were obtained in vineyards located in Spanish regions representative of the variability found in warm semi-arid Mediterranean regions. We developed and validated functions to estimate vine biomass for all vine organs. The models obtained estimated accurately the biomass fixed by each organ separately and even more accurately at the whole plant scale. To illustrate the potential of the models, they satisfactorily assessed the influence of seasonal vine water status on vine biomass production and partitioning using an independent data set. Conclusions and Significance of the Study The models constitute a powerful tool to determine in a non-destructive and cost-effective manner standing biomass from simple vine measurements, which makes them suitable for quantifying carbon stocks and allocation patterns, and for evaluating the influence of climate or cultural practices at large scale to estimate better – at a regional or international level – the contribution of grapevine culture to CO2 balances.

The reconstitution of European vineyards after the phylloxera outbreak was performed with few high-aptitude varieties. In Navarre (Spain), the variety used was mainly ‘Garnacha’, though the inclusion of a small number of plants of different varieties traditionally grown in this area within each vineyard was relatively frequent. In this context, in 2008 and 2009, a systematic survey was performed on the oldest vineyards (>50 years) from Navarre in order to gather the intravarietal diversity that could be found within ‘Garnacha’ in the region, but subsequent field observation showed 197 plants to be different from ‘Garnacha’. The aim of this study was to identify the varieties corresponding to those plants. Molecular profiles were determined using 25 SSR markers, and 33 varieties were identified: 28 of them after comparisons with national and international databases and the remaining five through other sources. Slight differences in SSR allele length were found in some of the plants identified as ‘Mazuelo’, ‘Rojal’, ‘Miguel de Arco’ and ‘Tortozona Tinta’. In addition, polymorphisms involving the appearance of a third allele were found in some plants identified as ‘Viura’, ‘Mandon’, Mazuelo’ and ‘Morate’. This study shows that an important biodiversity reservoir still remains within old vineyards and, therefore, systematic surveys on them could allow gathering the varietal richness that still can be found in the region. Additionally, somatic variation at SSR loci has been shown to occur in several grape varieties, especially in the ancient ones where the likelihood that mutations are accumulated and fixed is higher.

The study of the natural abundance of stable isotopes in grapevine organs and tissues started in the late 1970s and, since then, a significant body of research has analysed how cultivar, rootstock, climate, soil and growing conditions affect the relative proportion of the stable isotopes of carbon (δ13C), oxygen (δ18O) and hydrogen (δD) in grapevine organs. Besides, some research has been devoted to the study of the isotope ratios of nitrogen (δ15N), strontium (δ87Sr), boron (δ11B) and sulfur (δ34S) in vineyards. This review presents the state of the art of stable isotope determination in viticulture, and outlines some approaches that, to date, have not been considered in viticulture and that could be applied in future research.

Aim: An advance in grapevine phenological stages (including ripening) is occurring worldwide due to global warming and, in the hottest seasons, already results in a lack of synchrony between sugar and phenolic ripeness, leading to unbalanced wines. In order to cope with this fact, a general effort is being made by researchers and growers aiming at delaying ripening through cultural practices, particularly under warm growing conditions, where these effects are more deleterious. The aim of this work is to evaluate to which extent severe trimming and enhanced competition of laterals can delay ripening in Tempranillo vineyards under semiarid conditions.Methods and results: The experiment took place during two consecutive seasons in Traibuenas (Navarra, Spain) in a cv. ‘Tempranillo’ vineyard trained to a vertical shoot positioned (VSP) spur-pruned bilateral cordon. Severe mechanical pruning was performed ca. 3 weeks after fruit-set in order to reduce leaf-to-fruit ratio, and in the trimmed plants, three irrigation doses were applied until harvest aiming at enhancing lateral growth, hypothesized to compete with ripening. All measurements were performed in six 10-vine replicates per treatment. Trimming significantly reduced leaf area and yield, resulting in higher water availability in trimmed plants. The whole ripening process was delayed by trimming: mid-veraison was delayed by about 5 days, and the delay in sugar accumulation and acid degradation was longer, differences being more marked in malic than in tartaric acid concentration. The use of increased irrigation levels compensated the losses in yield caused by trimming, enhanced laterals’ growth and implied an additional delay in ripening.Conclusion: trimming and increased irrigation had an additive effect in terms of delaying ripening, and they can be used jointly when that delay is needed.Significance and impact of the study: this study proves the potentiality of the joint use of trimming and increased irrigation to delay ripening, although it is necessary to analyze the implications the obtained delay has on other quality aspects. The lower anthocyanin and phenolic values observed in trimmed vines were not solely due to delayed ripening, as lower values were observed even when data were compared for a given total soluble solid content.

[Background and aims] Viral diseases in grapevines result in reduced vineyard performance, but it remains unclear to which extent some of their effects are direct or indirect, or if both kinds of effects co-occur. The aim of this work is to evaluate the effect of three virus diseases (GFLV, GLRaV and GFkV) on cv. Tempranillo., [Methods and results] A wide dataset that comprised yield components and grape composition of 531 cv. Tempranillo accessions for seven years was used, comparing their performance depending on the presence of each virus. GFLV showed the highest deleterious effects, followed by GLRaV-3, whereas GFkV had no effect. GLRaV-3 and, especially, GFLV effects were very relevant., [Conclusions] Regression analyses demonstrated that GFLV increases soluble solids (TSS) and colour density (CD) independently of yield reduction or advanced ripening, and causes higher pH independently of TSS. Similarly, GLRaV-3 detrimental effect on CD is not caused only by delayed ripening, and higher pH is associated to imbalanced ripening., [Significance of the study] Our results highlight that a detailed analysis of a wide agronomic dataset allows a better understanding of virus diseases, unveiling to which extent some of their effects are direct or indirect., This work has been performed within the following projects: “Selección y mantenimiento en campo de fenotipos del cv. Tempranillo de la D.O.Ca. Rioja; estudio de su contenido fenólico y mejora de su extracción” (1998, CDTI/ADER) and “Creación de un banco de germoplasma de cv. Tempranillo de Rioja. Contenido fenólico de las variedades autóctonas, optimización de la extracción y estabilización”. VIN00-043-C3 (2000, INIA).

Carbon isotope ratio (δ 13 C) is known to be related to water use efficiency and water status in grapevines. However, there is no consensus on which is the temporal sensitivity of this parameter, i.e. which is the time-span this parameter integrates best. The aim of this work was to evaluate the usefulness of whole berry δ 13 C to integrate plant water status in grapevine, and to determine its temporal sensitivity. Comparing δ 13 C of berries sampled 10 days after veraison and at harvest with average stem water potential at different moments of the season; we observed that the moment at which water deficit occurs remarkably conditioned the response observed. The moments for which the sensitivity was greatest were two periods critical for sugar accumulation: veraison and 4–6 weeks before harvest. This gives a particular relevance to δ 13 C measured in whole berries, as its sensitivity is higher at critical moments of berry ripening, but it also implies that care has to be taken when interpreting δ 13 C values, considering the variations in sensitivity depending on sampling time.

A set of 493 old and local Spanish accessions of apple (Malus x domestica Borkh) maintained at three collections in Northeastern Spain was studied using 16 simple sequence repeats in order to estimate their genetic diversity and to identify the genetic structure and relationships among their accessions. An additional diverse set of 45 apple cultivars, including old Spanish and international cultivars, was added as reference. Genetic analyses performed by Bayesian model-based clustering revealed a very strong differentiation of two major groups. The first one clustered 159 individuals (52 % of unique genotypes) including local accessions and six old Spanish cultivars. The second major group was formed by 145 individuals, including 38 international reference cultivars and one old Spanish cultivar. Nested Bayesian clustering was applied to those two groups and two and four sub-groups were found at each one, respectively. The identification of private and unique alleles, and the remarkable differences in allelic richness among groups and sub-groups constitute further evidence of a clear genetic structure. The results obtained through the factorial correspondence and analyses of molecular variance confirmed those obtained by Bayesian analyses, revealing moderate but significant differentiation among the two major groups (F ST = 0.076) and the six sub-groups (F ST = 0.111). Our results highlight that the genetic diversity encompassed by currently cultivated apple accounts only for a small fraction of that existing within the species, and that an important part (≈60 %) of the local material analyzed constitutes a good example of genetic distinctness with respect to the main cultivars used in European orchards.

Grape must and wine colour is traditionally assessed by several indexes calculated after measuring absorbance at 420, 520 and 620 nm. In the last years tristimulus colorimetry (mainly CIELab colour space) is increasingly used in research and wineries, since it seems to be a more accurate method to evaluate wine colour, especially at hue junctions when visual colour is quite subjective. The aim of our work is to compare CIELab parameters (L*, c*, h) to classical colour indexes in grape must. Total (TAnt) and extractable (EAnt) anthocyanin content was measured in more than 1600 samples of 4 cultivars ('Cabernet Sauvignon' - CS, 'Grenache' - GA, 'Graciano' - GR, and 'Tempranillo' - TE) at 3 stages of ripening by Glories method. In the same macerated extracts, tristimulus colour measurements were made with a Minolta reflectance spectrophotometer, using 2 and 10 mm path length quartz glass cells. Luminosity has been the parameter that has allowed the best estimation of TAnt and EAnt. However, the correlation coefficient found for EAnt was relatively low (R2=0.75) due to differences between cultivars; GA and GR showing lower luminosity for a given EAnt value than CS and TE. These differences are probably a result of differences in the anthocyanic profile of these cultivars, which may affect directly (differences in absorbance pattern) or indirectly (co-pigmentation and self association process) the colour when the whole spectrum is taken into account. Colorimetic measurements have been shown to allow estimating the classic colour parameters (provided varietal differences are considered) and to detect more subtle differences between samples.

Background and Aims: In viticultural and oenological research, grape samples are frequently stored frozen to overcome time and facility restraint. However, there is little knowledge on how freezing, variety and storage time affect the changes occurring in grape quality parameters. The aim of the paper was to evaluate these effects using cv. Cabernet Sauvignon (CS), Grenache (GA) and Tempranillo (TE) samples. Methods and Results: Quality parameters were assessed in fresh grapes and after 1, 3 and 6 months of frozen storage. Soluble solid concentration remained unchanged. Freezing decreased titratable and tartaric acidity. pH increased after 1 and 3 months of storage, but decreased after 6 months. Freezing increased malic acid concentration only in GA. Yeast assimilable nitrogen diminished with freezing time, with each variety behaving differently. A significant colour enhancement was found (EAnt, L*, C*), whereas degradative reactions for polyphenols occurred at any storage time for GA, and for all varieties after 6 months. Conclusions: Variety and storage time play a large role in the changes occurring in stored frozen grape samples. Not considering these factors may lead to misinterpretation of results obtained through subsequent use of these grapes. Significance of the Study: Specific correcting factors for each quality parameter, variety and storage time are needed when working with stored frozen samples.

Background and Aims: Irrigation management requires the collection of up-to-date information that allow growers to make rapid decisions, water potential being one of the most used parameters in irrigation scheduling. The goal of this research was to determine whether predawn (Ypd) and stem (Ys) water potential can be used equally well, quantifying the effect external factors have on the relationship between them. Methods and Results: Ypd, mid-morning (Ys-m) and noon (Ys-n) stem water potential were measured at seven cv. Tempranillo vineyards. Climatic conditions, vine growth and fruit load affected daily water potential dynamics. A greater decline of Ys occurred when temperatures were higher and there was no dew formation, as well as under larger canopies and fruit load. While the relative impact of these variables on water potential was not particularly high, it was by no means negligible. Conclusions: Data collected in this study did not favour Ypd, Ys-m or Ys-n as a preferred measure to evaluate plant water status. It is important to remark that similar Ypd values do not necessarily indicate the same level of deficit, and that similar Ys values do not always mean similar water availability. Therefore, a straightforward interpretation of Ypd and Ys can sometimes be misleading. Significance of the Study: The results obtained provide significant explanation to the lack of agreement in the literature regarding the most suitable time to measure water potential. Vineyard managers and scientists should select it according to the level of stress expected, climatic conditions and irrigation frequency. Abbreviations BN berry number; DR discriminating ratio; ET evapotranspiration; LWD leaf wetness duration; YL leaf water potential; Ypd pre-dawn leaf water potential; Ys-m mid-morning stem water potential; Ys-n stem water potential at noon; SBA sum of shoot basal cross-sectional area; VPD vapour pressure deficit.

4 Pags.- 2 Tabls. Articles derived from XIV EUCARPIA Symposium on Fruit Breeding and Genetics (Bologna,Italy. June 14-18 2015) . The definitive version is available at: http://www.actahort.org/index.htm, The description of phenotypic traits in apple cultivars is generally performed using internationally agreed descriptors such as UPOV guidelines, which defines for each trait several states of expression. However, it is not always possible to classify a cultivar unambiguously using those guidelines, because in practice the states are not clearly enough defined or the example cultivars are not always available in the collections. This work presents the results of a harmonization project performed by the teams responsible of the main apple germplasm collections in Spain. The objective was to develop a standardized method for the 57 traits included in the TG/14/9 UPOV guidelines for apple characterization, defining their states of expression in a clear and unambiguous way for Spanish germplasm. Phenotypic data collected for more than 1,600 accessions from Spanish collections were used and the method to define each state depended on the type of expression. For quantitative traits the number of states and their limits were defined according to the variability that exists within and between accessions. For qualitative traits, high-resolution images clearly depicting each state were selected. A standardized characterization protocol for the 57 traits of apple germplasm has been provided, enabling to comparing properly the phenotypes of Spanish genetic resources., This Project has been funded by the Spanish Ministry of Science and Innovation/National Institute for Agricultural and Food Research and Technology (RF2011- 00017-C05-00).

The influence of the species in spring frost sensibility was determined for the Prunus species peach (P. persica (L.) Batsch), sweet cherry (P. avium L.), almond (P. dulcis (Mill.) Webb/P. amygdalus Batsch), japanese plum (P. salicina Lindl.), and blackthorn (P. spinosa L.). The confidence intervals for lethal temperatures of 10% (LT10) and 90% (LT90) bud injury were also determined. In 2000 and 2001, seven frost treatments were made for each one of the phenological stages comprised between B (first swell) and I (jacket split) in two cultivars per each species. The relationships between frost temperature and the proportion of frost damaged buds for each cultivar, year, and phenological stage were adjusted to linear regression models. The 95% confidence intervals were also calculated. The spring frost hardiness order of the species, from the least to most hardy, was as follows: sweet cherry, almond, peach, japanese plum, and blackthorn. Despite the highly homogeneous nature of the frost and bud characteristics, the temperature range for a given injury degree was quite broad, since the confidence interval's breadth for LT10 was as high as about 3 °C and as high as about 6 °C for LT90. Consequently, when critical temperatures are used in making decisions as to when to begin active frost protection, a prudent measure would be to take the temperature references from the upper limits in the confidence intervals.

Determination for the genetic variability on species such as cardoon (Cynara cardunculus L.) allow the evaluation of their aptitude in genetic improve, and so shorten the time needed in the process. In this work 17 local population were evaluated, 13 from the germplasm bank located in Zaragoza and 4 selections from "Verde de Peralta". Analysis was performed trough 80 RAPD markers. Population homogeneity was fairly high: intra-cultivar similarity was above 0.83 except for 'Sin Pincho' from Segovia, and in the 'Seleccion 1er ano ITGA' from Navarre. The latter cultivar was selected according to industrial criteria and in the second year of improvement their homogeneity was similar to the rest, so that characters used in the selection were genetically regulated. Inter-cultivar variability suggests that this specie is fairly homogeneous. Cluster analysis showed three well-defined groups, one including all the cultivars from the mid-Ebro Valley, a second one with segovian populations and a third with the rest.

11 Pags.- 6 Tabls.- 2 Figs., Isoenzymes from grapevine woody stems and shoots were evaluated for their use in identification of varieties and clones. Plant extracts were separated by polyacrylamide gel electrophoresis. Isoenzyme analysis was carried out for esterases, peroxidases, catechol oxidase, glutamate oxalacetate transaminase and acid phosphatase. The plant material was grown and sampled at two localities in Spain, with different climatic conditions. Sampling was carried out bimonthly for two consecutive years in order to find out the influence of the environment and time of the year. Each isozyme system had a pattern defined by ‘fixed’ bands, that were always present at both localities and during the resting period of the plant (fall—winter). Esterases had a pattern with very few ‘fixed’ bands. Catechol oxidase was the most polymorphic system, thus being highly discriminating. The studied isoenzyme systems gave differences among varieties, although not among clones of the same variety. The use of this methodology for identification of grapevine plant material is discussed., This study has been carried out with financial support provided by 'Comisión Interministerial de Ciencia y Tecnologia' (C.I.C.Y.T.), Project AGR 0070-91-C01-C02.

A collection of 141 old and local Spanish accessions of pear (Pyrus communis) from the Escuela Tecnica Superior de Ingenieria Agraria-Universidad de Lleida (ETSIA-UdL) Pear Germplasm Bank in Lleida, Spain, were studied using a set of eight microsatellite markers to estimate the genetic diversity of the collection, to identify the genetic structure and relationships among its accessions, and to establish a representative core collection. An additional set of 13 well-known pear cultivars, currently grown in Spain and which represent a wide genetic diversity, were added as reference. The eight simple sequence repeat (SSR) loci amplified 97 alleles, with nine to 15 alleles per locus, and with the expected heterozygosity ranging from 0.65 to 0.89. All of the accessions except for 16 had at least one of the 48 rare alleles (frequency < 0.05) identified, and seven unique alleles were found in six accessions. Fifteen accessions were identified as synonyms and were excluded from the analysis. Genetic analyses performed by hierarchical clustering, Bayesian modelbased clustering, and factorial correspondence analysis supported the existence of three groups among the accessions with moderate [fixation index (FST) = 0.074], but significant, differentiation. As a whole, most of the germplasm (about 75%) curated at the collection showed its genetic distinctness with respect to the main pear cultivars used in European orchards. In fact, most reference cultivars were included in one single cluster that, moreover, had the lowest genetic diversity and allelic richness, in spite of having been chosen as heterogeneous material from different origins. The obtained results were also used to create a core collection with 35 accessions constituting an efficient and accessible entry point in the ETSIA-UdL pear collection for breeding and research communities. Pear (Pyrus spp.) is one of the most important fruit crops of the Rosaceae family, ranking second to apple (Malus ·domestica) in world and European production of pome fruit tree species (Food and Agriculture Organization of the United Nations, 2010). Pyrus communis is the most commonly cultivated pear species in Europe, America, and Africa, whereas Pyrus pyrifolia is the main cultivated species in Asia (Bell, 1991). Worldwide production of P. communis pears is based upon relatively few cultivars, most of them selected in late 18th and 19th century, or derived from those. Furthermore, the genetic base of cultivated pear in western Europe has significantly narrowed in the last few years. In 1986, seven cultivars accounted for 58% of pear production in western Europe (Bell, 1991), but nowadays, seven cultivars account for 75% of the production (World Apple and Pear Association, 2009). ‘Conference’ has become predominant in most European producing countries, and accounts for nearly one-third of European Union production. The reasons for this concentration are varied, but include economic and market factors, changes in consumption patterns, and biological aspects, such as productivity, storage ability, and susceptibility to pests and diseases (Bell, 1991). As a consequence, many of the traditional or local cultivars have been considered obsolete and replaced, leading to a dramatic loss of genetic diversity. The recognition of the need for the collection and preservation of endangered fruit germplasm has encouraged the establishment of genetic resource conservation programs. In 1986, a germplasm bank of old and local pear cultivars was established by the Horticulture section of the ETSIA-UdL. This germplasm bank currently maintains 114 Malus and 169 Pyrus accessions, collected at 12 northern Spanish provinces (Urbina et al., 2007), at the Estacion Experimental de Lleida of the Institut of Recerca i Tecnologia Agroalimentaria (IRTA) in Lleida, Spain. In 2002, a research program was launched to evaluate the genetic diversity of the collection through detailed morphological and agronomical description, and fingerprinting analysis based upon molecular markers was initiated in 2005. Microsatellite or simple sequence repeat (SSR) markers have been favored over other methods in establishing unique genetic identities or fingerprints and in assessing genetic diversity within a collection due to their high polymorphism level, reproducibility, and relative ease of analysis (Schlotterer, 2004). Moreover, SSR have also proven useful in creating core collections that represent not only the genetic structure of germplasm collections, but also their phenotypic structure (Santesteban et al., 2009). The SSR markers used in the earliest studies in pear were derived from apple (Yamamoto et al., 2001; Hemmat et al., 2003), as apple proved to be highly conserved in pear. However, after the development of SSR derived from asian pear (P. pyrifolia) and Received for publication 10 May 2010. Accepted for publication 28 June 2010. Financial support for this work was provided by INIA, Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (project grant nos. RF2004008-C03-00, RFP2004-009, and RFP-0000-68). Corresponding author. E-mail: carlos.miranda@unavarra.es. 428 J. AMER. SOC. HORT. SCI. 135(5):428–437. 2010. Table 1. Pear accessions maintained by the Escuela Tecnica Superior de Ingenieria Agraria Universidad de Lleida (ETSIA-UdL) Germplasm Bank and reference cultivars that were included in the study, in alphabetical order. Accessions selected to constitute the core collection are indicated in bold. Collection information includes accession name and bank code, site of collection, specific latitude and longitude, approximate elevation, and collecting source code according to Food and Agriculture Organization of the United Nations/International Plant Genetic Resources Institute (FAO/IPGRI, 2001) multicrop passport descriptors. Accession name Accession code Site of collection in Spain Latitude Longitude Elevation (m) Collecting source Agramunt 1 PRF-135 Puigvert d’Agramunt, Lleida 41.78 1.13 360 23 Agua PRF-030 Nalda, La Rioja 42.33 –2.48 530 23 Agua Iglesia PRF-028 Lardero, La Rioja 42.42 –2.45 435 23 Agua Magistral PRF-029 Lardero, La Rioja 42.40 –2.47 460 23 Aguilar 1 PRF-011 Aguilar de Campoo, Palencia 42.78 –4.25 900 23 Almenar 1 PRF-071 Almenar, Lleida 41.77 0.62 270 62 Angelina PRF-141 Isona i Conca Della, Lleida 42.08 1.12 1000 23 Areny 1 PRF-091 Areny de Noguera, Huesca 42.25 0.73 670 62 Areny 2 PRF-092 Areny de Noguera, Huesca 42.25 0.73 675 62 Areny 3 PRF-093 Areny de Noguera, Huesca 42.25 0.73 675 62 Areny 4 PRF-113 Areny de Noguera, Huesca 42.25 0.72 750 23 Azucar verde 1 PRF-007 Albelda de Iregua, La Rioja 42.37 –2.47 490 21 Azucar verde 2 PRF-008 Albelda de Iregua, La Rioja 42.37 –2.47 490 21 Balaguer 1 PRF-066 Balaguer, Lleida 41.75 0.77 220 23 Balaguer 2 PRF-067 Balaguer, Lleida 41.75 0.77 220 23 Balaguer Flix 1 PRF-046 Balaguer, Lleida 41.73 0.93 290 62 Balaguer Flix 2 PRF-047 Balaguer, Lleida 41.73 0.93 290 23 Balaguer Flix 3 PRF-048 Balaguer, Lleida 41.73 0.93 290 23 Balaguer Flix 4 PRF-049 Balaguer, Lleida 41.73 0.93 290 23 Balaguer Flix 5 PRF-050 Balaguer, Lleida 41.73 0.93 290 23 Balaguer Flix 6 PRF-051 Balaguer, Lleida 41.73 0.93 290 23 Balart PRF-070 Almenar, Lleida 41.77 0.58 280 23 Benavent de la Conca 1 PRF-142 Benavent de la Conca, Lleida 42.08 1.12 985 23 Bergamota PRF-112 Sopeira, Huesca 42.33 0.73 780 23 Bescano 1 PRF-121 Bescano, Girona 41.97 2.75 110 23 Bescano 2 PRF-122 Bescano, Girona 41.97 2.72 110 23 Biscarri 1 PRF-143 Biscarri, Lleida 42.12 1.12 920 23 Blanca d’aigua PRF-079 Baix Pallars, Lleida 42.33 1.0

The lowest flower in the pear (Pyrus communis L.) cluster usually develops and blooms first and also has a greater sink potential. For this reason, resources are preferentially utilized by the lowest fruit, and this is also one of the reasons why most thinning practices tend to favor their set. However, it is not always possible to perform selective thinning. This study was undertaken to determine if hindering pollination in the most developed flowers in the cluster influences yield or quality compared to that obtained in a whole open-pollinated cluster. The treatments were made in `Blanquilla' (Spadona, Agua de Aranjuez) and `Conference' pear within a wide range of flower densities for each cultivar. Pollination was hindered by cutting off the flower styles. The factor tested was style removal intensity (SRI). Treatments consisted in removing the styles of two, four(always the most developed), or all flowers in each cluster. Flower density was used as a covariate in an analysis of covariance to account for differences in flower densities in response to SRI treatments. In all experiments the covariate was not significant; therefore, SRI effect was not affected by flower density. `Blanquilla' and `Conference' had similar responses to treatments, so that when at least three flowers are susceptible to be openly pollinated, fruit set, seed content, and cluster yield were similar to control clusters, therefore the growth potential of fruit from partially damaged clusters in their most developed flowers is similar to undamaged open pollinated clusters. The reduced set of parthenocarpic clusters implies yield reductions ranging between 40% and 60% in `Conference', and up to about 60% in `Blanquilla'.

The apical or king (K) flower in the apple (Malus ×domestica L. Borkh.) cluster usually develops and blooms first and also has a greater sink potential. For this reason, resources are primarily used by the K fruit, and this is also one of the reasons why most thinning practices tend to favor K fruit set. However, it is not always possible to retain the K flower and remove the lateral ones. This study was undertaken to determine if the removal of the most developed flowers in the cluster influences yield or quality compared to that obtained in a whole cluster. The treatments were made in `Golden Delicious' and `Royal Gala' apple cultivars, within a wide range of flower densities for each cultivar. The factor tested was the intensity of flower removal (FRI); the treatments consisted in removing one, two, or three flowers in each cluster. Flower density was used as a covariate in an analysis of covariance to account for differences in flower densities in response to FRI treatments. In all experiments the covariate was not significant; therefore FRI effect was not affected by flower density. `Golden Delicious' and `Royal Gala' had similar responses to flower removal, so that when at least three flowers in a cluster remained, fruit set and cluster yield were similar to whole clusters. Only when two or fewer poorly developed flowers remained after FRI treatments, yield was reduced by as much as 25%. Fruit from FRI clusters were even heavier than those from whole clusters, due to reduced competition among the fruit, so that the growth potential of fruit from the first and second lateral flowers was similar to clusters with K fruit, in clusters where the K flower had been removed.