Impact of Climate Change on Voltinism and Prospective Diapause Induction of a Global Pest Insect – Cydia pomonella (L.)

Global warming will lead to earlier beginnings and prolongation of growing seasons in temperate regions and will have pronounced effects on phenology and life-history adaptation in many species. These changes were not easy to simulate for actual phenologies because of the rudimentary temporal (season) and spatial (regional) resolution of climate model projections. We investigate the effect of climate change on the regional incidence of a pest insect with nearly worldwide distribution and very high potential for adaptation to season length and temperature – the Codling Moth, Cydia pomonella. Seasonal and regional climate change signals were downscaled to the hourly temporal scale of a pest phenology model and the spatial scale of pest habitats using a stochastic weather generator operating at daily scale in combination with a re-sampling approach for simulation of hourly weather data. Under future conditions of increased temperatures (2045–2074), the present risk of below 20% for a pronounced second generation (peak larval emergence) in Switzerland will increase to 70–100%. The risk of an additional third generation will increase from presently 0–2% to 100%. We identified a significant two-week shift to earlier dates in phenological stages, such as overwintering adult flight. The relative extent (magnitude) of first generation pupae and all later stages will significantly increase. The presence of first generation pupae and later stages will be prolonged. A significant decrease in the length of overlap of first and second generation larval emergence was identified. Such shifts in phenology may induce changes in life-history traits regulating the life cycle. An accordingly life-history adaptation in photoperiodic diapause induction to shorter day-length is expected and would thereby even more increase the risk of an additional generation. With respect to Codling Moth management, the shifts in phenology and voltinism projected here will require adaptations of plant protection strategies to maintain their sustainability

The relationship between xylem differentiation and dormancy evolution in apricot flower buds (Prunus armeniaca L.): the influence of environmental conditions in two Mediterranean areas

Environmental and climatic conditions affect the flower bud growth, flowering and yield performance of fruit species. Temperature and water availability appear to be important factors for temperate fruit trees in mild climates. The aim of this research was to study the involvement of temperature regime on biological processes, such as xylem differentiation and dormancy evolution, in apricot flower buds (Prunus armeniaca L.). Over three consecutive years, biological and anatomical investigations were carried out in Tuscany (Italy) and Murcia (Spain) on two cultivars characterized by a different Chilling Requirement (CR): Currot, a traditional Spanish cultivar with a very low CR, and Stark Early Orange (SEO), a North American cultivar with a very high CR. Currot had a regular bearing, and was characterized by a synchronism between endodormancy release and xylem differentiation. On the other hand, SEO showed an irregular flower bud growth leading to flowering and fruit set failure, even with a high level of chilling accumulation. No relationship was found in SEO between xylem development and flower bud growth reactivation. The de-synchronism between these processes could determine the poor adaptability to different environmental areas of SEO cultivar, and its very high CR is not the main hypothesised cause of the altered flower bud development

Dissecting apple tree architecture into genetic, ontogenetic and environmental effects : mixed linear modelling of repeated spatial and temporal measures

UMR DAP, équipe AFEF, Correspondance: [email protected] audience• The present study aimed to dissect tree architectural plasticity into genetic, ontogenetic and environmental effects over the first 4 yr of growth of an apple (Malus . domestica) F1 progeny by means of mixed linear modelling of repeated data. • Traits related to both growth and branching processes were annually assessed on different axes of the trees planted in a staggered-start design. Both spatial repetitions, (i.e. different axis types) and temporal repetitions (i.e. successive ages of trees) wereconsidered in a mixed linear model of repeated data.• A significant genotype effect was found for most studied traits and interactions between genotype and year and/or age were also detected. The analysis of repeated temporal measures highlighted that the magnitude of the decrease in primary growth is mainly determined by the first year of growth, and the decrease in bottomdiameter increment is concomitant with the first fruiting occurrence.• This approach allowed us to distinguish among the traits that were under genetic control, those for which this control is exerted differentially throughout tree life or depending on climatic conditions or an axis type. Mapping quantitative trait loci (QTL) that are specific to these different effects will constitute the next step in the research

Flower bud differentiation and development in fruiting and non-fruiting shoots in relation to fruit set in apricot (Prunus armeniaca L.)

30 Pag., 2 Tabl., 8 Fig.Situations of high flower bud drop and low fruit set without apparent causes are common in fruit trees. The term flower quality has been coined to explain differences among flowers in their capacity to set fruit, but the causes underpinning these differences are largely unknown. This lack of knowledge is based on the fact that these differences are established a posteriori and there are no criteria to determine a priori what will make a flower to set a fruit or to drop. In this work, we profit from the empirical knowledge that there are fruiting and non-fruiting shoots to explore to which extent flower bud differentiation and bud development will affect the subsequent fruit set. For this purpose, the processes from flower bud differentiation to fruit set were sequentially analyzed in both types of shoots, over 2 years. More than half of the buds from long shoots aborted development and dropped before flowering. At anthesis, most of the remaining flowers showed underdeveloped pistils that failed to sustain pollen germination or pollen tube growth along the pistil. This unsuccessful development resulted in clear differences in fruit set between both types of branches. These results highlight that flower bud differentiation and development play an important role for fruit set and that developmental timing appears critical to reach anthesis with a fully developed pistil.Financial support for this research was provided by Ministerio de Ciencia e Innovación—EU-FEDER (CICYT AGL2006-13529-CO2-00, AGL2009-12621-C02-00), Gobierno de Aragón (Grupo de Excelencia de Aragón A-43), and Instituto Nacional de Investigación y Tecnología Agroalimentaria (Doctoral fellowship INIA2003-8 to C.J.).Peer reviewe

Optimisation of apricot breeding by a joint conventional and molecular approach applied to the main agronomics traits

Preliminary results of the European ABRIGEN (FAIR6 CT98-4345) are presented. The general objective is the optimization of the apricot selection methodology in order to improve breeding strategies. It is based on a multidisciplinary research dedicated to the genetic determinism of the main agronomic traits, the quality of the fruit and the resistance to major diseases. It is mainly focus on: (i) the inheritance of the major agronomic traits, fruit quality and resistance to sharka and bacteriosis; (ii) the analysis of possible linkages or associations between traits; (iii) the identification of associated molecular markers. The work is based on the analysis of a 9x9 diallel cross, with 61 families and more than 3700 offspring. Teams including geneticists, development biologists, plant pathologists, physiologists and molecular biologists have been joined to reach the objective