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Enrichment with CO2 and a commercial mix of plant growth regulators were tested to improve the plant quality and survival of pregerminated cherry tree seedlings. Pregerminated seeds were transferred from a cold chamber to a climatic chamber where the CO2 was set at 800 µmol·mol−1 CO2 or at the ambient CO2 concentration. Also, half of the plants were sprayed with the mix of plant growth regulators and disposed randomly. The experiment lasted 18 days and physiological measurements, such as plant physiological status and growth, number of leaves, net CO2 assimilation (ACO2), internal CO2, stomatal conductance, and transpiration, were taken every 4 days. Also, at the end of the experiment, other parameters—such as total leaf area, photosynthetic pigments, soluble sugars, and starch—were recorded or quantified. During the experiment, plants cultured under CO2 enrichment exhibited a rapid increase in their photosynthetic rates, height, and leaf number; the commercial mix also increased plant height but inhibited leaf expansion and growth. At the end of the experiment, the amounts of starch and soluble sugars had increased in the plants grown under elevated CO2, compared with those plants grown in control conditions or with the commercial mix. Thus, culture at elevated CO2 achieved higher percentages of plant survival and of plants in active growth. We suggest that CO2 plays an important role—by increasing ACO2, water use efficiency, soluble sugars, and starch—which results in plants that are physiologically more prepared for transfer to the field.

The increase in the ambient concentration of CO2 and other greenhouse gases is producing climate events that can compromise crop survival. However, high CO2 concentrations are sometimes able to mitigate certain stresses such as salinity or drought. In this experiment, the effects of waterlogging and CO2 are studied in combination to elucidate the eventual response in sweet cherry trees. For this purpose, four sweet cherry cultivars (‘Burlat’, ‘Cashmere’, ‘Lapins, and ‘New Star’) were grafted on a typically hypoxia-tolerant rootstock (‘Mariana 2624’) and were submitted to waterlogging for 7 days at either ambient CO2 concentration (400 µmol mol−1) or at elevated CO2 (800 µmol mol−1). Waterlogging affected plants drastically, by decreasing photosynthesis, stomatal conductance, transpiration, chlorophyll fluorescence, and growth. It also brought about the accumulation of proline, chloride, and sulfate. Nonetheless, raising the CO2 supply not only mitigated all these effects but also induced the accumulation of soluble sugars and starch in the leaf. Therefore, sweet cherry plants submitted to waterlogging were able to overcome this stress when grown in a CO2-enriched environment.

Climate change is submitting countries of the Mediterranean arc to periods of drought alternating with heavy rain and waterlogging. Eventual floods along with the rising CO 2 in the atmosphere present an unpredictable scenario that affects crop survival. The effect of both stresses combined has been studied in sweet cherry plants. ‘Gisela 5’ and ‘Gisela 6’ were evaluated as rootstocks of the sweet cherry cultivar ‘Burlat’. Plants were placed in a controlled-climate chamber for 7 days, then they were submitted to waterlogging for another 7 days and the response to this stress and the subsequent recovery were studied (7 more days). The experiment was carried out at 400 μmol mol −1 CO 2 (ambient CO 2 ) and 800 μmol mol −1 CO 2 , at 26 °C, and plant water status and growth, net CO 2 assimilation, transpiration, stomatal conductance, water potential, chlorophyll fluorescence, relative water content, anions content, proline, lipid peroxidation, soluble sugars, and starch were measured. Differences in the response and in its intensity were detected in both rootstocks. Some parameters – such as photosynthesis, soluble sugars, starch, TBARS, and NO 3 − – varied depending on the CO 2 conditions and the waterlogging effect. Elevated CO 2 was able to increase photosynthesis and thereby help plants to overcome waterlogging.

High CO2 is able to ameliorate some negative effects due to climate change and intensify others. This study involves the sweet cherry (Prunus avium) cultivar 'Burlat' grafted on the 'Mariana 2624', 'Adara' and 'LC 52' rootstocks. In a climate chamber at two CO2 concentrations, ambient (400 µmol mol-1 ) and elevated (800 µmol mol-1 ), the plants were submitted to waterlogging for 7 d, followed by 7 d of recovery after drainage. Waterlogging drastically decreased the rate of photosynthesis, significantly endangering plant survival, particularly for the 'LC 52' and 'Adara' rootstocks. 'Mariana 2624' was also clearly affected by waterlogging that increased lipid peroxidation and the Cl- and SO42- concentrations in all the studied plants. Nevertheless, CO2 was able to overcome this reduction in photosynthesis, augmenting growth, increasing soluble sugars and starch, raising turgor and regulating the concentrations of Cl- and SO42- , while lowering the NO3- concentration in leaves of all the studied rootstocks. In concordance with these results, the proline levels indicated a more intense stress at control CO2 than at high CO2 for waterlogged plants. 'Mariana 2624' was more resistant to waterlogging than 'Adara', and both were more resistant than 'LC 52' in control CO2 conditions; this clearly enhanced the chance of survival under hypoxia.

International audience

The influence of Adara, Gisela 5, Gisela 6, Mariana 2624, MaxMa 14, Mayor, Piku 1, Piku 3, Piku 4 and Saint Lucie GF 64 rootstocks onto vigour, yield and fruit quality of ‘Newstar’ cultivar was studied during four years. The experiment was performed in Jumilla (Murcia, Spain), on a heavy and calcareous soil. Significant differences in parameters such as vigour, yield, fruit weight and size, soluble solids content, titratable acidity, skin colour and firmness were found among some rootstocks. Most of them achieved optimal coloration values that would have a high commercial acceptance. Gisela 6, Piku 1, SL 64 and Mayor rootstocks showed high mortality by root asphyxia strongly related to drainage problems in heavy soils. Fruits from trees grafted on MaxMa 14 had the smallest size and the most intense coloration. The excessive vigour reduction in Gisela 5, together with a low yield and fruit quality, resulted in a non-interesting rootstock for our growing conditions. By contrast, Mariana 2624, Mayor and Adara were the most vigorous rootstocks and presented the highest yields with good fruit quality and the best agronomic performance, being their use advisable in warm Mediterranean regions such as the Region of Murcia. Although Piku 3 induced low yield and obtained the highest values in fruit size, soluble solids content and fruit firmness, which, along with its low mortality, seem to recommend its introduction and use for producing high quality sweet cherries. The work demonstrates that rootstocks have been decisive in the vigour and yield of the grafted cultivar, as well as the size, acidity, colour and firmness of the fruit.

The increase in the ambient concentration of CO

Climate change is submitting countries of the Mediterranean arc to periods of drought alternating with heavy rain and waterlogging. Eventual floods along with the rising CO

High CO

Professional and scientific networks built around the production of sweet cherry (Prunus avium L.) led to the collection of phenology data for a wide range of cultivars grown in experimental sites characterized by highly contrasted climatic conditions. We present a dataset of flowering and maturity dates, recorded each year for one tree when available, or the average of several trees for each cultivar, over a period of 37 years (1978–2015). Such a dataset is extremely valuable for characterizing the phenological response to climate change, and the plasticity of the different cultivars’ behaviour under different environmental conditions. In addition, this dataset will support the development of predictive models for sweet cherry phenology exploitable at the continental scale, and will help anticipate breeding strategies in order to maintain and improve sweet cherry production in Europe.