Institut für Züchtungsforschung an Obst
In Germany, more than 45,000 hectares are planted with different types of fruit. Apples account for 70% of this area, followed by sweet cherries at 11.5%. As a result of climate change, fruit trees are increasingly exposed to extreme heat events and water shortages during the growing season, threatening fruit production even in irrigated areas. Sweet cherries are more susceptible to drought stress than apple trees. This susceptibility can be explained by the shallower root system of the sweet cherry, its lower tolerance to fluctuations in the water balance, and its high water requirements during fruit development. Water deficiency during fruit development not only leads to significant yield losses of 30-40%, but also hurts fruit size and quality. In addition, drought stress has a long-term effect on the vitality of sweet cherry trees, leading to a continuous weakening of the plants, which increases their disease susceptibility.Irrigation in sweet cherry production is now essential in most regions to avoid drought stress and ensure high fruit quality and yields. During the primary growing season (May to July), approximately 30 litres of water per square metre of tree canopy are required to supply the roots with sufficient water. In addition to the targeted use of irrigation, selecting suitable sweet cherry varieties is a key measure for resource-efficient and conservative water use. In this context, selecting varieties and suitable rootstocks for cultivation that can be managed with minimal irrigation is recommended. However, little is known about the specific water requirements of common sweet cherry cultivars and rootstocks. Therefore, there is an urgent need for systematic and detailed studies on the drought stress tolerance of common sweet cherry cultivars and rootstocks. The aim of the planned project is therefore to evaluate both established and new sweet cherry cultivars and rootstocks for their tolerance to drought stress.Using the Fylloclips, 13 sweet cherry cultivars and 6 sweet cherry rootstocks (see Table 1 in the Appendix) will be evaluated at the Julius Kühn Institute (JKI-ZO) for their drought stress tolerance. For this purpose, the selected sweet cherry cultivars and rootstocks will be tested in two consecutive randomised pot experiments under two irrigation regimes. For this purpose, 13 sweet cherry cultivars will be grafted on Piku 1 rootstocks in 6 replicates. For the evaluation of sweet cherry rootstocks, 6 rootstocks will be grafted with two varieties that showed very high drought stress (e.g., 'Lapins') and very low drought stress (e.g., 'Vanda') during the evaluation of sweet cherry varieties in the JKI genebank collection in summer 2024. Three grafts per cultivar/rootstock will receive optimal water supply, while the other three grafts per cultivar/rootstock will receive reduced water supply. During the trial, transpiration will be measured using the Fylloclips and the data will be recorded via WLAN for subsequent data analysis. Other parameters such as wilting, chlorophyll content, stomatal density, and proline content are also recorded. For the experiment, the plants are grown in pots with artificial irrigation. The pots are covered with foil to prevent them from being wetted by precipitation.The data obtained can be used to make recommendations for the cultivation of drought-tolerant sweet cherry varieties and rootstocks. At the same time, measuring transpiration with the Fylloclips will allow continuous monitoring of water availability in the field. If proven practical, these sensors could be used in commercial orchards to detect water shortages efficiently and in real time, enabling growers to irrigate their orchards in a targeted, cost-effective, and resource-efficient manner. The studies will also provide important insights into the genetic mechanisms of drought stress tolerance. This is essential for breeding resistant varieties and making new drought-tolerant sweet cherry varieties available for cultivation in the future.
QS Fachgesellschaft Obst-Gemüse-Kartoffeln GmbH
