Water Stress in Dwarfing Cherry Rootstocks: Increased Carbon Partitioning to Roots Facilitates Improved Tolerance of Drought

Cherry orchards are transitioning to high-density plantings and dwarfing rootstocks to maximize production, but the response of these rootstocks to drought stress is poorly characterized. We used a 16-container, automated lysimeter system to apply repeated water stress to ungrafted Krymsk® 5 and 6 rootstocks during two growing cycles. Drought stress was imposed by withholding irrigation until the daily transpiration rate of each tree was 25% and 30% of the unstressed rate during the first trial and second trial, respectively. After this point was reached, the root-zone water status was restored to field capacity. Whole-tree transpiration measurements were supplemented with leaf-level gas-exchange measurements. Krymsk® 6 had a higher rate of photosynthesis, more vigorous vegetative growth and less conservative stomatal regulation during incipient drought than Krymsk® 5. At harvest, carbon partitioning to roots was greater in Krymsk® 6 than Krymsk® 5. The conservative rate of water use in Krymsk® 5 could be a function of greater stomatal control or reduced carbon partitioning to roots, which thereby limited transpiration rates. Further studies are needed to confirm that these results are applicable to trees grown using a common grafted scion under field conditions.

Metabolomics and Transcriptomics Analyses of Two Contrasting Cherry Rootstocks in Response to Drought Stress

Drought is one of the main factors affecting sweet cherry yields, and cherry rootstocks can provide a range of tree vigor levels to better match sweet cherries with the characteristics of the soil. To investigate the molecular events of the cherry to water deficiency, we performed transcriptomic and metabolomic analyses of Prunus mahaleb CDR-1 (drought-tolerant cherry rootstock (DT)) and P. cerasus × P. canescens Gisela 5 (drought-susceptible cherry rootstock (DS)), respectively. The results revealed 253 common drought-responsive genes in leaves and roots in DT and 17 in DS; 59 upregulated metabolites were explored in leaves in DT and 19 were explored in DS. Differentially expressed metabolites related to the cyanoamino acid metabolism pathway and phenylpropanoid biosynthesis pathway may be key factors in the difference in drought resistance in the two rootstocks. Moreover, six central metabolites—3-cyanoalanine, phenylalanine, quinic acid, asparagine, p-benzoquinone, and phytosphingosine—were identified as potential biological markers of drought response in cherries and may be key factors in the difference in drought resistance, along with caffeic acid and chlorogenic acid. We also selected 17 differentially expressed genes as core candidate genes and the mechanism of DT in response to drought is summarized.

Sweet cherry rootstocks.

All commercial sweet cherry trees are either budded or grafted. This chapter deals with sweet cherry rootstocks. Rootstocks are used for several purposes: (i) ease for propagating and producing more trees of a superior cultivar; (ii) better adaptation to particular soil or site characteristics; and (iii) the potential improvement of production due to additional traits like precocious flowering, higher productivity, and greater or reduced scion vigor as appropriate. Unfortunately, no one rootstock can satisfy all the requirements for consistently producing high yields of large, firm fruit of premium quality. Growers are advised to consider carefully the effects of each specific scion-rootstock combination as a function of environmental and cultural practices when replanting an orchard. Selecting the proper rootstock depends not only on the management skills of the grower, but also on the scion cultivar, training system, and site climate and soil selected for the orchard. Dwarfing, semi-dwarfing and even semi-vigorous rootstocks have major economic advantages over full-size rootstocks. The development of these new, precocious rootstocks has been almost as significant to the sweet cherry industry as to the apple industry several decades ago. When compared to Mazzard, Colt and even Mahaleb, size-controlling rootstocks have allowed sweet cherry growers an opportunity to plant high density, pedestrian orchards that become profitable more quickly, are more readily protected with orchard covering systems, and promote greater labor efficiency, easier management, and a safer and more productive work environment.

Scientific achievements and realities of the sweet cherry (Cerasus avium L.) cultivation intensification at the current stage of the horticultural science development

The authors present the results of the comprehensive analysis of the influence of the modern horticultural science achievements on the sweet cherry cultivation intensification. Today in the world’s horticulture practice the main direction of increasing this crop plantations productivity is its comprehensive intensification. Its main link is the type of an orchard, and components – cultivar, rootstock, planting plan and the crown formation methods. In this relation, the major elements of the modern sweet cherry industrial cultivation technologies concerning these components were developed the place of the new inland developments being determined. The analysis of the approaches to the modern intense sweet cherry plantations creation has shown that they do not always correspond to this crop biological characteristics and sometimes are usual adoptions from the similar developments for apple. At the same time the development of the basic elements of the sweet cherry rootstocks and cvs growing intensification lag behing the requirements significantly and cannot be used in apple super-dense orchards. The Institute of Horticulture of the National Academy of Agrarian Sciences (NAAS) of Ukraine for the first time recommended for the Lisosteppe in of Ukraine three new types of orchards on vigorous, medium-sized and semi-dwarf rootstocks with the tree density placement from 417 to 1250 trees/ha in order to ensure the efficient industrial production of sweet cherries in particular, for the export purposes. These orchards are based mainly on using inland high-productive cvs, rootstocks and crown formation methods. The density of the trees placement in such orchards has been optimized by applying the mathematical modeling and tested in long-term field experiments. That enables to utilize effectively these orchards productivity potential. Their advantage as compared to foreign ones is that these plantations construction takes into account both the rootstocks vigour and the variety biological peculiarities. That is the basis for their application in the technologies for growing valuable sweet cherry cultivars which possess the increased consumers demand. The intensification of the sweet cherry growing should be based mostly on the creation of optimally dense plantations that meet the biological peculiarities of a concrete rootstock-cultivar combination

Promise stone fruit crops clonal rootstocks bred at the Krymsk Experimental Breeding Station

The authors present data of the studying of promise stone fruit crops clonal rootstocks bread at the Krymsk FBS in the nursery and orchard. Besides, their ability of cuttings rooting, compatibility with perspective stone fruit crops cultivars were researched as well as suitability for growing in different regions of the country. The prospect of applying industrial the intensive technologies of the sweet cherry cultivation in the south of Russia, became possible in the recent years in connection with the creation of new high-quality and productive varieties and inland low-growing clonal rootstocks, more adapted to the unfavourable environmental conditions, which often occur here. The low-growing rootstocks obtained recently at the Krymsk FBS concerning their characteristics can compete with the well – known foreign semi-dwarf ones, such as Gizela 5, Gizela 6, Inmil, Piku 1, Piku 3, Piku 4. The plum and peach dwarf rootstock Upriamiets as regards vigour similar to BBA 1, reduces the growth of the trees grafted on it by 50-60 %, is characterized with early maturity and compatible with all the varieties of the tested above mentioned crops. RVL 9 is a medium-sized and Rulan 8 semi-dwarf sweet cherry rootstocks. They have a very strong root system that provides good trees anchoring in the orchard and form root sprouting when have non-considerable mechanically damage only. Sweet cherry trees on RVL 9 are by 25-30 % and on Rulan 8 35-40 % a size smaller as compared to those grafted on cherry seedlings. The fruiting begins in the third year, the yield is high. The propagation using hard-wood cuttings, which does not require special structures, has significant advantages over others methods. It ensures the high reproduction coefficient at minimum expenditures, including manpower. Therefore just this method is the most perspective for utilizing in production. Among the zoned sweet cherry clonal rootstocks easily propagate only VSL 2, VSL 1 and L 2 are propagated easily when hard-woody cuttings are applied. The study of RVL 9 and Rulan 8 as for their ability of reproduction using the above mentioned cuttings has shown that in this respect they are close to the control standard clonal rootstock VSL 2. As a result of the breeding work which we have carried out, the clonal rootstocks Upriamiets, RVL 9 and Rulan 8 have been entered in the State Register of Breeding Achievements admissed for the application in Russian Federation.

Sweet cherries

This book contains 12 chapters focusing on the current trends in sweet cherry production, cherry flowering, fruiting and cultivars, sweet cherry rootstocks, planning a new cherry orchard, orchard establishment and production, the fundamentals of sweet cherry pruning, various sweet cherry training systems, management of the orchard environment, fruit ripening and harvest and management of orchard pests, pathogens and disorders. The promising future of cherry production is also discussed.