Ecological characteristics of natural and culturated species, their comparison in Prunus genus

Summary: Plum species are found native throughout the nothern hemisphere, but mostly in the temperate zone. The earliest writings about plum date back some 2000 years (De Candolle, 1894; Cullinan, 1937) puts the age of plums at 2000-4000 years old (Bagenal, 1954). However, the stone core findings suggest a greater past. The question is difficult to conclude because the large number of species of the genus are taxonomically unclear and spread over a wide geographical area. The taxonomic position of stone fruit species and varieties can also be different, especially for Prunus species (Kárpáti, 1967; Terpó, 1974; Raming & Cociu, 1991; Faust & Surányi, 1997; Surányi, 2013). The study analyzes the average relative ecological value measurement numbers of 75 species, including 120 cultivars, in terms of diversity and similarity. It is novel that, based on the sources, the author used the Ellenberg-Borhid values for the European, Asian, North American and other species, expanding them with transitional subgenera (e.g. Microcerasus ). It was also possible to pay attention to a North African, Central and South American Prunus/Prunophora species. Following the accounting of economic and fruiting values, the species, subspecies, and varieties of the European and Mediterranean regions are the finalists, but species hybrid plums, rootstocks, or Prunus species whose values have not yet been known can play a role. Although the kéköny is a known species, it can become a cultivated fruit species due to the high antioxidant content of the fruit (Hegedűs & Halász, 2019).


Introduction
Among the temperate fruit-bearing species, the plum offers an opportunity for a joint, comparative analysis of ecological and genetic diversity.Moreover, in terms of taxonomy and nutrition-physiology, there is already a difference in terms of the concept of plum fruit.
However, in the current study, there are also evaluated a large number of non-6 cultivated wild species, possibly growing species used as subjects, as well as Pruno-and Microcerasus taxa.The relative biological value figures developed for cultivated plums, such as open pollination (OP), degree of frost resistance (FR), relative value of Sharka virus sensitivity (SS) and measuring of disease resistance (DR) data (Surányi, 2015) for non-cultivated plums they could not be available for plums (natural wild species).
Prunus sp.taxonomic investigation of species in the 17-18 up to the 20th century, many valuable results had already been achieved, but Kárpáti (1967) rightly claimed that the taxonomic problems of cultivated plum varieties cannot be closed -not even today.The present study is an attempt to determine whether the natural and cultivated forms of the plum can be examined together based on ecological relative values, namely in differentiation according to genetic (Hegedűs & Halász, 2019) and eco-geographical (Surányi, 2019) diversity.
For the most part, pomology uses the tools and methods used for the sake of cultivars, therefore, floral biology (Dahl, 1935) or other vegetative and reproductive organ studies (Röder, 1940;Tóth, 1957;Surányi, 1991Surányi, , 2019) are important additions.The economic advantages offered by the feverish variety production and variety exchanges pushed the ecological approach into the background, i.e. economic interests came to the fore.Fortunately, however, resistance issues became more prominent (Nicotra et al., 1983;Ramming & Cociu, 1991;Faust & Surányi, 1997;Surányi, 2019).
The role of diversity and its approach are not possible without ecological certification of old, actual and new varieties.

Surányi, D.
As we mentioned above, in the case of cultivated varieties, it became necessary to look for new indicators (cf.Surányi 2015Surányi , 2022)).However, in order to be able to compare cultivated varieties and natural (wild) species, but now we could take them into account -due to the large number of wild species With all of this, the research result was to promote further breeding work by presenting the high species richness of the Prunus genus on the one hand, and using it on the other.

Materials and methods
More than 60 natural and cultivated species, as well as subspecies, types, and cultivars are included in large numbers in the study: 7 tables and an Appendix present the scope of the investigations.The investigated materials are there in the following.

Methods
The expression of the ecological experiences in form of relative indicator values is not a new classification experiments to compare the ecological species.In this paper we consistently use Borhidi (1993Borhidi ( , 1995) ) fundamental work of the ecological values of the indigenous flora of data it.At first, Iversen (1936) applied relative indicator values for characterizing salt-resistance of coastal plants, suggesting a three-grade scale.Ellenberg (1950Ellenberg ( , 1952) ) worked out the ecological indicator values of a larger number of meadow plants and different weeds for several ecological factors and the first experiment for applying these indicator values in typing plant communities.Ellenberg (1963) were applied 5-grade scales and the moisture scale amplified later to a 10-grade scale.
The development of the indicator values, an important contribution was made by Zólyomi's TWR system (1964) and that improved their staff (Zólyomi et al. 1967).
The TWR-system consisted of a 10-grade temperature scale (T), an 11-grade water content or soil moisture scale (W) and a 5-grade soil reaction scale (R), which was worked out to 1400 native species of the Hungarian flora and weeds (Kárpáti, 1978) and with some critical taxonomic groups (Borhidi, 1969 and others).The TWR formed an ecological reference system for plant communities and to place a multidimensional ecological space (cf.Précsényi, in Zólyomi 1964;Zólyomi & Précsényi, 1974;cit. Borhidi, 1993;Zólyomi, 1987).Ellenberg (1974) elaborated an ecological behaviour indicator values with regard to the seven main environmental factors; three of them are climatic ones: temperature (T), light (L), and continentality (C), further three indicators related to soil factors, i.e. moisture or water supply (F), acidity or soil reaction (R) and nitrogen supply (N), the salinity has been recently actualized (Ellenberg et al. 1991).Although the indicator values of Ellenberg were not used in the Hungarian botanists, it had been included into the Synopsis of Soó (1964Soó ( -1985)): the TFRN-values of SOÓ can be obtained by dividing the Ellenberg's figures.Kovács (1979) elaborated the Ellenberg's indicator values of 1300 plant species of Romania and a register of other biological characteristics too.Borhidi (1993 and1995) are found the ecological indicator values of the Hungarian flora in the following order, which we applied in recent study of pomological species.In the following, we take the figures as defined in Borhidi (1993 and1995) study, as well as extend the cultivated fruit varieties in Hungarian cultural flora.

TB:
The relative temperature figures reflecting the heat supply of the habitats where the species occur (mainly based on the distribution according to the latitudinal vegetation zones and altitudinal belts).The temperature figures of Ellenberg's 9grade scale (T) applied by Borhidi (B)

RB:
Reaction figures, according to the nine-grade Ellenberg's scale, reflect to the occurrence of the plants in relation of the soil reaction of the habitats (Tüxen & Ellenberg, 1937).In the 5-grade Zólyomi's scale calciphilous and salt tolerant or even halophilous plants are equally treated as basiphilous plants.
Here the two groups are differentiated by their positive or negative salt figure category.A comparison of the reaction value scales according to Ellenberg's versus Zólyomi's classification was carried out by Pichler & Karrer (1991, cit. Borhidi, 1995)  The ecological conception by Borhidi diverts (1995) was same with the ecological figures of Ellenberg et al. (1991), although methodologically and in general concept follows it completely.

Results and discussion
The Prunus genus belongs to the Rosaceae family and includes a large number of species.They are partly of disputed taxonomic classification, mainly trees and shrubs, with very different ecological needs.Regarding the number of species, due to systematic differences, their number means at least 200-250 species (according to Plant List=PL or the Integrated Taxonomic Information System=ITIS).Terpó (1974) defined subgenera (Padus, Cerasus, Microcerasus, Amygdalus, Prunus -with several sectios), but Rehder (1954), Krüssman (1978), Ramming & Cociu (1991) followed a different classificationeven within the genus Prunus.Prunus species are predominantly native to the northern hemisphere, in the temperate zone, and are mostly deciduous, but evergreens are also known.However, the area of some species is in Central America (Prunus serotina ssp.capuli) or the Andes (e.g.Prunus amplifolia Pilg.) (Figure 1-15).
The study could not undertake either a taxonomic or a wide-ranging (thus origin) comparative analysis, it only carried out an ecological assessment of the species that actually produce plum fruit and may provide them with rootstock.We drew attention to its importance in the recently published plum monograph.The taxonomic place and circle of kinship of domestic plum (Rehder, 1954;Ramming & Cociu, 1991;Faust & Surányi, 1997;Faust et al., 2011) and mostly the ecogeographical and morphological system of plum species and varieties (Surányi, 2019) formed the basis of this work.
Most authors consider the species Prunus domestica to be a spontaneous crossing of P. spinosa and P. cerasifera, which was also confirmed by recipt crossings (Rybin 1935(Rybin , 1936;;Kovalev, 1955;Kápáti, 1967;Ramming & Cociu, 1991).However, the parent species differ in size, lifestyle and fertility, as well as in relative temperature (TB) and light requirement (LB), as well as classification according to continentality (KB) (Table 1).The relative ecological values of the true European plum species showed significant differences only in a few cases; partly P. x italica and partly P. x syriaca differed from the other taxa (Table 2).
The number of species from Asia Minor and Central Asia is -true -high, but among them, the different scientific names given after the authors' definition are only synonyms.However, since we had no way to make a morphogenetic comparison and the relative ecological values were not sufficient to decide this, we included all of them as small species in Table 3.In essence, this explains the low level of diversity; these are mainly montane species, they have high light requirements and high salt tolerance.This can be attributed to the fact that in Iran and Central Asia, more of the endogenous wild plums are being cultivated (own observations in 2002).
The similarity in ecological value is largely explained by the properties of P. salicina and the successful cross-breeding with other species over several centuries.And the plums from the Ussuri River region are somewhat different from the others because the ecological factors in Manchuria are also different from those in the interior regions of China, which shaped them over centuries (Table 4).Ramming & Cociu (1991), Faust & Surányi (1997) and Surányi (2019) presented 32 plum species native to North America.Each of the 7 species that also plays a role in cultivation, as indicated by the note in Table 5, is represented by the average of four varieties (species names in bold and asterisks).For the time being, New World species seem to have a more significant role in evolutionary biology, taxonomy and ecology.Because European and Japanese plums have a much greater nutritional weight worldwide, although in the Mediterranean region (California, Florida) Prunus salicina and its hybrid species dominate.In Table 5, the species differed only slightly, based on the known descriptions.According to our assumptions, if a sufficient number of cultivated varieties of most species were available, ecological diversification would also be better appreciated.
Four Microcerasus species presented here separately, and it is not surprising that they are significantly different from the North American species.We know little about the Prunus species found in the Andes (only one herbarium sheet), just as little is known about the Central American subspecies of P. serotina there (P.serotina ssp.capuli /Cav./Vaugh).According to the calculated and estimated TB data, the relative ecological values were found to be significant (Table 6).For the temperature values, a higher LB value could only be observed in the species group with TB 5-6 classification, otherwise the differences are within the margin of error.

SB:
Salt figures for indicating plant occurrence in relation to the salt concentration of the soils in a 9-grade scale, according to Scherfose (1990).1. Halophob species not occurring in salty or alkalic soils 2. Salt tolerant plants but living mainly on non-saline soils 3. Oligohaline plants living on soils of extremely few chloride content 4. Beta-mesohaline plants living on soils of few chloride content 5. Alfa/beta mesohaline plants living on soils of intermediate chloride content 6. Alfa-mesohaline plants living on soils of middle chloride content (0.7-0.9%) 7. Alfa-mesohaline to polyhaline plants living on soils of middle to high chloride content 8. Polyhaline plants on soils of high chloride content (1.2-1.6%) 9. Euhaline plants living on soils of very high chloride content 10.Euhaline to hypersaline plants living on soils of extremely high chloride content Taxon names in bold indicate the average of four cultivars, all other data are estimates.12Surányi, D.
to the Hungarian flora.Plants of semidry habitats 5. Plants of semihumid habitats, under intermediate conditions 6. Plants of fresh soils 7. Plants of moist soils not drying out and well aerated 8. Plants of moist soils tolerating short floods 9. Plants of wet, not well aerated soils 10.Plants of frequently flooded soils 11.Water plants with floating or partly emergent leaves 12. Water plants, most wholly submersed in water.
Ellenberg (1974)moisture figures (occurrence in relation to soil moisture or water table) according to the 12-grade F-scale ofEllenberg (1974).The scale is very similar to the W-scale ofZólyomi (1964), but the water plants have a more detailed categorization, as follows:1.Plants of extremely dry habitats or bare rocks 2. Xero-indicators on habitats with long dry period 3. Xero-tolerants, but eventually occurring on fresh soils 4.

Table 1 .
Relative ecological indicator values of different parents.Taxon names in bold indicate the average of four cultivars, all other data are estimates.

Table 2 .
Main plum taxons and estimated types.Taxon names in bold indicate the average of four cultivars, all other data are estimates.

Table 3 .
Estimated ecological values of wild and cultivated types for Minor and Central Asian plums.

Table 4 .
Ecological characterization of East Asian plums and cultivars.Taxon names in bold indicate the average of four cultivars, all other data are estimates.

Table 5 .
Microcerasus and North American plums and cultivars.
Note: Taxon names in bold indicate the average of four cultivars, all other data are estimates.

Table 6 .
Caracterization of North Amarican plums on based of TB values.

Table 7 .
Description of geographical and genetic plum groups.