No abstract

In Germany, planting of trees and shrubs in an open landscape is regulated by law (Federal Nature Conservation Act §40) because of supposed genetic differences and regional adaptations to habitat conditions (mainly climatic and soil). Therefore, for trees and shrubs to be planted in the open landscape, Germany is divided into six officially designated regions of origin, often referred to as provenances. Propagation and use of plants must be carried out according to these provenances. To evaluate whether plants from different populations differ in their physiological and biochemical reactions, two years old cuttings of Corylus avellana from four populations with different climatic and soil conditions were evaluated in an early frost experiment under controlled conditions. Relative electrolyte leakage as a measure of damage due to frost increased with decreasing temperatures. Selected biomarkers (glucose, fructose, sucrose, starch and proline) were used to assess biochemical reactions of these populations. Increases due to frost were small and in most cases reflected the ranking of the unstressed plants of the populations. Only few statistical differences were found. There were no clear, consistent trends in spite of varied climatic conditions and geographical distance between the populations. Plants from all populations survived frost until -27°C. Hence there are no severe risks in populations' transfer within these latitude and altitude margins with regards to early frost.

Outplanting performance of trees and shrubs cultivated in tree nurseries is assumed to be better if propagation material is sourced from the designated areas of future growth. However, this requires a local nursery to produce that cultivar, which might reduce the availability of that species. In this study we evaluated drought reactions of 2.5-year-old hazelnut (Corylus avellana L.) from four population origins. After container cultivation, plants were subjected to drought by irrigating 25% (fast stress) or 50% (slow stress) of the lost water. Control plants were well irrigated. Depending on stress development and hence stress duration, different physiological (stomatal conductance, predawn water potential, relative water content) and biochemical (glucose, fructose, sucrose, starch, proline) responses to drought were found. Independent of stress development, only few differences among populations were found. These differences were mostly not related to precipitation in their area of origin, suggesting no local adaptation within the ecological range investigated.

Prunus spinosa species is distributed across wide range of geographical areas which are subject to climatic, edaphic factors and long-term divergent selection. This could lead to local adaptation hence ecotypes in terms of morphological, physiologically and or biochemical inclination to their local environment. To investigate whether the species (Prunus spinosa) has been influenced by their local environmental conditions and whether populations (ecotypes) are adapted to local conditions, cuttings from different demarcated areas of origin in Germany and Italy were sourced and cultivated optimally in common container area. Growth, bud sprout and bud set were evaluated in spring, summer and autumn respectively. Soluble sugars (Glucose, fructose, sucrose and starch), N, P, K, and proline concentrations were analysed in spring and autumn for three years. The findings indicated that plants grown from different locations mostly differed in N, P, K, soluble sugars and starch in spring. Nonetheless, these geographic variations were hardly observed either in summer or in autumn. On phenology, German populations did not differ at all in phenology (flushing and growth cessation) while the Italian population always sprouted earlier and ceased growth later. The results indicate that the German populations are not differentiated by climatic variations across latitude or altitude. In contrast the Italian population is differentiated from German population Brandenburg mostly by latitudinal differentiation. Nevertheless, their inherent ability to sprout earlier and late  growth cessation might expose the population to frequent frost damage when transplanted to more northern latitude.

Nutrient loading applies more fertilizer compared to non-loading. Conventional loading delivers nutrients to the plants in a more or less constant rate mainly using slow release fertilizer; for exponential loading liquid fertilizer is used increasing exponentially towards the end of the vegetation period. Nutrient loading aims to build nutrient reserves, especially N, in the plants to improve transplanting success. Until now the effect of this fertilization technique on abiotic stress reactions is not known. The reactions of Rosa majalis cultivated for one vegetation period (2010) without loading and with conventional or exponential loading were investigated in early frost (autumn 2010), late frost and drought (spring resp. summer 2011) under controlled conditions. In all treatments, the absolute level of damage, relative electrolyte leakage (REL), was low in early frost. However, relative electrolyte leakage significantly increased at-8°C for the exponentially loaded plants while this was the case only at-16°C for the conventionally loaded and non-loaded plants. Similarly for late frost, REL increased already at-5°C for the exponentially loaded plants and only at-9°C for the non-loaded and conventionally loaded ones. At-5°C the absolute level of damage was low for plants from all treatments and high for-9°C. In both frost experiments, possible cryoprotective compounds like sucrose and glucose in most cases did not differ between the previous fertilization treatments. However, concerning drought reactions, exponentially loaded plants had an advantage compared over conventionally loaded and nonloaded ones in postponing wilting. They closed their stomata earlier and synthesised highest concentrations of proline and sucrose compared to non-loaded and conventionally loaded plants. Possible reasons are discussed. The results indicate that the technique of exponential nutrient loading might be helpful to improve the plants' ability to perform well after being transplanted to drought prone sites. However, increased frost sensitivity has to be considered as well.