ABSTRACT
The multipurpose crop enset (Ensete ventricosum) has been traditionally cultivated in Ethiopia since ancient times. The main food product is the starch-rich fermented kocho made from the pseudostem and corm. There are many vegetatively propagated landraces utilised by farmers, but no concisions breeding have taken place, and there are requests for improved cultivars. There are also populations of wild ensets which propagate sexually, and the variation in characteristics among the wild is not studied. We suggest investigating the variation among the wild, in order utilise the most proper combinations of parent plants when breeding for different purposes. We analysed kocho, after 30 and 90days of fermentation, from three wild genotypes and three cultivars, to compare how and how much they differ in components and perceived food quality. The three cultivars scored generally higher than all the three wild genotypes for protein, fat, sugar and minerals, while the wild had larger fraction of starch. On average, panellists rated all the cultivated significantly higher than all the wild regarding the investigated characteristics (colour, texture, taste and overall). However, there were nine out of 25 panellists who rated at least one wild genotype higher or equal to at least one cultivar regarding taste, showing that people can be open for unfamiliar kocho. Therefore, we conclude that further investigations of the variation among wild plants should be done, aiming to get a larger gene pool with improved characteristics as e.g. disease tolerance or superior mineral uptake; by careful selection of parent plants, desired combinations can be achieved.
ABSTRACT
BACKGROUND AND AIMS: Temperate forests are disjunct in the Northern Hemisphere, having become fragmented from the earlier widespread (Tertiary) boreotropical forest. We asked 'What are the contemporary patterns of population variation in ecological traits of a Tertiary relict in a macroecological context?'. This issue underpins our understanding of variation in populations occurring in the same biome but on different continents. METHODOLOGY: We examined characters associated with root and shoot emergences among populations of Viburnum opulus in temperate forests of Asia, North America and Europe. This species has complex seedling emergence extending over several years and requiring various temperature cues. PRINCIPAL RESULTS: Populations varied in germination responses and clustered into groups that were only partly related to varietal status. Whereas roots (at warm temperatures) and shoots (following a cold period) simultaneously emerged from seeds of all populations when simulated dispersal occurred in winter, they were delayed in some populations when dispersal occurred in summer. CONCLUSIONS: Viburnum opulus populations, some separated by 10 300 km, showed high similarity in seedling development and in germination phenology, and we suggest that stabilizing selection has played a key role in maintaining similar dormancy mechanisms. Nevertheless, there was some degree of variation in other germination characters, suggesting local adaptation.
ABSTRACT
BACKGROUND AND AIMS: Comparative studies of closely related taxa can increase understanding of adaptations and changes in seed dormancy and germination preferences in an evolutionary perspective. For such studies, a method to describe and compare the performance of taxa in a general way is needed. The germination ecology of four Papaver taxa was studied with the aim of describing and comparing their responses to different seasonal temperature regimes. METHODS: Germination of Papaver argemone, P. rhoeas, P. dubium ssp. dubium and P. dubium ssp. lecoqii was investigated in three different artificial climates over 2.5 years. Seeds were collected in southern Sweden, and samples from different populations were used as replicates of taxa. KEY RESULTS: Despite substantial intra-taxa variation, there were clear taxon-specific responses. Most germination occurred in the warmest climate. In general, the warmer the climate the more germination occurred in autumn instead of spring. Papaver argemone, phylogenetically most distant from the other taxa, was, in contrast to the others, restricted to germinating only at lower temperatures. CONCLUSIONS: Seed dormancy and germination may be described by dormancy pattern, germination preferences and dormancy strength. The general dormancy pattern was a common feature for these taxa and therefore probably an evolutionary conservative character. Germination preferences varied between taxa, resulting in different temperature optima and intervals for germination, and dormancy strength was to some extent taxon-specific, but highly variable. The dormancy pattern explained how the taxa can perform as winter annuals in warmer climates, but mainly as summer annuals in colder climates. Hence, there is no need to interpret the within-taxon temporal differences in seedling emergence as local adaptations. In the field, an entire seed cohort will not germinate during a single season. Instead, emergence will be distributed over several seasons, regardless of local climate, weather and soil cultivation methods.
Subject(s)
Germination , Papaver/physiology , Seeds/growth & development , Climate , Seasons , Species Specificity , TemperatureABSTRACT
BACKGROUND AND AIMS: The shrub Viburnum tinus is widely distributed in mattoral vegetation of the Mediterranean basin. The purpose of the present study was to classify the seed dormancy type and examine the requirements for embryo growth, root protrusion and shoot emergence. METHODS: Overwintered fruits were collected in western Spain in April 2001 and prepared in three ways: entire pericarp was removed, exocarp and mesocarp were removed or fruits were left intact. Fruits treated in these three ways were subjected to artificial annual temperature cycles or to constant temperature regimes for 1.5 years. KEY RESULTS: Removal of exocarp and mesocarp was necessary for embryo growth and germination. High temperature favoured dormancy alleviation and embryo growth, intermediate to low temperatures favoured root protrusion, and intermediate temperature shoot emergence. There was substantial germination at constant temperature regimes, indicating an overlap between temperature intervals suitable for the different stages of embryo and seedling development. Functionally, V. tinus has the same root and shoot emergence pattern that is described for other Viburnum species considered to have epicotyl dormancy. However, the requirement for high and low temperatures for radicle protrusion and epicotyl emergence, respectively, was missing in V. tinus; these characters are the foundation for the epicotyl dormancy classification. CONCLUSIONS: It is concluded that V. tinus does not have epicotyl dormancy. Instead, there is a combination of a weak morphophysiological dormancy and a slow germination process, where different temperatures during an annual cycle favour different development stages. The present study suggests that the first complete seedlings would emerge in the field 1.5 years after fruit maturation in October, i.e. seed dispersal during winter, embryo growth during the first summer, root protrusion and establishment during the second autumn and winter, and cotyledon emergence during the second spring.
