Laila M. Karlsson

A Comparative Study of Germination Ecology of Four Papaver Taxa

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.

Inter-species comparison of seed dormancy and germination of six annual Asteraceae weeds in an ecological context.

To understand germination timing in an ecological context, the response to environmental events that affect seed dormancy is central, and has to be combined with knowledge of germination responses to different circumstances. In this study, seed dormancy, germination, and emergence phenology of six annual co-occurring weedy Asteraceae species were investigated. Three pre-treatments (warm and cold stratification, and dry storage) were tested as possible dormancy affecting environmental events. Seeds were also sown outdoors. Species-specific differences were revealed in analyses. To facilitate general descriptions of dormancy patterns and germination preferences separately, condensed responses to the different possible dormancy affecting treatments and relative germination in different environments were plotted, giving species-specific patterns. Most species exhibited decreased dormancy to two or three pre-treatments. Dormancy was most effectively reduced by cold stratification for three species (Guizotia scabra, Parthenium hysterophorus, Verbesina encelioides), by warm stratification for two (Bidens pilosa, Galinsoga parviflora) and by dry storage for one (Tagetes minuta). All species germinated more when provided with light than in continuous darkness. Temperature levels most suitable for germination varied from low (15/5-20/10°C) for Verbesina encelioides to high (25/15-30/20°C) for Bidens pilosa. It is concluded that, even though the species have different dormancy patterns and germination preferences that suggest different possible distribution ranges, the species achieve similar emergence timing in the field in environments with a pronounced dry period after dispersal and small annual temperature fluctuations.

Nutritive values of the drought tolerant food and fodder crop enset

Enset ( Ensete ventricosum ) is a drought tolerant crop, traditionally grown in Ethiopia. It has many usages: food, fodder, fibres and traditional medicine. Being perennial, enset improves local climate and soil conditions. It could contribute to improved food security in several drought-prone parts of the world. The aims of this study were to reveal the amino acids of enset corm, which can be cooked as a root crop, and to increase the general knowledge regarding chemical composition and energy values of different enset fractions. Water content was high, 85 to 90%, which is beneficial when used as fodder during dry periods. Enset corm contained 17 of 20 amino acids and had similar or higher concentration than potato of 12 of these. Leaves had 13% protein, among the highest available in Ethiopia, 20% crude fibre and 10% sugar; a good fodder and suitable for ensilage. The pseudostem, the main food source, was rich in soluble carbohydrates (80%) and starch (65%), but had low protein content (4%). An enset based diet should be supplemented with protein and complementary amino acids; for example from beans, which are suitable to intercrop with enset.

Seed dormancy pattern of the annuals Argemone ochroleuca and A. mexicana (Papaveraceae).

Summary Seed dormancy of the tropical annual weeds Argemone ochroleucaSweet and Argemone mexicanaL. was studied in a series of experiments. Factors investigated included : light, darkness, five temperature regimes and combinations of periods of light, darkness and the different temperature regimes for various time periods (up to one year). Furthermore, germination in solutions of gibberellic acid, after leaching, after mechanical treatments, and after periods of dry storage, was studied. Since the seed s have underdeveloped embryos, their growth was also studied. There was no, or very little, germination (< 5%) or embryo growth in most experiments, irrespective of light and temperature conditions. Argemone ochroleucaafter-ripened slightly and germinated to 10 – 20% after one year of dry storage. Germination to 100% occurred only after artificial treatments, either after removal of part of the seed coat and endosperm or after incubation in gibberellic acid solution. The significance of the strong dormancy w as confirmed in the field for A. ochroleuca when only 8% of seeds sown produced seedlings in the first season after shedding. We conclude that the majority of seeds normally do not germinate during their first season after shedding, but instead enter into the seed bank, thus producing seedlings, even in a well-maintained field, probably for several years.

Seed germination and seedling development ecology in world-wide populations of a circumboreal Tertiary relict.

Ecological traits of the circumboreal plant Viburnum opulus were examined to improve understanding of the variation of populations occurring in the same biome but on different continents. Seedling development/emergence is shown to be highly similar but some degree of variation was present in other traits, among populations.

Nutritional and chemical properties of fermented food of wild and cultivated genotypes of enset (Ensete ventricosum)

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.

EFFECT OF CULTIVAR, TRADITIONAL CORM PRE-TREATMENT AND WATERING ON SPROUTING AND EARLY GROWTH OF ENSET (Ensete ventricosum) SUCKERS

Enset [Ensete ventricosum (Welw.) Cheesman (Musaceae)] is a multi-purpose and drought-tolerant crop, traditionally grown in Ethiopia. Food from enset has nutritive values similar to potato; it could improve food and livelihood security for many in larger geographical areas. Agronomical advice is needed which requires increased knowledge of management techniques. The purposes of this study were to (i) compare traditional corm pre-treatments when planting for sucker production, (ii) compare all six officially released cultivars regarding sprouting and (iii) investigate the effect of watering on newly buried corms. Emergence rate and number and characteristics of sprouts were recorded. Corms, from 63 two year old plants, were buried in local soil supplied with cow manure in Wolaita Sodo, Ethiopia. Emergence was recorded daily. After nine months, including one rainy season, all suckers (totally 4405) were harvested and individually recorded. Regardless of cultivar, minimum time to emergence was 50 days. Sprouts from split parent corms emerged earlier than from entire. Emergence occurred from 100% of corms, number of sprouts was strongly correlated to cultivar: average 28-106. The cultivars responded similarly to corm splitting: the more pieces the corm was split into, the more sprouts per parent corm. Average pseudostem diameter of the seven largest per parent corm: 8-10 cm for all cultivars, leaf length: 3.1-3.7 m, remaining 2700 smaller suckers: diameter 3 cm (SD 1.8). Watering decreased the average time to emergence and levelled out the differences between pre-treatments. The traditional belief is that watering as well as manure on corm cause rotting; manure is therefore usually put on the soil surface. On the contrary, full emergence and unexpected large suckers may be a result of careful soil preparation with manure applied on corm directly; watering resulted in an even emergence and growth. In conclusion, vegetative propagation of enset is efficient, but methods used and agronomical advice can be improved.

Higher fear of predators does not decrease outdoor range use in free-range Rowan Ranger broiler chickens

ABSTRACT Organic chicken production is currently experiencing a boom in Sweden, but has only recently gained access to a commercial slow-growing broiler strain, the Rowan Ranger. While these chickens are reported to grow at rates better suited to organic production than previously available strains, anecdotal evidence suggested increased fearfulness in this strain and concerns were raised that this may deter the birds from accessing the range. We subjected Rowan Rangers and fast-growing Ross 308 raised on the same organic farm to a set of behavioural tests while also tracking activity and outdoor use. The results suggest that although Rowan Rangers indeed show longer durations of tonic immobility, an index of predator-related fear, both strains made an outdoor visit on average once every 1.5 h and typically spent around 5% of their days in the range. Overall however, our results support the transition to Rowan Rangers in organic chicken production in Sweden.