Jørgen L. Christiansen

A phenetic analysis of morphological variation in Citrullus lanatus in Namibia.

Morphological data recorded from field trials using Citrullus lanatus germplasm collected in Namibia were used to analyse and compare the various morphotypes of this species. The experiment comprised wild types and local landraces as well as commercial cultivars. Cluster analysis supported the indigenous classification system used in Namibia, in which Citrullus types are distinguished based on gross morphology, ecology and usage and grouped into seed, cooking and fresh-eating (watermelon) types. Commercial watermelon cultivars formed a distinct cluster. Wide variation was found within the local types whereas the genetic basis of the commercial type appears to be narrow. The commercial cultivars were most closely related to local watermelon types and more distantly related to the wild types, whereas the cooking melons form an intermediate group.

Weed Harrowing and Inter-Row Hoeing in Organic Grown Quinoa (Chenopodium Quinoa Willd.)

Weeds, with their negative influence on both yield and quality, constitute a major problem in the organic production of quinoa, a potential new seed crop for protein feed and human consumption in Europe. To attain effective weed control, mechanical weeding strategies, such as weed harrowing and inter-row hoeing, were studied. Weed harrowing operates over the entire plot with flexible tines, affecting both crop and weeds, whereas inter-row hoeing is performed between the rows, aiming only at the weeds. The study showed that both hoeing and harrowing reduced the quinoa density in one out of two years, whereas there was no effect on quinoa density in the other year. Yield was increased by both methods, but hoeing increased yield more than harrowing due to better weed control. Regression analysis showed that crop yield was related to weed dry matter and showed no indications of higher crop damage associated with weed harrowing. Protein content was low when weeds were not treated, and increased significantly when weeds were controlled. As a conclusion, inter-row hoeing was more efficient than weed harrowing with respect to weed control; however, weed harrowing should be optimized in future trials in narrow row spacing systems, and the results indicate that weed harrowing can be used as a supplement to inter-row hoeing.

Variability in Namibian landraces of watermelon (Citrullus lanatus)

An on-station experiment was carried out in northern Namibia to compare local landraces of watermelon to modern varieties. Three groups of local watermelon are distinguished by farmers in Namibia: watermelons for fresh consumption, cooking melons used for porridge, and seed melons for oil pressing. The present study was carried out to estimate agronomic potential of the local landraces and verify whether agronomic characteristics would justify the local groupings. Important agronomic and fruit-quality traits (yield, earliness, fruit weight, fruit number, rind thickness, soluble solids, seed weight, and tolerance to biotic and abiotic stress) were measured in seven landraces (three watermelons, three cooking melons and one seed melon)and compared to three modern cultivars frequently grown in Namibia. The study revealed that well-adapted, productive Citrullus lanatuslandraces are available, and cultivated by local farmers throughout the northern regions of Namibia. Based on a combination of agronomic characteristics these local varieties could be grouped into three distinct types: watermelons, cooking melons, and seed melons, in agreement with farmers classification. Landrace water melons were characterized by smaller, less sweet fruits with larger seed and a thicker rind compared to modern varieties. Yield level was comparable but development was later and fruit number in some cases higher. Cooking water melons were less sweet than local water melon with large fruits comparable in size to modern cultivars. The only included seed watermelon had small fruits with large seeds and low soluble sugars. Yield varied from 118 t/ha for a giant cooking melon, out yielding all other accessions, to only 10t/ha for the seed melon type, but with considerable variation within groups. The earliness of commercial varieties maybe of interest in developing a mixed portfolio of short- and long-cycle landraces, whereas plant vigour, resistance and seed characters in some of the Namibian landraces may be important traits for breeding for both local purposes and for commercial varieties.

Validating a core collection of Peruvian quinoa germplasm

A Peruvian quinoa core collection, containing 103 chosen ecotypes or landraces, was defined on a geographically stratified non-overlapping sampling procedure. The objective was to determine whether this protocol was correct. Hence, a phenotypic distance matrix among 76 accessions from this core collection was created by calculating the difference between each pair of accessions for each characteristic. These 76 accessions were chosen because they had complete data for eight morphological descriptors. The diversity index was calculated by averaging all the differences in the phenotypic value for each quantitative descriptor divided by the respective range, and considering a matching coefficient for the qualitative descriptors, i.e., 0 for characteristics that matched, and 1 if they did not. The total sum of squares from the analyses of variance for the phenotypic diversity index, based on morphological descriptors, was partitioned between and within Peruvian Departments. The between Department cluster variance was smaller (0.0022) than the within Department cluster variance (0.0144), because accessions with the same stem colour or similar inflorescence type and colour were grouped together irrespective of their Department. This was further corroborated by the average linkage cluster analysis, which was performed on the phenotypic diversity matrix to study the pattern of variation and the relationship between the quinoa landraces of this core subset according to their geographical origin. Within each sub-cluster (based on above qualitative descriptors) accessions were ranked by their Department of collection, which indicated that the sampling method was appropriate for choosing accessions for the Peruvian quinoa core collection.

Potential of landrace germplasm for genetic enhancement of white lupin in Egypt

Landraces of white lupin (Lupinus albus L.) collected in Egypt were evaluated along with locally developed cultivars and selected foreign germplasm for yield and major morphological characteristics in five different locations. These locations represent different soil types and climatic conditions in Egypt. The results showed an outstanding performance of the local cultivar checks across traditional locations for lupin cultivation, which supports the utilization of local germplasm for further improvement of locally adapted lupins in Egypt. The results further suggest that local landrace germplasm may be an important source of alleles for shortening the vegetative period, reducing plant height and stem length, as well as for improving some yield components as number of pods and seeds per plant. The genotype-by-location interaction was significant for all characteristics. Mass selection in the Egyptian germplasm collection of white lupin has the potential for enhancing yield, especially in germplasm adapted to newly reclaimed desert locations.

Partial resistance to a Fusarium root disease in Egyptian white lupin landraces

A Fusarium sp. root pathogen of lupin is the causal agent of the most important disease that affects the cultivation of white lupin (Lupinus albus L.) in Egypt. The aim of our research was to investigate whether host resistance to Fusariumroot disease was available in Egyptian landraces ofLupinus albus. Five Fusarium isolates collected from white lupin samples in Egypt were tested with an Egyptian landrace and a French cultivar. The most aggressive isolate was used to screen an additional 15 Egyptian landraces, two cultivars released in Egypt after selection among landraces, one Polish cultivar, and two French cultivars. The assessment of host response to Fusarium was performed in a field, and under controlled conditions in a greenhouse pot experiment. Most landraces and the two Egyptian cultivars showed better resistance with good accordance between field and pot experiment. This experiment showed that Egyptian genetic resources of white lupin possess partial resistance to Fusarium root rot. Egyptian germplasm may be an alternative genetic source for incorporating partial resistance to Fusarium root rot into the breeding pools.

Quinoa, Chenopodium quinoa, Provides a New Host for Native Herbivores in Northern Europe: Case Studies of the Moth, Scrobipalpa atriplicella, and the Tortoise Beetle, Cassida nebulosa

Abstract The Andean grain, quinoa, Chenopodium quinoa Willd. (Caryophyllales: Amaranthaceae), is gaining increasing attention as a future food and fodder crop in Denmark and other parts of Europe. Prior to 2005, pest problems in the crop were negligible in Denmark, however native insects may become adapted to this new host. Herbivores feeding on the closely related and very common weed in arable crops Chenopodium album L. present a special risk. In 2006 there was a heavy attack of Scrobipalpa atriplicella (Röslerstamm) (Lepidoptera: Gelechiidae) larvae in the maturing inflorescence of C. quinoa. Gelechiidae are the most important pests on C. quinoa in the Andean region. In 2007 another herbivore on C. album, the tortoise beetle Cassida nebulosa L. (Coleoptera: Chrysomelidae), was a serious problem on C. quinoa in southern Jutland. This is the first published record of these two pests on C. quinoa. The future pest status of C. quinoa in northern Europe is discussed.

Cropping Systems, Uses, and Primary in situ Characterization of Tanzanian Pigeonpea (Cajanus cajan (L.) Millsp.) Landraces

Landraces of pigeonpea (Cajanus cajan (L.) Millsp.) were collected from farmers fields in its major cropping areas in Tanzania. Passport data, including descriptors, information on cultural practices and uses were recorded. Pigeonpea intercropping with maize, sorghum and cassava were found to be the dominating cropping systems, with characteristic differences between regions. In the northern part of the country pigeonpea has been developed into a relatively high yielding cash crop. Also in part of the Coastal Zone and Eastern Plain a market, particularly for green pods, have been developed. It is also in these areas near Dar es Salam that pigeonpea is most frequently found as a garden crop.The study showed that farmers mainly relay on self-saved seed, but seed is also quite often provided from other sources. About one third of the farmers selected sowing seed in the field at harvest. Seed storage was considered a great problem, and a variety of indigenous storage techniques were recorded. Chemical seed dressing was only common in the Northern Highlands, where the crop plays an important role as a cash crop. In all areas pigeonpea was consumed green as well as dry. Dry pigeonpea was most often consumed as whole grains, but dehulling was common especially in the Southern Plain. Most landraces identified were long-duration types, medium-duration types only being common in the Coastal Zone. The recorded plant and seed traits varied considerably, but the frequency of landraces with relatively large white or cream seeds and large pods was high in all regions. A number of accessions with potential resistance to fusarium wilt, bruchids and pod borer were identified.

Assessment of Phenotypic Variation in Winter Barley in Scandinavia

Phenotypic diversity for agronomic characteristics was determined in an experiment without fertilizer in 1998 in 41 two-row and 21 six-row winter barley accessions, provided by the Nordic Gene Bank, at Højbakkegård (Denmark). There were significant differences among these 62 accessions for spring establishment, early flowering, covering, plant height, lodging, tillering, spike length, number of kernels per spike and thousand kernel weight. On average, two-row barley accessions had better establishment, covering and standability (although they were slightly taller) but showed lower tillering than six-row barley accessions. Two-row barley accessions also had larger spikes with fewer kernels, but heavier weight, than six-row barley accessions. There were significant phenotypic correlations among the characteristics scored. However, not all of them were common to two- and six-row barley accessions, which suggests the evolution of distinct genetic systems controlling these associations in the two sets of barley accessions. Average linkage cluster analysis and principal component analysis confirmed number of rows as an important characteristic to discriminate among cultivated barley accessions.

On-farm yield potential of local seed watermelon landraces under heat- and drought-prone conditions in Mali

On-farm yield experiments were carried out in the Tombouctou region of Mali in 2009/10 under heat- and drought-prone desert conditions with three local landraces of seed-type watermelons. The landraces, named Fombou, Kaneye and Musa Musa by the farmers, exhibited distinct characteristics for fruit morphology, but in particular for seed traits. On average, the three landraces produced a fruit yield of 11·6 t/ha and an estimated seed yield of 364 kg/ha, with no significant differences among landraces. Kaneye showed the highest stability of fruit number/ha in different field environments, suggesting this landrace is the best among the three for a poor growing environment, whereas Fombou and especially Musa Musa responded positively to more favourable environments. Seed weight revealed a different trend, with Fombou as the most responsive to favourable conditions, while Kaneye and Musa Musa were less responsive. The yields obtained suggest that these local landraces of watermelon are valuable plant genetic resources for securing food supply in arid, heat- and drought-prone areas.