Effects of storage methods and seasons on seed quality of jute mallow morphotypes (Corchorus olitorius) in Siaya and Kakamega counties, Kenya

Jute mallow is an important source of nutrients, income and traditional medicine inKenya. It is extensively grown and consumed in Western Kenya. However, itsproduction is constrained by lack of quality seeds due to varied farmers’ agronomic andpostharvest practices. The aim of the study was to investigate the effect of storagemethods on seed quality of jute mallow in Western Kenya. Seeds of two morphotypesof C. olitorius(with 70% and above germination)were stored in clay pots, transparentplastic jars, brown paper bags and polythene bags at room temperature in Kakamegaand Siaya Counties. Seeds were also stored in a freezer at Chepkoilel campus in Eldoretat -20C. In Kakamega County, average room temperature was 230C and relativehumidity was 85% during the storage period of May to July 2006. In Siaya County, theaverage room temperature was 250C and relative humidity was 80% during the sameperiod. Between December and February 2006, the average room temperature was260C while relative humidity was 80% in Kakamega County. In Siaya County, theaverage temperature was 280C and relative humidity 65% for the same period. Storageduration was 90 days, which is the length of time farmers in the study areas store jutemallow seeds to avoid seed dormancy. Seed viability and vigourof the seeds wasdetermined. Data obtained were subjected to Analysis of Variance (ANOVA) and Ttestsusing Statistical Analysis Software (SAS) programme. Season of growth andstorage methods influenced the seed quality. Seeds stored in clay pots, brown paperbags, plastic transparent jars and freezer had higher seed quality than those stored inpolythene bags. Even though there was varied response to different storage methods,generally it was recommended that in order to obtain high quality seeds, farmers shouldstore jute mallow seeds in clay pots or brown paper bags or plastic transparent jars orfreezer.Key words: jute mallow, seed vigour, seed viability, storage methods, Corchorusolitoriu

Effects of Packaging and Storage Conditions on Quality of Spider Plant (Cleome gynandra l.) Seed

In Kenya, spider plant (Cleome gynandra L.) has gained popularity among consumers due to its nutritional and medicinal values. In the local markets, bundles of leafy shoots as well as uprooted young plants are offered at fairly high prices in many parts of Kenya. Existing evidence suggests that spider plant is endowed with higher level of nutrients than its exotic counterparts. The leaves contain over and above the normal recommended adult daily allowance of vitamins A and C, calcium and iron. However, quality of spider plant seed is affected by one or more factors that cause negative response during seed handling and storage. The purpose of this research was to increase insight into how the seed quality of spider plant is affected by different packaging containers, seed moisture content and storage temperatures, with a view to finding out the optimal method of packaging and storing of these seeds. This study was carried out using seeds dried above silica gel to four target moisture levels: 20%, 10%, 5% and 2% moisture content. Dried seeds were sealed in aluminum foil packets and polyethylene packets and stored at three storage temperatures: ambient (22oC to 30oC), 5oC and minus 20oC for three and six months. After each storage period, seed samples were drawn and viability and vigour tests carried out. Data sets were factorially combined and subjected to Analysis of Variance (ANOVA)and descriptive analysis. Means separation was by Least Significance Difference (LSD).Levels of significance, means and standard deviations were obtained for various data sets. Seed stored for six months at 5% moisture content and minus 20oC recorded the highest seed quality. There were no significant differences between seeds packaged in aluminum foil packets and polyethylene packets. In this study, a germination of 85% was recorded for seed dried to 5% moisture content and stored at room temperature. Therefore, on the basis of these findings, farmers can dry their seeds at about 5% moisture content, package them in polyethylene (since readily available) and store at room temperatures for six months.Key words: Containers, moisture content, storage temperature

Pollen loncevity in ecologically different zones of Western Kenya

Maize (Zea mays L.) is the most important staple crop in Kenya with the small holder farming systems accounting for about 75-80% of the total production. Most of the small-scale farmers plant locally adaptedlandraces and there are concerns about the possible contamination of these through geneflow from novel varieties, including the transgenics. The survival of pollen after dehiscence is an important factor affecting the geneflow. Studies were conducted to investigate the duration of pollen viability in two locations in western Kenya - Eldoret and Kakamega, representing the highland tropical and moist  mid-altitude/transitional zones, respectively. Pollen was collected at dehiscence and exposed as a thin layer in the open air for 0 (control), 15, 30, 60, 120 and 240 minutes. Pollen viability was assessed by measuring the seed set after pollination, scoring percentage pollen color change and percentage pollen germination. Pollen maintained viability for 120 minutes after dehiscence in Eldoret (T=23-240C; RH=45-55%; Ø=-109 to -82 MPa) and for 240 minutes in Kakamega (T=25-270C; RH=68-83%; Ø=-53 to -26 MPa). The differences in pollen longevity were attributed to the differences in atmospheric waterpotential between the two locations. The results suggest that the likelihood of genetic contamination of the landraces through geneflow from novel varieties is higher in the moist mid-altitude zones than in the highland tropical zones of Kenya

Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora

Background The best documented survival responses of organisms to past climate change on short (glacial-interglacial) timescales are distributional shifts. Despite ample evidence on such timescales for local adaptations of populations at specific sites, the long-term impacts of such changes on evolutionary significant units in response to past climatic change have been little documented. Here we use phylogenies to reconstruct changes in distribution and flowering ecology of the Cape flora - South Africa's biodiversity hotspot - through a period of past (Neogene and Quaternary) changes in the seasonality of rainfall over a timescale of several million years. Results Forty-three distributional and phenological shifts consistent with past climatic change occur across the flora, and a comparable number of clades underwent adaptive changes in their flowering phenology (9 clades; half of the clades investigated) as underwent distributional shifts (12 clades; two thirds of the clades investigated). Of extant Cape angiosperm species, 14-41% have been contributed by lineages that show distributional shifts consistent with past climate change, yet a similar proportion (14-55%) arose from lineages that shifted flowering phenology. Conclusions Adaptive changes in ecology at the scale we uncover in the Cape and consistent with past climatic change have not been documented for other floras. Shifts in climate tolerance appear to have been more important in this flora than is currently appreciated, and lineages that underwent such shifts went on to contribute a high proportion of the flora's extant species diversity. That shifts in phenology, on an evolutionary timescale and on such a scale, have not yet been detected for other floras is likely a result of the method used; shifts in flowering phenology cannot be detected in the fossil record

Contrasting Biogeographic and Diversification Patterns in Two Mediterranean-Type Ecosystems

The five Mediterranean regions of the world comprise almost 50,000 plant species (ca 20% of the known vascular plants) despite accounting for less than 5% of the world’s land surface. The ecology and evolutionary history of two of these regions, the Cape Floristic Region and the Mediterranean Basin, have been extensively investigated, but there have been few studies aimed at understanding the historical relationships between them. Here, we examine the biogeographic and diversification processes that shaped the evolution of plant diversity in the Cape and the Mediterranean Basin using a large plastid data set for the geophyte family Hyacinthaceae (comprising ca. 25% of the total diversity of the group), a group found mainly throughout Africa and Eurasia. Hyacinthaceae is a predominant group in the Cape and the Mediterranean Basin both in terms of number of species and their morphological and ecological variability. Using state-of-the-art methods in biogeography and diversification, we found that the Old World members of the family originated in sub-Saharan Africa at the Paleocene–Eocene boundary and that the two Mediterranean regions both have high diversification rates, but contrasting biogeographic histories. While the Cape diversity has been greatly influenced by its relationship with sub-Saharan Africa throughout the history of the family, the Mediterranean Basin had no connection with the latter after the onset of the Mediterranean climate in the region and the aridification of the Sahara. The Mediterranean Basin subsequently contributed significantly to the diversity of neighbouring areas, especially Northern Europe and the Middle East, whereas the Cape can be seen as a biogeographical cul-de-sac, with only a few dispersals toward sub-Saharan Africa. The understanding of the evolutionary history of these two important repositories of biodiversity would benefit from the application of the framework developed here to other groups of plants present in the two regions

Diversification into novel habitats in the Africa clade of Dioscorea (Dioscoreaceae): erect habit and elephant’s foot tubers

Background: Dioscorea is a widely distributed and highly diversified genus in tropical regions where it is represented by ten main clades, one of which diversified exclusively in Africa. In southern Africa it is characterised by a distinct group of species with a pachycaul or “elephant’s foot” structure that is partially to fully exposed above the substrate. In contrast to African representatives of the genus from other clades, occurring mainly in forest or woodland, the pachycaul taxa and their southern African relatives occur in diverse habitats ranging from woodland to open vegetation. Here we investigate patterns of diversification in the African clade, time of transition from forest to more open habitat, and morphological traits associated with each habitat and evaluate if such transitions have led to modification of reproductive organs and mode of dispersal. Results: The Africa clade originated in the Oligocene and comprises four subclades. The Dioscorea buchananii subclade (southeastern tropical Africa and South Africa) is sister to the East African subclade, which is respectively sister to the recently evolved sister South African (e. g., Cape and Pachycaul) subclades. The Cape and Pachycaul subclades diversified in the east of the Cape Peninsula in the mid Miocene, in an area with complex geomorphology and climate, where the fynbos, thicket, succulent karoo and forest biomes meet. Conclusions: Diversification out of forest is associated with major shifts in morphology of the perennial tuber (specifically an increase in size and orientation which presumably led them to become pachycaul) and rotation of stem (from twining to non-twining). The iconic elephant's foot morphology, observed in grasslands and thicket biomes, where its corky bark may offer protection against fire and herbivory, evolved since mid Miocene. A shift in pollination trait is observed within the forest, but entry into open habitat does not show association with reproductive morphology, except in the seed wing, which has switched from winged all round the seed margin to just at the base or at the apex of it, or has been even replaced by an elaiosome

Available technologies to replenish soil fertility in East Africa

Low inherent soil fertility in the highly weathered and leached soils largely accounts for low and unsustained crop yields in most African countries. But in particular, the major nutrients, nitrogen (N) and phosphorus (P), are commonly deficient in these soils. This scenario of nutrient depletion is reflected in food deficits and hence the food aid received continuously, specifically in sub-Saharan Africa. Undoubtedly, substantial efforts have been made in the continent to replenish the fertility of degraded soils in attempts to raise crop yields, towards self-sufficiency and export. Such efforts consist of applications of both organic and inorganic resources to improve the nutrient status of soils and enhanced nutrient uptake by crops, provided that soil moisture is adequate. Overall, positive crop responses to these materials have been obtained. Thus in the East African region, maize (staple) yields have been raised in one growing season from below 0.5 t/ha without nutrient inputs, to 3–5 t/ha from various nutrient amendments at the smallhold farm level. However, in spite of the positive crop responses to nutrient inputs, farmers are generally slow to adopt the soil fertility management technologies. In this paper we review the impact of some technologies, focussing the use of nutrient resources of different characteristics (qualities) in relation to improved crop yields, with an overall goal to enhance technology adoption. Thus, inorganic resources or fertilizers often give immediate crop responses, but their use or adoption is rather restricted to large-scale farmers who can afford to buy these materials. Organic resources, which include crop residues, water hyacinth and agroforestry shrubs and trees, are widely distributed, but they are generally of low quality, reflecting the need to apply large quantities to meet crop nutrient demands. Moreover, most organics will add N mainly to soils. On the other hand, phosphate rocks of varying reactivity are found widely in Africa and are refined elsewhere to supply soluble P sources. The recently developed soil fertility management options in East Africa have targeted the efficient use of N and P by crops and the integrated nutrient management approach. Some people have also felt that the repackaging of inputs in small, affordable quantities, such as the PREP-PAC described in this paper, may be an avenue to attract smallhold farmers to use nutrient inputs. Nonetheless, crop responses to nutrient inputs vary widely within and across agroecozones (AEZs), suggesting specificity in recommendations. We highlight this observation in a case study whereby eight soil fertility management options, developed independently, are being tested side-by-side at on-farm level. Farmers will be empowered to identify technologies from their own choices that are agronomically effective and economically friendly. This approach of technology testing and subsequent adoption is recommended for technology development in future