231 |
Konsumtionen av baljväxter hos vuxna : En enkätstudie / The consumption of legumes in adults : A survey studyElmblad, Ida, Cecilia, Lago January 2024 (has links)
Bakgrund: Generellt sett är den växtbaserade kosten den bästa för miljön, speciellt om man tillagar mat av exempelvis baljväxter ifrån grunden istället för att använda sig utav substitut. Intresset av vegetarisk mat har ökat och om man äter en vegetarisk kost eller byter ut köttet till baljväxter kan man minska risken för eventuella sjukdomar. Vi har idag 13 olika sorters baljväxter som odlas, skördas, förpackas och kontrolleras här i Sverige. Syfte: Syftet med denna studie var att undersöka hur vuxna människor i Sverige involverar baljväxter i kosten, hur nöjda de är med sin konsumtion och vilka motiv som ligger bakom konsumtionen. Metod: Den metod som valdes var en kvantitativ metod där vuxna människor mellan åldrarna 25–65 år fick svara på en webbenkät. Detta eftersom vi ville samla in en större mängd data för att jämföra resultat från våra informanter baserat på ålder och kön. Resultat: Motiven till att konsumera baljväxter var att för att det var gott, följt av att de är hälsosamma. Varför de inte konsumerade baljväxter handlade om ovana, okunskap, sensorik, fysiskt obehag (magont). Slutsats: För att svara till syftet om hur informanterna involverade baljväxter i kosten så var det främst vid middag och lunch som baljväxter konsumerades. Och de vanligaste baljväxterna som konsumerades var gröna ärtor och haricots verts.Mer än hälften av våra informanter ville konsumera mer baljväxter men flera av dem var även med sin konsumtion. Vad som avgjorde våra informanters inköp av baljväxter var priset och svensk producerat. Motiven till att de konsumerade baljväxter var att de tyckte det var gott samt att de tyckte de vart hälsosamma. / Background: Generally speaking, the plant-based diet is the best for the environment, especially if you prepare food from, for example, legumes from scratch instead of using substitutes. Interest in vegetarian food has increased and if you eat a vegetarian diet or replace meat with legumes, you can reduce the risk of possible diseases. We currently have 13 different types of legumes that are grown, harvested, packaged and controlled here in Sweden. Aim: The purpose of this study was to investigate how adults in Sweden include legumes in their diet, how satisfied they are with their consumption and what motives lie behind the consumption. Method: The method chosen was a quantitative method where adults between the ages of 25-65 years answered a web survey. This is because we wanted to collect a larger amount of data to compare results from our informants based on age and gender. Results: The motives for consuming legumes were because it was tasty, followed by the fact that they are healthy. Why they did not consume legumes was about unfamiliarity, ignorance, sensory, physical discomfort (stomach). Conclusion: To answer the purpose of how the informant's involved legumes in the diet, it was mainly at dinner and lunch that legumes were consumed. And the most common legumes consumed were green peas and green beans. More than half of our informants wanted to consume more legumes, but several of them were also with their consumption. What determined our informants' purchase of legumes was the price and Swedish production. The reasons why they consumed legumes were that they thought it was good and that they thought it was healthy.
|
232 |
Effect of extrusion on the nutritional value of peas (Pisum sativum), chickpeas (Cicer arietinum) and faba beans (Vicia faba) and inclusion in feeds for European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata)Adamidou, Styliani January 2008 (has links)
The current general economic and food crises have generated an unsettled future for food and feed production and prices in general. Increasing demand, prices and fluctuations in supply in world markets for fishmeal, fish oil, soybean meal, maize and wheat meal emphasize the need to reduce the dependence of the fish feed industry on these ingredients by increasing choices among a wider range of raw materials. Legume seed such as peas, chickpeas and faba beans are promising ingredients for aquafeeds due to their high protein compared to cereals but also for their energy content. The objective of the present study was to investigate the use of these legumes in both high and low inclusion level in diets for the two main species farmed in the Mediterranean countries namely, European seabass (Dicentrarchus labrax L.) and gilthead seabream (Sparus aurata L.). In Chapter 3 the effects of different processing conditions were examined on whole seed flours of tested ingredients with respect to both nutritional and antinutritional factors and physical characteristics of the experimental diet pellets including high and low levels of each legume. Extrusion of raw material resulted in a clear reduction in trypsin inhibitors (TI) with chickpeas showing a decrease of up to 90% and complete inactivation for wheat flour, while for peas and faba beans reduction was less than 50% in most cases. Extrusion processing was less effective in the reduction of phytic acid and total tannins, occasionally reaching 22% and 18% respectively. Oligosaccharides and total NSP were not drastically affected by processing, however faba bean NSP showed greater reduction. A redistribution of soluble and insoluble NSP fractions was noted for chickpea and pea flours after extrusion. Physical characteristics of the pellets were not negatively affected for any of the tested diets. In Experiment I the effects of total or partial wheat substitution by legumes were investigated on nutrient digestibility, gastrointestinal evacuation rate and serum glucose response of European seabass. Use of legumes in seabass and seabream diets resulted in an overall increase in gastrointestinal evacuation time and a delay in glucose load. Specifically, gastric evacuation time was greatly delayed when seabass was fed a diet with high levels (30%) of chickpeas, while foregut evacuation time was mostly delayed by the diet including a high level (30%) of faba beans. In addition, glucose levels in seabass serum were also affected by the type of carbohydrates ingested with wheat starch showing more rapid increase and decrease of glucose compared to fish fed pea and chickpea diets, while faba bean starch resulted in a lower glucose peak. In Experiment II growth, digestibility, hematological parameters, histological effects and fillet organoleptic characteristics and the interaction between starch inclusion level (8% and 16% or 17% and 35% of legumes respectively) and legume type were estimated when tested legumes replaced wheat in European seabass diets. Digestibility coefficients were satisfactory for all nutrients (>93%) while legume diets at a low level had beneficial effects on growth parameters when compared to the control diet, with chickpeas showing a significant improvement in SGR (P<0.05). High level legume diets did not result in any negative effect on growth. HSI was increased with increasing starch/legume inclusion in the feed and serum glucose also increased for fish fed high levels of faba beans and chickpeas. Carcass proximate composition was not affected by replacement of wheat in the diets, excluding the increase of fat content in fish fed chickpeas. Sensory analysis showed no differences between fish fed the control and high legume inclusion diets. Lastly in Experiment III growth, hematological parameters, histological effects and the interaction between starch inclusion level (low and high) and legume type were evaluated when tested legumes were included in gilthead seabream diets. Decreased, but not significantly so, growth was observed for all diets including legumes compared to the control. Poorer SGR were observed for pea and faba bean diets when these legumes were included at high levels. Liver glycogen increased with increasing starch level, but HSI did not differ significantly for any of the diet treatments. Histological examination of hindgut did not show pathological effects, such as enteritis, for in either species or for any of the diets. Increased absorptive vacuoles were found for control and pea diets (high level) only for seabass. The findings of this thesis showed that the two important species cultivated in Mediterranean countries responded differently to the same raw materials used at high levels in the diets. Overall legumes had a strong effect on gastrointestinal evacuation reducing the rate of feed or digesta passage. Peas, chickpeas and faba beans successfully replaced wheat in seabass diets resulting in improved growth coefficients. However, when the same legumes included in seabream diets growth performance was not improved compared to the wheat based diet.
|
233 |
Influence of phosphorus, sulfur, and molybdenum fertilization on the seedling vigor of selected legumes adapted to the Appalachian RegionGodbey, Alan Lee January 1985 (has links)
Legume establishment is difficult on many moderately acid, infertile soils in the humid northeastern United States. Legume seedling vigor as influence by P, S, and Mo fertilization was studied in order to determine fertilizer needs for improved establishment. A Gilpin silt loam was fertilized with 0, 22, 67, and 201 mg P kg⁻¹ in combination with 0, 22, 67, and 201 μg Mo kg⁻¹ in a greenhouse experiment in 1983. Legumes studied in this experiment were red clover (<i>Trifolium pratense</i>), white clover (<i>T. repens</i>), and birdsfoot trefoil (<i>Lotus corniculatus</i>). Field experiments with red clover, birdsfoot trefoil, and flatpea (<i>Lathyrus sylvestris</i>) were initiated in the spring of 1983 and 1984 using 0, 50, 150, and 450 kg P ha⁻¹, 0 and 60 kg S ha⁻¹, and 0 and 874 g Mo ha⁻¹. Seedling vigor as measured by plant height, trifoliate leaf count, dry weight, and trifoliate leaf area increased the greatest in the greenhouse using 22 mg P kg⁻¹ relative to the higher rates of P fertilization. Seedling vigor without applied P was poor, which clearly indicated the essential need for P in the early stages of legume growth. Molybdenum applied at 201 μg kg⁻¹ increased the growth of the greenhouse grown legumes the greatest above the 0 μg Mo kg⁻¹ rate within each added P treatment. Seedling vigor however, was not enhanced with Mo fertilization until the P deficiency was corrected. Field established legumes increased in height and dry matter yield the most using 50 kg P ha⁻¹ with respect to the additional increments of applied P, but the increase was not as great as that obtained in the greenhouse using 22 mg P kg⁻¹, This was attributed to a higher extractable P level before fertilization within the field experiments. Sulfur fertilization generally did not enhance seedling vigor in the field studies; although, red clover yield was increased using 60 kg S ha⁻¹ in the 1984 field experiment, Molybdenum applied at 874 g ha⁻¹ increased seedling vigor as measured by plant height and yield in the field experiments with or without P or S fertilization. Phosphorus uptake and Mo concentrations were increased in the plant tissues with either P or Mo fertilization. / Master of Science / incomplete_metadata
|
234 |
The influence of forage legumes on annual fodder grasses in different intercropping systems in the Limpopo ProvinceBoloko, Mahlodi Solomon January 2004 (has links)
Thesis (M.Sc. (Agricultural Management)) --University of Limpopo, 2004 / Identification of annual grass/legume intercropping or mixtures with superior nutrient traits and Dry matter (DM) production is critical to increasing productivity of the crop and animal production among small-scale farmers in the Limpopo Province. Three similar field experiments were established at different locations in the Province to determine the significance of the contribution of annual summer legumes, and cutting treatments on the nutritive value and dry matter accumulation of the popular forage sorghum (Sorghum spp) and pearl millet (Pennisetum glaucum) intercropped with cowpea (Vigna unguiculata) and dolichos (Lablab purpureus). The cropping systems evaluated were sole sorghum, sole pearl millet, sorghum + cowpea, sorghum + dolichos, pearl millet + cowpea and pearl millet + dolichos. The treatments sole sorghum and pearl millet significantly (P<0.05) outperformed the other treatments in terms of DM production at most cutting stages. The remaining four treatments though, inferior in DM in this study, yielded better than the average yield on farmers' fields in the Province. Higher protein content was obtained in mixtures than in sole cropping, and generally there was lower protein production and content at matured stages (CT3) in the study. The other chemical composition analyzed in the study was not significant for both mixtures and sole cultures.
|
235 |
Quantification and estimation of nitrous oxide emissions from dairy manure applications in a western Quebec pea-forage and an eastern Ontario alfalfa-forage cropping system : by Lynda G. Blackburn.Blackburn, Lynda G. January 2006 (has links)
No description available.
|
236 |
Quantification and estimation of nitrous oxide emissions from dairy manure applications in a western Quebec pea-forage and an eastern Ontario alfalfa-forage cropping system : by Lynda G. Blackburn.Blackburn, Lynda G. January 2006 (has links)
Agricultural systems are known to emit nitrous oxide (N2O)---a potent greenhouse gas. The roving flux tower measuring system of Agriculture and Agri-Food Canada was used to make continuous measurements of N2O fluxes in an edible pea field in Western Quebec in 2003-04 and then in an alfalfa-timothy forage field in Eastern Ontario in 2004-05. The experiment was designed to capture, at the field scale, the expected large N2O emissions occurring as a result of fertilizer application for a year, in relation to both large precipitation events and spring thaw. / Growing season N2O emissions averaged 0.5 to 5 mg N2 O-N m-2 d-1 with peaks following snow melt (between 5 and 8 mg N2O-N m-2 d-1) and manure applications (8 to 37 mg N2O-N m-2 d -1). Although generally small (<0.25 mg N2O-N m -2 d-1), emissions were detectable during the fall and winter, indicating the importance of including them in annual emission totals. / The measurements were used to verify the performance of the simulation model DNDC (DeNitrification-DeComposition) in estimating N2O emissions from legumes and in response to dairy manure application. Sensitivity tests were also carried out in which baseline input values were modified. Results suggest that the current model version (DNDC8.9) requires further modification prior to application for estimating greenhouse gas emissions in national accounting systems.
|
237 |
Flour from the Morama bean : composition and sensory properties in a Botswana perspectiveMmonatau, Yvonne 12 1900 (has links)
Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2005. / This study was undertaken in view of the high incidence of malnutrition problems such as protein-energy malnutrition and diabetes type 2 in countries like Botswana, and due to worldwide interest in underutilised and underdeveloped crops.
Morama bean, the seed of Tylosema esculentum (family Fabacae), occurs naturally in the drier areas of Southern Africa, including Botswana, where it is, to a small extent, harvested as wild plant for human consumption. Due to the potential of this crop there is increasing interest in its cultivation. Despite its traditional use as food source in Botswana, little is known about its nutritional value, benefits and disadvantages, and its use as food was therefore the reason for this research. A specific aim was to improve the school feeding programme with this readily available indigenous product.
|
238 |
Morpho-physiological characterisation of bambara groundnut (Vigna subterranea L) landraces collected in Mpumalanga ProvinceMagongwa, Selwana Michael 09 1900 (has links)
MSCAGR (Plant Production) / Department of Plant Production / See the attached abstract below
|
239 |
The effect of chemomutagenesis on root nodulation and seed protein in tepary bean (Phaseolus acutifolius)Mashifane, Dipoo Charity 18 May 2018 (has links)
MSCAGR (Plant Production) / Department of Plant Production / Tepary bean (Phaseolus acutifolius) is an important food legume originating from South America and the South-western parts of the United States. The crop is produced in many countries worldwide including South Africa. It is highly tolerant to drought and the seed contains a wide range of vitamins, minerals and protein of high nutritional quality. The genetic base of tepary bean is narrow but can be widened by chemical mutagenesis. However, there are no reports on the impact of chemical mutagenesis on the root nodulation and seed storage proteins in tepary bean. Therefore, this study was designed to examine root nodulation attributes and seed storage proteins of three tepary bean genotypes in the early mutagenic generations (M2 to M4) derived through treatment with varying doses (0.0, 0.5, 1.0, 1.5 and 2.0 v/v) of ethyl methanesulfonate (EMS). The experiment on root nodulation attributes was laid out as a 3 x 5 x 3 (genotypes x EMS doses x mutant generations) factorial design replicated three times. At harvest, shoot height (SHT), primary root length (PRL), dry weights (shoot, root and nodule), number of nodules per plant (NNP) and grain yield components such as the number of pods per plant (NPP) and number of seeds per pod (NSP) were measured. Highly significant (P≤0.01) dose effects were observed for SHT, PRL, shoot dry weight (SDW) and root dry weight (RDW). Highly significant (P≤0.01) interaction effects of mutant generation x genotype x dose were observed for NSP. A highly significant (P≤0.01) positive linear relationship was observed between the NNP and nodule dry weight (NDW). Increase in the PRL suggested that tepary bean mutants could be important in drought tolerance. EMS treatment led to an enhanced partitioning of dry matter (assimilates) to the shoots and roots. There was a three fold increase in most of the root nodulation traits at the 0.5% EMS dose.The Kjeldahl method was used for crude protein determination whereas the sodium dodecyl sulphate – polyacrylamide gel electrophoresis (SDS PAGE) was utilized in determining the protein banding patterns of the bean. There were highly significant (P≤0.01) differences among the genotypes in crude protein accumulation. Highly significant (P≤0.01) mutant generation x genotype x dose were observed for seed protein accumulation. ‘Genotype 3’ attained the highest protein content (24.23%) at 1.5% EMS dose in the M4 generation. EMS doses ≥0.5% positively stimulated protein accumulation in all genotypes but high EMS doses (2.0%) depressed protein content. There were significant variations in seed storage protein profiles among the genotypes and mutant generations. ‘Genotype 6’ showed a distinct 15.0kDa protein fragment which was absent in the majority of the remaining genotypes. The presence of distinct protein subunits in the three genotypes could be used in varietal / NRF
|
240 |
Exploring niches for short-season grain legumes in semi-arid Eastern KenyaSennhenn, Anne 06 November 2015 (has links)
Poor agricultural productivity and food security remain challenging problems for the majority of smallholder famers in Sub-Saharan Africa, including semi-arid Eastern Kenya. However, there is a general consensus that there is urgent need to significantly increase food production to meet the growing demand aligned with the continuing population growth. Furthermore, the intensification and stabilization of agricultural productivity of small-scale farming systems in Sub-Saharan Africa holds a key position to contribute to the economic development and reduce poverty. The major driver for declining or stagnating agricultural productivity in many parts of Sub-Saharan Africa, such as semi-arid Eastern Kenya, is the decline in soil fertility. Food production is not keeping pace with rapid population growth, forcing farmers to change their traditional farming systems characterized by shifting cultivation, fallow and the use of animal manure. Land and labour restrictions, as well as an increased limited resource endowment further impose the mainly smallholder farmers to focus on the production of staples, such as maize in Eastern Kenya. The investment in soil fertility management strategies remains low and the change from traditionally diverse farming systems to cereal-based monocultures has further increased the susceptibility of the fragile production systems, in particular, to impacts of climate change and variability. The predicted increase in temperature as well as inter- and intra-seasonal rainfall variability will additionally challenge the largely rainfed smallholder farming systems to sustain their productivity in the future. The integration of legumes within the farming system has been part of traditional soil fertility management strategies since legumes are able to fix atmospheric nitrogen and yields of cereal crops are generally better if grown in rotation or intercropped with legumes. In particular grain legumes are highly valued components in smallholder farming systems due to their direct contribution to food and nutrition security. Moreover, legumes display a great agro-morphological diversity with great potential for challenging environments. Challenges aligned with climate change, such as increased rainfall variability, and restricted short growing periods, make short-season grain legumes a viable option as their adaption strategy of completing their life cycle before the onset of terminal drought seems to be advantageous for cropping with frequent droughts in semi-arid areas. However, to understand the temporal and spatial resource use and use efficiency of potential short-season grain legumes, especially in respect to light and water, it is of fundamental importance to design strategies for climate smart agriculture in risky environments, including areas of semi-arid Eastern Kenya. Furthermore,quantifying possible magnitudes of yield increase of different grain legumes can be useful in identifying niches in smallholder farming systems to increase overall farm productivity and sustainability. In order to explore the potential of certain crops and cropping strategies in diverse smallholder farming systems, the development and application of crop growth simulation models proved to be an excellent tool. Since African farming systems are highly heterogeneous and dynamic simulation models manage to address the complexity of these systems which is difficult to address through classical agronomic experiments alone. Simulation models are able to capture interactions between climatic conditions, soil type and nutrient dynamics. One of the most applicable models to better understand the complexities of plant growth in response to the environment has been the Agricultural Production System sIMulator (APSIM) framework, which has been successfully used for numerous farming system analyses in semi-arid areas in the past already. Against this background the objectives of this PhD thesis were, first, to compare growth and development of three promising short-season grain legumes (common bean, cowpea and lablab) in response to plant density and water regime to evaluate their production potential and resource capture in semi-arid environments (research chapter II). This was undertaken by the implementation and analysis of comprehensive field experiments carried out over two season 2012/13 and 2013/14 in Machakos, Eastern Kenya. Additionally to this comparative study of three legume species, the photo-thermal response of early-flowering lablab types were examined in a more detail from a combination of field experiments in South Africa and controlled environments studies conducted in Göttingen, Germany with the aim to evaluate their potential adaption to (sub)-tropical environments as a climate smart farming practice (chapter I). During the field experiments conducted in Machakos Kenya crop development, biomass and yield accumulations as well as leaf area index (LAI) were measured intensively throughout the growing period to determine import agronomic and physiological parameters, such as biomass partitioning coefficient, harvest index (HI) and radiation use efficiency (RUE) for the short-season legumes common bean, cowpea and lablab (chapter II). The output derived from the field experiments was further used to quantify essential cultivar-specific parameters to better calibrate (and later validate) APSIM to simulate growth and development of short-season grain legumes under semi-arid conditions (chapter III). Finally the agro-climatic conditions and changes as well as associated risk for rainfed crop production along the Machakos-Makueni transect in semi-arid Eastern Kenya was characterized in detail to identify possible niches for short-season grain legumes. For that purpose growth and development, as well as water use and use efficiency were simulated along the environmental gradient using APSIM (chapter IV). Within the first research chapter (chapter I) a comprehensive analysis of three datasets derived from field experiments in South Africa (different sites and sowing dates) and growth chamber experiments in Germany with a combination of two temperature and four daylength regimes were analysed to evaluate the response of temperature and photoperiod on flowering time of ten promising short-season lablab accessions (CPI 525313, CPI 52533, CPI 52535, CPI 52535, CPI 52552, CPI 52554, CPI 60795, CPI 81364, CQ 3620, Q 6880B). Hence, knowledge of phenological development and, in particular, time to flowering is crucial information needed for estimating the possible production success of new accessions in new and challenging environments, such as semi-arid Eastern Kenya. Therefore, the photoperiod sensitivity was quantified using the triple-plane rate model of flowering response with time to flowering expressed in thermal time (Tt, °Cd). Additionally, piecewise regression analysis was conducted to estimate the critical photoperiod ( ) above which time to flowering was delayed significantly. Relatively high variation of time to flowering among and within accessions in days after planting (DAP) was observed, ranging from 60 to 120 DAP depending on the site, sowing date or daylength/temperature regime. Furthermore, a clear positive effect of temperature on growth and development of the tested accessions was found and time to flowering, expressed as thermal time, were relative consistent for the tested accessions, ranging from 600 to 800 °Cd for daylength <13.5 h. Only at daylength of ≥13.5 h and temperatures above 28 °C development towards flowering was delayed significantly for accessions CPI 52513, CPI 52535, CPI 52554 and CPI 60795 with vegetative growth continuing for >110 DAP. The tested lablab accessions are, therefore, considered only weak photoperiod responsive and are classified as short-day plants (SDP). Since daylength does not exceed 13 h between latitude 30°N to 30°S covering the semi-arid tropical regions, these lablab accessions can be recommend for further evaluation of their adaption to, and productivity under, on-farm conditions. However, not only lablab offers a great potential for farming in semi-arid areas, legumes in general have proved to be a promising option in small-scale farming systems by combining benefits for the farmer, soil and environment. Therefore, effects of plant density and drought on growth and development of three promising short-season grain legumes including common bean, cowpea and lablab were quantified in detail to evaluate their agricultural production potential for semi-arid areas (chapter II). Two comprehensive field experiments; a plant density trial (three different plant densities; low, medium, high) and a water response trial (three different irrigation level: rainfed, partly irrigated (total 50 mm of water per week with supplementary irrigation till bud formation, i.e., onset of flowers), fully irrigated (total of 50 mm of water per week with supplementary irrigation throughout the growing period) were conducted to quantify the effect of plant density and water availability on canopy development, biomass accumulation and partitioning to evaluate resource use and use-efficiency of the different legumes. Therefore, biomass accumulation, leaf area index (LAI) and fractional radiation interception were measured repeatedly during the growing period while grain yield were measured at maturity. From the data collected, harvest index (HI), biomass partitioning coefficient and radiation use efficiency (RUE) were calculated. It was found that clear differences in temporal and spatial development and growth among the evaluated grain legumes are the major drivers for the observed variance in the fraction of intercepted radiation, biomass accumulation and grain yield. Moreover, the response of RUE to plant density and moisture availability differed among the three legumes. Common bean had a very short growing period (10 weeks), limiting the overall production potential (1000-1900 kg ha-1) under favourable conditions through limited source-sink dynamics in terms of time and space. Nevertheless, the short life cycle and the comparatively high RUE of common bean could be advantageous in environments with very short cropping windows. Cowpea showed a high phenological plasticity and potential to respond to favourable water supply in wet years by out-yielding the other legumes and reaching yields up to 3000 kg ha-1 under non water limited conditions. However, leaf development was observed to be sensitive to drought leading to decreased biomass development and consequently yield accumulation. The RUE of both common bean and cowpea was relatively low under rainfed conditions reaching only 0.49 and 0.54 g MJ-1, respectively, but more than doubled with supplementary irrigation. In contrast, lablab displayed stable RUE values (0.76 - 0.92 g MJ-1), and was not affected by limiting water availability, resulting in yields of 1200 to 2350 kg ha-1 across all water regimes. Nevertheless the growing period length of lablab was by far the longest (~100 days) compared to common bean and cowpea. The information revealed from the field experiments conducted in semi-arid Eastern Kenya was used to determine genetic coefficients and site-specific soil characterization to parameterize APISM for short-season legumes and semi-arid conditions (chapter III). The models were validated against data from the plant density and water regime trial conducted for two season (2012/13 and 2013/14) including observed data on soil moisture, phenology, biomass accumulation and yield development. Further, the adapted APSIM legume models were used in a long-term simulation experiment to evaluate the yield potential of the different short-season legumes under various management practices. The model accuracy to predict flowering time and time of physiological maturity was excellent and with a mean root squares of derivation (RMSD) of 5 days and less. For the different plant density and water regime treatments model predictions of biomass and grain yield were satisfactory reaching RMSD values expressed in % of the observed mean of about 12 for common bean biomass and grain yield and 23.5 and 26.0 and 20.8 and 25.1 for cowpea and lablab biomass and grain yield respectively. A good relationship between simulated yield and in-crop rainfall highlighted the importance of taking a water-limited potential yield into account when management practices are designed. To further quantify the potential of different short-season grain legumes in semi-arid areas where water is the most limiting factor for agricultural production the fourth research chapter aimed to examine the water use and water-use efficiency of short-season grain legumes along an environmental gradient in semi-arid Eastern Kenya (chapter IV). First, the climate variability along this transect was characterized in great detail including the analysis of annual and seasonal temperature development, inter- and intraseasonal rainfall variability as well as the analysis of the dry spell probability throughout the year. Second, growth and development of the short season grain legumes was simulated along the transect using APISM to assess the overall performance of the short-season legumes at different sites (potential rainfall areas) and evaluate the impact of various soil types to estimate their overall agricultural production potential. The analysis of long-term weather data from the Machakos – Makueni transect in semi-arid Eastern Kenya revealed large inter-annual as well as inter- and intra-seasonal variation in rainfall. Further trends showed that the growing season rainfall slightly decreased within the last decades. A decrease in mean rainfall intensity (rainfall per rain day) was observed for the past years as well. Regarding temperature development a slight increase in mean minimum and maximum temperatures was observed over the last decades, associated with an increase in days with maximum temperatures over 25 °C. Further analysis indicated an increased probability of long dry spells within the growing periods along the Machakos - Makueni transect and highly variable start and length of growing periods - creating a risky production environment. The observed variability of determined WUE of the different short-season grain legumes in terms of dry matter and grain yield production from the long-term simulations can be attributed to the effects of both the amount of rainfall and its distribution through the growing period. Water-potential yield of common bean was relatively stable (1000 kg ha-1), independent of total in-crop rainfall and soil conditions. Cowpea growth and development was, however, very responsive to in-crop rainfall. This is obvious as in wet years cowpea yield is very high (3000 kg ha-1), whereas in drier years grain yields (>500 kg ha-1) are even lower than common bean grain yields. Lablab yields instead, were fairly robust (1000 – 3000 kg ha-1) and higher than those observed for common bean, even at low in-crop rainfall levels. Determined WUE in terms of biomass production was highest for cowpea and lablab (8 – 12 kg ha-1 mm-1 Et) in comparison to common bean (6 – 8 kg ha-1 mm-1 Et), but in terms of grain yield production only lablab (4 - 6 kg ha-1 mm-1 Et) achieved higher values compared to common bean (3 - 5 kg ha-1 mm-1 Et) and cowpea (2 - 4 kg ha-1 mm-1 Et). The magnitude of the soil impact on crop growth and development as well as water use and use efficiency differed with texture and water-holding capacity of the soil, soil evaporation and the interaction between these factors, rainfall pattern, crop canopy architecture and management. The current results revealed that resource capture of the studied legumes was primarily outlined by their characteristic phenological development and further determined by phenological plasticity related to water deficit and the ability to respond to environmental conditions. Pronounced spatial and temporal differences in water use and use efficiency of the studied legumes were therefore first driven by the varying phenological development and secondly by species-specific morphological and physiological characteristics and mechanisms. However, the ability of the legumes to respond to environmental conditions and the degree of phenological plasticity have evolved different strategies to cope with challenging conditions in semi-arid areas. To consider the pronounced temporal and spatial differences in resource use and growth characteristics is fundamental to better design strategies for climate smart agriculture in the smallholder farming systems of Eastern Kenya. The calibrated and validated APSIM legume models can be used to make appropriate management decisions to provide smallholder farmers in semi-arid with alternative options to better integrate short-season legumes to improve the overall farm productivity and sustainability. Crop models such as APSIM allow to account for necessary complexity but at the same time manage to address high location specificity. This is particular important in diverse smallholder farming systems in semi-arid areas to adequately address their individual needs and opportunities. The variability in phenological development and resource use and use efficiency observed for the different legumes and their different adaption mechanism to semi-arid areas offer great potential for small-scale farming systems in challenging environments. APSIM seems to be a great tool to explore their site-specific agricultural production potential and the impact of different management strategies is semi-arid Eastern Kenya. However, socio-economic constraints including labour requirements and market opportunities need to be assed in more detail to better channel agricultural recommendations to increase the possible adaption among farmers. Furthermore, long-term aspects of better integrated legumes towards improved farm sustainability and increased eco-efficiency need to be determined with the help of multidimensional whole farm analysis tools in order to proceed beyond crop and plot level in the future.
|
Page generated in 0.0412 seconds