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GROWTH, REPRODUCTIVE AND YIELD RESPONSES AND OIL CONTENT OF ETHIOPIAN MUSTARD (Brassica carinata A. Braun) GENOTYPES AT DIFFERENT ALTITUDES
(Hawassa University College of Agriculture, 2021) YENENESH TEFERA WOLDE
Ethiopian mustard (Brassica carinata A. Braun) is an important vegetable and oil seed crop in the highlands of Ethiopia. The crop has attracted a lot of interests in recent years due to its potential as a feedstock and as a biofuel crop. However, there are little research effort towards the crop in terms of productivity and optimized agronomic requirements. The seed and oil yield of the crop is constrained by a number of factors among which the growing climate is the paramount factor. Therefore, a pot experiment was conducted at three locations with varying altitudes to investigate the impact of altitude on phenology, reproduction, growth, yield and oil content of 11 Brassica carinata genotypes. The study was conducted from January 2011 to June 2011, at three altitudes i.e. high (Bale Goba, 2743 masl), mid (Arsi Negele, 2043 masl) and low (Dilla, 1416 masl)) under irrigated condition using 11genotyp of Brassica carinata which resulted in 33 treatments. The factorial experiment was laid out in a completely randomized (CRD) design with three replications as pot experiment in a controlled edaphic condition. Data were collected on phenological and reproductive traits, growth parameters, yield and yield related traits and oil content. The result of the study revealed that interactions between altitude and genotype very highly significantly (p<0.0001) influenced all characters, except number of leaves per plant and pod length which were only influenced by the main factors. Increasing the altitude from low to high delayed the time for all the studied phenological traits. As a result, the number of days for 50% emergence, 50% flowering and 90% maturity were increased from 6.33 to 17.67, 50 to 107.33 and 92.67 to 147 respectively and the earliest genotypes to attain days to 50% emergence and days to50% flowering were 23601 respectively. The genotype to attain shortest days to maturity (92.67 days) was genotype 21338 at lower altitude. Reproductive traits showed an increase with increasing altitude. Hence the highest flower number per plant (218.6) was attained from genotype 23601 at higher altitude. Similarly Yield and yield components are also increased with increasing altitude. The maximum seed yield per hectare (194556Kg) was recorded from genotype 23601 at high altitude followed by the genotypes 202488(1538.89Kg) and 215187(1503.33Kg) at mid altitude. The highest oil percentage (41.79%) was recorded from genotype yellow dodolla at the same altitude. Hence, from the result it can be concluded that, high and mid altitudes respectively were appropriate to maximize Brassica carinata seed and oil yield. However, since the experiment was done only for one season and with limited number of genotypes repeating the experiment over different seasons with more number of genotypes at field condition will be demanding to come up with plausible recommendation.
CASSAVA PRODUCTION PRACTICES, UTILIZATION AND EVALUATION AS INGREDIENT FOR INJERA MAKING AT AMARO AND OFFA DISTRICTS, SOUTHERN ETHIOPIA
(Hawassa University College of Agriculture, 2021) SHIFERAW BOGALE MANDOYE
Cassava is commonly known as the poor man’s crop and emerging as dominant staple and alternative food security crop in southern Ethiopia. However, limited research has been done so far for identifying suitability variety as ingredient for injera making. Therefore, household survey and laboratory analysis experiment were conducted to determine farmer’s practices in selecting suitable cassava variety with its ratio as ingredient of injera making. Based on the survey result laboratory analysis was conducted with different ratio of cassava blended with teff to verify the farmer’s practice. Purposive sampling technique was used to select the respondent households. The survey result revealed that Qulle (20.8%), Kello (12.5%) and both Qulle and Kello (70%) were identified as the common cassava varieties in the study area. The household reported that, yield, maturity earliness, resistance to disease and pest (53.3%) are the major criteria for selecting the variety. About 45% of the respondent were used 40 to 60 ratio of cassava with teff followed (38.3%) by 50 to 50 as ingredient of injera. During the laboratory analysis, two cassava varieties (Qulle and Kello) and five blending ratios (10, 20, 30, 40 and 50%) of cassva with teff were tested in Randomized Completed Design with three replications. Teff with 100% was used as a control. The result revealed that, cassava varieties and blending ratio had significant effect on protein, fiber, fat, ash and cyanide content while non-significant effect on moisture and carbohydrate, respectively. Higher protein, fiber and fat, ash content was recorded from 90% teff with 10% Qulle and Kello variety. The result further explained that, as cassava proportion were increased; protein, fat, ash and fiber content decreased but moisture and carbohydrate content were increase. Composite injera with 50% of Kello variety has highest cyanide content (0.48mg/100g) than that of Qulle. Higher score of acceptability for texture (7.23%), sourness (7.56%), aroma (7.58%) and taste (7.33%) were recorded from 10% of Kello variety than Qulle. Therefore, it can be concluded that, for cassava-teff injera preparation mixing the cassava up to 30% is found to be acceptable. Further research should be done in cassava starch characterization as the staling and less eye formation are the major traits to be improved for increasing the quality of injera prepared from teff mixed with cassava.
MORPHO - PHYSIOLOGICAL BASED SCREENING OF SWEETPOTATO (Ipomoea batatas L.) VARIETIES FOR MOISTURE STRESS CONDITION AT HAWASSA, ETHIOPIA
(Hawassa University College of Agriculture, 2021) SERKALEM ESHETU G/WOLD
Sweetpotato is one of the potential root and tuber crop playing major role in food security due to its high yielding and adaptability to diverse environmental conditions. However, various constraints like biotic and abiotic factors reported for the low productivity of the crop. Therefore, the study was designed to evaluate sweetpotato varieties morpho-physiological characters under different irrigation interval in shade house condition at Hawassa, Ethiopia from October to March, 2019/20. The treatment were comprised of a factorial combination of three sweetpotato varieties (NASPOT 12 O, Kulfo and Dilla) and four irrigation intervals (daily, 7 days, 14 days and 21 days) in complete randomized design (CRD) with three replications. Data on morpho-physiological and yield parameters were collected. The result revealed that, main effect of varieties and irrigation interval has a significant effect on vine length, leaf temperature and vine fresh weights. Leaf number, leaf area, chlorophyll a, b and total (TC), maximum quantum yield, proline content, photosynthesis rate, transpiration rate, stomata conductance, IWUE, RLWC, tuber fresh weight, total biomass and tuber number were significantly influenced due to interaction effect of two main factors. Most of parameters were significantly reduced with increased irrigation interval except Proline content and leaf temperature. Maximum tuber fresh weight (700 g) was recorded from NASPOT 12 O as compared to Dilla (533.33 g) and Kulfo (233.33 g) varieties. In the case of physiological response NASPOT 12 O treated with daily irrigation gave maximum concentration of chlorophyll a, b and total (TC), Photosynthesis rate, transpiration rate and stomata conductance in leaf as compared to other varieties. The maximum proline content was observed from variety “NASPOT 12 O” with 21 days irrigation interval whereas; the minimum was from all varieties with daily, seven and fourteen days irrigation which was statistically similar. Dilla and NASPOT 12 O varieties had better relative leaf water content as irrigation interval increases but variety Kulfo show strong reduction. It can be concluded that, Variety “NASPOT 12 O” was considered to be more tolerant as compared to other varieties. This is, therefore, NASPOT 12 O with 7 days irrigation interval recommended and in areas where moisture is a limiting factor NASPOT 12 O varieties with 14 days irrigation interval might be recommended for small scale farmers. Consequently, further research is needed for morphological and physiological responses under different varieties and water stress under open field condition before a generalized conclusion can be drawn.
ASSESSMENT OF SWEETPOTATO (Ipomoea batatas (L.) Lam) SEED SYSTEM AND THE EFFECT OF VINE CUTTING PORTIONS ON PERFORMANCE OF SELECTED VARIETIES
(Hawassa University College of Agriculture, 2021) REHIMA SHUKRE SEID
Sweetpotato is an important subsistence crop with high food and nutrition security significance in Southern Ethiopia including Sidama Region. The productivity of sweetpotato in Ethiopia is very low compared to the global average. The low productivity of sweetpotato in Ethiopia is often linked to multitude of factors, but mainly ascribed to seed vine inaccessibility, lack or less adoption of improved varieties and use of sub-optimal agronomic practices, particularly related to seed vines. The present study was conducted with the objective of assessing sweetpotato seed system and evaluation of the performance of selected varieties established from different vine cutting portions in Sidama Region, Ethiopia. The seed system assessment was conducted in 2018/2019 involving 120 sweetpotato growing households from four Kebeles of Boricha and Dale woredas while the field experiment was done at Hawassa University research field. Survey results revealed that sweetpotato production in Sidama mainly occurs in smallholder settings on average farm size of ≈ 0.15 ha under variable socio-economic contexts. The highest average number of planted sweet potato seed vines (6855.53) per household was reported from Debub Mesenkele whereas the lowest (1704.03) was reported from Hanja Chafe. Most farmers used vine with middle cutting portions and medium seed age in studied area. Farmer’s meet their seed needs from multiple sources including own-saving, free purchasing, institutional donations, and exchange with relatives and fellow farmer friends across the community, but they heavily rely on their own stocks and on immediate circle of relatives and friends. The field experiment consisted three cutting portions (apical, basal and middle) combined with four selected varieties (Awassa-83, Alamura Hawassa -09 and Kabode) arranged in factorial-RCBD using three replications. The result revealed that from the 20 examined response parameters, only three including marketable root yield (ton/ha), root dry weight (g) and leaf area (cm 2 ), were significantly affected by vine cutting portions and varietal interaction effects. The remaining 17 parameters showed only main effect factors either for vine cutting portion, variety or both. The apical vine portion with total root yield of 38.5 ton/ha produced almost twice as high as basal cutting portion (19.8 tone/ha). Similarly, for marketable root yield (ton/ha), taking vines from older basal portion instead of the tender terminal apical regions of vines can decrease total marketable root yield by up to 51.43 %, depending on varieties. Variety Hawasa-09 out-performed the other three varieties for yield and yield component traits including total root yield (49.6 ton/ha), total root number and marketable root number. In the inter-trait correlation analysis, significant (p < 0.05) and negative correlations showed that early bud sprouting (r = -0.51) and crop maturity (r = - 0.49) did not favor for higher marketable root yields. Overall, sweetpotato production in Sidama is constrained severely by limited access to the required quantity of good quality seed-vines. From our experiment, regardless of varietal differences, apical seed-vine portions out-performed for important yield and yield component traits. We recommend evaluation of more number varieties accompanied by GXE multi-locations trials for evaluation of vine cutting portion for use as planting materials.
VOLTAGE CONTROL OF A DC-DC BUCK CONVERTER FOR ELECTROLYSIS USING FRACTIONAL ORDER SLIDING MODE CONTROL
(Hawassa University, 2020-10-22) DEMOZ LISANEWORK WELDETSADIK
Switching DC-DC converters are non-linear and the most widely used circuits in power
electronics. Generally, they are used in all conditions where there is need of stabilizing a
given DC voltage to a desired value. DC-DC buck converters are used in voltage step down applications. A DC solar energy is converted to the desired voltage level using the a
buck converter, for hydrogen generation with electrolysis process have been investigated.
The electrolysis load for hydrogen production especially needs low voltage and high
currents. To have these conditions the converter must be designed and controlled
sensitively. For this aim, the fractional order sliding mode (FOSM) controller is used as a
solution in this paper.
Simulation results showed that, FOSM controller improved the rise time and settling time
by 2% and 15.3% respectively compared the values using PID controller. Similarly, FOSM
controller shows comparatively best performance improvement over SOSM in terms of
high reduction of unwanted oscillation in addition to the rise time, settling time
improvements. The overshoot is reduced from 46.3% to 5.208% using PID controller while
it is totally removed when SOSM and FOSM controllers are applied. Both SOSM and
FOSM controllers overcome the effect of electrolysis load variations. The actual output
voltage is not deviated from desired value even for large input voltage variation using
FOSM controller. Furthermore, the performance of controller was tested by increasing
and decreasing 58.52% electrolysis load from operating point while desired output voltage
is decreased by 50% and increased up to 20% from operating point. Generally, from the
above analysis results it is evident enough that FOSM is better and preferable controller
than the SOSM and PID controller