Improved Fast Neutron Spectroscopy via Detector Segmentation

Organic scintillators are widely used for fast neutron detection and spectroscopy. Several effects complicate the interpretation of results from detectors based upon these materials. First, fast neutrons will often leave a detector before depositing all of their energy within it. Second, fast neutrons will typically scatter several times within a detector, and there is a non-proportional relationship between the energy of, and the scintillation light produced by, each individual scatter; therefore, there is not a deterministic relationship between the scintillation light observed and the neutron energy deposited. Here we demonstrate a hardware technique for reducing both of these effects. Use of a segmented detector allows for the event-by-event correction of the light yield non-proportionality and for the preferential selection of events with near-complete energy deposition, since these will typically have high segment multiplicities.Comment: Accepted for publication in Nuclear Instruments and Methods in Physics Research Section

Food insecurity in Farta District, Northwest Ethiopia: A community based cross–sectional study

Background Access to sufficient food is essential for household welfare as well as for accomplishing other development activities. Households with insufficient access to food often face other challenges related to food insecurity including poor health and a decline in productivity. These challenges can often create a vicious circle whereby households are unable to produce enough food even during a good crop season. Thus, this study aimed to determine the magnitude of food insecurity and its determinants in rural households of Farta District, Northwest Ethiopia. Methods A community based cross-sectional study was conducted from September to October 2012. Household heads were recruited using a multistage random sampling technique. Data were collected by face-to-face interviews using the Household Food Insecurity Access Scale (HFIAS) tool after verbal informed consent. Data were entered to Epi info 2002 and exported to SPSS version 16 for analysis. Multiple logistic regressions were fitted and odds ratios with 95% confidence intervals were calculated to identify associated factors and control confounding effect. Results A total of 836 households were included in this study. Nearly three quarters of the households (70.7%) had food insecurity. Households headed by females (AOR = 3.18, 95% CI:1.08, 15.21), lack of education (AOR = 2.59, 95% CI: 1.46, 4.60), family size of 4-7 (AOR = 2.39, 95% CI: 1.21,4.70), family size of >7 (AOR = 13.23,95% CI:6.18, 28.32), few or absence of livestock (AOR = 5.60, 95% CI:1.28, 24.43), absence of income from off-farm activities (AOR = 3.12, 95% CI:1.53, 6.36), lack of irrigation (AOR = 3.54, 95% CI:2.14, 5.18) and lack of perennial income (AOR = 3.15, 95% CI:1.88, 5.27) were factors associated with food insecurity. Conclusions This study revealed that most households of the district were food insecure. Hence, the promotion of contraceptive use, off-farm employment activities and the development of small scale irrigation are important recommendations to reduce food insecurity

Efficient in vitro multiplication protocol for Vanilla planifolia using nodal explants in Ethiopia

Vanilla planifolia Andr. is a tropical commercial spice crop known for its popular flavoring substance called vanillin. Vanillin is the second most expensive spice in the world market, next to saffron. Ethiopia has favorable environment for vanilla production and the crop has huge local and international market. There is a soaring investors’ interest to produce vanilla in the country provided there is plenty and reliable planting material supply. In line with this, we report efficient and reproducible tissue culture based mass propagation protocol for elite vanilla clones introduced into the country. Significant difference (p < 0.0001) was observed among selected hormone combinations for rate of shoot multiplication. An average number of 3.12 to 4.17 shoots were obtained after 45 days of nodal culture on MS media supplemented with BA combined with KIN and NAA. The optimum level found was 1 mg/L BAP combined with 1.5 mg/L KIN. Both hormone free and MS media supplemented with different levels of NAA gave 100% rooting for shoots separated and transferred onto rooting media. More than 85% survival rate was achieved during acclimatization. The availability of this protocol is a key step towardslarge scale vanilla production in Ethiopia

Performance assessment of drought tolerant maize hybrids under combined drought and heat stress

Open Access Journal; Published online: 22 Nov 2018Drought and high temperature are two major factors limiting maize productivity in sub-Saharan Africa. An increase in temperature above 30 °C reduces yield by 1% under optimal rain-fed condition and by 1.7% under drought stress (DS) and up to 40% under combined drought and heat stress (DSHTS). Approaches that improve performance under the two stresses are essential to sustain productivity. The objectives of this study were to (i) assess the extent of variation in tolerance to DSHTS from among the existing best drought tolerant (DT) hybrids; (ii) examine the response patterns of the hybrids to DSHTS; (iii) identify traits that contributed to better performance under DSHTS; and (iv) select the best hybrids with tolerance to DSHTS stress. We evaluated 40 DT hybrids under DSHTS, DS, and well-watered (WW) conditions for three years. Highly significant (p < 0.001) differences were found among hybrids for grain yield and other traits. Moderately to low repeatability values were detected for grain yield under DS (0.63) and under DSHTS (0.48). Grain yield under DS was not correlated with grain yield under DSHTS (r = 0.29; p = 0.06), but it was correlated with grain yield under WW (r = 0.74; p < 0.001). Grain yield was strongly correlated with ears per plant, ear and pant aspects, days to anthesis and silking under both DS and DSHTS. Tassel blast accounted for 28% of the yield reduction under DSHTS. The top five DT hybrids produced 9 to 26% more grain yields than the best commercial hybrid. Three hybrids produced high grain yields under DTHTS and DS as well as under WW. These hybrids will be tested further in collaboration with partners for possible release

Assessing effect of marker-based improvement of maize synthetics on agronomic performance, carotenoid content, combining ability and heterosis

Open Access Journal; Published online: 22 Oct 2020Vitamin A deficiency (VAD) is a serious problem in sub-Saharan Africa (SSA) and other parts of the world. Understanding the effect of marker-based improvement (MARS) of two maize synthetics (HGA and HGB) representing different heterotic groups on their agronomic performance, carotenoid content, and combining abilities could help identify suitable sources to develop divergent inbred lines for optimizing heterosis. This study involved three selection cycles each of the two synthetics and their nine varietal-cross hybrids together with a released check variety was conducted across four diverse locations in Nigeria in 2018 and 2019. Environment and hybrid effects were significant on grain yield and other agronomic traits as well as provitamin A content and other carotenoids. Genetic improvement per cycle of MARS in the parental synthetics was 15% for provitamin A, 25% for β-carotene and 26% for lutein in HGA and 4% for grain yield, 3% for zeaxanthin and 5% for α-carotene in HGB. Grain yield and agronomic traits of the two maize synthetics were controlled by additive and non-additive gene effects, while provitamin A content and other carotenoids were mainly controlled by additive gene effects. Some selection cycles which were high in grain yield and provitamin A content were identified as potential sources of new and divergent maize inbred lines in maize breeding programs. Some varietal-cross hybrids expressed significant mid-parent heterosis for grain yield and moderate mid-parent heterosis for provitamin A, β-carotene and xanthophylls. These hybrids could be commercialized at reasonable prices to small-scale farmers in rural areas that are most affected by vitamin A deficiency

Identifying suitable tester for evaluating Striga resistant lines using DArTseq markers and agronomic traits

Open Access Journal; Published online: 18 June 2021A desirable tester that elicits greater genetic difference in Striga resistance among test crosses in a breeding program has not been reported. Therefore, this study was conducted to characterize 30 Striga resistant yellow endosperm maize inbred lines and three testers with varying resistance levels to Striga using DArTseq SNP markers and agronomic traits to identify a suitable tester for resistance hybrid breeding. Marker-based and agronomic trait-based genetic distances were estimated for yellow endosperm maize inbred lines and testers with varying resistance levels to Striga. The Marker-based cluster analysis separated the Striga resistant lines and testers into two distinct groups. Although the susceptible tester (T3) was the most distantly related to the 30 Striga resistant inbred lines, it exhibited a narrower range in genetic distance estimates and poor agronomic performance under Striga infestation in crosses with the resistant lines. In contrast, the resistant tester (T2) showed a broader range in genetic distance estimates in pairs with the 30 resistant lines. Also, it formed many high yielding hybrids with desirable traits under parasite pressure. Furthermore, the most significant positive association between agronomic trait-based and marker-based distance estimates (r = 0.389, P = 0.01) was observed when T2 has paired with the Striga resistant maize inbred lines. It thus appears that T2 may be used as a suitable tester to determine the breeding value of lines in hybrid maize resistance breeding programs. T2 was the most suitable tester, with a tolerant tester (T1) as an alternative tester to characterize the combining ability of Striga resistant maize inbred lines. This result can also encourage other breeders to investigate testers relative discriminating ability with varying levels of resistance in hybrid breeding for resistance to diseases, pests, and other parasitic plants

Effectiveness of yellow maize testers with varying resistance reactions to Striga hermonthica for evaluating the combining ability of maize inbred lines

Open Access Journal; Published online: 28 Aug 2020The choice of an appropriate tester is important for success in resistance hybrid breeding programs. Limited information is available on the most suitable testers that allow the selection of yellow endosperm maize inbred lines with good combining ability for resistance to witchweed (Striga hermonthica) and superior agronomic performance in hybrids targeted to areas infested with the parasite. Testcrosses of 30 Striga-resistant yellow endosperm maize inbred lines with three testers having varying levels of resistance to S. hermonthica were evaluated at Abuja and Mokwa in Nigeria under Striga-infested and non-infested conditions in 2018 and 2019. The lines × tester interaction was significant for grain yield under Striga infestation, indicating that the performance lines in testcrosses varied with the testers. The respective average general combining ability effect of lines and testers was 1.5 and 32.4 times greater than the corresponding specific combining ability effects under infestation, showing the greater importance of additive gene action controlling the performance of testcrosses under Striga infestation. The different testers exhibited a different capacity to discriminate among the test lines with the susceptible tester being the least effective. Most of the criteria used to determine the best tester favored the selection of the tolerant and resistant testers as promising candidates to identify superior Striga-resistant yellow endosperm inbred lines for the hybridization and development of resistant hybrids. The results of this study demonstrated that testers with a high frequency of desirable alleles were superior to the tester with a low frequency of favorable alleles in hybrid breeding programs for resistance to S. hermonthica