Factors in the suboptimum performance of rural water supply systems in the Ethiopian highlands

Access to safe drinking water services in the Ethiopian Highlands is one of lowest worldwide due to failure of water supply services shortly after construction. Over hundred water supply systems were surveyed to find the underlying causes of failure and poor performance throughout the Amhara Regional State. The results show generally that systems with decision-making power at the community level during design and construction remained working longer than when the decisions were made by a central authority. In addition, the sustainability was better for water systems that were farther away from alternative water resources and contributed more cash and labour. The results of this study of the importance of decision-making at the local level in contrast to the central authority is directly applicable to the introduction of rain water management systems as shown by earlier efforts of installing rain water harvesting systems in the Ethiopian highlands

Exploiting Grain-Filling Rate and Effective Grain-Filling Duration to Improve Grain Yield of Early-Maturing Maize

Early-maturing maize (Zea mays L.) genotypes yield 15 to 30% less than late-maturing genotypes. One strategy for improving grain yield in the early-maturing group involves assessment of grain-filling traits as secondary traits for selection for high grain yield. In this study, we investigated the possibility of using grain-filling rate and duration for improving grain yield in early-maturing tropical maize. Forty-four hybrids generated using North Carolina design II were evaluated at CIMMYT-Zimbabwe during the 2011/2012 season under irrigated and nonirrigated environments. Although grain-filling rate and effective grain-filling duration were negatively correlated, several hybrids were distinctly above the trend line. The earliest-maturing hybrid took 127 d to reach physiological maturity and produced grain yields comparable to those of the medium-maturing genotypes (7 t ha−1). It had a high grain-filling rate of 2.40 g per plant d−1 (18% higher than those of the low-yielding hybrids) and a relatively longer effective grain-filling duration. Grain-filling rate and effective grain-filling duration had high coefficients of genetic determination, positive correlations with grain yield, low error terms, and low genotype × environment interactions, making them appropriate selection traits for improved grain yield. The study shows that it is possible to develop high-yielding early- to medium-maturing maize hybrids based on favorable combining ability values for grain-filling rate and duration

Variability of Grain-filling Traits in Early Maturing CIMMYT Tropical Maize Inbred Lines

Grain-filling rate (GFR), effective grain-filling duration (EGFD) and total grain-filling duration (TGFD) are important physiological traits of maize (Zea mays L.) grain yeild (GY) formation. To devise effective breeding strategies, the genetic nature of these traits is pre-requisite for improvement in early maturing maize

Evaluating maize genotype performance under low nitrogen conditions using RGB UAV phenotyping techniques

Maize is the most cultivated cereal in Africa in terms of land area and production, but low soil nitrogen availability often constrains yields. Developing new maize varieties with high and reliable yields using traditional crop breeding techniques in field conditions can be slow and costly. Remote sensing has become an important tool in the modernization of field-based high-throughput plant phenotyping (HTPP), providing faster gains towards the improvement of yield potential and adaptation to abiotic and biotic limiting conditions. We evaluated the performance of a set of remote sensing indices derived from red–green–blue (RGB) images along with field-based multispectral normalized difference vegetation index (NDVI) and leaf chlorophyll content (SPAD values) as phenotypic traits for assessing maize performance under managed low-nitrogen conditions. HTPP measurements were conducted from the ground and from an unmanned aerial vehicle (UAV). For the ground-level RGB indices, the strongest correlations to yield were observed with hue, greener green area (GGA), and a newly developed RGB HTPP index, NDLab (normalized difference Commission Internationale de I´Edairage (CIE)Lab index), while GGA and crop senescence index (CSI) correlated better with grain yield from the UAV. Regarding ground sensors, SPAD exhibited the closest correlation with grain yield, notably increasing in its correlation when measured in the vegetative stage. Additionally, we evaluated how different HTPP indices contributed to the explanation of yield in combination with agronomic data, such as anthesis silking interval (ASI), anthesis date (AD), and plant height (PH). Multivariate regression models, including RGB indices (R2 > 0.60), outperformed other models using only agronomic parameters or field sensors (R2 > 0.50), reinforcing RGB HTPP’s potential to improve yield assessments. Finally, we compared the low-N results to the same panel of 64 maize genotypes grown under optimal conditions, noting that only 11% of the total genotypes appeared in the highest yield producing quartile for both trials. Furthermore, we calculated the grain yield loss index (GYLI) for each genotype, which showed a large range of variability, suggesting that low-N performance is not necessarily exclusive of high productivity in optimal conditions.This research and APC was funded by Bill & Melinda Gates Foundation and USAID Stress Tolerant Maize for Africa program, grant number [OPP1134248], and the MAIZE CGIAR research program. The CGIAR Research Program MAIZE receives W1&W2 support from the Governments of Australia, Belgium, Canada, China, France, India, Japan, Korea, Mexico, Netherlands, New Zealand, Norway, Sweden, Switzerland, U.K., U.S., and the World Bank

Genetics of grain yield and its components in wheat under heat stress

Heat stress is a matter of a great concern for the wheat crop. Heat stress usually either hastens crop development or shortens the grain filling duration, which severely reduces grain yield. Being a complex trait, understanding the genetics and gene interactions of stress tolerance are the two primary requirements for improving yield levels. Genetic analysis through generation mean analysis helps to find out the nature of gene actions involved in a concerned trait by providing an estimate of main gene effects (additive and dominance) along with their digenic interactions (additive × additive, additive × dominance, and dominance × dominance). In the present investigation, we elucidated the inheritance pattern of different yield contributing traits under heat stress using different cross combinations which could be helpful for selecting a suitable breeding strategy. Thus six generations of five crosses were sown normal (non-stress, TS) and late (heat stress, LS) in a randomized block design with three replications during two crop seasons. The model was not adequate for late sown conditions indicating the expression of epistatic genes under stress conditions. The traits i.e. Days to heading (DH), Days to anthesis (DA), Days to maturity (DM), Grain filling duration (GFD), Grain yield (GY), Thousand grain weight (TGW), Grain weight per spike (GWS) and Heat susceptibility index (HSI) under heat stress conditions were found under the control of additive gene action with dominance × dominance interaction, additive gene action with additive × dominance epistatic effect, dominance gene action with additive × additive interaction effect, additive and dominance gene action with dominance × dominance interaction effect, additive gene action with additive × dominance epistatic effect, additive gene action with additive × additive interaction effect and dominance gene action with additive × additive interaction effect, respectively

Improvement in yield of bread wheat cultivars released in Ethiopia from 1949 to 1987

Thirteen bread wheat ( Triticum aestivum L.) cultivars popular in the highlands of Ethiopia and representative of the period from 1949 to 1987 were studied for two cropping seasons in Ethiopia to estimate progress made in improving grain yield. The selected cultivars were grown with the effects of other genetic changes minimized by using fungicides to control foliar diseases, nets to prevent lodging, and periodic hand weeding to control weeds. Adequate levels of nutrients were also supplied. Significant differences were observed among cultivars for all crop parameters studied. The grain yield of bread wheat cultivars released since 1949 has increased at a mean rate of 77 kg ha-1yr-1 (2.21%) as measured in central Ethiopia and 50 Kg ha-1y-1(1.77%) under warmer and drier conditions in southeastern Ethiopia. Grain Yield was significantly and positively correlated with harvest index, grains m-2, spikelets spike-1 and grains spike-1. Genetic improvement has substantially increased the grain yield of rainfed bread wheat in the highlands of Ethiopia, resulting from an improved harvest index associated with an increased number of grains spike-1 and, as a result, grains m-2. Wheat breeders in Ethiopia should continue to emphasize spike fertility as a selection criterion for high grain yield

Improvement in Yield of Bread Wheat Cultivars Released in Ethiopia From 1949 to 1987

Thirteen bread wheat ( Triticum aestivum L.) cultivars popular in the highlands of Ethiopia and representative of the period from 1949 to 1987 were studied for two cropping seasons in Ethiopia to estimate progress made in improving grain yield. The selected cultivars were grown with the effects of other genetic changes minimized by using fungicides to control foliar diseases, nets to prevent lodging, and periodic hand weeding to control weeds. Adequate levels of nutrients were also supplied. Significant differences were observed among cultivars for all crop parameters studied. The grain yield of bread wheat cultivars released since 1949 has increased at a mean rate of 77 kg ha-1yr-1 (2.21%) as measured in central Ethiopia and 50 Kg ha-1y-1(1.77%) under warmer and drier conditions in southeastern Ethiopia. Grain Yield was significantly and positively correlated with harvest index, grains m-2, spikelets spike-1 and grains spike-1. Genetic improvement has substantially increased the grain yield of rainfed bread wheat in the highlands of Ethiopia, resulting from an improved harvest index associated with an increased number of grains spike-1 and, as a result, grains m-2. Wheat breeders in Ethiopia should continue to emphasize spike fertility as a selection criterion for high grain yield