Heritability of drought adaptive traits and relationships with grain yield in maize grown under high plant population

In low-moisture stress areas with unpredictable rain-free season, high-plant population is suggested for screening maize genotypes with tolerance to drought at flowering as alternative to stressed normal plant density. To confirm efficiency of this option, randomly derived 196 S1 lines from A-511 Maize Population were tested at two plant densities in combination with well watered and drought stressed at flowering. In each of the four environments, the S1 lines were grown in 14 x 14 alpha lattice experimental design to estimate: (i) broad-sense heritability of each tested trait; and (ii) relationships between grain yield and drought adaptive traits. The broad sense heritabilities of flowering traits were relatively high across all growing conditions. In contrast, the heritability for number of ears per plant (EPP) increased with increasing plant density and/or drought stress as for yield and most other traits decreased. Besides, significant association of grain yield with its components and flowering traits observed across all growing conditions in the same direction and opposite direction, respectively. Although relationships of yield with the drought adaptive traits increased consistently with increasing stress, it was highly dependent on its components in all environments but only under stress condition on anthesis-silking interval (ASI). In addition to significant expression of desirable parameters for a population improvement in the stress tolerance, ASI and EPP are relatively easily measured on field as compared to other drought adaptive traits. Thus, the strong dependence of yield on both traits and their high heritability in each or combination of the two stresses have confirmed possibility of using them for screening drought tolerant maize under high plant density, specially in areas that lack rain-free season.Keywords: Drought adaptive trait, high plant density, heritabilit

Mega-Environment Targeting of Maize Varieties using Ammi and GGE Bi-Plot Analysis in Ethiopia

አህፅሮት በቆሎ በኢትዮጵያ  ከሚመረቱ የምግብ ሰብሎች መካከል በምርትና ምርታማነቱ ግንባር ቀደም ስፍራን የያዘ ሰብል ነው፡፡  የሰብሉን ምርታማነት ከሚደግፉ የተለያዩ መንስዔዎች  ውስጥ በዋናነት ከፍተኛውን  ቦታ  የሚይዙት ከጥናትና ምርምር  የተገኙ የተሻሻሉ ዝርያዎች ቢሆኑም ሁሉም ዝርያዎች   በበቆሎ አብቃይ ስነ-ምህዳሮች  ላይ ተዘርተው  በምርታማነታቸው ወጥነት የማያሳዩ መሆናቸው ይታወቃል፡፡ እንደየአካባቢው የአይር ፀባይ፤ የአፈር ዓይነትና የዝናብ መጠን እንዲሁም የመሬት ከባህር ወለል ከፍታ ልዩነት የተነሳ በምርታማነታቸው ለየአካባቢው ተመራጭና ተመራጭ ያልሆኑ ዝርያዎችን መለየት ይቻላል፡፡ በዚህ ምክንያት ለተለያዩ ዝርያዎች ምርታማነት ተስማሚና ወካይ የሆኑ ስፍራዎችን  ለይቶ በማወቅ የትኛው ዝርያ በየትኛው ስፍራ ላይ ቢዘራ  ሁለንተናዊ የአካባቢ ባህሪያትን  ተላብሶ ከፍተኛ ምርት ሊሰጥ ይችላል?  እንዲሁም የትኛቹ ስፍራዎች በአየር ንብረት ተቀራራቢነት በጥቅል ተደምረው አንድ ዝርያ በወጥነት  በሁሉም ስፍራ ተዘርቶ ምርታማ የሚያደርጋቸውን አካባቢዎች ለይቶ ለማወቅ ጥናቱ ተደረገ፡፡ ጥናቱ ለምርት በምርምር የተለቀቁ  19 ዲቃላ የበቆሎ ዝርያዎችን በማካተት  ወይናደጋማና ደጋማ ስፍራዎች ላይ ተዘርተው የተለያዩ መረጃዎችን  በማሰባሰብ እንዲጠናቀር ከተደረገ በኋላ ለጥናቱ ስኬት   ከፍተኛ ትኩረት ተሰጥቶት  ለውሳኔ  እንዲያመች ከየአካባቢው የተሰበሰቡ የዝርያዎቹ ምርት አግባብ ባላቸው ሳይንሳዊ ዘዴዎች እንዲሰሉ ተደረገ፡፡ በስሌቱ መሰረት ከዝርያዎቹ በአማካይ በሔክታር 4.47 ( BH545)  እስከ 7.49  ( BH546) ቶን  ምርት ተመዘገበ፡፡ እንዲሁም በተደረገው ስሌት G14  እና  G1  ተብለው የተለዩ ዝርያዎች ለአብዛኞቹ የጥናቱ ስፍራዎች ተስማሚ  እንደሆኑ  ቢታወቅም  BH546  በሚባል ስያሜ የሚለየው ዝርያ በከፍተኛ ደረጃ ተመራጭ እንደሆነ ለማረጋገጥ ተችለሏል፡፡ በሌላ በኩል E9  በተባለ ምህፃረ-ቃል የሚለይ ስፍራ በአብዛኛው ዝርያዎች  ተመራጭ እንደሆነ ስሌቱ ሲያሳይ ፤ E1  የተባለው ግን ተመራጭ እንዳልሆነ ታውቋል፡፡ ሆኖም ግን 11 የጥናት ስፍራዎች በሶስት ዋና ዋና ፤ እያንዳንዳቸው በዝርዎቹ ምርታማነት የጎላ ልዩነት በሚታይባቸው ወጥ ክፍሎች እንደተከፈሉ የስሌቱ ውጤት ለይቶ አሳይቷል፡፡ በዚህ መሰረት E9 በሚል ስያሜ የሚለየው ስፍራ በብቸኝንት እንደ አንድ ዋና ክፍል የተከፈለ ሲሆን በሁለተኛ  ክፍል ውስጥ  በጥቅል  ዘጠኝ  አካባቦዎች  E1, E2, E3, E5, E6, E7, E8  እና E11  በአንድነት ተደመሩ፤ እንዲሁም  E4 እና  E10 በሶስተኛው ክፍል ውስጥ ተመደቡ፡፡ E3, E5 and, E7 በተባሉ ምህፃረ-ቃል የተለዩ ስፍራዎች ለዝርዎቹ ምርታማነት ወካይና ተመራጭ መሆናቸውን ጥናቱ አሳየ፡፡  ነገር ግን E4, E9 and E10  የተባሉ አካባቢዎች በውስን ስፍራዎች ውስጥ  ምርታማ የሚሆኑ  ዝርያዎችን መለየት የሚችሉ መሆናቸውን ጥናቱ ያረጋግጣል፡፡  በሌላ በኩል E8 and E11 የተባሉ ስፍራዎች የዝርያዎችን ምርታማነትና ተመራጭነት  በጉልህ ለማሳየት ምንም አስተዋፅዖ ያላበረከቱ መሆናቸውን ጥናቱ አሳይቷል፡፡ በመጨረሻም የዚህ ጥናት ውጤት ወጥነት ያላቸው ሶስት ዋና ዋና ስነ-ምህዳራትን ለይቷል፤  ዝርይዎች በምርታማነታቸው   ተመራጭነት  የሚኖራቸውንና  የማይኖራቸውነ  ለይተው የሚያሳዩ ስፍራዎችን  ጠቁሟል እንዲሁም በምርታማነቱና ለአብዛኛው አካባቢዎች  በወጥነት ተስማሚነቱን የሜያሳይ ዝርያ ለይቶ አሳይቷል፡፡ Abstract In multi-location experimental trials, test locations must be selected to properly discriminate between varieties and to be representative of the target regions. The objective of this study were to evaluate test locations in terms of discrimination ability, representativeness, and desirability, and to investigate the presence of mega-environments using AMMI and GGE models and to suggest representative environments for breeding and variety testing purposes.  Among 19 maize varieties tested across 11 environments, mean grain yield ranged between 4.47 t/ha (BH545) to 7.49 t/ha (BH546). Both AMMI and GGE  models identified   G14 and G1 as  desirable hybrids for cultivation   because they combined stability and higher average yield. Nonetheless, as confirmed by GGE analysis BH546 was most closest to the ideal genotype hence, considered as best hybrid.  Environment wise, E9 and E4 were the most stable and unstable test environments, respectively. The 11 test environments fell into three apparent mega-environments.  E9 formed one group by its own, E1, E2, E3, E5, E6, E7, E8 and E11 formed the second group and E4 and E10 formed the third group.  E3, E5 and, E7 were both discriminating and representative therefore are favorable environments for selecting generally adapted genotypes. E4, E9 and E10 were discriminating but non-representative test environments thus are useful for selecting specifically adapted genotypes. E8 and E11 were non-discriminating test environments hence little information about the genotypes. The results of this study helped to identify mega-environments, also representativeness and discriminating power of test environments better visualized with the GGE bi-plot model

Factors that transformed maize productivity in Ethiopia

Published online: 26 July 2015Maize became increasingly important in the food security of Ethiopia following the major drought and famine that occurred in 1984. More than 9 million smallholder house- holds, more than for any other crop in the country, grow maize in Ethiopia at present. Ethiopia has doubled its maize produc- tivity and production in less than two decades. The yield, currently estimated at >3 metric tons/ha, is the second highest in Sub-Saharan Africa, after South Africa; yield gains for Ethiopia grew at an annual rate of 68 kg/ha between 1990 and 2013, only second to South Africa and greater than Mexico, China, or India. The maize area covered by improved varieties in Ethiopia grew from 14 % in 2004 to 40 % in 2013, and the application rate of mineral fertilizers from 16 to 34 kg/ ha during the same period. Ethiopia ’ s extension worker to farmer ratio is 1:476, compared to 1:1000 for Kenya, 1:1603 for Malawi and 1:2500 for Tanzania. Increased use of im- proved maize varieties and mineral fertilizers, coupled with increased extension services and the absence of devastating droughts are the key factors promoting the accelerated growth in maize productivity in Ethiopia. Ethiopia took a homegrown solutions approach to the research and development of its maize and other commodities. The lesson from Ethiopia ’ s experience with maize is that sustained investment in agricul- tural research and development and policy support by the national government are crucial for continued growth of agricultur

Heterosis and combining ability of drought-tolerant maize lines for grain yield in contrasting moisture and plant density environments

In drought prone areas of Ethiopia, maize is produced by small-scale farmers’ where additional inputs are rarely applied. Although genetic tolerance is recommended for moisture stress, there is limited information on drought-tolerant genotypes reaction to variable environments. In this study, eight drought tolerant lines and their diallel crosses were tested separately in randomized complete block design under normal and high plant densities that combined with well watered and drought stress to estimate performance, heterosis and combining ability for grain yield. Both types of genotypes gave highest grain yield under well watered high plant density. However, least performance of inbred lines and highest heterosis was recorded under drought stressed high density, which confirmed more stress tolerance of hybrids than their parents. Although the predominant role of non-additive effects was observed for grain yield in most environments, the highly significant GCA x E and SCA x E interactions shows that combining ability effects change with growing conditions. Moreover, the observed weak association between grain yield of hybrids and inbred lines per se suggested the importance of evaluation of crosses in variable environments. Some of the new crosses gave better yield than local hybrids in less stress and stress environments. Generally, this study confirmed that hybrids developed from drought-tolerant inbred lines combined stress tolerance and high yield potential

Melissopalynological analysis and floral spectra of Apis mellifera scutellata Lepeletier bees in different agroecologies of southwest Ethiopia

The availability of bee forage limits honeybee productivity and is very important for beekeepers. Therefore, the current study aimed to identify the major botanical resources of honeybee, A. mellifera scutellata, in Southwest Ethiopia. Between October 2019 and October 2020, 69 group discussions (8–12 beekeepers), field observations, and pollen analysis were used to collect data. A total of 72 honey samples were collected from five districts at different seasons for pollen analysis. Most of the honey samples tested (93.06%) were multifloral, while 6.94% were monofloral. Melissopalynological analysis indicated that Eucalyptus camaldulensis (52.02%) was the predominant pollen type and is considered monofloral honey. Terminalia spp. (25.96%), Guizotia spp. (17.80%), and Bidens spp. (17.61%) were secondary pollen types and classified as multifloral honey. Terminalia spp., Guizotia spp., Vernonia spp., Bidens ssp., Plantago spp., and E. camaldulensis were pollen types recorded in honey samples in all agroecologies. Beekeepers ranked Schefflera abyssinica, Vernonia amygdalina, and Cordia africana as the first source of pollen and nectar for honeybees in highland, midland, and lowland, respectively. Additionally, V. amygdalina, Coffea arabica, Croton macrostachyus, and C. africana were commonly observed bee flora in all agroecologies. Honey bee management, such as bee forage shortages, the occurrence of brood and swarming, varied significantly (P < 0.05) among different agroecologies. In the present study, 53 honeybee plants were identified as pollen and nectar sources for honeybees. Various herbs (41.50%), trees (30.20%), and shrubs (28.30%) played a major role in honey production. Thus, beekeeping should be integrated with vegetation conservation for livelihood improvement and food security. Furthermore, existing bee flora should be cultivated in areas to increase the harvesting of honeybee products and improve the apiculture industry

Factors associated with successful vaginal birth after one lower uterine transverse cesarean section delivery

Abstract A Trial of labor after cesarean section is an attempt to deliver vaginally by a woman who had a previous cesarean delivery and when achieved by a vaginal delivery it is called successful vaginal birth after cesarean section. Vaginal birth after a caesarian section is a preferred method to decrease complications associated with repeated caesarian section delivery for both mother and fetus. It has a higher success rate when the right women are selected for a trial of labor. This study aimed to assess factors associated with successful vaginal birth after one lower uterine transverse cesarean section and to validate the Flamm and Geiger score at the public hospitals of Bahir Dar City, Northwest, Ethiopia, 2021. A health facility-based retrospective cross-sectional study was conducted from March 1 to 15/2021. A medical record review of 408 women charts with a trial of labor after one lower uterine transverse cesarean section from January 1/2020 to December 31/2020 was done and 345 women charts with complete maternal and fetal information were included in the study with a response rate of 84.6%. The data were collected using a structured checklist, entered into Epi data 3.1, and analyzed using SPSS 25.0 version. Logistic regression analyses were done to estimate the crude and adjusted odds ratio with a confidence interval of 95% and a P-value of less than 0.05 considered statistically significant. This study identified that the trial of labor after cesarean section rate was 69.5%, and the success rate of vaginal birth after one lower uterine transverse cesarean section was 35.07%. Of the failed trial of labor, fetal distress (38.9%) and failed progress of labor (32.1%) were the main indications for an emergency cesarean section. The maternal age group of 21–30 years, prior vaginal birth after or before cesarean section, non-recurring indication (fetal distress and malpresentation), ruptured membrane, cervical dilatation ≥ 4 cm, cervical effacement ≥ 50%, and low station (≥ 0) at admission were associated with successful vaginal birth after one lower uterine transverse cesarean section. For the Flamm and Geiger score at a cut point of 5, the sensitivity and specificity were 73.6% and 86.6% respectively. In this study area, the trial of labor after cesarean section rate is encouraging, however, the success rate of vaginal birth after one lower uterine transverse caesarian section was lower. The maternal socio-demographic and obstetric-related factors were significantly associated with successful vaginal birth after one lower transverse caesarian section delivery. This study indicated that when the Flamm and Geiger score increases, the chance of successful vaginal birth after one lower uterine transverse caesarian section also increases. We suggest emphasizing counselling and encouraging the women, as their chance of successful vaginal delivery will be high in the subsequent pregnancy, especially if the indications of primary caesarian section delivery were non-recurring