Low phytic acid in soybean [Glycine max (L.) Merrill] is a significant attribute to its dietary consumption. The presence of high phytic acid in soybean impacts negatively on the bioavailability of minerals and protein digestion for humans and livestock. Understanding the stability of phytic acid accumulation in soybean varieties is essential for formulating genetic improvement strategies to develop cultivars with reduced phytic acid. The objectives of this study were to determine genotypic variation of soybean genotypes for seed phytic acid content, assess its stability, and seed yield in multi-environments. Forty-eight soybean genotypes were evaluated in an Alpha Lattice design across three locations over two cropping seasons. Genotype was the main determinant of the variation in phytic acid content. However, environmental factors significantly contributed to the phenotype mean value for phytic acid across environments. Commercial genotypes Hill, EAI 3600, DPSB 19, and SC Saga had lower mean phytic acid content of 3.6, 3.5, 3.5, and 3.2 mg g-1, respectively, than the mean (3.8 mg g-1). However, all the commercial genotypes had higher phytic acid content (3.2-4 mg g-1) compared to the mean (1.5 mg g-1) of N6003LP, the check genotype. The mean yield across sites ranged from low (0.3 t ha-1) for N6003LP to 1.5 t ha-1 for genotype NJSB 6. The results provide critical information for planning a breeding strategy for low phytic acid cultivars.

Sorghum is an essential staple cereal crop in sub-Saharan Africa, Asia, and Latin America. Its uses have expanded to include livestock feed, forage, brewing, and ethanol production. However, sorghum accessions in eastern Africa remain underutilized by breeding programs as potential sources of genes for improving grain quality for various end-use products. This study aimed to assess the genetic diversity and population structure of sorghum germplasm to enhance grain quality. A diversity panel of 94 sorghum germplasms, including landraces, commercial varieties, and breeding lines from eastern Africa, was assembled. We evaluated the panel in field trials at two locations in Kenya, focusing on grain quality traits. Genetic diversity and population structure were analyzed using 6994 SNP markers from Diversity Array Technology. Out of 94 germplasm evaluated, 62 were durra, 14 were bicolor, 13 were caudatum, and 5 were guinea. Germplasm was grouped into two distinct genetic clusters based on population structure and hierarchical clustering. Germplasm from Cluster 1 exhibited high starch content, while those from Cluster 2 had high seed tannin and nitrogen levels. The germplasm showed significant diversity for quality traits, indicating its potential for selecting desirable grain quality alleles to improve sorghum products. The revealed diversity, including genotypes Gicamunkoni, EST 42, and Siaya 46–1 from cluster 1, which have high starch levels, and genotypes Shambuko and Macia from cluster 2, characterized by low grain tannin and high nitrogen, provides breeders with opportunities to develop strategies for enhancing sorghum grain quality.

Stem rust, caused by Puccinia graminis f. sp. tritici, is a destructive fungal disease of bread wheat (Triticum aestivum L.) and poses a major challenge to wheat production in sub-Saharan Africa and Asia. The continuous evolution and variable nature of stem rust predispose wheat to serious genetic vulnerability, necessitating proactive incorporation of new and effective resistance sources into breeding lines. This study evaluated 25 wheat genotypes over three seasons at the Kenya Agricultural and Livestock Research Organization (KALRO), Njoro, to assess resistance mechanisms and yield stability under stem rust pressure. A 5 × 5 partially balanced alpha lattice design was employed. Disease progression was assessed using final disease severity (FDS) and area under the disease progress curve (AUDPC), alongside evaluations of agronomic performance. Statistical analyses revealed significant (P ≤ 0.001) effects of genotype, season, and genotype × season interaction for AUDPC and agronomic traits. Grain yield (GY) was significantly (P ≤ 0.001) negatively correlated with disease components, and positively correlated with kernels per spike (KS), biomass (BM), harvest index (HI), and thousand kernel weight (TKW). Broad-sense heritability (H2) estimates ranged from 59.90% for grain filling period to 95.58% for FDS. Adult plant resistance genes Lr34/Yr18/Sr57, Lr46/Yr29/Sr58, Sr2/Yr30, and Lr67/Yr46/Sr55/Pm46 were detected in various combinations across 21 genotypes. Based on disease response and yield performance, genotypes 8790929, 8790027, 8790948, and 8790935 exhibited the highest levels of resistance and superior grain yield. These genotypes represent valuable sources of stem rust resistance and are recommended for use in breeding programs for gene introgression and varietal development.

The development of novel improved varieties adapted to unstable environmental conditions is possible through the genetic diversity of breeding materials. Potato is among the most important food crops worldwide; however, there are still significant hindrances to breeding gains attributed to its autotetraploid and highly heterozygous genome. Bacterial wilt caused by the Ralstonia solanacearum species complex is an important disease affecting potato among many economically important crops worldwide. No cultivated potato genotypes have shown a satisfactory level of resistance to bacterial wilt. Nevertheless, resistance can play a crucial role in effective integrated disease management. To understand the genetic landscape of bacterial wilt resistance in cultivated potato, we evaluated the diversity of 192 accessions from the International Potato Center (CIP) using 9,250 single-nucleotide polymorphisms and their associations with the response to bacterial wilt disease evaluated over two independent trials. Twenty-four accessions showed high resistance throughout both trials. Genetic diversity analysis revealed three major clusters whose subgroups were mostly represented by CIP clones derived from common parents. Genome-wide association analyses identified six major hits: two on chromosome 8 and one on each chromosome 2, 4, 5, and 9. These results facilitate genetic dissection of bacterial wilt resistance and enable marker-assisted breeding in elite genotypes for potato breeding initiatives.Copyright (c) 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Root system architecture is important for common bean (Phaseolus vulgaris) adaptability to diverse environments. Beans employ complex adaptive root mechanisms for coping with multiple stresses in production environments. Understanding genetic control of root traits is central to improvement of common bean for adaptation to marginal environments. The objectives of this study were to (i) determine combining ability of root and agronomic traits and (ii) estimate the heritability and genetic correlation of root and agronomic traits in common bean. Four bean lines with superior root traits were crossed with four locally adapted varieties in a North Carolina II mating scheme to generate 16 crosses. The 16 F(1)s were selfed and advanced to F-2 generation. Eight parents and their F-2 progenies were evaluated in an alpha-Lattice design with two replications. General and specific combing ability mean squares were significant (p <= .05) for all traits measured. General predictability ratios ranged from .47 to .68 across locations suggesting that both additive and non-additive gene action modulate root traits and seed yield. Positive and significant (p <= .05) phenotypic and genetic correlations revealed significant association between root traits and yield. Moderate to high heritability estimates of between .43 and .67 were realized. Such estimates point to possible deployment of a successful selection programme. Genotype AFR398 displayed significant positive GCA effects among its crosses for both root and agronomic traits hence a potential candidate genotype for inclusion in a bean genetic improvement programme for marginal environments.

Common bean is a significant pulse crop worldwide but widely grown and consumed in Latin America and sub-Saharan Africa where it is a major source of dietary protein and minerals. Current global production is largely hindered by abiotic stresses due to unfavorable soils and extreme weather events arising from negative effects of climate change. Enhancing root system architecture is a key breeding objective towards developing cultivars suitable for adaptability to hostile production environments. The objective of this study was to identify common bean genotypes with stable root traits and seed yield in a multi-environment trial. Forty-nine genotypes were planted in a simple Lattice design across three locations over two years comprising of six environments based on year-location combinations. Residual maximum likelihood estimates revealed significant (P < 0.01) genotype -by-environment interaction effects for root traits and seed yield, demonstrating significance of environment on genotypic expression. Acute angles between vectors of different years at the same locations, established repeatability of environments in evaluating genotypes for root traits and yield. Genotypes DAB256, DAB398, DAB236, AFR398 and Guropequeno had superior overall performance and stability for root traits and seed yield across environments. High positive correlation between seed yield and both deep roots and deep root angles of >= 40 degrees from the horizontal, demonstrated the role of root architecture in aiding remobilization of dry matter from vegetative structures to pod filling and seed yield enhancement under varied conditions. Identified genotypes are useful genetic sources for improvement of root traits in common bean for adaptation to drought and heat alongside poor soils.

Bacterial wilt caused by Ralstonia solanacearum is one of the most destructive and widespread diseases of tomato in Kenya. The objective of this study was to determine the combining ability effects and gene action conditioning bacterial wilt disease resistance in tomato. Eight parents were crossed in North Carolina II mating design scheme to produce sixteen F1 hybrids. The F1 hybrids and the parental genotypes were evaluated for bacterial wilt in an alpha lattice design. Among the parents, KLF acc III was the best general combiner for area under the disease progress curve (AUDPC) and disease incidence across the two cropping cycles. Red Diamond × KLF acc III, Money Maker× KK acc I, Oxyly× KLF acc III and Money Maker× KK acc II were the best specific combiners for AUDPC. Low narrow sense heritability values of 0.14, 0.16 and 0.20 were obtained for AUDPC, disease incidence and plant survival. Relative weights of additive versus non-additive gene action obtained for AUDPC, disease incidence and plant survival were 0.19, 0.20 and 0.50. General predictability ratios (GPR) values of 0.27, 0.29 and 0.50 were obtained for AUDPC, disease incidence and plant survival. These results indicated the predominance of non-additive gene action in governing the traits. Key words: Disease resistance, bacterial wilt, combining ability, gene action, tomato.

Drought stress contributes significantly to economic yield losses in finger millet (Eleusine coracana)production.This study evaluated morpho-physiological and agronomic traits among 25 finger millet genotypes for drought tolerance under field conditions.Out of the 25 genotypes, 24 were advanced lines preselected for drought tolerance from ICRISAT, KALRO and Egerton University seed units and one check cultivar P-224.The study was conducted at two drought endemic locations (Koibatek, Baringo County and Soin, Kericho County) in Kenya during 2020 cropping season using 5 × 5 triple Lattice design with three replicates.Results revealed that genotype was significant (P<0.001) for seedling vigour, peduncle length, plant height, number of productive tillers number of fingers and harvest index (P<0.01)and finger length (P<0.05).Location was significant (P<0.001) for plant stand, number of fingers, finger length and days to 50% flowering and peduncle length.The interaction effect between genotype and location was significant (P<0.001) for number of fingers, yield and harvest index.There were significant and positive correlation between ET and HI (r = 0.537***), ET and grain yield (r = 0.611***), root relative water content (RRWC) and HI (r=0.442***).Lines ICFX 1420314-2-1-1-1 (7), KNE 814 X Ex Alupe (P) P8-1-1-1-1 (24) and ICFX 1420415-3-1-1-2 (14) were identified as the most suitable genotypes for drought tolerance based on their superior morpho-physiological traits to withstand soil water deficit with higher grain yield.These identified genotypes can be recommended to farmers and incorporated in breeding programs to improve production in the semi-arid areas.

Eastern Africa is a significant region of common bean (Phaseolus vulgaris L.) production and genetic diversity. Insect pests are a major biotic constraint in subsistence crop production systems. Bean fly (Ophiomyia spencerella) is a serious pest of beans in eastern Africa highlands. Breeding efforts focus on combining adaptability traits with user preferred seed types. However, lack of information on molecular markers linked to genes modulating bean fly resistance has slowed breeding progress. The objectives were to: (i) characterize genetic diversity and uncover putative bean fly resistant genotypes within diverse seed types and market classes and (ii) identify genomic regions controlling bean fly resistance using genome-wide association analysis (GWAS). A set of 276 diverse genotypes comprising local landraces and varieties from Kenya alongside introductions from International Centre for Tropical Agriculture (CIAT), were assembled. The germplasm represented varied bean production ecologies and seed types. Genetic diversity conforming to Andean and Mesoamerican genepools was established. Out of 276 genotypes evaluated, 150 were Andean, 74 were Mesoamerican and 52 were admixed. Twenty-two genotypes were resistant to bean fly. Association mapping results for stem damage score and plant mortality identified six significant single-nucleotide polymorphisms (SNPs) on chromosomes Pv01 and Pv09. The most significant SNP marker was 12 kilobases downstream of Phvul.001G074900 gene with LOD score > 4.0 hence in linkage disequilibrium with the postulated gene. The identified candidate gene is pleiotropic and modulates both flowering time and plant responses to stress. These findings are a key step towards marker-enabled breeding in common bean for sub-Saharan Africa.

Common bacterial blight (CBB) of mungbean ( Vigna radiata [L.] Wilczek var. radiata ) is a major limitation to mungbean production in semi-arid areas of the world where mungbean is a major crop. Deployment of resistant varieties is a significant sustainable strategy for controlling CBB in marginal production systems. The objective of this study was to identify sources of resistance and the stability of mungbean landraces to CBB attack across drought-endemic environments. A total of 240 mungbean genotypes were evaluated for CBB resistance and performance of agronomic traits in an alpha lattice design at four locations for 2 years (2019, 2020). Data were subjected to residual maximum likelihood (REML) analysis to partition variance components attributed to main effects and interactions, respectively. REML analysis revealed significant main effects for genotype, environment (combination of cropping season and location) and genotype-by-environment interaction ( p < 0.01), demonstrating the influence of environment on genotypic expression. A genotype main effect plus genotype-by-environment biplot was used to analyse the multi-location trial data based on CBB score to determine genotypic stability. The GGE analysis demonstrated that the Kambi Ya Mawe location in 2019 was the most suitable environment for the assessment of CBB resistance. Accessions GBK 004852, GBK 004789, GBK 026986, GBK 004970, GBK 004961, GBK 004882 and GBK 043573 were selected as having high and stable resistance across all environments. The identification of high and stable resistance sources is a first step towards deploying resistance in mungbean breeding programmes against CBB and the future deployment of resistant cultivars.

Common bean ( Phaesolus vulgaris L.) distribution across eastern, central and southern Africa region is widely driven by choice of grain types, which is affecting the genetic composition and adaptation to target production environments for biotic and abiotic constraints. Two bean fly species, Ophiomyia spencerella and Ophiomyia phaseoli are harmful insect pests of beans causing significant yield losses. Our objectives were to assess the population structure of common bean germplasm of different market classes and to identify polymorphic loci associated with resistance to O. spencerella . The study was carried out on a diversity panel of 284 genotypes using 9040 SNP markers. The genotypes were differentiated in to 14 distinct clusters. The mean F ST of 0.4849, revealed major differentiation among the populations. Andean gene pool was more diverse compared to Mesoamerica gene pool which could be attributed to preference for large seeded cultivars. Multi-dimensional scaling and structure analyses revealed admixture among seed types. From genome wide association studies (GWAS), major genomic regions associated with O. spencerella resistance were identified on chromosome 1 (Pv01). The most significant SNP on Pv01 was aligned to gene PHAVU_001G075500g that is related to the Interleukin-1 receptor-associated kinase (IRAK) pathway, critical in regulating inherent immune responses to disease infection and insect herbivore attack. The diversity uncovered on the basis of market classes of beans and the presence of QTL regions associated with resistance to bean fly could serve as a valuable genetic resource for improvement of beans of different seed types in eastern and southern Africa region. Core Ideas * BAK1 : brassinosteroid insensitive 1-associated receptor kinase 1 BLASTn : basic local alignment search tool for nucleotide BLASTx : basic local alignment search tool for translated nucleotide BR : brassinosteroid BSM : bean stem maggot CIAT : International Centre for Tropical Agriculture DArT : Diversity Array Technology ECABREN : Eastern and Central Africa Bean Research Network FAOSTAT : Food and Agricultural Organization statistics FDR : false discovery rate GBS : Genotyping by sequencing GeRRI : Genetic Resources Research Institute GS : genomic selection GWAS : genome-wide association study IRAK : Interleukin-1 receptor-associated kinase KALRO : Kenya Agricultural and Livestock Research Organization MAF : minor allele frequency MDS : multi-dimensional scaling MLM : mixed linear model PABRA : Pan-African Bean Research Alliance PC : principal component Pv : Phaseolus vulgaris REML : residual maximum likelihood QTL : quantitative trait loci SNP : single nucleotide polymorphism.

Stem rust (Puccinia graminis f. sp. tritici) is one of the three rust diseases that infect triticale (X. Triticosecale Wittmack). Twenty-six triticale genotypes were evaluated for adult plant resistance (APR) to stem rust (Sr) infection in the greenhouse in a Randomized Complete Block Design (RCBD). R-TR (resistant –trace or minimal uredinia) reactions were observed on 6 genotypes EUT046, EUT59, EUT090, EUT093, 118 and EUT139 at adult plant stage. Reactions of 5RMR (5% disease severity with resistant-moderately resistant reactions) were observed on EUT001, EUT034, EUT035, EUT123 and EUT124. Four of the genotypes evaluated showed moderately resistant (MR) reactions with severity ranging from 10 MR to 15 MR. Effects due to genotype, stage and genotype × stage interactions were significant (p<0.001) for length, width and area of spore. The mean length of spore increased from 0.75 mm at 17 days to 2.65 mm at 35 days after inoculation (DAI). The mean area of spore ranged from 0.27 to 1.33 mm2 between the 17 and 35 DAI. The slowest development (0.003 mm2 day-1, 0.006 mm2 day-1 and 0.009 mm2 day-1) of Sr spore was observed between 17-20 DAI for EUT035, EUT123 and EUT034, respectively. Triticale genotypes were also significantly (p<0.001) different for the latent period, AUDPC, number and weight of grains per spike. The mean latent period ranged from 10.00 days for EUT004 to 22.66 days for EUT001 and EUT087. Triticale genotypes that showed high level of APR were identified and can be used as sources of resistance in triticale breeding programs against stem rust. Key words: Adult Plant Resistance, Stem rust, Resistant, Triticale genotypes.

Genetic diversity of blackberry (Rubus subgenus Rubus Watson) is essential for efficient breeding and improvement of its pomological traits and yield. In this research, simple sequence repeats (SSRs) were used to determine the genetic diversity of 90 blackberry accessions collected from six different counties in Kenya. From 11 SSR markers used to genotype the blackberry accessions, a total of 127 alleles were generated. The average number of alleles (A) per locus was 4.00 while the expected heterozygosity (HE) of the SSR loci varied between 0.34 and 0.50, with a mean of 0.467. Polymorphism information content (PIC) values ranged from 0.357 to 0.753 with a mean of 0.520. HE of the blackberry accessions were higher than the observed heterozygosities (HO), having 0.75 and 0.64, respectively. Analysis of molecular variance (AMOVA) revealed 95% variability within accessions and 5% (P<0.01) among accessions. Cluster analysis using the Jaccard's similarity coefficient grouped the accessions into three classes: I, II and III, consisting of 31, 52 and 7 accessions, respectively. The clustering was random and did not group the accessions according to their geographical origin, indicating that accessions found in Kenya are closely related. This study detected considerable levels of genetic diversity within the analyzed accessions, which could be exploited in a blackberry breeding program. Key words: Simple sequence repeats (SSRs), Rubus subgenus Rubus Watson, genetic diversity.

Stem rust (Puccinia graminis f. sp tritici) poses a major threat to wheat (Triticum aestivum L.) production worldwide.The interaction between wheat and pathogen in presence of favorable environment can cause a complete crop failure.This study was conducted with the objective to identify wheat genotypes with resistance to stem rust with high and stable yield under four environments in Kenya.Forty wheat genotypes were tested in two consecutive growing seasons, using an alpha lattice design with three replications.Host response to stem rust was recorded based on the modified Cobb scale.The disease severity was recorded on scale of 0 to 100%.The results of the coefficient of infection indicated that about 30% of genotypes were moderately resistant.Yield and disease data were subjected to statistical analyses to estimate the stability parameters.The top three genotypes in yield performance were G25, G18 and G29 with 2.07, 1.98 and 1.97 t ha -1 respectively.Considering both stem rust and yield stability G5, G16, G18, G24 and G36 were the best genotypes which could undergo further testing for future release.

Stem rust (Puccinia graminis f.sp.tritici) is a major disease of wheat that occurs more in the main wheat growing regions of Kenya. The objective of this study was to assess the incidence and severity of wheat stem rust during the 2015 growing season. A survey was conducted in Mau-Narok, Njoro and Kabatini regions. During the survey work, 149 small scale wheat growers’ fields were assessed. The results revealed that stem rust incidence of the three surveyed areas ranged from 11.3 to 77.8% and severity 20 to 60%. The survey confirmed that the incidence and severity were associated with the farming practices such as chemical control, varieties grown, use of certified or uncertified seed and cropping systems. The survey showed that high to moderate incidence and severity levels were found on fields with one or two sprays with a fungicide. The use of fungicide was the major practice by growers for stem rust control reporting Mau-Narok with 43.2%, Kabatini 38.9% and Njoro 17.8%. The varieties grown had a relationship to disease incidence and severity percent levels. The use of uncertified seed by farmers contributed to high disease incidence. About 50.6% growers preferred old varieties mainly Robin and NjoroBWII. About 97.8% of the farmers practiced crop rotation of wheat with legumes. A multi-tactic disease management approach mainly two fungicide sprays per growing season, use at recommended rates, planting of certified seed of resistant varieties and crop rotation of legumes with wheat are required as stem rust effective management strategies. Key words: Wheat production, farm classifications, disease assessment, survey.

Stem rust (Puccinia graminis f.sp.tritici) of wheat (Triticum aestivum) has caused wheat yield losses in Kenya for years and the trend shows the situation has worsened. The objective of the research was to identify elite genotypes for adult plant and seedling stage resistance. Adult plant resistance study was done under natural conditions in three locations. Scoring was done following the modified Cobbs scale. Seedling stage resistance was done in the greenhouse and scored following the Stakmans scale. Genotype KSL 144, 71, 50, 31 44, 115 were identified as having seedling stage resistance. Area Under Disease Progress Curve (AUDPC) and Final Disease Severity (FDS) when used for adult plant revealed KSL 142, 71, 144, 50, 31, 44, 115, 146, 69 and 76 as having resistance. The variance (Si) and Coefficient of Variation (CVi) was calculated from the FDS and yield values, which distinguished stable genotypes. The stable genotypes for disease severity were KSL 69 (8.8%), 161 (14.9%), 54 (12.4%), 156 (18.24%). The relationship between yield and AUDPC was strong and negative, r=-0. 943 same as yield and FDS relationship r= -0.84. Variation for yield performance was recorded KSL 137 (2.63t/ha), KSL 31 (2.52 t/ha) showing high performance. The thousand kernel weight values were not significant for the three location at (P<0.05). The advanced genotypes that consistently performed better should be released as varieties or used in improving local varieties in the Kenyan wheat stem rust breeding programme or potentially in the Eastern Africa region. Key words: Ug99, disease severity, Area Under Disease Progress Curve (AUDPC), resistance.