Common Bean Genotypes Research Articles

Environmental variability in indirect selection for grain yield in common bean lines

An approach to the number of experiments that should be used in correlation analyses aimed at increasing efficiency in indirect selection for grain yield is unprecedented for common bean (Phaseolus vulgaris L.). We hypothesize that trait correlation estimates vary in response to the growing environment. This study was undertaken to investigate the correlations between plant architecture and yield traits in common bean lines and to determine the minimum number of experiments required by Pearson’s linear correlation analysis to increase efficiency in indirect selection for grain yield. Seventeen common bean genotypes were evaluated for 17 agronomic traits in four experiments. Pearson’s linear correlation analyses were carried out using data from individual experiments and different combinations of growing seasons and years. Ten out of the 17 agronomic traits showed a significant genotype × environment interaction effect, meaning that common bean genotypes exhibited variation for most of the traits evaluated in different growing seasons and years, which resulted in changes in the correlation estimates between these traits. Pearson’s linear correlation estimates obtained between plant architecture and yield traits varied in significance, magnitude, and sign when data from individual experiments and combinations of growing seasons and years were considered. The number of grains per pod is the most promising agronomic trait used in indirect selection for grain yield in common bean lines. Data from at least three experiments should be used in Pearson’s linear correlation analysis to achieve greater efficiency in indirect selection for grain yield in common bean lines.

Stem, leaf and cotyledon resistance responses to a prevalent Sclerotinia sclerotiorum pathotype in Australia highlight new opportunities to improve white mould resistance in common bean

Context White mould (Sclerotinia sclerotiorum) inflicts major yield losses on common bean (Phaseolus vulgaris); yet, commercial cultivars known for their high yields and market-adapted grains lack physiological resistance to this disease. Aims This study aimed to test diverse common bean genotypes for resistance in stem, leaf and cotyledon tissues. Methods Thirty-four common bean genotypes with a wide range of agronomic traits and grain types, including genotypes noted previously for susceptible and resistant responses to white mould, were inoculated with the prevalent S. sclerotiorum isolate MBRS-1. Then they were assessed for resistance in stem, leaf and cotyledon tissues under controlled environment conditions, by inoculating plants with a 105 mL−1 hyphal fragment concentration. Key results There was significant (P < 0.001) variation in resistance responses in stem, leaf and cotyledon tissues across the genotypes. Contender, ICA Bunsi, XAN 280 and Taisho-Kintoki showed the highest resistance in stems, whereas Norvell 2558, Pico de Oro, Sanilac, Othelo and Negro Argel exhibited notable resistance in leaves. Metis, Canario 107, Pico de Oro, Pogonion and Jubilejnaja 287 displayed the most resistance in cotyledons. Conclusions This is the first reported attempt to determine the response of common bean germplasm to a prevalent pathotype of S. sclerotiorum in Australia. Bean genotypes exhibiting high-level resistance to white mould identified in this study can be used as parental lines for crosses in common bean breeding programs and/or directly as improved cultivars. Implications The study highlighted both the value of screening under controlled environmental conditions to reliably locate new stem, leaf and/or cotyledon resistances and the possibility of using rapid cotyledon screening to indicate stem resistances because the expression of resistances in cotyledons generally correlated strongly with those in stems.

Multivariate analysis applied to the evaluation of genetic variability for the physiological quality trait of common bean seeds

Abstract: Knowledge of the genetic variability and of the variables for evaluating common bean lines for the physiological seed quality trait is important for the selection of promising common bean genotypes for this trait in breeding programs. Through multivariate analysis, the objective of this study was to evaluate the efficiency of physical and physiological tests for studies of genetic variability in seeds of common bean lines. Twenty lines of common bean were evaluated for thousand-seed weight, first count, germination, tetrazolium, electrical conductivity, accelerated aging, field emergence and seedling performance. The experimental data were subjected to analysis of variance, analysis of genetic parameters and multivariate analysis of principal components. Genetic variability was observed among the common bean lines, and two groups of lines with superior physiological performance according to the germination and seed vigor tests were identified. First germination count, germination, seedling length in the field, accelerated aging and emergence speed index tests are the most promising for characterizing the physiological potential of seeds of common bean lines.

Environmental variability in simultaneous selection of common bean for grain quality and mineral concentration traits

The selection of common bean (Phaseolus vulgaris L.) lines based on grain quality and mineral concentration traits will be more efficient if a minimum number of experiments is established. This study was carried out to determine whether grain quality and mineral concentration traits are significantly affected by the genotype × environment interaction; to estimate heritability and genetic gain in individual and combined experiments; and to select superior common bean lines considering a minimum number of experiments. A total of 17 common bean genotypes were evaluated in four experiments. Grain quality was determined through seven traits, and the concentration of six minerals was analyzed by acid digestion. Statistical analyses were completed using data obtained from both individual (I, II, III and IV) and combined (I and II; I, II and III; and I, II, III and IV) experiments. Except for the potassium concentration, all traits showed a significant genotype × environment interaction effect. Heritability and genetic gain estimates of grain quality and mineral concentration traits varied when the data were obtained from one or more experiments. Genetic gain may be inflated because of the data being based on one or two experiments. Four carioca bean (BRS MG Uai, LP 09-33, LEC 01-16 and Pérola) and four black bean (TB 02-19, CHP 04-239-52, TB 03-11 and IAC Netuno) genotypes were selected for their high grain quality and mineral concentration based on four experiments. Data from at least four experiments should be used to select common bean lines superior in grain quality and mineral concentration traits to increase the efficiency of simultaneous selection.

Reação de genótipos de feijoeiro a nematoides de plantas

ABSTRACT Among the efficient strategies to manage plant parasitic nematodes, the use of resistant cultivars stands out for being frequently the easiest and least expensive approach that can be adopted by farmers. However, for the common bean, in Brazil, few sources of resistance have been identified so far. This study aimed to assess the reaction of 81 common bean genotypes to the most abundant and harmful plant parasitic nematode species in Brazilian crop fields. Genotypes resistant to all tested nematodes were observed: 7 to Heterodera glycines, 2 to Pratylenchus brachyurus, 15 to Meloidogyne incognita and 8 to M. javanica.

Screening of snap and dry bean (Phaseolus vulgaris L.) genotypes for resistance to Bean common mosaic virus and Bean common mosaic necrosis virus

The most effective control of Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) is achieved by using the seeds of resistant cultivars. During conventional breeding, resistance against BCMV and BCMNV in common bean can be developed by pyramiding the strain-nonspecific dominant I gene with strain-specific recessive (bc-) resistance genes for long-term virus control. In this study, a total of 58 bean genotypes involving registered green and dry bean cultivars, local genotypes, and breeding lines were tested for the presence of known resistance genes. First of all, each genotype was inoculated with the NL-3 strain of BCMNV and the NL-4 strain of BCMV separately, and the plants were evaluated for the symptom appearance and tested by DAS-ELISA to confirm the presence or absence of the virus after three weeks of sap-inoculation. In the last part of the study, the resistance genes in bean genotypes were investigated by SCAR markers of SW-13 linked with the I gene and SBD-5 linked to bc-12. According to the phenotypic and molecular tests, out of 58 common bean genotypes tested, 37 involved the I gene, and seven and three genotypes contained bc-22 and bc-12 genes, respectively.

Resistance to Pythium root rot and anthracnose among Kenyan common bean genotypes and marker-assisted introgression of resistance genes

ABSTRACT Common bean (Phaseolus vulgaris L.) is an important food legume crop and major protein source in Kenya and many parts of the world. However, the yields are low due to the diseases like anthracnose caused by Colletotrichum lindemunthianum and Pythium root rots. The study, therefore, sought to screen Kenyan common bean genotypes for anthracnose and Pythium resistance and to improve the resistance of local landraces to the two diseases. Local landraces and commercial cultivars were screened for resistance under greenhouse conditions for Pythium and in vitro for anthracnose. The results showed that majority of the landraces were moderately resistant to anthracnose and Pythium root rot. The study further utilized molecular markers linked to anthracnose and Pythium resistance, respectively, to determine their potential to detect specific resistance genes among the test genotypes. None of the markers amplified the test genotypes except the control genotypes pointing toward different resistance genes. Further, cultivars G2333 and KK8 were used as donor parents for anthracnose and Pythium resistance, respectively, in a marker-assisted backcross breeding program involving three high-yielding farmer-preferred landraces. A number of lines were developed that carry both resistance genes. These lines can be advanced for release as new cultivars to enhance common bean production in Kenya.

Analysis of Nuclear DNA Content and Karyotype of Phaseolus vulgaris L.

The common bean (Phaseolus vulgaris L.), whose annual production is 26 million tons worldwide, is one of the main sources of protein and is known as one of the most important food sources. In this study, the karyotype variations and the genome size of four common bean genotypes in Turkey were investigated to determine whether the geographic variables in these regions affected the genome size and the karyotype parameters. In addition, it is known that as that the cytological and chromosomal parameters change under the influence of the climatic conditions of each region, appropriate and stable cytological methods for each plant facilitate and enable the determination of the chromosomal structure and the identification of specific chromosomes in the genotypes of the relevant region. Correct and valuable information such as this enables breeders and researchers to determine the correct shape and actual size of chromosomes. The genome size of the genotypes was measured with a flow cytometer, and chromosome analyses were performed with the squash method. For each genotype, the karyotype parameters, such as the number of somatic chromosomes, the Mean Total Chromosome Length (MTCL), the Mean Centromere Index (MCI), and the Mean Arm Ratio (MAR), were measured. The results showed that the highest and the lowest amounts of DNA per nucleus (3.28 pg and 1.49 pg) were observed in the Bitlis and Elaziğ genotypes. In addition, all genotype chromosome numbers were counted to be 2n = 2x = 22. The Mean Total Chromosome Length varied from 15.65 µm in Elaziğ to 34.24 µm in the Bitlis genotype. The Mean Chromosome Length ranged between 1.42 µm and 3.11 µm in the Elaziğ and Bitlis genotypes. The Hakkari and Van genotypes consist of eleven metacentric chromosomes, while the Bitlis and Elaziğ genotypes consist of ten metacentric chromosomes and one sub-metacentric chromosome. However, the Mean Centromere Index and Arm Ratio differed considerably among the genotypes. The highest (46.88) and the lowest (43.18) values of the Mean Centromere Index were observed in the Hakkari and Elaziğ genotypes, respectively. On the other hand, the lowest (1.15) and the highest (1.36) values of the Mean Arm Ratio were obtained in the Bitlis and Elaziğ genotypes, respectively. Eventually, intraspecies variations in genome size and chromosomal parameters were observed, and it was determined that the changes in nuclear DNA content and different chromosomal parameters among the four Phaseolus genotypes from four different regions of Turkey indicate the effect of climate change in the regions on these parameters. Such information in these areas can be used as useful information for the improvement of this plant and breeding programs.

Yield performance and adaptation of advanced large-seeded common bean (Phaseolus vulgaris L.) genotypes in Ethiopia

To ensure the food demand of the rapidly growing population along with changing climate and limiting resources, development and adoption of high-yielding crop cultivars adapting to the adverse effects of climate is crucial for enhancing food production and productivity. The objective of this study was to evaluate the performance and adaptability of 23 advanced bean lines generated by single-seed descent and two commercial varieties (Batu and SAB-736), using additive main effects and multiplicative interaction (AMMI) and genotype plus G x E interaction (GGE) models. Field experiments were conducted in 2019 wet season (from July to October) at five diverse growing environments of Ethiopia. Wide variations were observed across the genotypes and environments for grain yield and other related traits. Mean performance of genotypes for yield ranged from 1.20 to 1.67 t ha −1 across environments, with a grand mean of 1.50 t ha −1 thereby favors genetic enhancement of the trait through selection. Environmental and interaction impacts were greater for all measured traits including yield. Except for number of pod plant −1 and 100 seed weight where interaction effect was more important, the percent variation due to environment was the highest for all traits expression, from 14.76 to 91.09%, to the total variation. Three advanced genotypes showed better yield than SAB-736 (the recent c. variety) and general adaptation across the environments. But, their consistency should be checked across seasons to suggest them for cultivation on these and other similar environments.

SSR and GBS based GWAS study for identification of QTLs associated with nutritional elemental in common bean (Phaseolus vulgaris L.)

Common bean is one of the important staple food legumes, and is a potential source of minerals with high content of P, K, B and S and is being targeted for nutritional improvement to overcome mineral malnutrition and hidden hunger problem globally. In the present study, we used Genome Wide Association approach (GWAS) for P, K, B and S using a core set of 96 genotypes of common bean representing landrace diversity of Western Himalayas. Significant variation in mineral content among the genotypes was observed and an inventory of nutrients for the available germplasm was established. Four genotypes (R9, WB1680, WB923 and N13) were found with highest content of P, K, B and S respectively. Moreover, we also categorized germplasm in 10 highest and lowest genotypes for utilization in breeding program. Further, the germplasm was genotyped using SSR's and SNP's (genotyping by sequencing; GBS) for studying genetic diversity and population structure. 22 SSRs selected from the linkage map that were distributed on 11 chromosomes of common bean were used. Moreover, GBS approach was also used for dense genome wide marker coverage. Based on SSRs, germplasm was divided into 2 subpopulations whereas SNPs divided the germplasm into 5 subpopulations. GWAS was also done for both the markers systems. Our study concluded with the establishment of nutrient inventory in the available germplasm and identification of 9 significant SSR markers and 35 significant SNP markers associated with these traits, out of which 4 SSR markers were located on chromosome 2 and 7. Most of the SNP markers were located on chromosome 10 which suggest that maximum genes responsible for nutrient accumulation might be present on chromosome 10 of common bean. Further 58 candidate genes near to the vicinity of significant SNPs were identified. The significant markers associated with the traits of interest after validation can prove an asset for plant breeders to enhance the nutrient status (biofortification) of common bean which can help in tackling the malnutrition and can solve the hunger related problems majorly in the developing countries as it forms the cheap but widely used energy source in these countries.

Performance Evaluation of Small white Common Bean Genotypes in Eastern Amhara, Ethiopia

Common bean regional variety trial was carried out at Sirinka, Jari, Cheffa and West belesa (Gondar) from 2017 to 2019 cropping season. The objectives of the trial were to evaluate the performance of genotypes for grain yield and yield related traits and to select and promote the promising ones for verification. Fourteen genotypes including Awash-2 (standard check) were tested using RCBD. Analysis of variance and GGE biplot analysis was employed on multi-environment grain yield data. The combined analysis of variance showed significant differences for both main and interaction effects of genotypes, locations which led to exploit the significant effect of genotype-by-environment interaction. Based on the analysis of variance and GGE biplot analysis, two varieties namely DAB-413 and ZABR 16575-51 F-22 with average grain yield of 2729 kg/ha and 2501 kg/ha, respectively were selected, verified and DAB-413 and have been released for Sirinka, Jari, Cheffa and similar areas in Ethiopia. Therefore, DAB-413 has been recommended for the tested and other similar common bean growing areas to increase production and productivity of this crop.

Screening a newly developed common bean germplasm with improved resistance to ashy stem blight in multiple environments.

Ashy stem blight (ASB) caused by the necrotrophic fungus Macrophomina phaseolina (Tassi) Goidanich is an important disease in common bean (Phaseolus vulgaris L.) in the Americas and worldwide. Low to intermediate levels of ASB resistance exist in cultivated and landrace genotypes of the common bean and the tertiary gene pool. However, cultivars with higher levels of resistance are not yet available. Our objectives were to 1) pyramid higher levels of resistance from multiple parent populations within the primary gene pool and 2) compare the response of the newly developed breeding lines (BL) with known sources of resistance. The BL UPR-Mp-22, UPR-Mp-34, UPR-Mp-42, and UPR-Mp-48, known sources of resistance, and susceptible checks were inoculated twice per plant with the PRI21 M. phaseolina isolate in the greenhouse and field trials conducted in Isabela and Lajas, Puerto Rico. None of the genotypes tested were resistant (mean scores 1-3). However, the new black UPR-Mp-42 and white UPR-Mp-48 BL had an intermediate response (mean scores 4-6) compared to white common bean genotypes 'Bella,' NY6020-4, and 'Verano' and black bean TARS-MST1 that were susceptible (scores ≥7) in all environments. Andean genotypes A 195, PRA154, PRA155, and UPR-Mp-22 were intermediate in the greenhouse. In contrast, UPR-Mp-34 had significantly lower scores than BAT 477 that had a susceptible reaction in the greenhouse in Isabela and in the field in Lajas and SEA 5 that was susceptible in all environments. These new BL possess an enhanced ASB resistance and may be used to improve common bean cultivars or germplasms of different market classes.

Combining ability of common bean (Phaseolus vulgaris) genotypes for root traits across diverse environments

AbstractRoot 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 F1s were selfed and advanced to F2 generation. Eight parents and their F2 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.

Determining the Relationship between SPAD Values and Common Bean Seed (Phaseolus vulgaris L.) Yield by Correlation and Path Coefficient Analysis Method by using Different Organic Fertilizer

Path coefficient analysis provides a much better understanding of the correlation coefficient values. Spad values give information about the state of the leaf. In the study, path coefficient analysis was performed, especially SPAD values in beans. The study was carried out Kahramanmaraş Sutcu Imam University, treatment area in 2021 year. Mispir cultivar and Aydintepe local common bean genotype were used, leonardite and chicken litter and their mixture were used, various doses (3,6,9 t ha-1 and conventional fertilizer (25 kg ha-1 N/64 kg ha-1 P2O5) and control application) were added to the soil. Leaf chlorophyll content was measured in three periods: early leaf (1st SPAD), flowering stage (2nd SPAD), post-flowering (3rd SPAD). In addition, seed yield and biomass yield values were determined. Chicken Manure 3 t ha-1 organic fertilizer application showed the best performance among all applications in terms of seed yield. And the Aydintepe local genotype showed higher performance than the Mispir cultivar for the most of the properties examined.

Rank‐based data synthesis of common bean on‐farm trials across four Central American countries

AbstractLocation‐specific information is required to support decision making in crop variety management, especially under increasingly challenging climate conditions. Data synthesis can aggregate data from individual trials to produce information that supports decision making in plant breeding programs, extension services, and of farmers. Data from on‐farm trials using the novel approach of triadic comparison of technologies (tricot) are increasingly available, from which more insights could be gained using a data synthesis approach. The objective of our study was to present the applicability of a rank‐based data synthesis approach to several datasets from tricot trials to generate location‐specific information supporting decision making in crop variety management. Our study focuses on tricot data from 14 trials of common bean (Phaseolus vulgaris L.) performed between 2015 and 2018 across four countries in Central America (Costa Rica, El Salvador, Honduras, and Nicaragua). The combined data of 17 common bean genotypes were rank aggregated and analyzed with the Plackett–Luce model. Model‐based recursive partitioning was used to assess the influence of spatially explicit environmental covariates on the performance of common bean genotypes. Location‐specific performance was predicted for the three main growing seasons in Central America. We demonstrate how the rank‐based data synthesis methodology allows integrating tricot trial data from heterogenous sources to provide location‐specific information to support decision making in crop variety management. Maps of genotype performance can support decision making in crop variety evaluation such as variety recommendations to farmers and variety release processes.

Canning quality of popular common bean germplasm in Eastern and Central Africa

Common bean (Phaseolus vulgaris L.) genotypes popular in eastern and central Africa were evaluated to determine their suitability for the canning industry. The genotypes were planted at the National Agricultural Research Laboratories (NARL), Kawanda-Uganda in the second rainy seasons (July-September) of 2015, 2016 and off season of 2017 (November- February). Two samples per genotype were evaluated at the canning facilities at Kawanda and Michigan State University (MSU) using a protocol based on home canning. One sample per genotype from the 2017 harvest was evaluated at Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre (AAFC-LRDC) using the industry canning protocol. Data (n=134) was collected on seed moisture content, dry and soaked bean weight, hydration coefficient (HC) and visual quality, including colour retention, appearance, brine clarity, bean splitting and freedom starch/clumps on replicated samples. Additional data on unreplicated samples were collected on 100-seed weight, seed solids for canning, hydration coefficient after soaking (HCS), hydration coefficient after blanching (HCB), drain weight (%), matting, appearance, seed color, texture, and cooking quality traits including hard seed and partially hydrated seed (%) and HC after cooking. Analysis of variance of data from MSU and Kawanda showed significant (P≤0.01) differences among genotypes for the assessed parameters. Majority of the genotypes expressed good soaking ability considering that their HC were above the 1.8 recommended for canning and 28% combined the two mentioned traits with good overall canning quality visual rating. Apart from 26, all other varieties had good HC based on data from Canada. About 24% of genotypes belonging to various market classes consistently combined this trait with good visual quality. The most outstanding genotypes based on these traits included SAB659 (red mottled), MAC44 (red mottled), NABE21 (cream), NABE12C (cream) and VAX5 (cream), KK8 (red mottled), Bihogo (yellow) and VAX4 (black). These genotypes were superior to the white beans: MEXICO 142, Awash1, and Awash Melka, that were considered as high-quality controls. Results indicated that genotypes of diverse backgrounds, with good canning quality traits exist among the currently utilised varieties and breeding lines. This diversity could be exploited for breeding and varietal promotion in the canning industry. Key words: Common bean, canning, hydration coefficient, visual quality, drained weight

Comparative Analysis of Untargeted Metabolomics in Tolerant and Sensitive Genotypes of Common Bean (Phaseolus vulgaris L.) Seeds Exposed to Terminal Drought Stress.

Many environmental stresses can affect the accumulation of metabolites in plants, including drought. In the present study, we found a great deal of variability in the seed metabolic profiles of the tolerant (Matterhorn, SB-DT2 and SB-DT3) common bean genotypes in comparison to the sensitive genotypes (Sawtooth, Merlot and Stampede) using ultrahigh performance liquid chromatography−tandem mass spectrometry (UPLC-MS). The genotypes were grown in the field and subjected to drought stress after flowering (terminal drought stress). We aimed to investigate the accumulation of genotype-specific metabolites and related pathways under terminal drought stress by comparing tolerant and sensitive genotypes within a race. A total of 26 potential metabolites were identified across genotype comparisons. Significant metabolic pathways, including monobactam biosynthesis, flavone and flavonol biosynthesis, pentose phosphate pathway, C5-branched dibasic acid metabolism, cysteine and methionine metabolism, vitamin B6 metabolism and flavonoid biosynthesis, were derived from the enriched metabolites. Many of these metabolic pathways were specific and varied with genotype comparisons. SB-DT2 vs. stampede revealed more significant metabolites and metabolic pathways compared to Matterhorn vs. Sawtooth and SB-DT3 vs. Merlot under terminal drought stress. Our study provides useful information regarding the metabolite profiles of seeds and their related pathways in comparisons of tolerant and sensitive common bean genotypes under terminal drought conditions. Further research, including transcriptomic and proteomic analyses, may contribute to a better understanding of molecular mechanisms and nutritional differences among seeds of common bean genotypes grown under terminal drought conditions.

Characterization of Western Himalayan small-seeded red beans (Phaseolus vulgaris L.) for yield, quality and resilience

Abstract Western Himalayan region is a rich repository of common bean genetic resources evolved over generations of farmer selection. The bean variability encompasses various use categories such as dry, snap and shelled beans. The present study aimed to characterize 40 small-seeded red common bean genotypes collected from different districts of Kashmir valley as well as Poonch, Rajouri and Bhaderwah areas of Jammu which are world famous for their beans. Based on 5-year evaluation, there was substantial variability for various qualitative traits as well as quantitative traits. Among variability parameters, higher PCV and GCV values were recorded for plant height, seed yield per plant and number of pods per plant and low for days to maturity, seed length and pod length. High heritability was recorded for all the traits ranging from 78.72 to 94.87%. There was substantial variability in root traits scored in laboratory and greenhouse as well as canopy temperature depression and relative water content. Various genotypes were found resistant to bean common mosaic virus (WB-N-1, WB-N-11, WB-1318, WB-401, WB-451, WB-1634); anthracnose (WB-1634 WB-83, WB-258, WB-1282, WB-1304); angular leaf spot (WB-6, WB-1634, WB-258, WB-451, N-1 and N-10); Fusarium wilt (WB-341, WB-451, WB-N-1 and WB-1587) and Ascochyta blight (WB-6). Similarly WB-92 was highly resistant to shattering. The genotypes WB-341, WB-1634, WB-N-1 performed better under water stress, WB-N-1 and WB-1634 were resistant to multiple diseases and WB-1634 had better cooking quality. The genotypes identified can be used in bean improvement programmes and have also been submitted to NBPGR for long-term storage.

The Evaluation of Common Bean (Phaseolus vulgaris L.) Genotypes under Water Stress Based on Physiological and Agronomic Parameters.

Drought affects common bean productivity, and the severity of its impact is expected to increase due to climate change. The use of versatile genotypes could contribute to securing future bean production. This study investigates the adaptability of 10 common bean genotypes of indeterminate growth type under water scarcity conditions by measuring agronomic and physiological parameters. The evaluation occurs under irrigation treatments applied at two different phenological stages (anthesis (WDA) and seed filling initiation (WDSF)). The recorded adaptabilities of the genotypes (G) showed that G10 produced the highest overall seed yield in the normal irrigation (NI) (197.22 g plant−1) and WDA (192.78 g plant−1), while the G6 had the highest yield at WDSF (196.71 g plant−1). For the genotype’s average mean, chlorophyll content decreased by 10.5% under drought at WDSF. Net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration rate (E) were reduced at WDA by 53%, 80.8%, and 61.4% and at WDSF by 43.75%, 57.7%, and 36%, respectively, while relative water content (RWC) reduced by 16.48%, on average, for both stages. G10 and G6 showed adaptability when water scarcity occurred at an early (WDA) or later stage (WDSF), respectively, providing insights into using germplasm resources to cope with the drought effect.

Heat Stress Tolerance: A Prerequisite for the Selection of Drought- and Low Phosphorus-Tolerant Common Beans for Equatorial Tropical Regions Such as Ghana

Forty common bean accessions of multiple genetic background trait attribution regarding drought tolerance were selected based on mean yield performance from an earlier field test evaluation conducted using augmented RCBD. The various bean genotypes were further evaluated with phosphorus and water treatment interactions at two different levels for each factor. The experiment was conducted in a 2 × 2 × 40 factorial using RCBD with three replications under screen-house conditions at the CSIR-Crops Research Institute, Kumasi-Ghana. The objective was to select drought- and low phosphorus-tolerant common bean genotypes; which are suitable for tropical climatic conditions. The results showed that common bean with drought and heat trait tolerance survived, developed flowers and podded with seeds to physiological maturity, whilst genotypes with no heat trait tolerance had impaired reproductive structural development and growth disruption; thus, flowers could not develop into pods with seeds. This reproductive developmental anomaly was due to prevailing average daytime and nighttime high temperatures of 35.45 °C and 29.95 °C, respectively, recorded during the growth period, which reduced pollen fertility. Among the 478 experimental bean plants (two plants were missing) analyzed, 141 (29.5%) did not flower, 168 (35.18%) had their pods dropped whilst 99 (20.7%) podded with seeds to achieve physiological maturity. The podded-seed bean genotypes were of the SEF-line pedigrees, which were shown to be heat and drought-tolerant. Meanwhile, bean accessions with SMC, SMN and SMR code prefixes did not pod into seed despite possessing drought-tolerant traits. The effects of interactions between phosphorus and water treatments on the root characteristics of drought-tolerant common bean were as follows: root length, root surface area, average root diameter and root volume growth extensions doubled dimensionally under optimum conditions (P2W2) compared to stressed conditions (P1W1). The results from the present study identified four SEF-bean genotypes, namely, SEF15, SEF 47, SEF 60 and SEF 62, as superior yield performers, even under low soil phosphorus and in extreme high temperature conditions. Therefore, breeding for the selection of drought- and low-P-tolerant common bean for tropical agro-ecological environments must also consider concomitant heat stress tolerance.