Variation in the Ratio of Oat (<Emphasis Type="Italic">Avena</Emphasis>) Protein Fractions of Interest in Coeliac Grain Diets

The previously found wide range in the ratios of avenin or methanol-precipitated fractions to residual proteins was revisited by studying 75 oat varieties, mainly representing landraces from Finland, and included old varieties or selections, cv. Kytö, synthetic hexaploid oats and an Avena strigosa line (HA 71–87). The means of the fraction ratios ranged from 4.17 to 6.46 with significant differences. Samples of 10 narrow-ratio and 10 wide-ratio oats were compared more closely. The wide-ratio sample had significantly higher total protein content and significantly lower content of the methanol-precipitated protein fraction. Therefore, both fractions in general appear to contribute to the ratio of the protein fractions. The wide-ratio sample had significantly lower grain mass and husk-free karyopsis mass. Samples of the extreme ends in the ratios of the protein fractions showed different electrophoretic protein patterns, which was also seen in samples representing the same population of origin. It is evident that polymorphisms in the protein fractions would allow breeding of oat cultivars showing further lowering of proteins putatively toxic to coeliacs assuming oats contain these toxic proteins.     

The Identification of Finnish Oat Cultivars (Avena sativa L.) by the Use of SDS-PAGE of the Avenins in Homogeneous and Gradient

Abstract

The Finnish oat cultivars were identified by homogeneous and gradient SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis on the basis of 7–14 avenin bands. REM (relative electrophoretic mobility) values of the avenins among the Finnish oat cultivars were determined by gradient SDS-PAGE to calculate the PH% (pattern homology percentage). Most of the cultivars (58%) had a PH% of over 75%, which indicates quite a. high degree of similarity between the cultivars. Homogeneous SDS-PAGE was used in addition to gradient SDS-PAGE to compare the electrophoregrams of the cultivars by the gel separation systems. Resolution of the avenins was better by homogeneous than by gradient SDS-PAGE. Ten oat cultivars out of the 28 tested could be identified individually in homogeneous SDS-PAGE, as opposed to three which were identifiable by gradient SDS-PAGE.     

NUTRIENT DENSITIES,CARBON: NITROGEN RATIOS,AND MIDDAY DIFFERENTIAL CANOPY TEMPERATURE IMPACT GRAIN YIELD OF STRESSED OAT

Nutrient densities, carbon:nitrogen (C:N) ratio, and midday differential canopy temperature (dT), were assessed in oat plants subjected to biotic stresses during two years. Large portions of variation in nutrient densities and C:N ratio of leaves at the boot stage and of kernels and groats at harvest were negatively impacted by the 2- and 3-way interactions of leaves, kernels, and groats with the biotic stress treatments and years. The C:N ratios, but not nutrient densities, were always smaller in groats than in kernels, and during the stress than the no-stress year. Temporal variation accounted for a small variance associated with nutrients in leaves; whereas, stress treatments accounted for the largest variances associated with nutrients in kernels and groats. These indirect relationships among plant architecture components, dT, nutrient densities and C:N ratios, illustrate the complex interactions of biotic and abiotic stresses and their impact on grain yield and its components in oat.     

Nutrient solution nitrogen form and barley yellow dwarf virus disease tolerance in oat and wheat

Abstract

The form of nutrient solution nitrogen (either NH₄‐N or NO₃‐N or mixtures of the two) provided to plants influences the severity of many crop diseases. This greenhouse study was conducted to determine how growth, grain yield, and yield components of oat (Avena sativa L.) and wheat (Triticum aestivum L.) plants given nutrient solutions containing different ratios of NO₃‐N to NH₄‐N would react to barley yellow dwarf virus (BYDV) infection. Fifteen‐day‐old seedlings (2nd leaf stage) were either infected with BYDV (PAV strain) or left uninfected. Nutrient solution treatments (started 19 d after germination) provided three ratios of NO₃‐N to NH₄‐N (100% NO₃, 50:50 NH₄:NO₃, or 100% NH₄) for a 30‐d period, after which plant height and tillers plant^?1 were measured. Oat and wheat plants given NH₄ had fewer tillers than plants given the other nutrient solution treatments. BYDV‐infected oat and wheat plants were shorter than uninfected plants. All pots then received NO₃ nutrient solution until plant maturity, after which days to anthesis, primary tiller height, grain yield and yield components were measured. In the NH₄ nutrient solution treatments, BYDV infection significantly reduced individual kernel weight in oat and primary tiller height in wheat. These same measures were not significantly affected by BYDV infection in the NO₃ or NH₄NO₃ nutrient solution treatments. There were no other significant nutrient solution by BYDV infection interactions for any other dependent variable measured. Nutrient solution treatments had no significant effect on grain yield, but BYDV infection reduced grain yield by 45% in oat and 46% in wheat. In conclusion, nutrient solution N form interacted with BYDV infection to alter disease tolerance in oat (kernel weight) and wheat (primary tiller height), but these alterations had no effect in ameliorating grain yield loss caused by BYDV disease.     

Genetic diversity in Sorghum bicolor(L.) Moench accessions from different ecogeographical regions in Malawi assessed with RAPDs

Genetic variation within and among several Sorghum populations from different agroecological zones in Malawi were investigated using random amplified polymorphic markers (RAPDs). DNA samples from individual plants were analyzed using 35 oligonucleotides of random sequence. Twenty five of these primers allowed amplifications of random polymorphic (RAPD) loci. Overall, 52% of the scored loci were polymorphic. Every accession was genetically distinct. The analysis of molecular variance revealed that the within-region (among accessions) variations accounted for 96.43% of the total molecular variance. Observed variations in allelic frequency was not related to agroecological differences. The degree of band sharing was used to evaluate genetic distance between accessions and to construct a phylogenetic tree. Further analysis revealed that the sorghum accessions analyzed were genetically close despite considerable phenotypic diversity within and among them. It is suggested that all the sorghum landraces currently available in Malawi should be conserved both ex situ and in situ to maintain the current level of genetic diversity.     

Survey of White Salted Noodle Quality Characteristics in Wheat Landraces

The introduction of novel quality characteristics from wheat (Triticum aestivum L.) landraces can enhance the genetic diversity of current wheat breeding programs. The composition of starch and protein in wheat is important when determining the end‐product quality, particularly for white salted noodles (WSN). Quality characteristics that contribute to the production of improved WSN include high starch pasting peak viscosity, low amylose content, high proportion of A‐type granules, low protein content, soft grain texture, and high protein quality as measured by SDS sedimentation volume. A survey of 133 wheat landraces from Afghanistan, China, Egypt, Ethiopia, India, Iran, Syria, and Turkey was conducted to examine the genetic variability of starch and protein quality characteristics. Two wheat cultivars, Rosella and Meering, were used as the quality controls. The variation in starch pasting peak viscosities observed among the wheat landraces had a range of 175–295 Rapid Visco Analyser units (RVU), where 52 of the landraces were not significantly different from Rosella, a commercial soft grain wheat with high pasting properties. The amylose content of the landrace population was 23.4–30.2%, where 17 landraces had significantly lower values than Rosella. The proportion of A‐type granules was 60.5–73.9%, where 112 landraces had significantly higher values than Rosella. The grain texture hardness score was 28.0–99.3, the total protein content was 8.0–15.1%, and the adjusted SDS sedimentation volume (SDS/protein) was 1.6–7.0 mL/%P. The landrace AUS4635 had high starch pasting peak viscosity, high breakdown, low amylose content, low protein content, soft grain texture, and high protein quality flour. This wheat is an ideal parent to use in a breeding program that increases the genetic variation available to develop cultivars with high‐quality WSN characteristics.     

Genetic variation in common and runner bean of the Northern Meseta in Spain

The genetic variation within and between Spanish landraces or varieties of Phaseolus vulgaris L. (common bean) and P. coccineus L. (runner bean) has been estimated by means of isozymes and random amplified polymorphic DNA (RAPD) analyses. Likewise, storage protein and amino acid content in dry seeds have been estimated. Fifteen landraces (60 accessions) of P. vulgaris and six of P. coccineus (six accessions) have been studied. Of the seven isozymatic systems analyzed only three systems and three loci showed variability in each species. Isozyme analyses revealed that genetic variability within and between landraces exist in both species. Even variability within accession was detected in some P. vulgaris landraces. Comparison of isozyme data indicated that Spanish landraces have a lower level of genetic variability than wild American materials and probably also lower than American landraces. RAPD analysis allowed for the uniquely distinguishing of all landraces. Genetic similarity among landraces, estimated by both isozymes and RAPDs, were not related with the seed morphological characters (color, size and shape) which define each variety or landrace. Variation in protein and amino acid content among landraces was also detected. The average protein content in common bean (20.48%) was similar to values previously reported in this species and higher than the average in the runner bean landraces (16.33%). In relation to the amino acid content methionine and cysteine showed the lowest values in all samples, although the content of these two amino acids varied widely among landraces.     

Genetic Diversity Among Brazilian Cultivars and Landraces of Tomato Lycopersicon Esculentum Mill. Revealed by RAPD Markers

Random amplified polymorphic DNA markers (RAPD) were used to estimate the variability of 35 tomato accessions (Lycopersicon esculentum Mill.). A total of 257 reproducibly scorable bands were obtained from 20 primers, 78.6% of which were polymorphic. The percentage distribution of RAPD markers shows a bimodal distribution, and the frequency of rare alleles is similar in commercial and landrace accessions. Genetic distances among accessions were calculated and a dendrogram showing the genetic relationships among them was constructed allowing for the separation of four groups. Twenty out of 23 Brazilian landraces fell within one group, whereas commercial cultivars were distributed in the four groups. AMOVA analysis of RAPD data showed that, despite the high within Brazilian landraces and commercial cultivars variation, these two groups are significantly different, indicating that landraces can be a source of variation for breeding programs.     

Variability in European Maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) Landraces under High and Low Nitrogen Inputs

An European maize (Zea mays L.) landrace core collection (EMLCC) was formed with samples from several countries. Evaluation of the EMLCC may contribute to broad the genetic base of maize breeding programs. The objective of this study was to assess the variability of EMLCC under low nitrogen (N) in relation to high N input. Eighty-five landraces of the EMLCC, grouped in four maturity groups, and three check hybrids were evaluated for response to low (0 kg ha⁻¹) and high (150 kg ha⁻¹) N in Spain and Greece. Five plant size traits (plant height, ear height, leaf length, leaf width and leaf area index), two grain traits (1000-kernel weight and grain yield), and two agronomic traits [growing degree units (GDU) and lodging] were studied. Overall means of plant size and grain traits increased when genotypes were grown at 150-N relative to 0-N input. The relative increase for grain traits was smaller in landraces than in hybrids. This suggests that landraces had lower grain yield response to N supply compared to hybrids. Linear regressions of plant size traits on GDU indicated that vegetative development was primarily associated with flowering lateness. The maturity group was the main source of variation for all traits. Landrace variability within maturity groups was significant for all traits across environments, despite significant landrace × environment interactions. Estimates of genetic and genotype × environment variances, and heritabilities at both high and low N inputs were not significantly different from each other. However estimates were generally larger at high N. Genetic and phenotypic correlation coefficients between the two N levels were very high for all traits.     

Screening of barley landraces by direct selection for crop improvement

Abstract

Barley (Hordeum vulgare L.) landraces display a high degree of variability in morphological and developmental traits, in disease resistance, and in protein content. Representatives of 29 barley landraces from southeast Turkey were collected from farmers’ fields, for a total of 800 accessions. The objectives of this study were to characterize these accessions over four years for morphological and agronomical traits to be used for future selection and breeding program. The observed variation between landraces was very large for all traits. In the first year of testing the accessions showed average grain yields ranging from 197–2225 kg ha^?1. After three years of selection, promising accessions were tested at two different geographical regions and using two different irrigation methods. One line was identified which significantly out-yielded the local landrace in all of the testing years and had a higher average yield than the check genotypes.     

Genetic diversity of cultivated flax (Linum usitatissimum L.) and its wild progenitor pale flax (Linum bienne Mill.) as revealed by ISSR markers

Little is known about the genetic diversity of pale flax (Linum bienne Mill.), the wild progenitor of cultivated flax (L. usitatissimum L.), and ex situ germplasm of pale flax was scarce. Effort was made to collect 34 pale flax accessions and five landrace accessions of cultivated flax in Turkey. The inter simple sequence repeat (ISSR) technique was applied to characterize this set of flax germplasm, along with one Turkish cultivar, one Russian cultivar, five winter and four dehiscent type accessions of cultivated flax. Twenty-four ISSR primer pairs detected a total of 311 DNA fragments, of which 298 bands were polymorphic across 493 flax samples (roughly 10 samples per accession). These polymorphic bands had frequencies ranging from 0.002 to 0.998 and averaging 0.38. Accession-specific ISSR variation (Fst values) ranged from 0.469 to 0.514 and averaged 0.493. There was 49.3% ISSR variation resided among these 50 accessions, 35.9% harbored among landrace, winter, dehiscent types of cultivated flax and pale flax, and 38.2% present among 34 pale flax accessions. Pale flax displayed more ISSR variation than landraces and dehiscent type, but less than winter type, of cultivated flax. Clustering 493 individual plants revealed that these assayed plants were largely grouped according to their plant types and that pale flax was genetically more close to the dehiscent type, followed by the winter type and landrace, of cultivated flax. Pale flax collected within the geographic range of 180 km displayed a significant spatial genetic autocorrelation. Genetic distances among the pale flax accessions were significantly associated with their geographic distances and elevation differences. These findings are significant for understanding flax domestication and its primary gene pool.     

Genetic variation in nitrogen‐use efficiency of tef

Tef (Eragrostis tef (Zucc.) Trotter) is the ancient and most important cereal food crop of Ethiopia. A set of 20 tef genotypes was investigated in field experiments at three environments in Ethiopia to estimate genetic variation in nitrogen (N)‐use efficiency and in characters related to N accumulation as well as their relationships to grain yield. In each environment, genotypes representing both widely grown landraces and recently released cultivars were grown under three N‐fertilizer rates (0, 4, and 8 g m^–2 N). In grain yield, modern cultivars were superior to landraces, whereas in other characters, differences were less clear. The variation in grain yield was significantly related to the variation in total grain N and total plant N. Grain yield weakly correlated with N‐utilization efficiency and N harvest index. Broad sense heritability was higher for grain yield, total grain N, total plant N, and N harvest index than for N‐use, N‐uptake, and N‐utilization efficiencies. The contribution of uptake efficiency to the variation in N‐use efficiency decreased from 75% to 55% and that of utilization efficiency increased from 22% to 43% at the 4 to 8 g m^–2 N‐supply rate change. This study clearly suggests that tef N‐use efficiency would be increased by selecting genotypes with greater uptake efficiency at low N‐supply levels.     

Post-harvest residues of field pea/oat mixtures as a source of biological nitrogen for hybrid winter rye

ABSTRACT

The conducted studies show post-harvest residues of sowing/pea mixtures limit leaching of mineral nitrogen deeper into the soil profile compared to post-harvest residues of sowing peas, as they affect the yield and amount of nitrogen accumulated in hybrid winter rye grain. The objective of the study was to determine the effect of the post-harvest residue biomass of field pea, oat and their mixtures on yielding and quantity of nitrogen accumulated in hybrid winter rye grain. Two factors were examined: factor I ? post-harvest residues of field pea 100% ? pure stand, oat 100% ? pure stand, field pea 75%?+?oat 25%, field pea 50%?+?oat 50%, field pea 25%?+?oat 75%; factor II ? forecrop harvest date: the stage of field pea flowering, the stage of field pea flat green pod. The obtained results demonstrated that the lowest mineral nitrogen content in two soil layers was recorded following oat harvested at the stage of field pea flat green pod. The research revealed that hybrid winter rye cultivated after the mixture consisting of 50% field pea and 50% oat should be recommended for wide agricultural application in order to obtain high grain yield.     

Genetic diversity in bambara groundnut (Vigna subterranea (L.) Verdc) landraces assessed by Random Amplified Polymorphic DNA (RAPD) markers

Genetic diversity in 12 landraces of bambara groundnut (Vigna subterranea), an indigenous African legume, was evaluated using Random Amplified Polymorphic DNA (RAPD) markers. DNA from individuals of each landrace was also analysed to determine the level of heterogeneity within landraces. RAPDs revealed high levels of polymorphism among landraces. The percentage polymorphism ranged from 63.2% to 88.2% with an average of 73.1% for the 16 RAPD primers evaluated. The construction of genetic relationships using cluster analysis groups the 12 landraces in two clusters. RAPDs are useful for the genetic diversity studies in V. subterranea and can identify variation within landraces.     

Effect of Developmental Stages Length on Yield and some Quality Traits of Turkish Durum Wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> L. Convar. <Emphasis Type="Italic">durum</Emphasis> (Desf.) Mackey) Landraces: Influence of Developmental Stages Length on Yield and Quality of Durum Wheat

The study aimed at exploring durum wheat landraces to be utilized in breeding programs. 566 single durum wheat plants selected from 117 populations collected from 12 provinces were studied. The selected material was planted for characterizing their some qualitative and quantitative traits such as percent vitreousness, pearling index, grain protein content, seed yield and thousand kernel weight; as well as determining time frame for germination-tillering, germination-shooting, germination-heading, germination-maturity, tillering-shooting (T-S), tillering-heading (T-H), tillering-maturity, shooting-heading, shooting-maturity, and heading-maturity. Mean, coefficient of variation, and confidence intervals (0.95) were computed for each of 12 provinces, for altitudinal origins with 200 m of ranges and, for each of two geographical regions separately. The highest variation existed for number of days between T-H and the lowest for number of days between T-S. The highest variation within developmental stages was observed in samples from Diyarbakir with a CV of 32.96%, from 600 to 799 altitude range with a CV of 18.86%, and from Southeast Anatolia with a CV of 20.12%.     

大豆种质资源RAPD标记遗传多样性研究

为深入研究并充分利用野生大豆资源,本文利用RAPD分子标记对40份大豆材料加以分析,旨在从DNA分子水平上探索野生大豆、地方品种和育成品种之间的遗传多样性状况。结果表明:50个RAPD引物筛选出具有多态性且扩增条带清晰的引物38个,共检测出407条带,其中多态谱带309条,多态性程度为75.92%。每个引物可扩增出2～14条多态性带,平均产生多态性谱带8.1条;平均多样性指数为2.3377,变幅范围为0.5865～4.2133。遗传相似系数变幅范围为0.44～0.92,平均为0.75。野生大豆的多态比例(94.35%)、多样性指数(2.2336)分别高于育成品种(87.47%、1.7331)和地方品种(83.54%、1.6198)。遗传相似系数为野生大豆(0.6498)地方品种(0.7015)育成品种(0.7177),育成品种与地方品种间为0.6599,育成品种与野生大豆间为0.6487,地方品种与野生大豆间为0.6045。UPGMA聚类分析结果表明,40份大豆材料聚为6类,育成品种和地方品种各自聚为一类,野生大豆聚为4类。野生大豆特异等位基因数远远高于育成品种和地方品种二者的相加之和。本研究从分子水平上揭示了野生大豆与栽培大豆区别明显,宜作为一个独立的种,同时野生大豆变异幅度大,遗传基础广,是大豆育种实践中的优良基因资源。     

RAPD Polymorphism of the White-Flowered Gourd (Lagenaria siceraria (Molina) Standl. Landraces and its Wild Relatives in Kenya

The present study was performed to investigate genetic diversity of Kenyan landraces of the white-flowered gourd (Lagenaria siceraria), which exhibits tremendous morphological variation. RAPD analyses were performed on 53 landraces of the cultivated species L. siceraria and 42 accessions of three wild species (40 L. sphaerica, 1 L. abyssinica, and 1 L. breviflora). A total of 432 polymorphic bands were detected using 54 primers. The four species were clearly differentiated from one another. Intra-specific variations were investigated with L. siceraria and its wild relative L. sphaerica. Landraces of the cultivated species collected from different ethnic communities or regions were differentiated. Morphological variations were not associated with RAPD variations. Bitter landraces collected in Maasai communities showed two specific RAPD bands. In the wild species, accessions collected from the eastern and western sides of the Great Rift Valley were genetically differentiated from each other. In both species, genetic and geographical distance matrices computed among all pairs of accessions were significantly correlated, implying that the observed geographical variation can be explained by the 'Isolation by distance model'. Progeny plants derived from a common mother in L. siceraria showed a low level of segregation in RAPD pattern, suggesting that collected landraces are cultivated, maintaining their inherent traits although they are monoecious and insect-pollinated, whereas the wild relative L. sphaerica showed a higher level of segregation. The morphological diversity observed among landraces of L. siceraria is the result of human selection and their genetic identities are maintained by inbreeding probably resulting from frequent self-pollination.     

Genetic diversity of landraces of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) from hilly areas of Uttaranchal,India

Seed samples of 27 landraces of wheat were collected from farmers’ fields of hilly areas of Himalaya in Uttaranchal state of India during April 2004. Genetic diversity among 41 genotypes (cultivars and landraces of wheat) was studied using morphological traits, microsatellite markers and SDS-PAGE of HMW-GS. The dendrogram and PCA (Principal Component Analysis) based on morphological data clearly separated landraces of wheat from cultivars. In the dendrogram based on microsatellite markers data all the wheat cultivars released after the introduction of high yielding dwarf wheat varieties from CIMMYT, used in this study, were grouped separately with the exception of NP4. The pre-green revolution indigenous varieties grouped with landraces suggesting that the same had been probably developed through selection among landraces in India. The landraces had higher diversity for HMW-glutenin subunits coded by Glu-B1, with distinct subunit combinations 6 + 8, 7 + 9, 13 + 16, than within the wheat cultivars analyzed. Most of the landraces except IITR10 and IITR14 are clearly distinct from the indigenous and modern wheat cultivars released in India in the 20th century. More than half of the landraces were heterogeneous mixture of plants with different glume color, awnness, grain color and HMW-GS profile and hence need purification through single plant selection. Some of the landraces with resistance to yellow rust and powdery mildew and distinct HMW-GS subunits can be used in appropriate breeding programs. It will be desirable to conserve and protect the landraces as geographical indications of Uttaranchal.     

Genetic diversity of melon landraces (<Emphasis Type="Italic">Cucumis melo</Emphasis> L.) in the Xinjiang Uygur Autonomous Region on the basis of simple sequence repeat markers

We investigated the genetic variation and relationships among 35 melon landraces collected from the Xinjiang Uygur Autonomous Region in northwestern China by using 19 polymorphic simple sequence repeat markers (SSRs). A total of 55 polymorphic alleles were amplified. The number of alleles per SSR locus ranged from 2 to 5 with an average of 2.89 alleles per locus. The average gene diversity (GD) was 0.42 with a range of 0.06–0.71, and the average observed heterozygosity was 0.22 with a range of 0.06–0.97, indicating that the genetic diversity among the Xinjiang melon landraces was abundant. Genetic variation was also detected between the landrace populations in different regions in Xinjiang. The most abundant genetic diversity was observed among the landraces in Eastern Xinjiang, with the highest GD of 0.45 and PIC of 0.39. Eleven alleles (20 %) were found exclusively in the landraces from Eastern Xinjiang, and two alleles (3.6 %) were unique to the landraces from Southern and Northern Xinjiang. The genetic similarity matrix was defined on the basis of Jaccard coefficient to determine the genetic relationships among Xinjiang landraces. Cluster analysis was performed using the unweighted pair group method with arithmetic means, showing that the ‘wild Hami’ (XJ-34) landrace was distinct from the 34 other landraces that were divided into three clusters. Therefore, the genetic background of XJ-34 differed from that of the other landraces. The landraces were not precisely separated on the basis of their geographic origins, although most of these landraces were likely grouped near one another, as visualized through principal coordinate analysis. Thus, western China is one of the primary or secondary centers of melon diversity because of the relatively higher genetic variation detected among Xinjiang landraces. Except the ‘wild Hami’ landrace, Xinjiang melon landraces could be classified into two botanical varieties, namely, var. inodorus and var. cantalupensis. However, the distinction between these two genotypes was not significantly different.     

Selection criteria for grain yield and stability in bambara groundnut (Vigna subterranean (L) Verdc) landraces

The potential of bambara groundnut as a crop-based approach for the sustainable reduction of protein–energy malnutrition prevalent in Nigeria is still being explored. However, one of the limitations to sustainable production of this adapted species is low and unstable yield. Here, we employed multiple statistical analyses to determine traits that could be useful in predicting grain yield. Furthermore, additive main effect and multiplicative interaction and genotype × genotype × environment models were used to identify high yielding and stable landraces. Twenty-four bambara landraces were evaluated in two contrasting dry land growing seasons at four environments. Based on the results of correlation, path coefficient values and stepwise multiple regression analysis, it is reasonable to assume that seed growth rate would be effective as indirect selection criteria for grain yield improvement in this set of breeding materials under early and late planting environment. However, optimizing biomass growth rate, pod fill period, 100-seed weight, number of pods per plant and time to flowering may have important role in the improvement of grain yield in bambara groundnut. Due consideration should be given to 100-seed weight and time to flowering in the early dry and late planting environment. The possibility of successful cultivation of bambara groundnut in forest–savannah transition agricultural zone of Nigeria, particularly when planting is done around early August has been established in this study. However, based on the strong association between seed yield and its related characters in early and late planting environments, selection for higher seed growth rate combined with large number of pods appears to be the best indirect traits when selecting bambara groundnut plants to enhance grain yield under early and late planting environments. While landraces TVSu 1520 and 1578 were considered the best adapted landraces, TVSu 1670 and 1518 are promising landraces that could contribute to increasing grain yield stability.