Combining ability analysis and association of yield and yield components among selected cowpea lines

The study was carried out to determine combining ability and association of yield and yield components among crosses derived from seven selected cowpea (Vigna unguiculata (L.) Walp) parents. Twenty-one hybrids were generated from diallel crosses excluding reciprocals. Hybrids along with seven parents were studied for combining ability and phenotypic correlations for seed yield and eight yield components. The result indicated that the general combining ability (gca) and specific combining ability (sca) were significant for most characters indicating the importance of both additive and non-additive genetic components. Additive gene action was important for eight characters except pod number, whereas non-additive gene action was not important for nodule number and grain yield. Parental lines IT86D-716 and IT81D-985 were found to be good general combiners for grain yield and other traits. The most promising specific combiners for yield and yield components were from crosses including IT87D-697-2 × IT86D-716, IT88D-867-11 × IT86D-716, IT93K-624 × IT87D-697-2, and IT87D-697-2 × IT92KD-405-1. Significant positive phenotypic correlations were observed between seed yield with pod length (POL), number of pods per plant (PON), and number of seeds per pod (SPD). POL, pod number per plant, SPD, and grain yield were identified as the best selection criteria that could be used in cowpea breeding programs.     

Variation in the storage proteins of peas in relation to sulphur amino-acid content

Summary A cellulose acetate electrophoretic technique has been used to characterise the storage proteins present in pea seeds in order to try and determine the proportions of proteins present which are enriched in sulphur amino-acids. Some of the eight varieties examined were shown to differ in their proportions of the various storage proteins. When the proteins were separated and estimated quantitatively and also characterised by their sub-unit composition, it was shown that cellulose acetate electrophoresis of crude protein extracts or of whole globulins did not give the degree of resolution required. The procedures which have to be undertaken in order to obtain this information are considered, and the difficulties of incorporating them into a plant breeding programme discussed.     

Variation and covariation in Vicia faba L. populations of Mediterranean origins

Summary Variation and covariation in 15 Vicia faba L. ssp. major populations from Italy. Greece and Egypt were analyzed. Ten quantitative morphobiological characters of agronomical and nutritional interest were observed. Differences among countries of origin were highly significant for all characters except for lowest podded node. Phenotypic distances among populations, both within and among origins, estimated on canonical variates evidenced that the Egyptian populations from a distinct group and that a relevant degree of similarity exists among the Greek and the Italian meterial. The covariation structure within populations, which was studied by means of factor analysis, was comparatively simpler in the Egyptian material than in that form the other two Mediterranean countries. The differences evidenced can be attributed to different gene associations between characters and suggest the possibility of obtaining, through recombination, genotypes agronomically more favorable.Research work supported by C.N.R., Italy, special grant. Sub-Project 1, Paper No. 299.     

Variation for natural out-crossing in pigeonpea

Summary Several researchers have reported a considerable degree of natural out-crossing in pigeonpea from different environments. This paper reviews the subject with respect to the variation for natural out-crossability, pollinating vectors, extent of natural out-crossing, isolation specifications, and the possible utilization of natural out-crossing in pigeonpea improvement.ICRISAT Journal Article No. 831.     

Variation in Okra

Summary A study of the variation of 29 characteristics of 585 varieties or seedlings of okra revealed that 17 West African varieties could be distinguished from all others on the basis of 5 discriminating characteristics. In addition, seedlings of the 3rd outcrossing generation of a population differed from a varietal collection in several characteristics, the most important of which were more seeds per pod and more pods per plant. This is believed to be the result of mass-selection. Country groups differed significantly in characteristics but these differences are believed to be due to small sample size. No such distinguishing characteristics were evident among country groups represented by large numbers of varieties.     

Genetic distance and its association with heterosis in peas

Summary The relationship between the genetic distance of parents and both the heterosis of F₁ hybrids and the variance of F₅ lines was investigated in 72 crosses of pea (Pisum sativum L.). The genetic distance between each pair of parents was estimated, using isozyme (GDi), morphological (GDm) or quantitative (GDq) markers and finally a combination of isozyme and morphological markers (GDi+m). GDm was poorly correlated with the other measures of genetic distance, which in turn were strongly correlated with each other. Genetic distance was moderately correlated with the level of heterosis for yield over midparent in the F₁ generation, with the highest correlation obtained from GDi+m. GD was not significantly correlated with heterosis for yield over the better or best parent but it was significantly correlated with all three measures of heterosis for pods per plant and hundred seed weight. There was no correlation between genetic distance and the level of heterosis for yield and total dry matter in the F₂ generation, but GDi, GDi+m and GDq were predictive for the level of inbreeding depression in grain yield and total dry matter. When parents were high in genetic distance, crosses produced highly transgressive segregants for basal branches per plant, hundred seed weight, harvest index and onset of flowering. Genetic distance between parents was thus a useful measure for predicting a portion of hybrid performance and also of the variance of derived inbred lines. It was concluded that when choosing parents for a cross, consideration should be given to their genetic distance as well as their overall adaptation and their yield. There is considerable potential for optimising choice of parental combinations in the development of improved pea cultivars.     

Genetical analysis of resistance to Mycosphaerella pinodes in pea seedlings

Summary In studies of the inheritance of resistance, pea seedlings of seven lines in which stems and leaves were both resistant to Mycosphaerella pinodes were crossed with a line in which they were both susceptible. With seven of the crosses resistance was dominant to susceptibility. When F₂ progenies of five crosses were inoculated on either stems or leaves independently, phenotypes segregated in a ratio of 3 resistant: 1 susceptible indicating that a single dominant gene controlled resistance. F₂ progenies of one other cross gave ratios with a better fit to 9 resistant: 7 susceptible indicating that two co-dominant genes controlled resistance. The F₂ progeny of another cross segregated in complex ratios indicating multigene resistance.When resistant lines JI 97 and JI 1089 were crossed with a susceptible line and leaves and stems of each F₂ plant were inoculated, resistance phenotypes segregated independently demonstrating that leaf and stem resistance were controlled by different genes. In two experiments where the F₂ progeny of the cross JI 97×JI 1089 were tested for stem and leaf resistance separately, both characters segregated in a ratio of 15 resistant:1 susceptible indicating that these two resistant lines contain two non-allelic genes for stem resistance (designated Rmp1 and Rmp2) and two for leaf resistance (designated Rmp3 and Rmp4). Evidence that the gene for leaf resistance in JI 1089 is located in linkage group 4 of Pisum sativum is presented.     

Somatic embryogenesis in pea (Pisum sativum L. and Pisum arvense L.): Diallel analysis and genetic control

Summary Six lines of Pisum were tested in vitro for their ability to produce somatic embryos from apices. Significant quantitative variation was observed. Inheritance of the ability to form somatic embryos was studied using a diallel cross among six different lines. About 80% of the observed genotypic variation was due to additive effects. There is a tendency for the favourable genes to be recessive. It appears that there are two genetic systems involved. Analysis of the distribution of F₃ families means from a cross among two extreme lines seems to indicate the presence of a few major genes in the control of somatic embryogenesis of pea.     

南通扁豆品种主要农艺性状的相关性和通径分析

对16个南通地方扁豆品种的10个主要农艺性状进行相关性分析及通径分析。结果表明,小区产量的变异系数较大,达到44.62%,而始收天数性状的变异系数仅为3.15%;百荚重与荚长等4对性状间呈极显著相关,7个性状与小区产量呈正相关;每荚粒数对小区产量的直接通径系数最大（P＝0.7054）,因此对每荚粒数进行直接选择是扁豆高产育种的有效方法;荚宽对小区产量的负向直接作用最大（P＝-0.5299）,因此在育种过程中选择荚宽较小的品种有利于获得高产,但荚宽过小会降低每荚粒数,从而影响产量性状。     

Variation among maize (Zea mays L.) accessions of Bendel State,Nigeria. Multivariate analysis of agronomic data

Summary Two multivariate techniques were used to characterize 30 maize accessions collected from three ecological zones of Bendel State, Nigeria. Differentiation of the 30 accessions into five distinct groups was achieved with the unweighted variable group method of the average linkage cluster analysis of 34 agronomic characters. Four of the taxonomic groups contained at least three accessions each, while a fifth group contained only one. The single accession contained in the fifth group was characterised by very early maturity, deeply pigmented leaves and ear husks and short statured plants. Clustering of the accessions into different phenetic groups followed substantially along geographical and traditionally trading routes. A few cases of overlapping of accessions from different geographical locations were obtained.Principal component analysis revealed that days to 50% tasseling and silking, number of nodes/plant, ear length, ear weight, leaf width, and kernel colour were the principal discriminatory characters that differentiated the accessions. Sixty-four percent of the total variation among the 34 characters were accounted for by the first five principal components while the first and second components accounted for 26 and 14 respectively.     

Characterization and classification of isozyme and morphological variation in a diverse collection of garlic clones

Summary Garlic (Allium sativum L.) has a long history of obligate vegetative propagation. In this study, isozyme and morphological characters were analyzed for 110 diverse clones of garlic and the proposed progenitor species, A. longicuspis. The clones displayed 17 different electrophoretic phenotypes, which were associated with morphological traits. An isozyme-based phenetic tree was contructed to explain the possible relationships of various garlic clones and A. longicuspis. The lack of unique isozyme and morphological characters of A. longicuspis suggests an artificial species separation.     

Variation for resistance to Fusarium head blight in spring barley

Fusarium head blight (FHB) is a fungal disease of barley and other cereals, causing substantial yield and quality losses, mainly due to the contamination of the harvest with mycotoxins. We aimed to evaluate genetic variation for resistance to FHB and its association with other plant characters in diverse barley germplasm in order to identify useful lines for resistance breeding. The 143 barley lines consisted of 88 current European spring barley lines and cultivars, 33 accessions from the genebank at IPK Gatersleben, and 22 lines obtained from North American institutions. We conducted artificially inoculated field experiments with Fusarium graminearum Schwabe during two seasons. FHB severity was evaluated by repeated assessment of visual symptoms. On a set of 49 lines several trichothecene mycotoxins were analyzed. Variation for FHB severity was quantitative. The lines with lowest FHB severity were 'CIho 4196' and 'PI 566203'. Also within the European spring barley collection variation for FHB severity was highly significant. There was a significant negative correlation between plant height and FHB severity (r=– 0.55). FHB severity assessed in the field and the amount of deoxynivalenol in the harvested grains were positively correlated (r= 0.87). Several lines with a useful level of FHB resistance were found or confirmed and are recommended as crossing partners.     

Variation of resistance to broomrape (Orobanche ramosa) in tomatoes

Summary Twenty five tomato cultivars and one accession of wild tomato were evaluated for their resistance to branched broomrape (Orobanche ramosa) infestation. Tomato cultivars were found different in their resistance to Orobanche based on different growth parameters. Total Orobanche number, haustoria development and number of emerged Orobanche shoots were all different between tomato cultivars. Differences in the growth and fruit yield among tomato cultivars were also found in response to Orobanche infestation. Ranking tomato cultivars for Orobanche resistance indicates the existence of different resistance mechanisms in these cultivars. Relatively high to moderate levels of resistance were obtained in Tiny Tim, Acora, Castler, Pomodora, Orient, Red Alert and the accession LA 1478 of L. pimpinellifolium. The cultivar Tiny Tim showed the highest level of resistance for all measured parameters and in all experiments.     

Variation between and within lentil landraces from Yemen Arab Republic

Summary The variation in 31 landraces of lentil collected from Yemen Arab Republic was partitioned to estimate the variation between populations and the variation between families within populations by studying a total of 568 progenies of randomly selected plants. There was significant variation between populations and between families within populations in seedling pigmentation, time to flower, time to maturity and plant height, but the predominant source of variation was between populations. This variation was unrelated to altitude of collection. The landraces were equally variable across characters. The implications of this analysis of variation on lentil breeding and germplasm collection are discussed.     

Variation for chemical characters in some promising strains of wild pomegranate (Punica granatum L.)

Summary In the present studies, distinct variations for chemical characters were obtained. The juice obtained from the grains of Tree No. 23 and 4 was highly red coloured followed by Tree Nos. 5, 21 and 26. The sugar to acid ratio was maximum in Tree No. 22 followed by Tree Nos. 16 and 23.     

Variation in high molecular weight glutenin subunits in landraces of hexaploid wheat from Afghanistan

Summary Variation for high molecular weight (HMW) glutenin subunits is reported in Afghan hexaploid wheat landraces from different locations in the country ranging in altitude from 395 to 3170 metres. The variation appeared to be independent of the altitude and geographical location of the landraces. Studies of a number of samples from each of five sites revealed that at some sites there was allelic variation at theGlu-A1 andGlu-B1 loci coding from HMW glutenin subunits, but there was no variation at theGlu-D1 locus within and between sites.     

Correlation and path coefficients analysis for reproductive traits in Guinea grass

Summary Correlation and path coefficients were calculated for seed yield per plant and its components from 36 clones comprising 8 parental and their 28 single cross clones in Guinea grass (Panicum maximum Jacq.) from data pooled over two years. Seed yield per plant showed significant positive correlation coefficients with branch number per panicle, panicle number per plant, panicle length, branch length, 100 seed weight and day to flower. Path coefficients analysis revealed that panicle number per plant had highest direct effect on seed yield per plant, followed by branch number per panicle, days to flower and 100 seed weight.     

Variation of hullability and other seed characteristics among sunflower lines and hybrids

Summary The hullabilities of 40 inbred lines (20 male sterility maintainers and 20 male fertility restorers) and 36 hybrids were studied in several environments in France. Thousand seed weight, oil and hull contents and the quantity of hulls remaining with the kernel after hulling were also measured. Principal component analyses and a hierarchical clustering method were used to described the variation of both inbreds and hybrids. Hullability varied from 11 to 66% for inbreds and 16 to 60% for hybrids. This variation is sufficient to permit breeding programmes for this character. Hullability is correlated positively with hull content (r=0.35^* to 0.69^*) but negatively with oil content (r=–0.34^*to–0.71^**). Large seeds generally hull better than small seed (r=0.21ns to –0.66^**). The value of the different classes of genotypes is discussed. Inbreds and hybrids producing achenes with a quite small hull content, a high oil content but a good hullability are the most promising for improvement of the quality of sunflower seed meal. Such genotypes are rare so that a recurrent selection programme is recommended to increase the frequency of favorable genes.     

Study of the variation in the somatic embryogenesis ability of some pea lines (Pisum sativum L. and Pisum arvense L.)

Summary Thirty lines of pea were tested in vitro to evaluate their ability to produce somatic embryos. Three distinct genotypic classes were detected (strong, medium and weak). The best responses were obtained in Pisum sativum. Abnormal somatic embryos and secondary embryogenesis seem to constitute the principal obstacle to the development of these structures.     

Variation in flower abscission of peppers under stress shading conditions

Summary Seedlings from 77 accessions including inbreds, F₁ hybrids and seven F₂ populations were exposed to approximately 60% shading for 35 days following transplanting into the field.Most of the lines did not set fruit under the shading due to heavy abscission of flowers. A few exceptional lines, hybrids and F₂ segregants showed resistance to abscission and set normal fruits under the shading regime. This procedure is suggested for screening against stress-induced flower abscission. An association is suggested between resistance to shading and to high temperatures and its genetic control.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel No. 1209-E, 1993 series.