Compensation-Induced Yield Gains in Mixtures of Common Bean (Phaseolus vulgaris L.)

Over the course of two planting seasons field trials were conducted at the CIAT farm in Palmira (Colombia). The experiments included nine tropical bean lines grown in pure stands and seven mixtures obtained by combining these lines on the basis of equal proportions in seed number.
In the case of several pure lines, inferior seed quality led to low germination and uneven population densities, especially in the first planting season. Analogously, missing plants also occurred with the corresponding mixtures. A significant and positive relationship between mixing induced yield gains and patchiness in mixtures was found, indicating that intergenotypic compensation was a major determinant for mixture effects on yield. In common bean as a tropical subsistence crop seed quality is known to be erratic. It is concluded that compensation effects in mixtures of common bean may be expected to be of practical importance regarding the improvement of yield stability over seasons.     

Agronomic performance and genetic shifts of genotype mixtures in peanut

Summary Little information is available on the genetic shifts that may take place when seed mixtures of peanut are grown over time. Five peanut lines with distinct seed coat colors, but similar plant types, pod yields, and maturities, were grown in pure stands for four years. A mixture with equal numbers of seed from each of the five lines was grown each year. All mixtures were subsampled and grown in subsequent years without reconstitution. Yield, 100-seed weight, and total sound mature kernel proportions from the mixtures were higher than the pure stand average of the five lines, but yield and total sound mature kernel proportions were lower than the average adjusted for individual line production. The best component line was significantly better than the mixture for pod yield, 100-seed weight, and proportion of sound mature kernels. Intergenotypic competition shifted the mixture composition to increase the proportion of one of the high yielding lines after only two years, while other high yielding lines in the test either maintained or decreased their original proportion. The two lowest yielding lines in pure stand also decreased in proportion over time.Contribution of the Florida Agricultural Experiment Station. Journal Series No. R-00550.     

Yielding Ability of Pure Stands and Equal Proportion Blends of Rapeseed (Brassica napus L.) with Double-low Quality

Yielding ability of intraspecific mixtures is an important issue not only for homozygous and homogeneous crops but also for heterozygous and/or heterogeneous ones. The goal of the present study was to examine the performance of mixtures and synthetics from double-low (low in erucic acid and glucosinolates) rapeseed ( Brassica napus L.) as compared to pure stands. The material consisted of seven lines and from 1982/83 to 1984/ 85 lines, all possible biblends and syn₁'s (1983/84 and 1984/85 exclusively) were grown in a completely randomized block design. An analysis of variance was conducted and general mixing effects (g.m.e.) and specific mixing effects (s.m.e.) were calculated for components of biblends. A few pure-standing lines yielded higher than some mixtures. Nevertheless, the overall mean of mixtures was not exceeded by any pure stand. For selection purposes, the higher variance of 'among lines' in comparison with 'among blends' would not result in higher yields because of the generally higher yielding ability of blends. Additionally, mixtures were marked by higher yield stability as compared to pure-standing lines. On the average of two years of testing yields of syn₁'s amounted higher than yields of mixtures. Differences between 'g.m.e.' of lines were proved and moreover, the variance component of 's.m.e.' was on a lower level than that of 'g.m.e.'. Consequently, in order to find the best mixture it seemed not necessary to analyse a complete diallel rather than to apply factorial or incomplete factorial concepts.     

Yield Formation in Mixtures of Rust Resistant and Susceptible Plants of Common Bean (Phaseolus vulgaris L.)

In a two-factorial trial, conducted in 1986 at the CIAT farm in Palmira (Colombia), the performance of nine tropical bean lines differing in resistance to rust and seven mixtures obtained by combining these lines on the basis of equal proportions in seed number was evaluated in a rust inoculated treatment and in a fungicide treated control.
Compared to the fungicide treated control, rust attack significantly reduced the yield of all susceptible lines by 24 to 56% in pure stands. In rust inoculated mixtures containing resistant, intermediate and susceptible genotypes, mixture effects on yield increased only by 3.3% compared to the fungicide treated control. In mixtures of common bean a higher proportion of resistant lines appears to be required compared to cereals for comparable reductions in the spread of rust due to lower plant density and correspondingly higher autodeposition rate of uredospores.     

Early Generation Selection for Grain Yield in Narrow-Leaf Lupin (Lupinus angustifolius L.)

Experiments were undertaken to identify an efficient method of selection for yield in early segregating generations of narrow-leaf lupin crosses. A first series of experiments involved simulation of F₂ populations with mixtures of ten cultivars and advanced breeding lines. The performance of genotypes in mixtures sown at different densities was compared with their monoculture [commercial density) yields m the same and the following year. These comparisons provided a basis for assessing the value of different planting designs and different selection criteria in early generation selection for yield. Correlated monoculture yield responses to simulated selection for single plant yield were similar for the honeycomb design and standard selection procedures at both low and commercial densities. These responses were much higher than that for grid selection in a low density population. Correlated monoculture yield responses to selection for other plant characters were substantial only for flowering time and number of pod bearing branches under certain conditions. These responses were greatest for selection in a low density mixture and in the year following selection. A procedure involving selection of the earliest flowering plants and selection within this group of plants with the highest number of pod bearing branches should be an effective approach to early generation yield selection in the narrow-leaf lupin.     

Genetic variation for resistance to low-temperature photoinhibition of photosynthesis in maize (Zea mays L.)

Summary In the partially allogamous faba bean, yield and yield stability can be improved significantly by heterozygosity and heterogeneity. The commercial production of hybrid varieties for the full exploitation of heterosis is still unfeasible. Hence, the breeding of synthetic varieties has repeatedly been recommended. The present study aimed at investigating whether and to what extent effects due to heterozygosity and heterogeneity occur in such varieties, particularly in relation to Syn-generation. A sample of 36 inbred lines (Vicia faba L. minor) was used to generate several entries of different population structure, e.g. blends of inbred lines (=Syn-0), experimental synthetics of generations Syn-1 to Syn-4 and polycross progenies. In 1986 to 1991 these entries were evaluated together with their parental lines grown in pure stands in six series of multi-locational field trials in West Germany. The yield of the synthetics increased with successive Syn-generations and asymptotically approached its maximum by as early as generations Syn-2 or Syn-3. The yield increase was mainly caused by heterozygosity. In two synthetics the yield increase corresponded to about one-half to two-thirds of the mid-parent heterosis. Effects due to heterogeneity were small and mostly non-significant. In one out of three expriments significant effects due to seed source were observed which, however, did not alter the yield increase with successive Syn-generations. Hence, Syn-generations Syn-2 or Syn-3 may be sold to the farmer.     

利用品种混合控制小麦病害之研究进展

作物多样性在病害防治上的应用包括多系混合、品种混合和物种混合,其中品种混合策略备受重视。对于小麦,品种混合与它的组分净种时的表现相比至少有两方面的优势,即增加籽粒产量的稳定性和减少病害的危害．特别是对减轻锈病和白粉病的危害更为明显。但是,由于病害防治而获得的产量收益比较小．一般平均只有4％-5％。对于小种专化的病原物,小麦混合群体中复杂小种(能侵染两个或两个以上混合组分)的相对频率高于简单小种的情况并不少见,因此有必要实行小组分数目品种混合系统的多样化、增加组分之间的抗性差异或增加混合组分数目。影响品种混合防病效应的因素是今后需要大力研究的问题。     

The Effect of Inoculum Pressure, Germplasm Selection and Environment on Spring Barley Cultivar Mixtures Efficacy

A range of mixtures including one set made from cultivars grown in the UK and one from cultivars grown in Poland, were included, along with their component cultivars, in nine trials at Scottish Crop Research Institute, Dundee, UK or at the Experimental Plant Breeding Station of the IHAR, Baków near Kluczbork, Poland, over five seasons. The effects of inoculum pressure, plot size, fertiliser level and germplasm on mixture efficacy were investigated. In the four trials where inoculum pressure was controlled, mixtures reduced infection more at lower inoculum pressures, but this did not translate into yield benefit. Smaller plots increased mildew in monocultures but not mixtures. Fertiliser levels increased mildew levels but did not affect mixture efficacy. There were large differences between both Polish and UK germplasm, and between Polish and UK trial sites, but the performance of the mixtures compared with their respective monoculture components was similar within both germplasm groups and trial sites. Mixtures reduced lodging and affected plant height and heading date. The advantages of mixtures for improving yield, reducing fungicide applications and improving agronomic characteristics was demonstrated and there seems to be great potential for their further improvement and exploitation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Complementary competition in cultivated barley (Hordeum vulgare L.)

Summary Grain yield and its endpoint components were studied for three barley varieties, Dayton, Hudson, and Tenn 60-34, as pure stands and two-way and three-way mixtures at three widely separated sites for two years. The populations, including the pure stands, produced similar grain yields. Complementary competition was observed in all mixed populations in which Tenn 60-34 occurred. Its yield was suppressed in mixtures about 20% while Dayton and Hudson increased a like amount so that total mixed population yield was equal to that expected from pure stand performance. Tenn 60-34 occurred at 33, 50, and 80% frequencies in mixed populations with no difference in competition, indicating a lack of frequency dependency for the effect.Yield component data indicated that the reduced yield of Tenn 60-34 in mixed stands was due entirely to a decreased number of spikes produced per unit area. It was inferred that this was due to competition at time of tillering although this could not be determined since the varieties were indistinguishable during vegetative growth.An examination of population-environment interaction provided some evidence for the idea that heterogeneous populations in which there is intense competition show greater micro-environment (within-site) instability. Heterogeneous populations generally showed lower than expected contribution to the population-environment variance although the differences were quite small.These results have important implications for the utilization of heterogeneous populations in agricultural production and for the management of genetically diverse populations in plant breeding practice since genotypic frequencies are expected to change rapidly with complementary competition.     

Recurrent selection for grain yield in early generations of two barley populations

Summary Two spring barley composites, one based on eight West-European two-rowed cultivars (A) and one, the predominantly six-rowed composite XXI, based on several thousands of barley cultivars (B), formed the starting point of a recurrent selection procedure. The aim was to study whether recurrent selection in early generations is an effective procedure to improve barley populations for agronomic characteristics, especially grain yield.After two cycles of recurrent selection in the two populations A and B separately, and consisting of single plant selection followed by line selection, one cycle of recurrent selection was applied to the population produced by intercrossing the selected A and selected B lines.The selection for grain yield in the F2 single plant stages and the F3 line stages was carried out by selecting the plants or lines with the largest mean head weight provided that they did not tiller too poorly. Also some selection was applied against extremes in heading date and against tall plants.After two cycles of recurrent selection the grain yield, tested over two years and two locations, had increased with 16.5% in population A and with 27.0% in population B. Both the single plant selection and the line selection had contributed significantly to this response.The population created by crossing the selected A with the selected B lines showed a significant reduction in yield compared to the mean yield of the A and B lines constituting this population. Single plant selection, followed by line selection did raise the yield level 5.7% above that of the mean of these A and B lines. Several lines produced from this intercross combined an excellent grain yield with outstanding resistance to barley leaf rust and powdery mildew. However, these lines like the entire intercross population suffered from susceptibility to lodging, a characteristic derived from population B.In five experimental situations mixtures of genotypes were compared with the mean of the monocultures of the constituting genotypes. The mixture yielded always more, the average mixture effect being 4.5%.     

Line selection for exploiting durum wheat (T. turgidum L. var. durum) local landraces in modern variety development program

Summary Pure line selection for grain yield applied within four durum wheat local landraces (Triticum turgidum L. var durum) was studied in an effort to determine: (i) the agronomic performance of selected line mixtures (bulks) and their value as potential new cultivars, (ii) the effectiveness of pure line selection for grain yield within local landraces and (iii) the correlated selection response of yield components and kernel quality traits. Four local durum wheat landraces were used. Two of them, Mytilini-1 and Mytilini-2 are still cropped in some rural areas of the island Mytilini whereas the other two, Limnos and Mavragani are maintained in the Greek Gene Bank. Following their preliminary evaluation for agronomic performance under current growing conditions, 100 individual plants from each landrace were randomly selected. Selected plants (pure lines) were field evaluated head to row during 1997–98 and 1998–99 growing seasons. Based on grain yield performance, bidirectional selection, high vs low, was practised within each landrace. Thus the five higher yielding lines and their corresponding lower ones from each landrace were identified. Selected lines, with no further progeny testing, were pooled using a balanced seed composite to form the high yielding five line bulk and its respective low counterpart. The resulting 16 bulks (eight high and eight low) along with their four source landraces and two commercial varieties, Mexicalli and Simmeto, used as checks, entered field testing for agronomic performance in two and one location during 1999–00 and 2000–01 growing seasons respectively. Data for grain yield and yield components (1000 kernel weight, number of kernels, and productive tillers) along with kernel quality data (protein content and vitreous) were recorded. Data for grain yield indicated that the landraces studied seemed to be line mixtures, as expected, since they responded to bidirectional phenotypic pure line selection. The high yielding bulks were of interesting agronomic performance, equivalent to or significantly better than that of the commercial checks and are worth further testing as potential cultivars. Selected high bulks of Mytilini 2 landrace significantly outyielded both the source landrace and the commercial checks maintaining the high protein content of the source landrace, which was significantly higher than checks. This performance provides evidence that the within landraces selection of lines combining high grain yield with high protein content seems to be feasible. In conclusion, evidence is presented that genetic variability seems to be available within the landraces studied which could be worth using in breeding programs. Furthermore the simple pure line selection breeding effort undertaken seemed to be effective in developing line bulks with promising performance and worth further testing as potential cultivars.     

Effekte der Sorten- (Weizen)und der Arten- (Weizen, Roggen) Mischung auf die Ertragsleistung krankheitsfreier Bestände

Effects of cultivar (wheat) and species (wheat, rye) mixtures on grain yield of desease-free stands
Cultivar mixtures (winter wheat) and species mixtures (winter wheat/winter rye) grown free from pests and diseases in different environments are compared to pure stands and analyzed with respect to inter-component relationships relevant for yield. All mixtures consisted from two components which were planted 1:1. Mixing effects (i.e. deviations from arithmetic mean of respective components grown in pure stands) on grain yield/ha and yield structure were dependent on components and growing conditions, particularly nitrogen availability. Under conditions suboptimal for one component, ontogenetic differences between components resulted in positive mixing effects on grain yield since the yield proportion of the accompanying partner increased more than proportionally. In several instances, yield proportions shitted without leading to mixing effects. In some experiments and/or mixtures mixing effects could not be observed at all.     

Comparative efficiency of honeycomb and conventional pedigree methods of selection for yield and fiber quality in cotton (Gossypium spp.)

The effectiveness of honeycomb pedigree selection (HPS) as compared to conventional pedigree selection (CPS) was studied in one intraspecific (G. hirsutum L. × G. hirsutum L.) cross population (population I) and one interspecific (G. hirsutum L. × G. barbadense L.) cross population (population II). Combined selection for yield and lint quality traits was applied for four cycles at two locations for population I and atone location for population II. Finally, the best F₆ lines derived by each method, together with the unselected population derived by single seed descent (SSD) and three check cultivars, were tested in comparative experiments, separately for each cross, at the same locations. In both populations the analysis of variance indicated significant differences among the groups of the material tested for seed cotton yield, mean boll weight, micronaire reading, staple length, and uniformity ratio. No significant differences were found with respect to plant height, lint percentage, and fiber strength in population I and with respect to lint percentage and fiber strength in population II. In population I, on the basis of mean seed cottonyield and number of superior lines derived by each method as compared to the check varieties and the unselected SSD population, HPS-lines were superior to CPS-lines for seedcotton yield, fiber length and boll weight. HPS-lines, however, did not differ significantly in seedcotton yield from the best check cultivar Eva. Finally, the material derived by CPS was earlier in maturity than the material derived by HPS and SSD. Also in population II, on the basis of mean seedcotton yield and number of superior lines derived by each method as compared to the unselected SSD population, HPS-lines were superior to CPS-lines. No significant differences, however, were identified between the material of the two methods for lint quality traits. It was concluded that in both populations HPS was more effective than CPS in identifying lines with high yielding ability and good lint quality. This superiority of HPS is attributed, at least partially, to its effectiveness in early generation selection. This revised version was published online in August 2006 with corrections to the Cover Date.     

An improved breeding strategy for autotetraploid alfalfa (Medicago sativa L.)

Alfalfa cultivar development will be enhanced by breeding strategies whichutilize the full potential of autotetraploid population genetic structures. Thisstudy evaluates the effectiveness of an allelic selection scheme, which wasdeveloped to overcome limitations of inbreeding depression and to exploitgeneral and specific combining ability effects in autotetraploid populations.Allelic selection entails the minimization of non-additive genetic effects byselecting among full-sib families (F1) which are at uniform levels ofheterozygosity. Such F1 lines are developed by crossing individuals fromtwo unrelated random mating populations. Selected F1 lines wereintercrossed to form an improved population. Eight random matingpopulations of alfalfa were developed to study the effectiveness of allelicselection. Selection for increased dry matter yield resulted in alfalfapopulations with 38 percent greater yield than the parent populations. Twocycles of intercrossing, among selected F1 lines, did not dissipate the gainfrom selection. This result has important implications for synthetic cultivardevelopment in which a major limitation is the decline in productivity withadvancing generations of seed increase. A positively correlated response toselection for dry matter yield was observed for plant height and stemdiameter. The results of this research indicate that continued testing of theallelic selection scheme is warranted and could have a significant impact onthe breeding of autotetraploid alfalfa, particularly for synthetic cultivardevelopment.     

Stability of performance of mixtures and multilines

Summary The effect of intra-populational genetic diversity on the stability of performance of equiproportional mixtures, as measured by their variance in yield over a range of environments, was investigated with a simple theoretical model.In the absence of intergenotypic interactions it was found that a mixture will be more stable than the most stable line (V_min) if:{fx405-1} where n is the number of lines in the mixture and {ie405-1} and {ie405-2} are the mean variance and covariance in yield of the component lines. In other words, the yield of multilines will vary less than that of their most invariant component only when the component lines respond quite differently to environmental changes.In the presence of intergenotypic interactions it was found that a mixture will be more stable than its best or better component (V_min) provided:{fx405-2} where n, {ie405-1} and {ie405-2} take the same meaning as before and {ie405-3} and {ie405-4} represent the mean variance and covariance of the interaction effects among the n lines. That is, when the components of a mixture significantly interact, then the dissimilarity in response of each component to environmental fluctuations must be even greater for there to be a stability benefit to mixtures.These findings are discussed in relation to the problem of developing commercially acceptable multiline varieties.     

Genetic divergence in parental genotypes and its relation with heterosis, F1 performance and general combining ability (GCA) in opium poppy (Papaver somniferum L.)

Summary Genetic divergence in 110 population (20 parents and 90 F₁ hybrids) of opium poppy was studied by multivariate analysis. All the entries were grouped in 14 clusters. Out of 20 parents, ten were accumulated in one cluster and rest 10 distributed over seven clusters. Estimates of cluster distance showed that maximum intra-cluster distance was in -cluster IX (25.62) followed by cluster I (22.41), V (22.23) and IV (21.06). The inter cluster distances varied from 16.62 (between cluster XII and XIV) to 195.10 (between cluster IV and IX). The cluster analysis indicated substantial diversity among the parental genotypes, which had the potential to release considerable variation in their crosses. The first four principal components (PCs) with eigen values >1 accounted for 68% of variation among the population. The first and second components could account for 29 and 20% of the total morphological and alkaloidal variations, respectively. The PC1 was closely related to yield and yield related traits. The characters contributing greatest positive weight on PC1 were opium yield, plant height, stem diameter, capsule weight/plant and seed yield/plant. The possibilities of relationship between genetic divergence, F₁ performance, heterosis and GCA of parents have been explored.     

Evaluation of parent selection methods for yield improvement of cowpea (Vigna unguiculata (L.) Walp.)

Summary The mean aim of this study was to identify an effective method of predicting cross-potential in respect of yield improvement of the cowpea (Vigna unguiculata (L.) Walp.) through hybridization and subsequent selection.Three prediction tests based on data collected from experiments with ten cowpea lines and the F1 and F2 generations of all possible crosses between these lines were evaluated. The three prediction tests were based on: i Yields of prospective parents. ii. General combining abilities estimated from F1 and parental data iii. Frequencies of superior plants in F2 populationsEach of the three procedures was used to identify the crosses with the lowest or highest yield potential, i.e. those crosses most likely to produce the greatest number of lines with yields higher or lower than those of either parent. Crosses selected on the basis of these criteria were evaluated in the following growing season on the basis of biometrical analysis of F2 and backcross populations and the performance of the respective F3 and F4 generations.Six different crosses were selected from the 45 tested on the basis of the three prediction tests. Analyses of F2 and backeross populations from each cross provided estimates of [d] the difference in parental means and 1/2D the additive genetic component which, in turn, were used to predict the frequency of transgressive inbred lines obtained by single-seed descent from the F2. Both crosses selected on the basis of F2 data were expected to produce a much higher frequency of transgressive lines than those selected on the basis of parental yields. The high potential cross selected on the basis of general combining ability was expected to produce a higher frequency of transgressive lines than the corresponding low yield potential cross. Replicated trails of F3 bulks of the selected crosses showed that high yield potential crosses were significantly higher yielding than low yield potential crosses for all prediction criteria. In a trial with 22F4 lines of each of the two crosses selected on the basis of parental yields and frequency of high yielding F2 plants, the high yield potential cross in each case had a greater mean and variance for seed yield than the corresponding low yield potential cross.It was concluded that parental yields provide a sound basis for an initial screening of prospective parents. This screening should identify a high yielding line which can be crossed with a number of contrasting lines to produce F2 populations for the final screening phase.     

Effects of dwarfing genes on yield and yield components under irrigated and rainfed conditions in wheat (Triticum aestivum L.)

Summary Near-isogenic tall (no dwarfing gene), semidwarf (Rht1 or Rht2) and dwarf (Rht1 + Rht2 or Rht3) spring wheat lines were evaluated for yield and yield components under irrigated and rainfed conditions. Under irrigated conditions, the dwarf and the semidwarf lines exhibited a significant yield advantage over the tall lines. Under rainfed conditions, the semidwarf lines outyielded the tall as well as the dwarf lines. Percent yield reduction in response to drought stress was highest with the dwarfs and lowest with the tall lines. Dry matter production of the tall lines and that of the semidwarf lines did not differ significantly and both produced significantly more dry matter than the dwarf lines under irrigated as well as rainfed conditions. Plant height and kernel weight decreased with increasing degree of dwarfness while number of kernels per spikelet, harvest index and days to heading increased under both moisture regimes. The dwarfing genes did not have any significant influence on number of tillers/m² and spikelets per spike in either moisture regime.     

A comparison of cytoplasmic and chemically-induced male sterility systems for hybrid seed production in wheat (Triticum aestivum L.)

A comparison of two male sterility systems was carried out in wheat for hybrid seed production and hybrid performance. Seventeen hybrid combinations based on Triticum timopheevi cytoplasm were compared with their genetically equivalent CHA-facilitated combinations. The same set of restorer lines was used as parents in CMS- and CHA-based hybrids to maintain genetic equivalence. In the first experiment aimed at study of female line behavior and crossed seed production, the CHA treated lines showed significantly shorter heights whereas CMS lines were similar to the control. The two systems were equally effective in sterilizing rate. The outcrossing percentage of the CMS lines was almost twice that of the CHA treated lines. Thousand-grain weight of the crossed seeds on CMS lines was greater than on the CHA treated lines and control. On average, the germination percentage of seeds on CMS lines was double that of the CHA treated lines and the percentage of effective outcrossed seeds in CMS lines was 3 times more than that from CHA treated lines. The second experiment was conducted to examine the yield performance of the hybrids derived from the two systems of male sterility. A total of 40 entries including 20 hybrids and 20 parents were evaluated in the experiment. The mean grain yield of the CMS-based hybrids was greater than that of the CHA-based hybrids,the B and R lines. All the CMS-based hybrids showed significantly higher grain yields than their better parents whereas all the CHA-based hybrids, except two,showed no significant yield increases over their better parents. Possible reasons for differences in CMS- and CHA-based hybrid performance are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effectiveness of early generation (F3) yield testing and the single seed descent procedures in two cowpea (Vigna unguiculata (L.) Walp.) crosses

Summary Two breeding procedures were compared in two cowpea crosses. Both procedures were started from the same selected F₂ plants in each cross. For the early generation yield testing, the F₃ lines were yield tested and a pedigree and bulk methods followed in F₄ and F₅. Each F₅ line was bulked to provide seed for a yield test in F₆. In the Single Seed Descent (SSD) procedure, a single seed was taken from each F₂ plant to produce the F₃ generation. The procedure was repeated for the F₄ and F₅. The F₆ SSD lines and the F₆ yield testing lines were compared in yield tests.The results showed that differences in yielding ability of F₃ lines persisted over generations indicating that selection was effective. This was confirmed by the high significant correlations between F₃ yields and those of later generations which ranged from r=0.51^* to 0.85^**.The grain yields of lines derived by the single seed descent procedure were as good as those derived from early generation yield testing.Significant linear correlation between visual rating of F₃ and F₆ yields with actual yields revealed that it is possible to identify promising lines of cowpea visually.