Relationships between seed yield and growth characters,yield components,seed quality of summer-type oilseed rape (Brassica napus L.)

Summary Five genotypes of rapeseed were observed in the field on a single plant and plot basis to evaluate growth characteristics, yield, yield components and seed quality. Observations were made in two years at two locations on three seeding date and three seeding rate treatments. Correlation of seed yield with growth characters demonstrated no consistent trend, indicating that an early maturity and high seed yield should be possible. Harvest index was strongly correlated with seed yield. Percent seed oil and protein were not directly related to seed yield.     

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.     

Genetic and environmental variation in architecture and yield components in determinate white lupin (Lupinus albus L.)

Summary Determinate architecture is of great interest for lupin production in Europe but the extent of genetic and environmental variation in the structure and yield of determinate lupins must be evaluated. Forty-three genotypes of determinate autumn-sown white lupin were studied in four environments in France in 1991/92 and 1992/93. Wide variation was observed for phenological (dates of mainstem and branch flowering, date of end of flowering and date of maturity), morphological (numbers of branch orders, branches and leaves) and seed characters (seed yield, mean seed weight, number of seeds/m²). Both genetic and environmental effects contributed to the observed variation. Heritabilities were high for all characters, and the interaction between genotype and location effects was low. There were significant positive correlations of flowering dates with vegetative plant development including the number of branches, number of leaves and number of branch orders. Seed yield and phenological and archtectural characters were significantly correlated. Distribution of yield on the vegetative orders showed important variations according the genotype, and the variations were related to variation for the architecture. There are possibilities for yield improvement using morphological characters in determinate autumn-sown lupin.     

Spaced-plant traits related to seed yield in plots of perennial ryegrass (Lolium perenne L.)

Summary Seed yield in perennial ryegrass is low and selection criteria for high seed production are lacking. Indirect selection in spaced plants would be efficient, but spaced-plant traits need to be identified that correlate with seed yield in drilled plots. Spaced plants were studied of nine perennial ryegrass cultivars with a different seed production when grown in plots. Genotypic variation within cultivars for seed yield components and other traits was assessed in four environments in replicated clonal experiments. Extensive genotypic variation for most traits was present within each cultivar. Based on cultivar means of 25 or 50 genotypes, significant differences among cultivars were found for most traits. Cultivar-year interactions were found for most traits, but no significant cultivar-location interactions were generally found. Spaced-plant traits in general showed poor correlation to corresponding traits in drilled plots. Cultivars with contrasting seed yield in plots could not be distinguished on the basis of their spaced-plant traits and therefore no criteria for indirect selection for seed production in drilled plots could be identified in spaced plants.     

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 the crude protein content of field beans (Vicia faba L.) in relation to the possible improvement of the protein content of the crop

Summary A survey of the protein content of various field bean varieties indicates a range of variation extending over sixteen units of crude protein from 22–38%. Analysis of single plants from within three WPBS varieties Dylan. Danas and Dacre indicates that a similar range exists within commercial varieties. Examination of the progenies of high and low protein single plant selections together with a preliminary estimation of heritability suggest that protein content is highly heritable. No significant correlations were found between protein content and seed yield.     

Variation in landraces of durum wheat (T. turgidum L. conv. durum (Desf.) M.K.) from Turkey

Summary Durum wheat is historically an important crop in Turkey. Diverse durum wheat germplasm has been recorded many times in Turkish collections. 812 single plant genotypes from 190 durum wheat populations of 23 provinces in Turkey have been studied for number of days to germination, tillering, shooting, heading, maturity, and yield per plant. Variation in samples for traits studied was large enough and subsamples with different characteristics were identified. Grouping samples into provinces and altitudes of origin have revealed that variation in samples existed for some traits depending on province and altitude of origin. Yield per plant were not correlated with any of the developmental stages: but developmental stages were correlated with each other in varying magnitudes. Variation in yield per plant was not explained as well by developmental stages studied under a dry-cold environment. Further studies on samples needed to explore genetic variation more for other traits of economic importance.     

Use of immature seed germination technique as an alternative to in vitro culture of sunflower (Helianthus annuus L.) embryos

Summary The importance of developing new techniques that would simplify the complexity and operative costs of genetic breeding plans has been widely recognized. In that sense, germination from immature seeds in sunflower is a simpler and cheaper alternative to that of in vitro embryo culture, as it is produced in non-sterile conditions. Different techniques to maximize germination percentage were tested using 15 day old seeds. The results indicate that it was important: 1) to scarify seeds and 2) to soak them in 100 ppm of gibberellic acid for 1 hour. Through the application of this technique more than 94% of the seeds germinated.     

Correlation and path-coefficient analysis of components of seed yield in bambara groundnut (Vigna subterranea)

Summary Direct and indirect effects of components of seed yield upon seed yield and those of leaf number and leaf size upon components of seed yield were examined using path analysis, in bambara groundnut germplasm from Ghana. The number of pods per plant and 100-seed weight had direct positive effects on seed yield, but the two traits were negatively correlated. The number of pods per plant gave the best indication of seed yield status. The number of leaves was more important in determining seed yield in the bunch types, but leaf size was rather more important in the spreading types. Seed size is genetically determined and the genes for seed size may have pleiotropic effects on leaf size. The genes for seed size may also be linked to genes for leaf size. Selection for varieties with high and stable number of pods per plant should improve production level of bambara groundnut.     

Seed yield related to crop development and to yield components in nine cultivars of perennial ryegrass (Lolium perenne L.)

Summary We had previously found differences for seed yield among nine perennial ryegrass cultivars which were not associated with variation for seed weight. To detect the physiological basis of these genetic differences for seed yield, growth analyses were carried out. We related crop development and components of seed yield to seed yield during three years on clay and sandy soil. No significant differences occurred among cultivars for accumulation and partitioning of dry matter or the pattern of tiller production. Seed yield of the cultivars was not associated with ear number or total dry matter yield of the seed crop. Seed yield was more correlated with the number of seeds per unit area than with seed weight. The number of seeds as calculated after harvest from seed yield and seed weight was much lower than the number of seeds as estimated prior to harvest from seed yield components. The number of spikelets differed significantly among the cultivars, but the ranking was different from that for seed yield. The physiological basis of the genetic differences for seed yield is not clear. Implications for breeding perennial ryegrass are discussed.     

Variation in developmental patterns of wild barley (Hordeum spontaneum L.) and cultivated barley (H. vulgare L.)

Summary Six wild barley (Hordeum spontaneum) accessions, from a diverse range of habitats, and two spring-cultivated barleys, were examined for variation in durations of development phases. The durations of the leaf initiation and spikelet initiation phases were longer and spikelet growth phases shorter, in wild than in cultivated barley. Across all wild and cultivated barleys the rate and duration of spikelet initiation were negatively correlated, but neither was related to the number of spikelets per spike. The number of spikelets was positively correlated with the number of leaves and the ratio of the number of spikelets to the number of leaves declined with increasing time to anthesis, indicating that each successive leaf was associated with a diminishing increase in the number of spikelets. The duration of culm elongation and final culm length were shorter in accessions of cultivated barley compared with wild barley. This paper also discusses the feasibility for increasing the number of spikelets per spike through breeding for genetic changes in lengths of pre-anthesis phases of development.Abbreviations ANOVA Analysis of variance - HV Hordeum vulgare - CE Culm elongation - DR Double ridge - HS Hordeum spontaneu - ° Cd Degree days     

Influence of variety, seed position and seed source on screening for coleoptile length in bread wheat (Triticum aestivum L.)

A study was conducted to evaluate the usefulness of somaclonal variation as a means to obtain powdery mildew resistance in the background of an agronomically elite, high-yielding barley (Hordeum vulgare L.) cultivar. A total of 170 R_o-derived lines were regenerated from embryo-induced callus of the barley cultivar Léger. Forty-five lines were selected and evaluated in replicated field plots at two locations in Eastern Canada. In comparison with Léger, one of the 45 lines was higher yielding, one produced a greater test weight, two had a greater seed weight, and one was shorter in plant height. Three lines were found to segregate for resistance to powdery mildew (Erysiphe graminis DC ex Merat f. sp. hordei EM). Many of the single-plant selections from the three resistant lines showed resistance to powdery mildew under field conditions for two years. Three lines were eventually promoted to the official registration tests in Ontario. One of the three lines was subsequently registered as a new cultivar (AC Malone) in Canada. To our knowledge, AC Malone is the world's first barley cultivar selected from somaclonal variation. The results of this study demonstrate that it is possible to obtain high- yielding or disease-resistant lines from callus culture in barley. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.     

Effects of seed irradiation on yield and quality of essential oil in palmarosa (Cymbopogon martinii Stapf.)

Summary Dry seeds of palmarosa (Cymbopogon martinii Stapf) var. motia were subjected to 12 doses of gamma rays ranging from 5 kr to 100 kr to find out the effects of gamma irradiation on growth parameters, herbage yield and yield and quality of essential oil. Several biological parameters such as seedling growth, pollen fertility, mitotic chromosome behaviour, productive tillers/plant, leaf area index, leaf/stem ratio (by fresh weight) and total herbage yield/ /plant together with yield and quality of oil have been studied in the first (M₁) generation. Marked stimulatory effects of gamma radiation in 10 kr and 15 kr doses have been compared with the control for herbage yield, oil percentage and total alcohols (free geranyl and geranyl acetate).The two yield contributing traits, herbage yield/plant and leaf area index were remarkably increased in 15 kr, which indicates that in palmarosa the 15 kr dose is more effective than the higher doses in producing microlevel mutations. The yield and quality of oil at 10 kr and 15 kr doses were enhanced significantly. The results on high yield and quality of oil as induced by gamma-irradiation were discussed from the point of view that a gene may have been altered by mutagen treatment to produce a metabolic block between geraniol and geranyl acetate on the biosynthetic pathway or that modifier genes controlling the expression of a key precursor molecule may have been further modified to give rise to a geraniol rich chemotype in palmarosa.     

Variation in pigment content of flour color in bread wheat (Triticum aestivum L.)

Summary Variation in pigment content of the flour of bread wheats (Triticum aestivum L.) was studied in the progenies of F₁ and F₂ of three crosses and their reciprocals. Reciprocal differences in pigment content were observed in the F₁ and F₂ means. Low pigment content was found to be partially dominant or over dominant in the crosses studied. There was evidence of substantial mid-parent F₁ heterosis in all crosses and betterparent F₁ heterosis in three crosses. In the F₂, heritability estimates were moderate to high. The F₂ frequency distributions were not normal. Estimation of effective factor pairs indicated the presence of one or two major gene pairs involved in the expression of pigment content in the flour. Action of modifiers was also assumed in one cross and its reciprocal. A factorial approach to metrical character suggested that the F₂ segregation ratios of low pigment content to high pigment content were 3:1, 15:1, 13:3 and 9:7 for the different crosses. Utilization of the findings in a wheat breeding program is briefly discussed.     

The Role of epistasis in controlling seed yield and other agronomic traits in an Andean × Mesoamerican cross of common bean (Phaseolus vulgaris L.)

Epistasis is a pervasive phenomenon in biology. Nevertheless, attempts at identifying epistatic interactions with quantitative trait loci (QTL) analyses have yielded inconsistent results. In this study, we attempt to determine the genetic control of outbreeding depression and the possible role of epistasis following a wide cross in common bean (Phaseolus vulgaris L.). A recombinant inbred population, derived from a cross between Andean and Mesoamerican common bean cultivars, was evaluated in two markedly contrasting environments. A low-density linkage map based on AFLPs was used to locate QTLs for the number of days to maturity, average daily biomass and seed yield accumulation, and harvest index. Both independently acting and digenic epistatic QTLs of similar magnitude were identified. A majority of the loci involved in these epistatic interactions did not have an independent effect. Although we did find evidence for strong epistatic control of the traits investigated, we also found, in contrast to other recent studies, that there was no evidence for a bias toward coadapted gene complexes at the level of digenic epistasis. We discuss these results in relation to the role of epistasis in the evolutionary history of the species and methodological difficulties in detecting epistasis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Three cycles of honeycomb selection for herb yield in davana (Artemisia pallens Wall.)

Summary Three cycles of honeycomb selection for herb yield, applied on widely spaced individual plants of davana (Artemisia pallens Wall.), resulted in an increase in yield of 12.4% per cycle when the resulting populations were evaluated at commercial plant density. The selection had no adverse effect on essential oil content, davanone content in oil and plant height.     

Comparison of pedigree selection and single seed descent for oil yield in linseed (Linum usitatissimum L.)

Summary Four populations of linseed derived from five parents were advanced from the F₂ to the F₆ generation by SSD and to the F₅ by pedigree selection. These populations were used to compare the efficiency of the two methods in order to provide superior genotypes with respect to grain yield and oil content, i.e. oil yield. The results showed minimum differences between pedigree and SSD lines for grain yield, where in only one cross the SSD lines were significantly superior to the pedigree lines. Since pedigree selection was carried out for both, seed yield and oil content, a positive response to selection was expected. However, early selection for yield, a character with low heritability, was not successful. On the contrary, significant differences for oil content were detected between the two groups of lines in three of the four crosses studied. In these cases the pedigree lines were superior to the SSD lines. These results demonstrate that strict selection in early generations for oil content, a character with comparatively high heritability, is feasible and successful in linseed. However, selection for seed yield should be postponed to later inbred generations. Consequently, in breeding for maximum oil yield of linseed a two-step selection procedure is recommended.Abbreviations PS pedigree selection - SSD single seed descent - TGW thousand grain weight     

Survey of safflower (Carthamus tinctorius L.) germplasm for variants in fatty acid composition and other seed characters

Summary Two hundred safflower accessions, originated in 37 countries, and multiplied in two environments, were evaluated for fatty acid composition of the seed oil and other seed characters. Overall mean values of stearic and palmitic acids were similar in both environments but differed for seed weight and oil content. Oleic and linoleic acids showed also similar overall mean content in both environments but some entries with intermediate contents of these acids displayed significant variation among environments. Oleic and linoleic acids showed a tremendous range of variation, from 3.1 to 90.60% and from 3.9 to 88.8%, respectively. The ranges of variation observed for stearic, oleic and linoleic acids indicate that all the reccessive genes, already discovered, controlling high content of these acids, st, ol and li, are present in the collection. Moreover, the upper values of oleic, ten points higher than the published values for the high oleic genotype olol, suggest than other genes controlling such levels may be present.     

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.