Selection for combining ability in Pyrethrum,Chrysanthemum cinerariaefolium Vis.

Summary Pyrethrum is grown for the insecticidal pyrethrins, present mainly in the flowers. It is a cross-fertilizing perennial which can be propagated vegetatively. The main selection criteria are fresh flower yield and pyrethrins content; important secondary criteria are flower size and resistance to lodging; dry matter content varies very little.For these traits, the breeding values (general combining ability) of 22 clones were determined by means of a polycross. The heritabilities were estimated from the regressions of the polycross progeny data on those of the female parent clones; these were: flower yield 0.31; pyrethrins content 0.70; flower size 0.80 and resistance to lodging 0.87. For dry matter content no correlation between parents and progenies could be measured. Independent heritability estimates, obtained from 33 single crosses between clones not represented in the polycross, were: flower yield 0.56; pyrethrins content 0.64. Of 18 single crosses, made between clones also represented in the polycross, the actual flower yields and pyrethrins contents were highly correlated with the estimated yields and contents which were calculated from the breeding values of the parent clones (r = +0.87 and +0.86, respectively).These data show that the performance of single crosses is caused predominantly by the general combining ability of the parent clones. Therefore, single crosses offer no fundamental advantages over synthetic varieties, so that, for practical reasons, the latter are preferred. At the same time it is recommended to practise reciprocal recurrent selection as this will exploit the general combining ability in the initial stages of selection and the specific component increasingly in later selection cycles.Published with the approval of the Director of Agriculture, Kenya.     

Possibilities of selection for keeping quality in tulip breeding

Summary The vase-life in tulip (Tulipa L.) is an important character. Research was done on the possibilities of selecting for keeping quality. It was found that the keeping quality of undetached flowers was strongly correlated with the keeping quality of cut flowers at 17°C in a glasshouse. The period from flowering date till 50% discoloration appeared to be highly correlated with days to perianth drop. For practical reasons the latter trait has preference in selection work. The number of days to discoloration is also an effective selection criterion. Flower longevity in the field in April/May and in the glasshouse were significantly correlated; thus, already in the field a first selection on keeping quality can be carried out. The increase in height for flowering (adult) and non-flowering (juvenile) plants during forcing did not appear to be significantly correlated with flower longevity, so preselection on this character is not promising. Flower longevity was positively correlated with forcing period. This poses some problems in selection, as a long forcing period is considered an undesirable character. The daily water uptake of cut flowers was significantly correlated with flower longevity.     

Development of a rapid method for identifying asparagus super-males using, N-(4-chloro-2-trifluoromethylphenyl)-N'- propoxyacetamidine to induce flowering

In order to shorten the term for the identification of asparagus super-maleplants, a method usingN-(4-chloro-2-trifluoromethylphenyl)-N'-pro-poxyacetamidine (AM12) toinduce flowering was developed. This method is conducted as follows: seedsfrom andromonoecious flowers are treated with AM12 to induce flowersto form on the seedlings, the new male flowers are crossed with normalfemale flowers, and the progeny seeds are again treated with AM12 toidentify super-male plants from the sex ratio of the seedlings.Asparagus officinalis cv. `UC157' seeds were treated with AM12.The seedlings were induced to flower at a high frequency in 25 days. Thesex ratio of the plants was 1:1 and the male flowers had the pollengermination ability. One male flower induced by AM12 was crossed withfemale plant. This cross produced many progeny seeds. The seeds weretreated again with AM12, and induced to flower. Two super-male plantswere found among the progeny of andromonoecious flowers of the all-malecultivar `Gijnlim' within six months by this method. This method thusshortens the time for identifying super-males. Since the female flowers werefertile as well, AM12 treatment would also be effective for cross breeding.     

Possibilities of selection for keeping quality in tulip breeding. 2

Summary Criteria of selection for keeping quality in tulip breeding are reviewed on the basis of a wide range of cultivars and species. The conclusion from an earlier, more limited study that there are large differences in keeping quality between cultivars in several characteristics is confirmed. The choice of the number of days between the onset of flowering and perianth drop as the best criterion is reconsidered because in some cases perianths may remain on the plant long after they have lost their attractiveness. It was found that the sequence in which the various stages (50% discoloration. perianth curving, perianth drop, leaves and stem no longer upright) are reached is not the same for all cultivars and species. None of these phenomena can therefore be used exclusively as criterion of keeping quality. A more comprehensive criterion as the number of days the flower maintains its ornamental value, is useful when commercial cultivars are compared, but for breeding and physiological research attention should be given to all individual aspects of the keeping quality of flower. stem and leaves.     

Pollen selection for chilling tolerance at hybridisation leads to improved chickpea cultivars

The potential of pollen selection as part of the breeding efforts to increase chilling tolerance in chickpea was investigated. This alternative approach to apply selection pressure at the gametophytic stage in the life cycle has been proposed widely, but there are no reports of the technique being implemented in a crop improvement program. In this paper, we describe how we developed a practical pollen selection technique useful for chickpea improvement.Pollen selection improved chilling tolerance in crossbreds compared with the parental chickpea genotypes and compared with progeny derived without pollen selection. This is backed up by controlled environment assessments in growth rooms and by field studies. We also clearly demonstrate that chilling tolerant pollen wins the race to fertilise the ovule at low temperature, using flower color as a morphological marker. Overall, pollen selection results in a lower threshold temperature for podding, which leads to pod setting two to four weeks earlier in the short season Mediterranean-type environments of Western Australia. Field testing at multiple sites across Australia, as part of the national crop variety testing program, shows that these breeding lines have a significant advantage in cool dryland environments.The major factors which affected the success of pollen selection are discussed in the paper, from generation of variability in the pollen to a means to recover hybrids and integration of our basic research with an applied breeding program. We conclude that chilling tolerance observed in the field over successive generations are the result of pollen selection during early generations.     

Breeding system of Solanum integrifolium Poir. with an emphasis on sex potential and intercrossability

Summary The breeding system of Solanum integrifolium has been studied with the view of setting up a breeding programme. Three flower types are distinguished on the basis of style length. The results of crosses among these types have elucidated that only long-style flowers are female-fertile. The medium and short-style flowers are unable to set fruits. Some of the flowers, irrespective of their stylar morphism, also exhibit male sterility which is uncommon in Solanum. The biological significance of the stylar heteromorphism has been discussed in relation to evolutionary trends in the genus and the probable cause of this phenomenon speculated upon.     

Breeding of transgenic orangePetunia hybrida varieties

Summary Flower colour is the major contributor to the total ornamental value of a flower. The combination of biochemical knowledge and genetic engineering technology has resulted in the addition of a new colour to the existing colour range ofPetunia hybrida. This has been achieved by expression of the maize dihydroflavonol-4-reductase (DFR) gene in a suitable petunia acceptor which leads to the accumulation of pelargonidin-derived pigments in flowers. The resulting flower colour, however, was a pale brick-red, which is commercially unattractive in petunia. Our objective was to produce a product suitable for commercialisation by introducing the DFR gene into our breeding material via normal sexual recombination. Although the initial transformant exhibited many negative characteristics, first analyses indicated that it was feasible to obtain material for creating commercial hybrids. Experimental hybrids based on F₄ lines were obtained with improved phenotypical expression of the orange flower colour in combination with a good general performance. In order to assess consumer-related characteristics, selected experimental hybrids were tested under field conditions. All transgenic plants had a normal appearance when compared to non-transgenic control plants. No linkage was observed between the transgenic trait and any negative characteristic. From these studies it can be concluded that through a combination of biochemistry, breeding and genetic engineering it is possible to generate unique flower colours in a cultivar with commercial potential.     

Breeding of transgenic orange Petunia hybrida varieties

Summary Colour is the major contributor to the total ornamental value of a flower. The combination of biochemical knowledge and genetic engineering technology has resulted in the addition of a new colour to the existing colour range of Petunia hybrida. This has been achieved by expression of the maize dihydroflavonol-4-reductase (dfr) gene in a suitable petunia acceptor which leads to the accumulation of pelargonidin-derived pigments in flowers. The resulting flower colour, however, was a pale brick-red, which is commercially unattractive in petunia.Our objective was to produce a product suitable for commercialisation by introducing the dfr gene into our breeding material via normal sexual recombination. Although the initial transformant exhibited many negative characteristics, first analyses indicated that it was feasible to obtain suitable material for creating commercial hybrids. Experimental hybrids based on F₄ lines were obtained with improved phenotypic expression of the orange flower colour in combination with a good general performance.In order to assess consumer-related characteristics, selected experimental hybrids were tested under field conditions. All transgenic plants had a normal appearance when compared with non-transgenic control plants. No linkage was observed between the transgenic trait and any negative characteristic. From these studies it can be concluded that through a combination of biochemistry, breeding and genetic engineering, it is possible to generate unique flower colours in a cultivars with commercial potential.     

A reproductive calendar of Lilium longiflorum Thunb. cv. Gelria

Summary The development and timing of different processes in the floral biology and sexual reproduction of Lilium longiflorum were studied and brought together into a chronological reproductive calendar. Care must be taken when emasculating flowers later than 4 days before anthesis (DBA), because the stomium of the anther was open from 8 DBA and the pollen grains appear to be mature from 3–2 DBA. The receptivity period of the pistil lasts for a rather long period, but before wilting of an unpollinated flower as determined by a change of the colour of the perianth from white into brown, the flower had already lost its receptivity. Because L. longiflorum pollen grains can easily be stored, the pistil receptivity should thus determine the pollination schedule. The relationships between pollen tubes and pistil are discussed with respect to plant breeding.Abbreviations DAA Days After Anthesis - DAP Days After Pollination - DBA Days Before Anthesis     

Breeding for improvement of flowering attributes of winterhardy Rosa rugosa hybrids

Summary The purpose of this study was to determine at what stage of seedling development the flowering attributes in winterhardy R. rugosa hybrids could be assessed and if these attributes could be improved through breeding. The analysis of flowering was based on the duration of the flowering period and on amount of flowers produced.Most seedlings from rugosa hybrids could be assessed at an age of 3 years. The duration of the flowering period and flower productivity were not correlated. Several seedlings were improved in both attributes over the longer flowering and more floriferous parent.     

Quantitative genetic analysis of flowering time in the Davis Population of gerbera

Summary Phenotypic and genetic correlations of flowering time (FT) with cut-flower yield (Y) were estimated from six generations of the Davis Population of gerbera (Gerbera hybrida, Compositae). The phenotypic correlation was –0.34; the genetic correlation was –0.47 when estimated from ANOVA of a NCII design and –0.72 when estimated from parent-offspring analysis. An indirect selection model was constructed to assess the efficiency of indirect selection for Y using FT as a marker. This model includes population size and generation time as variables because they differ for FT and Y. The results indicate that indirect selection will be more efficient than direct selection.Correlations of FT with flower quality traits, including scape length (SL), flower diameter (FD), scape dry weight (SDW) and flower dry weight (FDW), were also estimated. FT was phenotypically independent of these traits. However, statistically significant estimates of genetic correlation indicate that FT may be correlated with flower quality traits. Thus, indirect selection on FT to increase Y may result in undesirable correlated responses for flower quality.     

Repetitive cycling and simple recurrent selection in traditional barley breeding programs

Summary A critical examination of three representative barley development programs from three barley producing areas of the world reveals that the evolution of each can be explained by the concepts of simple or phenotypic recurrent selection. Typically, each has utilized only 13 to 16 separate genetic sources in their program. Most of the sources were introduced over 50 years ago and have been progressively recombined through a simple recurrent selection process. The time period required for selection, testing, and reincorporation of improved genetic recombinants into the breeding program, or the completion of a cycle of recurrent selection, ranged from 6.5 to 10.5 years. If the major operative force in barley breeding is recurrent selection, then additional attention should be given to increasing the genetic base and reducing the time required to complete cycles of selection.     

大红花蝴蝶兰杂交后代观赏性状分离规律研究

[目的]为研究蝴蝶兰观赏性状遗传规律,优化杂交亲本,更加高效的培育高品质的蝴蝶兰新品种。[方法]以5份大红花蝴蝶兰为材料,设计了3组正反交杂交组合,并对杂种后代花底色、花径、花朵数、花梗高度、植株冠幅等主要观赏性状进行了观测分析。[结果]结果表明,3个组合正反交杂种后代,花底色、花朵数、花梗高度等性状杂种优势明显,在花色上出现了亲本没有的花斑变化,正反交分离表现明显不同,深紫红色大红花作为母本时,获得深色杂种后代的几率更高;3个杂交组合正反交杂种后代花径分离表现不尽相同,‘T’和‘R’组合正反交杂种后代花径则表现超亲优势,而‘133’和‘62’,‘J’和‘62’正反交则表现出一定程度的衰退现象,当母本花径较大时,杂种后代花径总体较大,但获得超亲花径的比例低;3个组合正反交植株冠幅均表现一定程度的衰退现象。[结论]该研究结果初步阐明大红花杂种后代主要观赏性状的分离表现,为蝴蝶兰育种亲本的选配和新品种选育提供理论依据。     

Evaluation of fineness of wrinkles on husks of malting barley (Hordeum vulgare L.) by texture analysis of digital image data

Summary It has been suggested that the selection based on the wrinkles on the husks of malting barley is useful especially during the early generation in breeding program, because the wrinkles can be an indicator of malting quality of grains. However, it can be done only visually and requires much labor. In this study, the evaluation of the wrinkles by texture analysis of digital image data, was examined for the quantitative evaluation of the fineness of the wrinkles and its automatic selection. The texture analysis based on co-occurrence matrices was applied and it was revealed that finely wrinkled grains can be clearly discriminated by discriminant analysis on several parameters estimated from the co-occurrence matrices.     

A methodological study on participatory barley breeding II. Response to selection

Farmer participation is increasingly seen as a key to develop technologies which are more relevant to farmers' communities. In plant breeding, farmer participation is seen as key to increase the probability of adoption of new varieties. This paper addresses the issue of selection efficiency in participatory plant breeding by testing the effect of selection environment and of who did the selection in one cropping season (1997) on the performance of the selected lines in the following cropping season (1998). Selection environment had a larger effect on response to selection than who did the selection, confirming the importance of decentralized selection. Selections made by the breeder and the farmers in 1997, differed in 1998 for a number of traits, but seldom for grain yield. When the difference for grain yield was significant, breeder's selection was more effective on station, while farmers' selection was more effective in farmers' fields. The results of this study indicate that it is possible to organize a plant breeding program with the objective of adapting crops to a multitude of both physical and socio-economic environments: such a breeding program will, at the same time, increase productivity and stability, enhance biodiversity and produce environmentally friendly cultivars. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analysis of diallel cross for some physical-quality traits in peanut (Arachis hypogaea L.)

The combining abilities for physical-quality traits in peanut were examined to understand the type of gene action governing these traits, and to identify peanut genotypes suitable for use as parents in breeding for quality improvement. The F₁ hybrids including reciprocals from a six-parent diallel cross along with the parents were evaluated in a randomised complete block design. Data were recorded on five quality traits in peanut viz., shelling outturn, 100-pod weight, 100-seed weight, Count and proportion of sound mature seeds. Substantial genetic variability was observed among the hybrids for the traits studied. Diallel analysis indicated that expression of majority of the quality traits is regulated predominantly by additive gene action suggesting possibility of early-generation selection, while non-additive gene action also plays an equally important role in the control of seed size. Significant reciprocal effect for all the traits denoted role of maternal parent in the expression of quality traits and importance of parental selection in quality breeding. Genotypes ICGV 86564 and TPG 41 were good combiners for seed size, while J 11 was a good combiner for improvement of shelling outturn and proportion of mature seeds. Association between general combining ability (GCA) effects and mean performance suggested that the performance per se of the genotype should be a good indicator of its ability to transmit the desirable quality attributes to its progenies. Though performance of crosses was found to be independent of parental GCA status, it is evident that at least one of the parents used in hybridisation should have large pods and seeds for obtaining better segregants.     

Inheritance of two components of early maturity in groundnut (Arachis hypogaea L.)

Summary Knowledge of inheritance of early maturity or its components is important to groundnut breeders in developing short-duration cultivars. This study was conducted to determine the inheritance of two components of early maturity: days to first flower from sowing, and days to accumulation of 25 flowers from the appearance of first flower, using three groundnut genotypes. Two early-maturing (Chico and Gangapuri) and one late-maturing (M 13) genotypes were crossed in all possible combinations, including reciprocals. The parents, F₁, F₂, F₃, and backcross populations were evaluated for days to first flower from sowing, and for days to accumulation of 25 flowers. The data suggest that days to first flower in the crosses studied is governed by a single gene with additive gene action. Chico and Gangapuri possess the same allele for this component of earliness. Three independent genes with complete dominance at each locus appear to control the days to accumulation of 25 flowers. In crosses between late (M 13) and early (Chico or Gangapuri) parents, a segregation pattern suggesting dominant-recessive epistasis (13 late:3 early) was observed for this component. Segregation in the F₂ generation (1 late:15 early) of both early parents (Chico x Gangapuri) indicated that the genes for early accumulation of flowers in these two parents are at different loci.Submitted as ICRISAT J.A. No. 1557.     

Breeding parthenocarpic pickling cucumbers (Cucumis sativus L.): Necessity,genetical possibilities,environmental influences and selection criteria

Summary Parthenocarpic pickling cucumbers have been selected after crossing pickling and slicing cucumbers. On the best lines 90% of the female flowers set fruit (up to 75 fruits per plant within six weeks). At declining daylength productivity decreased, mainly because of a reduced flower initiation and partly by a reduced parthenocarpic potential.The correlation between several selection criteria and the possibilities of preselection of young plants is discussed.     

Genomic constitutions and flower characteristics of selected Aranda orchid cultivars

Summary Ten Aranda cultivars commercially grown in Singapore were selected to study their genomic constitutions and flower characteristics. Cytological evidence and breeding records of these cultivars showed that they are of three genomic classes. Four of them are diploid with AV genomes (one Arachnis and one Vanda genome), another four are triploid with AVV genomes and the remaining two are tetraploid with AVVV genomes. Sizes of flowers as well as of sepals and petals generally show significant increases from diploid to tetraploid. This trend reflects the increasing influence of Vanda resulting from additional one and two Vanda genomes in triploid and tetraploid respectively as compared to diploid cultivars. Among the three genomic classes, diploid cultivars generally bear less flowers per spray than those of triploid and tetraploid although exceptions may occur. There is no clear trend in the length of inflorescences although diploid cultivars tend to have less compact spray with flowers more distantly spaced out.     

Genetics of Six Components of Autofertility in Vicia faba

The inheritance of six components of autofertility was studied in faba beans in two consecutive years (1989 and 1990) by analysing parents, Fl and segregating generations of 14 crosses between preselected pure lines. Genetic analysis was performed by a joint scaling test proposed by Cavalli (1952). Additive gene effects were more important than dominance effects in flowers/node, pods/flower and ovules/ovary. In contrast, characters directly related with the seed such as pods/node, seeds/pod and, to a lesser extent, seeds/ovule showed high positive values of dominance. The three latter traits in general exhibited strong heterosis, probably due to genetic interactions. In order to produce selection gain, any breeding programme has to consider that dominance and heterosis vary according to the character involved. The present study reveals different degrees of dominance expression depending on cross specificity as well as on environmental conditions. The advantages of studying segregating generations instead of diallel crosses and the need for a simultaneous study of many crosses are emphasized in this paper.