摘要:

AbstractResistance toSeptoria nodorumwas investigated in seedlings of an amphiploid generated fromTriticum dicoccumShübl. andAegilops squarrosaTausch, and in a series of substitution lines of single chromosomes from this synthetic hexaploid intoTriticum aestivumcv. ‘Chinese Spring’ in three tests to determine the chromosomal location of resistance. From the Ae. squarrosa parent (D genome), chromosome 5D was found to confer a high level of resistance, reducing lesion cover to near that of the amphiploid in the three tests. Chromosomes 3D, and to a lesser extent, 7D were also found to confer significant resistance to the amphiploid. Three chromosomes, 2A, 3B and 5A, from theT. dicoccumparent (AB genomes) also conferred resistance but to a lesser extent than 7D. Two chromosomes, 2B and 2D, caused a significant decrease in resistance. ‘Chinese Spring’ may thus carry genes for resistance toS. nodorumon these chromosomes which are absent in the synthetic h

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00575.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn order to improve regenerative potential inBeta vulgarisL. cultural conditions were established for efficient plant regeneration from cotyledon‐derived calli. Organogenic calli were initiated at frequencies of 8–59 % with six sugarbeet lines. N6‐benzyl‐ammopurine (1 mg/1) associated with 2,3,5 triiodobenzoic acid (0.5 mg/1) was found to be the best combination to alter the endogenous phytohormonal balance in 21 ± 1 day‐old seedlings. Flow cytometry was used to determine nuclear DNA Content (ploidy) in cotyledons, calli and regenerated plants, and suggested that 88 % of the regenerants were diploids. The relatively high cytological stability of the regenerants was attributed to the rapid cell differentiation within initiated calli. The problem of vitrification was overcome by using phloridzin and high agar con

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00576.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractStriga hermonthicais a widespread parasitic weed in Africa, causing severe damages to the major cereal crops: millet, sorghum and maize. Considering the subsistence nature of farming in Africa, the development of resistant or tolerant varieties is the most promising cost‐effective approach to overcoming the weed problem. A simple, inexpensive and sufficiently uniform infestation technique has been developed by the research department of AgSeeds Ltd., Zaria, Nigeria, which is based on mulching a field with matureStrigaplants collected in neighbouring farmers' sorghum fields. With this method, rapid progress was achieved in the development of experimental maize hybrids with high levels of tolerance toS. Hermonthicaand good yield potential. Among 34 lines with improved tolerance, two (nos. 74 and 785) showed particularly high levels of tolerance. The hybrid between these two lines had a significantly higher yield (47.6 %) underStrigainfestation than the tolerant check 8322‐13 developed by I

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00577.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractConditions for the effective experimental regulation of ploidy level in regenerants from callus cultures derived from young, undifferentiated leaves and panicles of haploid sorghum were established. Diploidization depended on the ontogenetic age of the explant and the 2,4‐D concentration in the medium. With a low 2,4‐D concentration (0.5 mg/1) and segments of young panicles (<35 mm long) the cultures produced only haploid regenerants. Diploid plants were formed from cultures derived from more mature panicles ( 35 mm long) and young leaves (15–65 mm long). Under a high 2,4‐D concentration (2.5 mg/1) diploid plants were regenerated from cultures derived from young panicles (less than 35 mm) except the most young ones (5–15 mm). The majority of the diploid regenerants contained mutations, mainly affecting male fertility and pla

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00578.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSeveral hundred breeding lines of summer and winter forms of turnip rape as well as winter rape, were sown on greenhouse tables filled with soil. A week later the cotyledons were artificially inoculated and covered with a plastic tunnel. Approximately two weeks later the average percentage of the wilted leaf area was estimated.The method is rapid and demands little labour. It is therefore suitable for testing large numbers of breeding lines. The response toPeronospora parasitica(Pers. ex Pers.) Fr. in the rape material varied from being highly susceptible to highly resistant. Only minor differences were detected between lines with high and low glucosinolate contents. All the turnip rape material had very high resistance toP. parasiticaat the cotyledonous stage.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00579.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAnalysis of a half diallel cross among four white clover cultivars, grown as monocultures and in mixtures (duocultures) with two separate perennial rye‐grass cultivars, confirmed that for stolon and leaf number a higher proportion of the genetic variance in duocultures was non‐additive. For canopy height and dry weight, however, this proportion was less affected by inter‐specific competition. An additive‐dominance model of gene action sufficed for all four characters in monocultures, but in duocultures epis‐tasis was just one of the factors complicating the genetic picture. This, coupled with short‐term reversals in the direction of dominance, merely illustrates the complexity of breeding white clover cultivars. Possible future developments in the breeding of white clover are discussed in the light of th

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00580.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe 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.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00581.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA variety cross diallel of five populations of maize (Zea maysL.) was evaluated in a cool, temperate environment. Two of the parental populations were Corn Belt Dent synthetics (AS3 and BS22), one was developed from selected lines from a CIMMYT population developed for highland regions of the tropics and four Corn Belt Dent inbred lines (NZS3), and the other two had the pedigrees ‘Criollo de Toluca’× AS32(NZS1) and ‘San Gerónimo’× BS222 (NZS2). ‘Criollo de Toluca’ is from the highlands of Mexico and ‘San Gerönimo’ is from the highlands of Peru. The objective was to study the influence of introgressing highland tropical germplasm into elite Corn Belt Dent synthetics on genetic effects, especially inbreeding depression, and to develop recommendations for the utilization of the introgressed populations.Inbreeding depression explained the greatest proportion of the variation among entries for grain yield, days to silking and plant height, but not for grain moisture at harvest and root lodging. For grain yield, NZS1, NZS2, and NZS3 had high levels of inbreeding depression and the difference between NZS1 and AS3 was statistically significant. High levels of root lodging were associated with NZS1 and high grain moisture at harvest with NZS2. These results indicate that a recurrent selection method, such as S1selection, which effectively reduces inbreeding depression, should be used in early cycles of selection with introgressed populations containing highland

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00582.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe relationship between frost tolerance and abscisic acid (ABA) accumulation was studied in callus cultures of three wheat cultivars differing in the level of frost‐tolerance, and of the 5A and 5D chromosome substitution lines from the frost‐tolerant variety ‘Cheyenne’ into frost‐sensitive ‘Chinese Spring’. Following cold hardening, the increase in ABA level in the calli of the two frost tolerant cultivars was significantly higher than in those of the frost‐susceptible cultivar. Similarly, in 5A and 5D substitution lines, significantly higher ABA levels were detected than in the recipient ‘Chinese Spring’. One week‐long ABA treatment at 26 °C induced a significantly higher level of frost tolerance than that achieved by cold hardening, irrespective of the frost sensitivity of

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00583.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractTwenty‐two durum wheat landraces of various origins were evaluated for performance and stability of grain yield, protein content and gluten strength (SDS sedimentation volume) at two sites of Northern Syria situated in the drought‐prone part of the local durum wheat belt. Yield was recorded in three seasons, while protein content and SDS volume were assessed in two seasons only. A high “entry X environment” interaction was observed for all traits, which was significantly attributable to heterogeneity of entry regressions on the environmental mean for grain yield only. Compared to the recently‐bred, widely‐grown variety ‘Sham I’, some landraces showed somewhat similar yield responses, whereas others proved more stable without being significantly lower yielding. Significant variation was found for SDS volume, though only few of the best‐ranking landraces for this trait also possessed an acceptable yield level. The entries did not significantly differ for protein content. The broad sense heritability estimates obtained for grain yield (0.59) and SDS volume (0.89) highlighted the interest in some of the landraces examined for improving grain yield and qual

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1993.tb00584.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY