摘要:

AbstractThe present paper reviews the results of comparative studies on old and modern small grain cereal cultivars. The contribution of genetic improvement to the increase in grain yield and the influence of environmental factors on the performance of old and modern cultivars are discussed. The evolution of grain yield components and the effects of breeding on numerous physiological, morphological and biochemical characteristics such as formation of above‐ground biomass, havest index, total N uptake, N harvest index, N concentration in the grains, canopy structure, carbon dioxide exchange, tiller survival, root growth, course of development and enzyme activities are considere

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00093.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe influence of silver thiosulfate (STS) on thein vitroshoot propagation of twenty dihaploid potato clons and their protoplast regeneration to plants was investigated. The addition of 1.5 mg/1 STS to the propagation medium led to an incrase of leaf material harvested per culture vessel. Depending on genotype, the increase ranged from 1.2 up to 2.3 times the yield obtained from medium without caused toxic symptoms in the plants to most of the genotypes tested, and it was not possible to isolate viable protoplasts. The addition of STS to the shoot regeneration medium considerably promoted the shoot regeneration from protoplast‐derived calli. This effect again was strongly genotype‐depend

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00094.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractHeritability studies suggest that variation among genotypes for callus inducibility should respond to selection. The objective of this study was to determine if crosses among parents with high callus initiation frequencies would produce segregation from which genotypes with improved callus inducibility could be selected. The winter wheat (Triticum aestivumL.) cultivars‘Centurk 78’, ‘Norstar’ and ‘Norwin’ were chosen as parents, based on their high callus initiation frequencies and diverse parentage. F2populations from crosses between each of these parents were evaluated for callus initiation frequencies and callus vigor as determined by growth rate and healthy appearance. Heterosis was detected for callus initiation in the‘Norwin’בNorstar’ cross and for callus vigor in all crosses. Broad sense heritability estimates of 0.25 and 0.37 for callus initiation in the ‘Centurk 78’בNorstar’ and ‘Norwin’בNorstar’ crosses, respectively, suggest this trait can be improved by selection. Heritability estimates for callus vigor were les

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00095.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractReliable and efficient methods of selection are important for improving disease resistance. Three methods of field assessment of the Septoria tritici blotch disease, caused byMycosphaerella graminicola(Fückel) Schroeter, were compared to identify the most reliable for selecting resistant wheats,Triticum aestivttmL. Nine cultivars which differed in disease reaction to plant height and maturity, and their progenies from several generations were used. The methods consisted of scoring chlorotic and necrotic leaf area covered with pycnidia on the flag leaf and the leaf below the flag leaf (flag leaf‐1) as percent of the total leaf area, on a plant‐basis, and the percent necrosis visually estimated on a plot‐basis. Plot data were greatly influenced by environmental changes leading to inconsistent genetic results. The flag leaf and flag leaf‐1 methods provided the most precise consistent results. The use of the flag leaf‐1 method is suggested for

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00096.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractMajor genes for resistance to powdery mildew were analysed in 24 Czechoslovakian wheat cultivars and, in part, in their parents. For this purpose individual isolates of the pathogen, able to differentiate host lines with known resistance genes, were selected. Eight of nineteen winter wheat cultivars do not possess any major resistance gene. Three cultivars have one and seven have two genes. One cultivar carries a combination of three genes (Pm2, Pm4b, Pm8). The most common resistance genes arePm4b, Pm5 and Pm8. Pm2is once combined withPm6. Only one of five spring cultivars lacked a major resistance gene.Mlkis once present alone and twice combined withPm5. There is one spring cultivar with a novel combination of three genes:Pm1, Pm5and another gene needing further characterization. The observations are discussed with additional results of parent lines and further information on pedigrees.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00097.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractLeaf segments from seedlings of 68 old barley varieties and 38 more recent cultivars of past or current importance in France were infected with 6—9 powdery mildew isolates in order to identify race‐specific resistance genes. No resistance gene was apparent in the 21 old winter varieties, 43 of 47 old spring varieties, 10 recent winter and 3 recent spring cultivars. Two old spring varieties (‘Colmar S 142’ and ‘Johanna’) were postulated to haveMlgandMl(CP), and two others (‘Pontrieux’ and ‘Finistère 62‐5’) had an unidentified, weakly effective gene.Mlg, Ml(CP), Mlb, Mla6andMlal3were the only genes detected in recent winter cultivars. Recent spring cultivars presented the greatest diversity; the presence of one or several genes amongMlal, Mla6, Mla9, Mla12, Mlg, Ml(CP), Ml(La), Mlkandmlowas postu

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00098.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA review of data on powdery mildew resistance genes in theMlalocus of barley reveals that there are at least 12 clusters of genes present, each comprising oneMlagene and one or more closely linked, additional resistance genes. Tentative designations are listed for 16 additional resistance genes. Many sources of powdery mildew resistance in barley appear to harbour multigene families in theMlaregion, not single ‘superior’ge

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00099.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractSynthetic lines ofBrassica napuswere derived by combining the genomes ofB. atlanticaandB. oleraceavar.alboglabra, which were respectively resistant and susceptible to foliar infection byLeptosphaeria maculans, with a susceptible line ofB. rapa.Resistance was expressed in the synthetic lines containing the genome ofB. atlantica.The high levels of alkenyl glucosinolates which occur in leaves ofB. atlantica, and which have been implicated in disease resistance, were also expressed within the synthetic lines, although the dominant glucosinolate had changed from sinigrin to glucobrassicanapin. Disease resistance and glucosinolate profiles did not co‐segregate in F2progeny from crosses between the synthetic line

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00100.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractEfficient nitrogen fixation by legumes has been proved to be important for yield of dry matter. A search was made for easily‐measurable characteristics associated with efficient fixation in young pea plants (Pisum sativumL.) which could be used in a selection programme for high yield. Altogether, 17 characteristics were investigated in 120 breeding lines of pea grown in a liquid solution. Of these characteristics, the protein content of the three upper leaves in a 30‐day‐old plant showed the best correlation with yield capacity. The correlation was also good (r = 0.32—0.94), when samples from the 3 upper leaves were taken in field‐grown material. The protein content of the 3 uppermost leaves can be used to reject genotypes that have low initial nitrogen fixation and thereby low yield capacity. This will increase the possibility of testing lines for other agriculturally important c

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00101.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractDespite a fovourable environment during seed filling, ripening and harvest, and good storage conditions subsequent to harvest, there is variation for the ability of seeds of progeny of pearl millet (Pennisetum glaucum[L.] R. Br.) composites to emerge under favourable conditions in pots, or in the field. Seedling emergence in pots and in the field was found to be a heritable trait in at least two of four composites that had not been specifically constructed for improvement of seedling emergence. The predicted genetic advance from selection for ability to emerge in pots is appreciable. From examination of genotypic correlations, there will be smaller but useful gains over selection cycles in ability to emerge in the field by selection for improved emergence in pots. Direct selection under carefully controlled conditions in the field will produce higher gains, but is more resource consuming than a pot test.We conclude that screening progenies in a pot test in a glasshouse and discarding progenies with poor emergence before a field progeny trial will reduce missing plots due to poor seedling emergence. Selection for improved emergence in pots should lead to an appreciable improvement in seedling emergence in the field over cycles of selection. The pot test is, therefore, a cost effective selection method for the important trait of high seedling emergence.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00102.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY