摘要:

AbstractWith the assumption of biallelism it is shown that differences in line values of genotypes from a random mating population can be predicted by the differences of values in top cross progenies with a heterozygous tester. This prediction is also valid in the case of multiallelism with a constant degree of dominance for each pair of alleles and if the tester is heterozygous for the more “distant” alleles. With an arbitrary tester, the efficiency of the prediction is affected by the proportion of the loci which are heterozygous for the more distant alleles. However, with the assumptions considered on multiallelism, with partial to complete dominance, the correlation between line value and combining ability with the tester is expected to be high for a large range of the repartition ot the loci. A two tester top cross design using highly complementary lines, could also be u

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00384.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe objectives of the study were to estimate the genetic components of variance, predict the response to selection and to evaluate observed response to selection using two populations namely, PSB 7 and PSB 3, of pearl millet (Pennisetum americanum[L.] Leeks). The observed response was studied using four methods of selection based on single and multitrait criteria in three types of families, namely S1, half‐sib (HS) and full‐sib (FS) families. One hundred SI, HS and FS families each were developed in PSB 7 and PSB 3. Plants within a population were pollinated with bulk pollen of other population to develop HS families. Crosses were made between a pair of plants using one plant from each of the two populations to develop PS families. Data were recorded on days to flower, plant height, tiller number, spike length, spike girth, seed yield per plant and spike weight. Additive genetic variance estimates were significant for all traits. The estimates of dominance and additive × location and dominance × location interaction components were not significant, except additive × location component in PSB 7 for seed yield and spike weight. The genotypic component of variance among S1 families and S1 × location interactions were significant except S1 × location interactions in PSB 7 for days to flower, spike length and spike girth.Twenty‐four strains were developed by intermating superior families identified on the basis of four selection methods in each of the six types of families.The selection methods were high seed yield (YS)per se; index selection (IS) for high tiller number and long and thick spike; truncation selection (TS) for high yield among the families having days to flower and plant height lower than the population mean: and visual selection (VS) after completion of flowering for good vigour, uniformity in plant height and good inflorescence attributes. YS and IS were found to be superior to TS and VS with respect to observed genetic gains for seed yield. That advance was higher in selection among SI families as compared with FS and HS families. In general, a good agreement was noted between observed and expected responses. Expected genetic gain from FS reciprocal (R) recurrent selection was higher than the average gain from HS

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00385.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractModified mass and family selection for seed yield production of berseem clover (Trifolium alexandrinumL.) c.v. ‘Fahl’ were applied for two generations. Two hundred plants (5 % intensity of selection) were selected for seed yield in the first season, 1985/86. In the second season, 1986/87, selection between and within half‐sib families was practiced. In addition, equal parts of seeds from each of the 200 selected plants were bulked to form the C1modified mass selection; after establishing, the same procedure was adopted to form the C2generation. The cycles 1 and 2 of half‐sib families and modified mass selection along with the base population family were evaluated for forage and seed yields. The realized gains from modified mass selection were 6.03 and 9.51 % for fresh forage yield, 5.57 and 10.86 % for protein yield and 13.23 and 16.19 % for seed yield in cycles 1 and 2, respectively, over the base population. The realized gain from family selection in cycle 2 as a percentage of the base population mean amounted to 11.32, 13.35, 17.47 and 3.15% for forage, protein, and seed yield and seed index, respectively.The broad sense heritability, as estimated from the variance components was 89.63, 63.03, and 76.67 % for dry forage, seed yield and seed index, respectively.Although, all these five traits (fresh, dry, protein, and seed yield and seed index) had positive correlation with each other, weak correlations were found between seed yield and forage yields. Furthermore, close associations were found among forage yield

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00386.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractFor maximizing genetic gains, with given resources, plant breeders generally conduct large but un‐ or inadequately‐replicated field trials especially during early generation evaluations and population improvement programmes. Checks arc often used to improve the precision of test plot comparisons. Adjustments by moving or weighted means etc. arc, however, empirical or based on assumptions too difficult to verify. An alternative stochastically best linear unbiased optimal locally weighted method of spatial prediction of micro‐environmental heterogeneity indices of treatment plots was examined. Two checks used in an unreplicated evaluation of 1560 test lines of winter wheat expressed the micro‐environmental variation in similar ways. About 46, 38 and 16 percent of the total variation in yield was a simple row and column effects, spatially dependent, and random errors, respectively. Optimal weights derived to simulate the micro‐environmental heterogeneity indices were sensitive to the position of the test plot and thus provided a better local control. The model was validated, and prediction standard deviations of simulations

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00387.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractUsing data from a triticale advanced line yield trial network, we attempt to define the zones, in Portugal, within which the joint regression can be established with enough accuracy and precision to be of practical value.The procedure comprises the following steps: adjustment of the joint regressions for the whole area; evaluation of the residuals in each trial; previous identification of geoclimatic zones; comparison of these zones with the residuals; adjustment of the regressions for the zones confirmed in the previous analysis, and testing the differences between the regressions for each zone.The experimental conditions allowed the differentiation of two main zones: “Nordeste Transmontano” and “Sul de Montejunto‐Estrela”, however, another zone, included in the latter and designated “Alentejo Litoral e Algarve”, is suggested though further experimental data are needed for soun

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00388.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractGenotype × environment (GE) interactions are a major problem in plant breeding programs that involve testing in diverse environments. These interactions can reduce progress from selection. Few studies have characterized the effects of weather variables on GE interactions in sorghum (Sorghum bicolor[L.] Moench). The present investigation estimated the contribution of environmental index, (Ȳ, or mean yield of all cultivars in jth environment minus Ȳ. xor overall mean yield for all cultivars and all environments), rainfall, minimum and maximum temperature, and relative humidity, to GE interaction. Yield means of 5 full‐season and 10 medium‐season grain sorghum hybrids grown during 1986—1988 at four locations were used in the study. The GE interaction was significant and partitioned into σ2i, components assignable to each genotype. Weather variables (covariates) were used to remove heterogeneity from the GE interaction. The remainder of the GE interaction variance was partitioned into variance components (s2i) assignable to each genotype. In both maturity groups, the environmental index removed most, although non‐significant, heterogeneity from the GE interaction sums of squares. Of all weather variables, preseason and seasonal rainfall contributed most to the GE interaction sums

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00389.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractResearch has been carried out on the inheritance of corolla size, number of stamens and percentage of plants with petaloid stamens (double flower) in evergreen azaleas (Rhododendron Subsect. obtusa). For this purpose two incomplete diallel crosses were used. The first one included seven species and one cultivar and the second diallel 13 cultivars. In both diallels for all three characters the GCA mean squares were high. Also, the positive correlation between the parental values and the GCA estimates for flower size and number of stamens indicates that the expression of these characters is mainly determined by additive gene action. A negative correlation was found between GCA estimates for die n number of stamens and the percentage of plants with petaloid stamens. When breeding azaleas with large double flowers, parents can be directly selected on the basis of these characters since additive genetic variance dominates. As no genetic correlations were found between corolla size and number of stamens (percentage of plants with petaloid stamens) the breeding will not be hampered by unfavourable linkage of genes for these characters.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00390.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of induced autotetraploidy on the response of red clover toSclerotiniaclover rot (SCR) was studied under laboratory, glasshouse and field conditions. To assess the response in the laboratory, the detached leaf technique was employed, whereas in the glasshouse and in the field, 6—14 weeks old seedlings and adult plants, respectively, were artificially inoculated with the pathogen grain inoculum.The results of the studies showed that great genotypic variability occurs within diploid (2×)and tetraploid (4×)red clover in response to that disease. Generally, tetraploid red clover, in comparison to diploid, is more resistant to SCR. The laboratory, glasshouse and field experiments showed that the effect of induced autotetraploidy on SCR resistance is positive. The hardening of plant with light and temperature enlarged the differences in reponse to SCR between ploidy levels, family pairs and individual strains with every testing method.Other factors, like plant age and flowering time, influencing red clover response to SCR are also discus

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00391.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractDifferences between the area under the disease progress curve (A‐value) and the rate of disease development (r‐value), the two commonly used measures of slow‐rusting resistance, are discussed with the help of theoretical models. A study on development of leaf rust (Puccinia reconditaf. sp.tritici) in two sets of breeding lines of wheat (Triticum aestivumL.) showed that the A‐value and the r‐value (calculated as slope of the regression line of disease progress data) are not necessarily correlated and that the initial inoculum level can have a large effect on the A‐value. These studies suggested that the A‐value and the r‐value measure different aspects of resistance and they should, therefore, be used with greater

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00392.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractA number of barley landraces collected in Syria and Jordan were evaluated for resistance to yellow rust, powdery mildew, scald and covered smut by inoculating single‐head progenies with local pathogen strains during two years of field tests. A large diversity in resistance was observed for each pathogen both between populations of different collection sites as well as between head progenies within collection sites. The level of resistance varied from absolute and partial resistant types up to highly susceptible lines. No consistent association between the environmental conditions of the collection site and the level of resistance of the landrace‐lines could be fo

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1989.tb00393.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY