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1.
Summary Yield data from the 5th–12th international mungbean nursery (IMN) trials conducted at 23 sites in 15 countries were analyzed by conventional stability analysis—regression of genotype mean on the environmental index, and by segmented regression analysis—fitting separate linear regressions in low yielding and high yielding environments. The gene pool base concept allows comparison of genotypes from different IMN trials grown in different years and sites. A very high positive linear relationship was observed between the regression coefficient and the average yield of cultivars, indicating that high yielding cultivars were less stable across environments. When data points of the regression of genotype mean and site mean for VC 1973A, a high yielding and widely adapted cultivar, were examined, the relationship appeared not to be linear. The segmented regression analysis improved the coefficient of determination (r2) and the genotypes were grouped based on regression coefficients in high yielding and low yielding environments. Different categories of genotypes suitable for high input environments, widely adaptable genotypes, and highly stable genotypes were identified.Texas Agricultural Experiment Station Technical Article 23208. 相似文献
2.
Global wheat (Triticum aestivum L.) production must increase 2% annually until 2020 to meet future demands. Breeding wheat cultivars with increased grain
yield potential, enhanced water-use efficiency, heat tolerance, end-use quality, and durable resistance to important diseases
and pests can contribute to meet at least half of the desired production increases. The remaining half must come through better
agronomic and soil management practices and incentive policies. Analyses of the recent International Yield Trials indicate
that grain yields of the best new entries were usually 10% higher than the local checks globally, as well as within a country
across sites. Variation in yield across sites within a country/region underline the role of genotype × environment (GE) interaction
and provides opportunities to select for stable genotypes, which is not often done. The lack of proper analysis undermines
proper utilization of germplasm with high yield potential and stability in the national wheat breeding programs. Some of the
best performers in irrigated areas were amongst the best in semiarid environments, reinforcing the fact that high yield potential
and drought tolerance can be improved simultaneously. The best performing lines often had genotypic base of widely adapted
genotypes Kauz, Attila, Baviacora, and Pastor, with genetic contributions from other parents including synthetic wheat. We
recommend within country multilocation analysis of trial performance for a crop season to identify lines suiting particular
or different locations within a country. The immediate feedback on GE interaction will also help in breeding lines for countries
having substantial variation across locations and years. 相似文献
3.
Organic farming requires cultivars that are specifically adapted to this low input cropping system. Hence, organic farmers
and scientists joined in a participatory breeding approach to develop region-specific genotypes of spring faba bean for organic
conditions in Germany. A set of 49 genotypes with contrasting degrees of heterozygosity and heterogeneity was used in field
trials across five locations in Germany during 3 years 2004, 2005 and 2006. The material involved 18 inbred lines, their 18
polycross progenies, one blend of inbred lines, one blend of polycross progenies, one blend of hybrids and ten checks. Inbred
lines are uniform, thus giving the option to be specifically adapted; whereas the polycross progenies and synthetics (Syn-1;
predicted from the inbred lines and polycross progenies performance) are partly heterogeneous and heterozygous, thus giving
the option to evolve. Agronomic performance was assessed and a “personal appreciation” score of the material was assigned
to each genotype by each partner. This personal appreciation was strongly influenced by biotic and abiotic constraints faced
by the crop in each location and by the expected grain yield of the genotypes. Uniformity was apparently appreciated by organic
farmers. In all locations, the highest yielding inbred line yielded slightly better than the predicted highest yielding synthetic.
However, this slight disadvantage of the synthetic is very likely to disappear if the synthetic (Syn-1) is propagated during
successive generations. 相似文献
4.
Genotype × environment interactions for tea yields 总被引：1，自引：0，他引：1
Several methods were used to evaluate phenotypic stability in 20 tea (Camellia sinensis) genotypes, many of which are cultivated widely in East Africa. The genotypes were evaluated for annual yields at two sites
over a six year period. Data obtained were used to compare methods of analysis of G × E interactions and yield stability in
tea. A standard multi-factor analysis of variance test revealed that all first order interactions (genotypes × sites; genotypes
× years; sites × years) as well as second order interactions (sites × genotype × years) were significant. Regression analysis
was used to assess genotype response to environments. Regression coefficients (bi) obtained ranged from 0.78 to 1.25. Deviations from regression (S2d) were significant (p < 0.05) from 0.0 for all the test genotypes. Analysis for sensitivity to environment change (SE2
i) revealed that the test genotypes differed in their level of sensitivity. The hierarchical cluster analysis method was used
to assemble the test genotypes into groups with similar regression coefficients (bi) and mean yield, which proved useful for the identification of high yielding genotypes for breeding purposes as well as for
commercial exploitation. Rank correlation between yield and some stability parameters were significant. Mean yield was significantly
correlated to bi (r = 0.80***) and SE2
i(0.74***) which is an indication that selection for increased yield in tea would change yield stability by increasing bi and SE2
i leading to development of genotypes that are specifically adapted to environments with optimal growing conditions. Genotypes
differed in response to years and sites. As stand age increased, genotype yields generally increased though annual yield fluctuations
were more pronounced in some genotypes than others. This response was not consistent across the sites for all genotypes indicating
the need to test clones at multiple sites over longer periods of time.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
Genotypic variation for root pulling resistance in potato and its relationship with yield under water-deficit stress 总被引：2，自引：0，他引：2
Summary An extensively distributed root system may reduce the probability of crop failure during periods of restricted water supply. A quantitative measure of root distribution in the soil profile, i.e. pulling resistance of roots (PR), was tested at two moderately droughted tropical field sites. A total of 250 genotypes were evaluated for PR, 45 days after planting and for tuber yield at harvest at separate sites and years. The need to use genotypes adapted to a specific location for comparisons, across sites or seasons was shown by the results of a random analysis of variance model partitioning across site-season, location, and year effects for PR and tuber yield.A combined PR and growth analysis on 31 early-maturing clones, 7 of which had tubers at the time of sampling, gave significant correlations between PR and root length, dry weight of pulled and residual roots, plant height, number of stems, and in the case of the 7 genotypes with tubers, tuberlet weight and number. A regression model to predict PR based on growth analysis data is presented. Neither tuberlet weight nor number contributed significantly to the prediction once root characters and vigour-related characters were incorporated. Variation for PR among clones was significant and the means ranged from 0 kg/plant to 37 kg/plant during the 3 trials. High PR was evident in both early and late maturing clones. Drought resistance (DR), defined as high yielding ability and high PR under water deficit conditions, of the clones Huinkul and MS-35.22.R was superior to that of the high-yielding and adapted LT-7 check, while moderate levels of DR were confirmed for the clones BR-63.15, Cruza 27, Haille, and MEX-21. Tuber yield and PR under moderate drought were significantly correlated (r=0.569***), which suggests that the PR method can be utilized to assist in the selection of high-yielding, drought resistant, potato genotypes adapted to tropics. 相似文献
6.
Summary Independent but simultaneous selection by two breeding teams of the same segregating two-row winter barley material at Cambridge, England and Fiorenzuola, Italy was carried out over the years 1978–1982 with the objective of comparing the individual selection of the two breeding teams and assessing the adaptation of the surviving selections. Visual selection in the generations F3 to F5 did not result in any clear cut compartmentalisation of the material and both teams were as likely to select from families previously selected only by the other team as from families they had themselves previously selected. Lines with specific adaptation to each site as well as lines well adapted to both sites were identified from yield trials carried out in F5 and F6. The former showed only a very small yield advantage over lines with general adaptation to both sites. 相似文献
7.
A. G. Balkema-Boomstra 《Euphytica》1992,65(2):99-106
Summary The objective of this study was to evaluate traits which can facilitate and improve selection for grain yield of spring barley. Five experiments were conducted in different environments to measure grain yield and yield related traits of breeding lines and exotic varieties. Differences for rate of canopy expansion were significant and offer the opportunity to select for a high weed suppressing potential but there was no relation to grain yield. Dry matter yield/m2 at anthesis and its water-soluble-carbohydrate content were not correlated with grain yield/m2 and number of grains/m2. Variation in biomass among breeding lines with a similar development and plant height was small. Biomass standardized for plant height was stable across environments and showed a good correlation with number of grains and grain yield. The contribution of pre-anthesis assimilation to grain yield was only important under low yielding experimental conditions, but the differences among the genotypes for this trait were inconsistent. It may be difficult to select genotypes with a high potential contribution of pre-anthesis assimilation to grain yield. 相似文献
8.
Summary Sixty genotypes of timothy, comprising 12 genotypes originating from each of five locations, were grown at the same locations in northern Scandinavia and Iceland, as a part of a joint breeding project in timothy. The trials were observed for two years and various characters were evaluated. Large genotype x environment interactions occurred for most characters and the response of individual genotypes. irrespective of origin contributed most to the variation. A superiority measure (P.), based on the genotype's response and the maximum response, averaged over all locations, was used to rank the genotypes with respect to yield and other morphological attributes. Based on this ranking it is possible to choose genotypes which are high yielding and show good stability over the area. 相似文献
9.
Summary Little information is available on the genetic shifts that may take place when seed mixtures of peanut are grown over time. Five peanut lines with distinct seed coat colors, but similar plant types, pod yields, and maturities, were grown in pure stands for four years. A mixture with equal numbers of seed from each of the five lines was grown each year. All mixtures were subsampled and grown in subsequent years without reconstitution. Yield, 100-seed weight, and total sound mature kernel proportions from the mixtures were higher than the pure stand average of the five lines, but yield and total sound mature kernel proportions were lower than the average adjusted for individual line production. The best component line was significantly better than the mixture for pod yield, 100-seed weight, and proportion of sound mature kernels. Intergenotypic competition shifted the mixture composition to increase the proportion of one of the high yielding lines after only two years, while other high yielding lines in the test either maintained or decreased their original proportion. The two lowest yielding lines in pure stand also decreased in proportion over time.Contribution of the Florida Agricultural Experiment Station. Journal Series No. R-00550. 相似文献
10.
Summary Aspects of selection for yield and harvest index were investigated by simulating selection using data from random pedigreed F2, F3, F4 and F5 derived lines from two crosses grown in plots at two sites over two years.Improvement in yield through selection was obtained when the response was measured at the same site and in the same year as the selection. Selecting the best 10 per cent of F2 to F4 derived lines gave F5 derived lines that outyielded random selections by 19 to 53 per cent for one cross and 5 to 23 per cent for the second cross. These lines were 41 to 50 per cent better than the mid-parent in one cross, but were less than the mid-parent in the other cross.However, the response to selection when measured in a different year was little better than random selection. The effect of different sites also reduced the effectiveness of selection.Selection of harvest index in early generations for improvement of yield was ineffective when response was measured at the same site in the same year, or in different years.Contrary to some theoretical proposals, the same improvement in yield was obtained by selecting in early or late generations. While high yielding genotypes may be lost by delaying selection, this is counteracted by the better predictive value of late generations due to their greater homozygosity and homogeneity. 相似文献
11.
Summary Thee groups consisting of 332, 243 and 280 barley breeding lines (entries) of known selection history were evaluated in 10, 9 and 8 environments, respectively, to determine the relationship between grain yield in low yielding (LYE) or high yielding (HYE) environment, and selection history and type of germplasm. One cycle of selection in LYE produced on average five times more entries outyielding the best check in LYE than selection in HYE. A retrospective analysis indicated that the highest yielding lines in LYE were lower yielding (15%–28%) in HYE when compared with the best check, and by 20% and 38% compared with the best entries in HYE. In contrast, the highest yielding lines in HYE were lower yielding (4%–33%) in LYE when compared with the best check, and by 33% and 40% when compared with the best entries in LYE. The highest yielding lines in LYE did not differ consistently from the highest yielding lines in HYE for a number of morphological and developmental traits including days to heading. This suggests there are many paths to high yield in LYE and that analytical breeding based on individual traits may not be appropriate for variable environments. Only 0.07% of the highest yielding entries in LYE was selected for high yield in HYE conditions confirming previous results indicating that selection for high yield in HYE is an inefficient strategy for improving yield in low yielding conditions. This frequency is 28 times lower than the frequency of high yielding entries in LYE selected from landraces or crosses with landraces in low yielding conditions. The results imply that the most cost-effective strategy for barley breeding in low yielding conditions is to select repeatedly in low yielding conditions and to include adapted germplasm (landraces) in the breeding material. 相似文献
12.
Summary The relative performance of synthetic varieties in faba beans (Vicia faba L.) as compared with line varieties is the result of the joint effect of several factors. Factors investigated in the present study were (1) effects of heterogeneity and (2) heterozygosity on agronomic performance, (3) genetic variance for the degree of cross-fertilization among inbred lines and (4) genetic variance among homozygous and heterozygous genotypes for yield. The evaluation was based on multilocational trials in Germany with 36 inbred lines and derived entries with contrasting population structure (levels of heterozygosity and heterogeneity). When inbred lines and F1-hybrids are included in the same mixture of genotypes, the resulting heterogeneity had a positive effect on yield. Relative mid-parent heterosis for yield was between 33% and 51%. The average degree of cross-fertilization was 53.5%, and its genetic standard deviation was 8.3%. The estimates for genetic standard deviation for yield among inbred lines were between 3.4 q/ha and 5.3 q/ha. The highest yielding synthetic variety is expected to outyield markedly the highest yielding line. 相似文献
13.
I. L. Gordon 《Euphytica》1979,28(1):81-88
Summary The variance of heritability ratios are considered for cases where data from perennial genotypes are collected serially over time. A random effect model for randomised complete blocks at a single location is examined. Estimation of the variance of estimates of heritability is presented for three types of heritability definition.Estimators are applied to two characters in a Yorkshire Fog grass germplasm collection evaluated for two years at one site. The precision of such heritability estimates is discussed. Estimators for the multiple sites model are available also, from the author. 相似文献
14.
Summary Two-way classification analysis, combined with analysis of variance and linear regression techniques, was applied to a set of yield data from twenty-one genotypes grown at twelve locations for two years in International Mungbean Nursery trials. Genotypes and environments with similar yield response patterns were grouped and differences between groups identified. Genotypes were also grouped on the basis of flowering time and the relation between days to flower and yield was examined. It was concluded that cluster and associated analyses are of value in determining response patterns of mungbean genotypes to a wide range of environments, and a useful aid in the selection of materials and locations for mungbean evaluation. In particular we note the adaptation of genotypes M409 and M1134 to high elevation locations, and the positive yield response of M374 (MG50-10A) to high yielding environments. Highest yielding lines were also the earliest to flower. Disease resistance was considered the most important breeding objective for mungbean yield improvement. 相似文献
15.
Summary Groups of 10 barley genotypes were selected for high grain yield under either high yielding (two groups) or low yielding conditions (two groups). The genotypes had a similar average grain yield across a wide range of yielding conditions, but differed in their linear response over environments (environmental sensitivity). The genotypes selected for high grain yield under low yielding conditions were less sensitive to changing environments than genotypes selected for high grain yield under high yielding conditions. The higher stability of genotypes selected under low yielding conditions was shown by both the linear regression analysis and the comparison of coefficients of variation. The use of a safety-first index showed that the probability of a crop failure of genotypes selected for high grain yield under high yielding conditions was between 1.8 and 2.7 times higher than for genotypes selected for high grain yield under low yielding conditions. The development of new cultivars for areas where a large proportion of the crop is grown by subsistence farmers should therefore be based on selection under low yielding conditions. 相似文献
16.
Summary In the early generations of a breeding programme to incorporate the successful Norin 10 semidwarfing genes into adapted tall or standard lines, the bread and durum wheat breeder must be able to recognise and discard those lines that are not homozygous for the dwarfing gene. A method which exploits the gibberellin insensitive reaction of lines carrying the genes combined with a single seed descent technique is described in which most unwanted genotypes may be removed as F2 seedlings. 相似文献
17.
Summary A 10×10 diallel cross experiment involving white modified opaque-2 maize inbred lines was grown at four sites. A stability analysis, based on both a combining ability and a heterotic pattern model, was developed. The stability analysis provided valuable information on the genotype x environment interaction properties of the 10 inbred lines. The Gail & Simon (1985) test for qualitative interactions provided a means of determining the nature of these interactions. The inbred, SO507W(M), is shown to have the best potential for use in a hybrid breeding programme, in terms of having the highest weighted general combining ability and line heterosis, and the best general adaptability to all four sites. The single cross, SO713W(P) x PO558W(F), has been identified as one of the genotypes to be used in a recurrent selection programme that favours specific combining ability. 相似文献
18.
J. M. Ngeve 《Euphytica》1993,71(3):231-238
Summary Two experiments, each involving a set of 10 sweet potato clones, were conducted for three years at 4 sites (Ekona, Ebolowa, Nkolbisson, and Bambui Plain) in Cameroon. Data obtained were subjected to analysis of variance to determine the presence of genotype x environment (G x E) interactions, and to regression analysis to assess the performance of clones across anvironments. Environments were assessed in two ways: (i) the mean response of all clones (dependent assessment), and (ii) the average performance of a different set of clones (independent assessment).The first experiment (Expt 1) produced higher yields but had fewer stable clones than the second (Expt 2).The analysis of variance revealed that the clones interacted significantly with environments for all traits.The study has identified high yielding and stable sweet potato clones for distribution to growers in the major areas of cultivation in the tountry. Despite slight differences in numbers of clones judged stable by the various regression indices in the two methods of environmental assessments, the rankings of clones on the basis of their linear regression coefficients were similar. In a developing country like Cameroon, with limited resources and where sophisticated equipment for obtaining physical or biological measures of the environment may be lacking, the mean performance of genotypes may still be the most reliable measure of environment in evaluating the stability of performance of crop cultivars. 相似文献
19.
J. E. Lu´quez L. A. N. Aguirrezábal M. E. Agüero V. R. Pereyra 《Journal of Agronomy and Crop Science》2002,188(4):225-234
The best‐yielding and most stable cultivars are identified by growing cultivars in different environments. The stability of grain‐quality traits has been less thoroughly investigated than the stability of grain yield. High‐oleic hybrids of sunflower have been available on the Argentinian seed market for several years. Research on the stability of these genotypes is scarce. The objectives of this work were (i) to compare, using three different methods, the stability and adaptability of high‐oleic hybrids for grain yield and oil and oleic acid contents, and (ii) to explore the advantages and disadvantages of each method in selecting stable or adapted genotypes with high grain yield and high quality. Stability and adaptability analyses were performed on results for grain yields and oil and oleic acid contents of 35 high‐oleic sunflower hybrids from 17 comparative yield trials conducted over 2 years in Argentina. Stability was estimated using two methods: Fisher's protected least significant difference (LSD) test, which compared hybrids with the best‐yielding hybrid in each environment, and the test of relative yield (RY), which uses standard deviation as the measure of stability. Adaptability was estimated using Piepho's method of ‘multiple comparisons with the best’. These three methods can be applied to unbalanced data. Piepho's method made little discrimination amongst the hybrids. The LSD and RY tests coincided in classifying the hybrids as stable and unstable in 85 % of cases for grain yield and 76 % for oil content. It is concluded that the most convenient method depends on characteristics of the experimental design and of variability of the evaluated trait. Results from the LSD test depend on the number of environments in which the cultivar is tested. The RY method is valuable for classifying some cultivars as high‐yielding and stable, avoiding the problem of high‐yielding environments biasing the general average. Use of both methods together could be effective for classifying hybrids when the number of environments is adequate. 相似文献
20.
Mean grain yield performance of 12 wheat and one triticale genotypes were measured at four locations over four consecutive years, using a randomized complete block design with four replications. The genotypes used were commercial cultivars and advanced lines from different wheat breeding projects located in different areas in Iran. Two locations were in semiarid regions and the other two locations in the temperate zones. The combined analysis of variance indicated highly significant genotype-environment (GE) interactions. From combinations of locations and years three sets of environments were generated. Set I and set II, each, consisted of eight environments (two locations and four years) representing semiarid and temperature environments, respectively. Set III consisted of 16 environments including both semiarid and temperate conditions. Set I and set II were used to measure specific adaptation of the genotypes while set III was employed for measuring general adaptation. The methods of Eberhart and Russell (1966) were used for partitioning GE interactions. The mean square associated with the heterogeneity of regression was highly significant under all sets of environments. These observations indicated that a major part of GE interaction could be accounted for by differences in the regression of the individual genotypes. All the genotypes had significant regression mean square under set I, set II, and set III environments, with the exception of two genotypes under set II. However, mean yields, regression coefficients, and the mean squares associated with deviation from regression greatly varied over the sets of environments. Only three genotypes, a commercial cultivar and two new advanced line, were identified as having specific adaptation and yield stability to semiarid environments. Among all the genotypes, only a commercial cultivar was identified as adapted and stable to temperate conditions. Two of the three genotypes which were adapted to semiarid environments also showed general adaptation to set III environments. However, the mean yield of these two genotypes under semiarid conditions (set I) were significantly greater than their respective mean yields under set III environments. Thus, wider adaptability was compensated by lower mean yield. The present study indicates that, while a wide range of environments is necessary and recommended for measuring general adaptation reactions and yield stability of various genotypes, one should not ignore the possibility of finding some genotypes with specific adaptation to specific environments and thus maximizing yield production. Stable genotypes with general of specific adaptation should be utilized in breeding projects in order to develop even more desirable lines. 相似文献