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1.
This study aimed to investigate a cultivar selection criterion based on income ha−1 in common wheat. Regional yield trials with 20 entries were planted in Diyarbakır, Hazro and Ceylanpınar in southeast Anatolia in the 2004/2005 growing season. A randomized complete block design with four replications was employed. Grain samples from each location were subjected to quality analyses, and then presented to randomly selected grain purchasers with the local commodity market for market price estimations. Entries 1, 9, 10, 7 and 6 were the top five ranking entries for grain yield, giving 5,320, 5,290, 5,280, 5,140 and 5,130 kg ha−1, respectively. From the market price perspective, entries 17, 3, 7, 20 and 8 received the five highest marketing price offers with the values 239.0, 238.1, 237.1, 236.9 and 236.7 US$ tonne−1, respectively. There was a US$ 10.94 tonne−1 market price difference between entries with the highest and the lowest market price. The only quality analyses showing significant correlations with market price were Zeleny sedimentation value and hectolitre weights (kg hl−1). From thev production income [= marketing price (US$ tonne−1) × grain yield (kg ha−1)] point of view, entries 9, 10, 1, 7 and 6 were ranked from 1st to 5th for production income ha−1 with the values 1,241.0, 1,238.0, 1,219.9, 1,214.2 and 1,209.3 US$ ha−1, respectively. All five high yielding entries were also high-income entries. A rank stability analysis further indicated that entry numbers 6, 7, 8, 4 and 1 stable for high production income ha−1. A simulation study, based on allocation of additional premiums for high quality indicated that entries 9,1,10, 7, and 6 would be top ranking for high income ha−1 if given an additional premium of as much as twice the standard deviations of market price for each entry (the highest premium limit; 20.24 US$ tonne−1). The order for cultivar preference for high production income ha−1 would change and would generate 1,321.94, 1,296.20, 1,281.11, 1,258.06 and 1,243.01 US$ ha−1, respectively. It was concluded that the relatively quality conscious Şanlıurfa commodity market does not offer adequate premiums for the high quality grains. This results in farmer preference for high yielding lower quality cultivars. Even though quality cannot be neglected, and cultivar preference could change with additional premiums, breeders must give more attention to high production income ha−1.  相似文献   

2.
Genetic variability, correlation, path coefficient analysis and test of normality was conducted in an F8 recombinant inbred aerobic rice population developed by single seed descent method to evaluate its potential as a mapping population. Estimates of genotypic variance, phenotypic variance, genotypic coefficient of variance (GCV), phenotypic coefficient of variance (PCV), heritability in the broad sense (H) and expected genetic advance at 5% selection index (GA) for grain yield and other attributing characters were computed. In all the cases, PCV was higher than GCV indicating the influence of environment on the characters. High heritability coupled with high GA was observed for several plant traits; number of tillers, plant height, total number of spikelets panicle−1, biomass plant−1, straw weight, harvest index and grain yield plant−1 and hence offered good scope for selection. Grain yield plant−1 was found to be positively correlated with plant height, number of tillers, panicle length, panicle exsertion, number of panicles plant−1, single panicle weight, test weight, number of fertile spikelets panicle−1, straw weight, biomass plant−1, harvest index and grain breadth both at genotypic and phenotypic levels. Harvest index exerted maximum positive direct effect, followed by biomass plant−1 and straw weight on grain yield plant−1 at phenotypic level. Shapiro-Wilks “W test of normality” indicated that the population was skewed towards female parent IR50 for some traits and for some others towards Moroberekan, the male parent. Most of the characters that showed skewness were platykurtic with a kurtosis value of less than 3.  相似文献   

3.
The improvement of cotton fiber quality has become more important because of changes in spinning technology. Stable quantitative trait loci (QTLs) for fiber quality will enable molecular marker-assisted selection to improve fiber quality of future cotton cultivars. A simple sequence repeat (SSR) genetic linkage map consisting of 156 loci covering 1,024.4 cM was constructed using a series of recombinant inbred lines (RIL) developed from an F2 population of an Upland cotton (Gossypium hirsutum L.) cross 7235 × TM-1. Phenotypic data were collected at Nanjing and Guanyun County in 2002 and 2003 for 5 fiber quality and 6 yield traits. We found 25 major QTLs (LOD ≥ 3.0) and 28 putative QTLs (2.0 < LOD < 3.0) for fiber quality and yield components in two or four environments independently. Among the 25 QTLs with LOD ≥ 3, we found 4 QTLs with large effects on fiber quality and 7 QTLs with large effects on yield components. The most important chromosome D8 in the present study was densely populated with markers and QTLs, in which 36 SSR loci within a chromosomal region of 72.7 cM and 9 QTLs for 8 traits were detected.  相似文献   

4.
Maize (Zea mays L.) is grown on 15 million ha in eastern and southern Africa. Several diseases are of common occurrence in the region and regularly result in significant yield losses. A collaborative regional disease nursery (REGNUR) project was initiated in 1998 to identify and increase access to disease resistant germplasm, generate and disseminate information on disease and insect resistance sources, and facilitate the development of resistant cultivars by project partners. A diallel among 12 elite inbred lines was formed with the specific objective of evaluating the combining ability of these inbred lines for grain yield and resistance to seven diseases. The trial was grown at six sites in 2001. Results showed that both general (GCA) and specific combining ability effects were significant for most diseases. On the average, GCA accounted for 69% of resistance to diseases and only 37% of variation for grain yield. Correlations between GCA effects for disease scores were generally non-significant, implying that it is possible to pyramid genes for disease resistance in inbred lines. This underscores the need for screening for resistance to prevailing diseases using artificial inoculation or reliable hot-spots. Based on GCA effects for grain yield and across diseases, P12 and P6 were the best inbred lines. The crosses P4 × P9 (6.7 t ha−1) and P4 × P12 (6.9 t ha−1) were the best hybrids in the earlier maturity group, while P3 × P9 (8.3 t ha−1) and P2 × P8 (7.4 t ha−1) were the best hybrids in the late maturity group.  相似文献   

5.
Evaluation of salt tolerance in rice genotypes by physiological characters   总被引：5，自引：0，他引：5  
The use of physiological characters as selection criteria in salt tolerance breeding requires the identification of the contribution each individual character makes to salt tolerance. Rice genotypes were evaluated for salt tolerance in terms of grain yield and physiological characters. Plants of twelve genotypes were grown in sand tanks in a greenhouse and irrigated with Yoshida nutrient solution. Sodium chloride and calcium chloride (5:1 molar ratio) were added at two concentrations to give moderate (4.5 dS m-1) and high (8.3 dS m-1) salinity treatments. One set of plants was harvested at 635 °Cċd (accumulative thermal time) after planting to determine LAI and mineral ion concentrations. Another set of plants was allowed to grow to maturity. High genotypic diversity for LAI and shoot ion contents was observed. LAI contributed the most to the variation of the grain yield under salt stress. Significant correlations between LAI and yield components in both salt-tolerant and-sensitive genotypes further confirmed the significant contribution of LAI to grain yield. K-Na selectivity increased with increasing salinity. Conversely, Na-Ca selectivity decreased with increasing salinity. Significant correlations were identified between grain yield and both Na-Ca and K-Na selectivity. Highly significant (p<0.001) correlations were identified between Na-Ca selectivity and the rankings among genotypes for grain yield. Thus, Na-Ca selectivity could be one salt tolerance component and an useful selection criterion in screening for salt tolerance. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

6.
Recombinant inbred line (RIL) populations of rice are useful genetic sources for map-based cloning of agronomically important genes. Zhe733 is a high-yielding indica cultivar from China conferring resistance to rice blast (RB), rice water weevil (RWW) and straighthead; whereas Kaybonnet low-phytic acid 1-1 (KBNTlpa) is a mutant of a tropical japonica cultivar from the US containing low-phytic acid with average yield, and is susceptible to some RB races, RWW, and straighthead. A 355 RIL F10−11 population derived from the cross of KBNTlpa × Zhe733 was recently released. Simple sequence repeat (SSR) markers were used to evaluate 269 RILs of this population. A total of 107 polymorphic markers were mapped on all rice chromosomes representing a total of 1,016.3 cM of genetic distance. Two hundred and thirty-five KBNTlpa × Zhe733 RILs (KZRILs) were clustered into seven groups based on allele frequencies of SSR markers. Twenty-three markers (21.1%) on chromosomes 3, 6, 7, 9, and 11 were found to favor Zhe733 (χ 2 = 16.8−189.7 and P < 0.01) and five markers (4.6%) on chromosome 1 and 6 were found to favor KBNTlpa (χ 2 = 18.5−46.6 and P < 0.01). Marker segregations were observed to be normal for both parents except 26 (10.2%) KZRILs were found to skew toward Zhe733 (χ 2 > 15.7 and P < 0.01). Furthermore, the average frequencies of heterozygosity and non-parental alleles per KZRIL were 1.3% (0.0−38.9%) and 0.4% (0.0−15.0%), respectively. Thirteen heterozygous KZRILs were found at more than five markers loci and nine KZRILs were found with more than five non-parental alleles representing 5.1 and 3.5% of 255 KZRILs. Overall, this KZRIL population is a good population with relatively low frequencies of heterozygosity and non-parental alleles, and with relatively low percentages of skewed markers and skewed KZRILs. The profiles of these SSR markers should facilitate molecular tagging critical genes controlling yield, RB, RWW, and straighthead resistance.  相似文献   

7.
This study was carried out to verify the applicability of variable rate fertilization (VRF) based on soil testing and diagnosis of rice plant growth for high quality rice production of var. Chucheongbyeo at the farm level. The field trials were conducted at Icheon in Gyeonggi province on a 10 ha farm consisting of 45 experimental fields. For comparative study, 15 field trials were carried out adopting fertilizer management (FPM) practices currently used by farmers. FPM fields were managed by each rice grower using current cultivation methods, but in each VRF field fertilizer application was prescribed using soil test results and the amount of N fertilizer for top-dressing at panicle initiation stage was calculated using rice growth value at that stage. In VRF fields, the total amount of N fertilizer application was less (72 kg ha−1) than that in FPM fields (103 kg ha−1). However, the amount of K2O fertilizer application was more in VRF fields (60 kg ha−1) than that in FPM fields (52 kg ha−1). The amount of P2O5 fertilizer application was similar between the VRF and FPM fields. Plant height was significantly shorter and the number of tillers was significantly more at VRF fields than at the FPM fields. Coefficient of variation (CV) of each growth characteristic measured in VRF was lower than that of FPM fields at panicle initiation stage. There was no difference in culm and panicle length and panicle number between them at the grain filling stage, but CV of panicle numbers per m2 decreased in VRF compared with that of the FPM fields. Rice yield was not different between VRF and FPM fields despite higher brown rice recovery and 1,000-grain weight in VRF fields. Under VRF management, head rice yield increased due to an increase in head rice ratio accompanied by a reduction in brown rice protein content and variation of quality characteristics. These results suggest that VRF application based on soil tests and measurement of rice growth value at panicle initiation stage has the potential for quality control and production of high quality rice through increasing uniformity of growth and reducing the variability in quality among individual fields.  相似文献   

8.
Summary During the last decades extensive progress has been achieved in winter barley breeding with respect to both, yield and resistance to fungal and viral diseases. This progress is mainly due to the efficient use of the genetic diversity present within high yielding adapted cultivars and – with respect to resistance – to the extensive evaluation of genetic resources followed by genetic analyses and introgression of respective genes by sexual recombination. Detailed knowledge on genetic diversity present on the molecular level regarding specific traits as well as on the whole genome level may enhance barley breeding today by facilitating efficient selection of parental lines and marker assisted selection procedures. In the present paper the state of the art with respect to virus diseases, i.e. Barley mild mosaic virus, Barley yellow mosaic virus, and Barley yellow dwarf virus is briefly reviewed and first results on a project aiming on a genome wide estimation of genetic diversity which in combination with data on yield and additional agronomic traits may facilitate the detection of marker trait associations and a more efficient selection of parental genotypes are presented. By field tests of 49 two-rowed and 64 six-rowed winter barley cultivars the genetic gain in yield for the period 1970–2003 was estimated at 54.6 kg ha−1 year−1 (r2 = 0.567) for the six-rowed cultivars and at 37.5 kg ha−1 year−1 (r2 = 0.621) for the two-rowed cultivars. Analysis of 30 SSRs revealed a non-homogenous allele distribution between two and six-rowed cultivars and changes of allele frequencies in relation to the time of release. By PCoA a separation between two and six-rowed cultivars was observed but no clear cut differentiation in relation to the time of release. In the two-rowed cultivars an increase in genetic diversity (DI) from older to newly released cultivars was detected.  相似文献   

9.
The agricultural use of water is higher than 85% in the western USA, resulting in an increasing water deficit in the region; this situation is commonly encountered throughout the world where irrigated and irrigation-assisted production systems are operational. The objective of this study was to examine differences among dry bean (Phaseolus vulgaris L.) landraces and cultivars in terms of water use efficiency (WUE), subsequently identifying those with a high water use efficiency. Six medium-seeded (25–40 g 100 seed wt−1) landraces and cultivars of pinto and red market classes were evaluated in intermittent drought-stressed (DS) and non-stressed (NS) environments at Kimberly, Idaho, USA in 2003 and 2004. Each market class comprised one each of a landrace and old and new cultivars. Mean evapotranspiration (ET) in the NS environment was 384 mm in 2003 and 432 mm in 2004; the respective ET values in the DS environment were 309 and 268 mm. Mean seed yield was higher in the DS (2678 kg ha−1) and NS (3779 kg ha−1) environments in 2004 than in 2003 (688 and 1800 kg ha−1, respectively). Under severe drought stress in 2003, WUE in the pinto bean ranged from 1.5 for the Common Pinto landrace to 4.4 kg ha−1 mm−1 water for cv. Othello. The Common Red Mexican landrace had the highest WUE (3.7), followed by cvs. NW 63 (2.8) and UI 259 (1.4) in the red market class. Under favorable milder climatic conditions in 2004, the mean WUE value was 10 kg ha−1 mm−1 water in the DS environment and 8.7 kg ha−1 mm−1 water in the NS environment. We conclude that dry bean landraces and cultivars with high WUE should be used to reduce dependence on irrigation water and to develop drought-resistant cultivars to maximize yield and WUE.  相似文献   

10.
We searched for QTLs involved in tolerance to barley yellow dwarf (BYD), a serious viral disease of small grain cereals in two wheat populations, Opata × Synthetic (ITMI)and Frontana × INIA66 (F × I), for which marker data had previously been generated. The populations were evaluated in replicated field trials under artificial inoculation with a BYDV-PAV-Mex isolate and under disease-free conditions. Disease symptoms (yellowing, dwarfism and biomass reduction) were visually recorded and agronomic traits (number of tillers,height, biomass, yield and thousand-kernel weight) were measured on five plants per plot. Phenotypic data on all evaluated traits showed normal distribution with high correlation between visual estimates and measured values. Heritabilities were mostly moderate to high in the 114 lines of the ITMI population, and from low to moderate in the 117 lines of the F × I population. QTL analyses were based on genetic maps containing 443 loci for the ITMI population and 317 loci for the F × I population. Using composite interval mapping, 22 QTLs in the ITMI population and seven in the F × I population were detected, explaining9.8–43.3% of total phenotypic variation (σ2 P)per agronomic trait in the first population, and 4.1–13.7% in the second. Individual QTLs explained less than 15.8%of σ2 P. In the F × I population a minor QTL explaining 7% of σ2 P for yellowing was detected on the short arm of 7D, linked to leaf tip necrosis, a morphological marker for linked genes Bdv1, Yr18 andLr34. A QTL consistently detected for several traits on 2D in the ITMI population and on the short arm of group 6 chromosome(6S) in F × I explained 10–15% of σ2 P. The large number of QTLs having mostly small effects and the continuous distribution of all evaluated traits confirmed the polygenic nature and complexity of BYD tolerance in wheat. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

11.
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   

12.
Salt tolerance of rice (Oryza sativa L.) at the seed germination stage is one of the major determinants for the stable stand establishment in salinity soil. One population of recombinant inbred lines (RILs, F2:9), derived from a cross between a japonica rice landrace tolerant to salt stress and a sensitive indica rice variety, was used to determine the germination traits including imbibition rate and germination percentage under control (water) and salt stress (100 mM NaCl) for 10 days at 30 °C. The multiple interval mapping (MIM) were applied to conduct QTL for the traits. The results showed that seed germination was a quantitative trait controlled by several genes, and strongly affected by salt stress. A total of 16 QTLs were detected in this study, and each QTL could explain 4.6–43.7% of the total phenotypic variance. The expression of these QTLs might be developmentally regulated and growth stage-specific. In addition, only one digenic interaction was detected under salt stress, showing small effect on germination percentage with R2 2.7%. Among sixteen QTLs detected in this study, four were major QTLs with R2 > 30%, and some novel alleles of salt tolerance genes in rice. The results demonstrated that the japonica rice Jiucaiqing is a good source of gene(s) for salt tolerance and the major or minor QTLs identified could be used to improve the salt tolerance by marker-assisted selection (MAS) in rice.  相似文献   

13.
Additive effects (A) and additive‐by‐environment interactions (A×E) for five rice yield components were analysed using 20 SSSLs under mixed linear model methodology. Thirty‐one QTLs were detected. Different yield components have different QTL‐by‐environment (Q×E) interaction patterns. No A×E interaction effects were detected for the four QTLs for panicle number (PN). Four QTLs detected for spikelets per panicle (SPP) had A×E interactions. Five of seven QTLs detected for grains per panicle (GPP), two of 10 QTLs detected for 1000‐grains weight (GWT) and three of six QTLs detected for seed set ratio (SSR) showed significant A×E interaction. Most of these QTLs were distributed in clusters across the genome. The complexity of linkage and pleiotropy of these QTLs plus environmental effect may result in the diversity of the yield phenotype in the SSSLs. Only S19 exhibited a significant increase in yield with a predicted gain by 281.58 kg ha?1. The results may be useful to design a better breeding strategy that takes advantage of QTL‐by‐environment interaction effects in each of the SSSLs.  相似文献   

14.
Segregation for salinity tolerance and ISSR markers based molecular polymorphism were investigated in a F3 plant population raised via single-seed descent method from a cross between salt-tolerant indica rice variety CSR10 and salt-susceptible premium traditional Basmati rice variety Taraori Basmati HBC19. A total of 130 F3plants were evaluated individually for salinity tolerance on 1–9 scale on the basis of seedling growth parameters; the average score ranged between 1.7 to 8.3. Frequency distribution curve obtained using the salinity tolerance data of F3 population and a chi-square analysis, showed a good fit to a normal distribution. Eleven plants each in the category of salt-tolerant and salt-susceptible were selected from the segregating F3 population for ISSR marker analysis. A total of 149 bands (4–11 bands per primer) ranging from 200 to 3530 bp were scored for the two rice varieties and the selected CSR10 × HBC19 segregating F3 plants using 26 ISSR primers. Of these, 89 were monomorphic and 60 were polymorphic. Of the 60 polymorphic bands,36 and 20 bands were specific to CSR10 andHBC19 respectively. The remaining four bands were amplified using UBC primers 810,848, 853 and 886 and present in only some of the CSR10 × HBC19 F3 plants. Notably, ISSR primers with dinucleotide repeat motif and 5'-anchored end amplified more number of bands (7.0 bands/primer) compared to3'-anchored dinucleotide primers (5.4bands/primer), but 3'-anchored dinucleotide primers revealed higher level of polymorphism (2.6 polymorphic bands/primer) compared to 5'-anchoreddinucleotide primers (1.43 polymorphic bands/ primer). While distribution of majority of the polymorphic bands were more or less in the expected ratios in salt-tolerant and/or salt-sensitive F3segregating plants, but some of the bands amplified using UBC ISSR primers 823, 825,826, 849, 853, 864, 866 and 884 showed highly skewed distribution. Such polymorphic bands stand greater chances of having a linkage with the genes/ QTLs for salinity tolerance and shall be the target for further studies. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

15.
Anther culture of recalcitrant indica × Basmati rice hybrids   总被引：1，自引：1，他引：0  
Fertile, green, di-haploid plants were obtained at high frequencies from several indica × Basmati rice F1 hybrids and/or F2 plant populations using an improved anther culture procedure. Anthers from cold-pretreated (10 °C for 10 d) panicles of six indica (HKR120, HKR86-3, HKR86-217, PR106, Gobind andCH2 double dwarf) and two Basmati rice (Basmati 370,Taraori Basmati) varieties and 14 heterotic indica ×Basmati F1/F2 hybrids were cultured in modified agarose-solidified N6M, Heh5M and RZM media. Best callus induction frequencies (2.6–78%) were obtained in RZM medium containing 4% (w/v) maltose,2,4-D, NAA and kinetin. F2 plants compared to F1 hybrids and parental rice varieties, were more responsive to anther culture. Androgenesis frequencies of 31–78% were obtained for indica × Basmati F2 plants in RZM medium in just 30 d which are comparable to or higher than that reported for japonica rice varieties and hybrids involving japonica rice parent(s). Agarose (1.0% w/v)-solidified MS medium containing 3.0% maltose, kinetin, BAP, and NAA, induced green shoot regeneration in 0–51% of the anther-derived callide pending upon the genotype. High plant regeneration frequencies (67–337 green plants per 1000 anthers)were obtained from anther calli of several F1hybrids (Gobind × Basmati 370 and HKR120 ×Taraori Basmati) and F2 plants (Gobind × Basmati370, Gobind × Taraori Basmati, HKR86-3 × TaraoriBasmati). A sample of 498 plants obtained from the above hybrids, were transferred to pots with>90% survival; 8–78% of these plants had >5%spikelet fertility and were diploid. In addition,18% of the haploid plants could be diploidized by submerging in 0.1% colchicine solution for 16–18 h. The improved anther culture procedure reported here, resulted in several fold increase in the recovery of green plants from recalcitrant indica × Basmati rice hybrids compared to previous published procedures. The study may accelerate the introgression of desirable genes from indica into Basmati rice using anther culture as a breeding tool. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
Anthocyanins and proanthocyanidins are the primary pigments of red rice and are also important functional nutrients for human health. To identify novel quantitative trait loci (QTLs) underlying anthocyanins and proanthocyanidins (ANC and PAC) in rice, a recombinant inbred line (RIL) derived from a cross of red rice ‘Hong Xiang 1’ (‘HX1’) and white rice ‘Song 98-131’ (‘S98-131’) was cultivated in six environments. A genetic map containing 126 markers covering 1833.4 cM with an average of 14.55 cM between markers was constructed. A total of 21 additive QTLs (A-QTLs) for ANC and PAC were identified from six environments using the IciMapping v3.3 software. Two new QTLs, qANC3 and qPAC12-4, were detected in several environments, and explained significant phenotypic variance. Nine QTLs of ANC and PAC were detected with additive × environmental interaction effects (AE effects) by QTLNetwork 2.1 software, but no epistatic and epistatic × environmental interaction effects (AA and AAE effects) were detected. The information obtained in this study could be useful for fine mapping and molecular marker-assisted selection of ANC and PAC in rice.  相似文献   

17.
Response to long-term selection in early maturing maize synthetic varieties   总被引：1，自引：0，他引：1  
A. Hyrkas  M. J. Carena 《Euphytica》2005,143(1-2):43-49
Long-term continuous selection is essential for germplasm improvement. However, choice of germplasm for long-term genetic improvement might limit the success of germplasm enhancement programs. The objective of this research was to report the response to long-term selection in early maturing North Dakota (ND) synthetic varieties. We wanted to determine whether the performance of three ND maize synthetic varieties was improved by long-term mass selection (M) and if the performance of one of them was improved by long-term modified ear-to-row (MER) selection. The evaluation of long-term selection response was performed at two plant densities. An experiment in a randomized complete block design with split-plot arrangement was used to evaluate NDSM(M), NDSAB(M), NDSCD(M), and NDSAB(MER) under 75,000 and 42,500 plants per hectare across seven environments. Long-term mass selection for grain yield and stalk lodging resistance in NDSM(M), NDSAB(M), and NDSCD(M) was not successful, since there were no significant changes in grain yield or stalk lodging in these populations at either low or high densities. On the other hand, long-term modified ear-to-row selection was effective for grain yield improvement in NDSAB(MER). Grain yield increased non-linearly from 3.9 Mg ha−1 in cycle 0 to 5.0 Mg ha−1 in cycle 12 at a rate of 2.5% per cycle. Interaction between plant density and genotype was not detected even though selection was performed at relatively low densities (20,000 plants ha−1 for mass selection and 50,000 plants ha−1 for ear-to-row selection). The confirmation of a lack of interaction between plant density and genotype suggests that selection at low plant densities might still be able to provide high-density stress resistance through density-independent genotypes, allowing progeny testing across multiple locations with better accuracy and fewer resources. Selection methods that emphasize both additive and dominance effects such as full-sib recurrent selection are recommended to maximize genetic improvement of advanced population cycles of early maturing synthetics.  相似文献   

18.
Lowland rice is often subject to iron toxicity which may lead to yield reduction. In order to cope with this nutrient disorder, plants have developed resistance strategies. The aim of this research was to assess morphological and physiological parameters linked to iron toxicity resistance mechanisms and to identify quantitative trait loci (QTLs) involved in their genetic determinism. A segregating population consisting of 164 recombinant inbred lines (RILs) derived from a cross between Azucena and IR64 was tested twice in hydroponics at the vegetative stage at 0 and 250 mg Fe2+ l−1. Morphological traits were measured on all 164 RILs. Physiological traits, which were too time-consuming to allow their measurement on all the population, were measured on the two parents and extreme individuals only, selected on the basis of their leaf bronzing index and shoot dry weight. A total of 24 putative QTLs was identified on chromosomes 1, 2, 3, 4, 7 and 11 for leaf bronzing index, shoot water content, shoot and root dry weight, relative variation of shoot and root dry weight, shoot iron concentration, stomatal resistance and chlorophyll content index. Several QTLs were detected in overlapping regions for different parameters. The pertinence of phenotyping extreme RILs only for a QTL analysis is discussed in this study. The QTL analysis allowed to better understand the physiological response of rice in the presence of an excess of ferrous iron, inclusive the relations existing between the stomata closure, the shoot water content reduction and the oxidative stress linked to these growth conditions.  相似文献   

19.
Genetic mapping for resistance to gray leaf spot in maize   总被引：1，自引：0，他引：1  
The molecular marker technology has been used on mapping of quantitative trait loci (QTLs) associated with plant resistance. The objectives of this research were to estimate genetic parameters and to map genomic regions involved in the resistance to gray leaf spot in maize. Ninety F3 families from the BS03 (susceptible) and BS04 (resistant) cross were used. Field trials were performed using a 10 × 10 square lattice design with three replications. Data from 62 SSR markers were used for linkage analysis. The locations of the QTLs on the linkage groups were determined by composite interval mapping method and the phenotypic variance explained by each marker was determined by regression analysis. Several QTLs associated to disease resistance were identified in the population BS03 × BS04. Some QTLs showed significant effects over the different environments studied. The existence of significant QTLs in common among different environments indicates these genomic regions as possible new tools for marker-assisted selection in maize breeding programs.  相似文献   

20.
Combining ability of seed vigor and seed yield in soybean   总被引：4，自引：0，他引：4  
Youngkoo Cho  Roy A. Scott 《Euphytica》2000,112(2):145-150
Studies have shown no consensus in relationships between seed yield and vigor in soybean [Glycine max (L.) Merrill]. The lack of information regarding the inheritance of seed vigor prompted this study to determine the types of gene action and combining ability estimates for seed vigor and its related traits. Five high and six low seed vigor soybean genotypes were crossed in a diallel, and selfed to produce 55 F2 progenies, which were examined, along with the parents, for seed vigor, yield, and seed weight. Significant genotype and environment effects were found for seed vigor and yield. General combining ability (GCA) effects for seed vigor and seed yield were significant (p≤ 0.01) and larger than specific combining ability (SCA) effects. Significant GCA and SCA effects were found for seed weight, indicating that both additive and non additive genetic effects were involved in conditioning seed weight. The ratios of mean square, 2GCA / (2GCA+SCA), were 0.96 for seed vigor and 0.93 for seed yield. These ratios indicated that additive gene effects were more important than non additive gene effects for seed vigor and seed yield in these crosses. Mean seed vigor(83.8%), as determined by accelerated aging germination, and mean seed yield (2,155 kg ha-1)in high vigor × high vigor crosses were higher than the high vigor × low vigor and low vigor × low vigor crosses. Mean percent accelerated aging germination rates in F2 populations from diallel crosses were significantly related to mid-parent seed vigor(r2 = 0.52**) and midparent seed size (r2 = 0.31**). These results indicated that levels of seed vigor can be improved through breeding, while maintaining high yields because of the predominance of GCA effects in both seed vigor and seed yield. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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