A monosomic set of male‐sterile ‘Chris’ (Triticum aestivum L.) with T. timopheevi Zhuk. cytoplasm was used to determine the chromosomal location of Rf‐genes in six male fertility restoring lines (FR‐lines) of T. aestivum L. The six FR‐lines were: R1‐Lee (Nebraska 542437/T. aestivum ‘Lee’), R2‐Sonora 64 (T. timopheevi/2*T. aestivum ‘Marquis’//‘Sonora 64’), R3 (T. timopheevi/3*T. aestivum ‘Marquis’), R4 (amphidiploid T. timopheevi‐Ae. squarrosa/3*T. aestivum ‘Dirk’), R5 (T. Zhukovsky Men. and Er.,/3*T. aestivum ‘Justin’), and T. aestivum ‘Primepi’. The relative proportions of male‐sterile and male‐fertile plants in the F2 and F3 from monosomic F1 indicated that chromosomes 1A and 7D of R1‐Lee, R2‐Sonora 64, R3, R4, and R5 had Rf‐genes. R2‐Sonora 64 and R5 each had a third Rf‐gene on chromosomes 6B and 7B, respectively. Primepi had Rf‐genes on chromosomes 1B and 5D. The inheritance of fertility restoration in control crosses and in some of the noncritical crosses indicated that R1‐Lee, R2‐Sonora 64, and R5 each had three Rf‐genes, and R3, R4, and Primepi each had two. The deficiency of certain chromosomes influenced the penetrance and expressivity of the Rf‐genes in certain crosses.
No abstract
Inter-generation correlations between F2-F3, F2-F4 and F3-F4 in six crosses of chickpea were calculated by using individual plant/progeny means. In general, correlation values in case of plant height, seeds per pod and 100-seed weight were higher between F3 and F4 than those between F2 and F3 and F2 and F4, However, inter-generation correlations were mostly nonsignificant in case of pods per plant and grain yield. These results clearly show that selection in F3 can be fruitful for seeds per pod and 100-seed weight. However, selection for pods per plant and grain yield in early generations may not show any relationship with later generation performance for these traits.To achieve maximum efficiency and progress in breeding for any character, effective selection carried out in early generations would be advantageous. SHEBESKI (1967) suggested yield testing in early generations when most of the variability is present, assuming that there is a positive relationship of the yield of the genotypes in the early generations with the yielding ability of the later generation derivatives of such genotypes. MAHMUD and KRAMER (1951) observed in soybean that F3 lines provided good estimates of the average yield potentials of F4 segregates if genotype-environment interaction can be kept under control.Results using the yields of F2 derived lines to predict the lines of later generations have been inconsistent (FREY 1954, MCKENZIE and LAMBERT 1961, BRIGGS and SHEBESKI 1971and KNOTT and KUMAR 1975 and often poor correlations were obtained. In some of these experiments, the generations were grown in different years, so the interaction between geriotype and environment could have affected the correlations. Often heterozygosity and variability within an F2 derived line is the cause of poor relationship between it and the ') Part of Ph, D, thesis submitted by the senior author to IARI,
Chickpea (Cicer arietinum L.) is an important crop for developed as well as underdeveloped countries, especially those in the Indian sub-continent that contribute more than 60% to both the global area and global production. The harsh environmental conditions under which chickpeas are generally grown impose restrictions on the expression of genetic yield potential. In the present study, a number of different breeding approaches for the development of genotypes possessing multiple resistances to different biotic and abiotic stresses, coupled with enhanced productivity are reported. In one study, 90 genetically diverse genotypes (35 medium-sized desi types, 35 bold-seeded desi types, 10 medium-sized kabuli types and 10 bold-seeded kabuli types) were tested in several locations in the 2000–2002 seasons, under rainfed (dryland) conditions and with supplemental irrigation. The bold-seeded desi genotypes gave superior performance in the rainfed environment, while the bold-seeded kabuli genotypes outyielded the other cultivars under supplemental irrigation. From crosses between accessions from geographically diverse sources, crosses between lines carrying multiple disease resistances, and crosses between the cultivated chickpea and the wild species, C. reticulatum, 23 selections were tested for yield and resistance to multiple stresses at various locations in northern and central India. From the crosses between geographically diverse parents, six high-yielding kabuli genotypes with wide adaptation and drought tolerance were identified. Pyramiding genes for multiple resistances proved useful in identifying eight lines possessing multiple disease resistance. Introgressing wild genes generated nine genotypes with high yield potential, resistance to soil-borne diseases and adaptation to water-limited environments. We conclude that high productivity, multiple resistance and wide adaptability can be achieved simultaneously by using potentially complementary approaches.
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