| Heterosis for important characters in hexaploid triticale
R.K. BEHL Department of Plant Breeding, Haryana Agricultural University, Hisar-125 004 (India) With recent realization of the possibility of producing F1 hybrid seed on a large scale, considerable emphasis has been given to exploitation of heterosis in self pollinated crops. Heterosis, the increased vigour of F1 hybrid over mid and better parent performance is the result of allelic or non-allelic interaction of genes under the influence of a given environment (MACKEY 1976). Directed heterosis and its fixation, therefore, appears to be a distinct possibility. In that context, ample evidence of significant heterotic effects and availability of some economic means of producing hybrid seed are two basic considerations. Such information in triticale is scanty. Present study deals with hetetosis in triticale cross combinations involving parental genotypes selected on the basis of genetic divergence. Materials and Methods Based on genetic divergence, 22 hexaploid triticale genotypes were selected from germplasm collection. Each of the 18 lines namely, 1. T24., 2. T103., 3. T125., 4. T130., 5. T134., 6. Tc13., 7. T137., 8. T139., 9. T146., 10. T145., 11. UPT74364., 12. UPT74418., 13. UPT74460., 14. UPT74536., 15. Arm147., 16. Armadillo., 17. Koala., 18. Cinnamon were crossed to each of four testers viz., 1. St69-1., 2. 6TA204., 3. T122., 4. UPT74535 to yield 72 F1 hybrids. Parents and hybrids were sown in randomized block design with three replications. Each genotype was accommodated in two rows, 3 meter long spaced 30 cm apart with intra-row distance among plants being 15 cm. Observations on randomly selected 5 plants were recorded for attributes related to plant morphology, grain yield and its components and physico-chemical qualities of grain. Percent heterosis measured as deviation of F1 hybrid performance from the mid, better and best wheat check performance, designated as relative heterosis, heterobelteosis and standard heterosis, respectively. Results and Discussion Analysis of variance revealed significant differences among parents and hybrids for all the characters. Significant parents vs hybrid component indicated the presence of over all dominance and heterosis for most of the traits except days to spike emergence, number of tillers per plant, grain density and grain protein content. Magnitude of heterosis varied from cross to cross and character to character (Table 1). Highest magnitude of relative heterosis and heterobelteosis was recorded for tillers per plant (80.5 & 72.3%) and grain crushing hardness (80.6 & 60.5%) followed by grain yield per plant (70.1 & 57.4%), 1000 grain weight (44.7 & 39.8%) and biological yield per plant (46.9 & 37.9%) etc. Heterosis as a phenomenon was relatively more frequent for characters like 1000 grain weight, harvest index and biological as well as grain yield per plant. No cross revealed appreciable heterosis for floret fertility and invariably negative heterosis for this trait was evident which might be attributed to meiotic disturbances in inter varietal F1 hybrids (GUPTA & PRIYDARSHAN 1982). No F1 should, therefore, be rejected unless floret fertility is very low as continued selection for this character has been found to be effective. Only one cross, UPT74364 x 6TA204 manifested desirable and significant negative heterosis (-15.14) for plant height. |
| --> Next |