| Relative importance of grain yield components in bread
wheat (T.aestivum L.) D. S. VIRK and M. M. VERMA1) Department of Plant Breeding, Punjab Agricultural University, Ludhiana, India Introduction Grain yield is a complex character and is greatly influenced by environmental factors. The plant breeders while formulating selection procedures do not rely directly on it especially in early generations but take into consideration the relative weight age of the ancillary traits such as grain number, spike number etc. One of the earliest method to identify the grain yield components has been the study of correlation coefficients (SIKKA and JAIN 1958, GANDHI et al. 1964, VIRK and ANAND 1970) but the technique of path coefficient analysis developed by WRIGHT (1921) and probably used for the first time in plants by DEWERY and LU (1959) has been found more useful as it differentiates specific forces acting directly and indirectly to produce a particular association. This way the relative contributions of component characters (causal factors) are unfolded and can be successfully employed in formulating efficient selection programmes. Material and methods The material consisted of 20 populations comprising 11 widely divergent wheat strains, viz., NP 825 and NP 847 from Delhi; C 273, C 303 and C 306 from Punjab; and S 210, S 227, S 354, S 355, S 409 and Mayo-64 from Mexico; and nine F2, hybrid populations between C 273 x S 354, C 273 x S 355, C 303 x S 409, C 303 x S 210, C 303 x S 227, C 303 x Mayo-64, C 306 x S 409, NP 825 x C 306 and NP 847 x C 303. These twenty populations were grown in a randomized block design with six replications at the Punjab Agricultural University, Ludhiana. Each population was provided a two row 3.5 meters long plot. The row to row and plant to plant spacings were 22.5 and 15.0 cm respectively. The data were collected on ten randomly selected plants from parents and 20 plants of each F2, population in each replication. The progeny means were used for calculating phenotypic correlations which were partitioned into path coefficients using the technique of DEWERY and LU (1959). Results and discussion The spike bearing tillers and 100-grain weight showed a high and positive correlation with each other and also with grain yield (Table 1) while the grain number exhibited a negative but non-significant association with grain yield. The correlations reported by SIKKA and JAIN (1958), GANDHI et al. (1964), VIRK and ANAND (1970), and VIRK and SINGH (1972) also revealed similar associations. Grain number was negatively associated with other component characters. The correlations thus revealed that selections based on spike number and 100-grain weight could be more rewarding than those on the basis of grain number. |
| 1) Assistant Professor and Associate Professor, respectively. |
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