Indian Agricultural Research Institute, Delhi-12
*Present address: Department of Plant Breeding, Punjab Agricultural University, Ludhiana.
1 A part of the thesis submitted by J. P. Tandon in partial fulfilment of the requirements for the of Doctor of Philosophy of the Indian Agricultural Research Institute.
The genetic basis of the association between yield per plant, number of tillers per plant, number of grains per ear and 100-grain weight were studied in a cross of barley varieties, G. 138-2 (6-rowed) × E.B. 4–10 (2-rowed) using the technique suggested by Nei and Syakudo (1956). Parental (P1, P2) F1, F2, 1st backcross (B1 and B2) and 2nd backcross (B11, B12 and B21) generations were used in the study. Most of the associations were found to be due to linkage. Pleiotropy was established only in the case of the association between grains per ear × 100-grain weight. The non-fixable component of genetic association was found to be of considerable importance and could be a major cause for the failure of prediction equations when selection is being conducted in heterozygous populations for more than one character simultaneously. Environmental component of association was also found to be of considerable importance in several of the cases. The results are discussed in relation to practical plant breeding problems in barley and general utility of the approach in plant breeding programmes is discussed.
