Division of Genetics, Indian Agricultural Research Institute, Delhi-12
*Present Address: Vegetable Research Station, Kalpa, Dist. Kinnuar, H. P.
1Part of the thesis submitted by P. P. Sharma in partial fulfilment of the requirements of the Master's degree in Agricultural Botany of the Indian Agricultural Researeh Institute, New Delhi, 1963.
Six parental inbred lines of maize and all possible single Crosses (excluding reciprocals) between them were grown in a randomized replicated trial. The characters studied were, tassel condensation index, number of secondary tassel branches, kernel row number, ear length and grain yield per plant. The objectives of the experiment were to work out correlations between the characters with a view to establishing selection indices for the isolation of superior inbred lines.
The ten possible paired correlations between the five characters mentioned earlier were calculated within inbred lines and within single cross progenies; moreover, characters of the inbred lines were correlated to the yield of the single cross progenies. The r values within the inbred lines indicated that in general, the phenotypic and genotypic correlations were positive and greater in magnitude than the values at the error level. It is interesting to note that the characters of the tassel and of the ear showed high and positive correlations to yield, those for ear length being of the highest magnitude being followed by tassel condensation index, number of secondary tassel branches and kernel row number. The correlation values within hybrids were, in general, low and positive at the phenotypic, genotypic and environmental levels except the values for kernel row number and car length to grain yield.
In the parent-single cross correlations the r values at the phenotypic and genotypic levels were negative and of high magnitude for the number of secondary tassel branches. When partial correlations were worked out between tassel condensation index, kernel row number, ear length and grain yield of the inbreds and the grain yield of single cross progenies, keeping number of secondary tassel branches constant, the values became positive and high for kernel row number and tassel condensation index.
