| Path coefficient analysis : Direct and indirect effects of yield componets based on genotypic and Phenotypic correlations revealed almost similar results (SAHU & PATNAIK 1979). Hence, results based on genotypic correlations are only presented (Table 4). Grain weight per ear had the largest direct effect (1.264) on plant yield followed by number of effective tillers per plant ( .638). Direct effect of number of spikelets per spike was trivial ( .077). Ear length and plant height had negatdve direct effect (-0.468 and -0.014 respectively), though they have shown positive correlation with effects yield (Table 3) which were mainly due to their positive indirect via gain weight per ear (Table 4). This suggests that selection merely on the basis of simple correlation will be misleading (V. SINGH 1972). The high positive correlation of grain weight per ear was due to its direct and indirect effects via each other. The direct contribution of grain weight per ear and its indirect importance from plant height and ear length distinctly emphasized the value of this character for selection of genotypes for breeding wheat under high temperature and moisture stress conditions. PATHAK & NEMA (1983) also reported direct bearing of this thait on plant yield under such conditions. Acknowledgement Authors are gmateful to the J.N. KURISHI Vishwa Vidyalaya, Jabalpur for providing physical facilities and to Dr. S.N. DUBEY, Director, Research Services for his interest and encouragement during the course of this study. References ASANA, R.D. 1974. Physiological responses of wheat to early sowing under non-irrigated cultivation and to late sowing under irrigation. Indian J. Genet. 34 : 190-95. ASANA, R.D. 1976. Physiological Appoaches to Breeding of Drought Resistant crops. I.C.A.R. Technical Bulletin (Agric) No. 52. DEWEY, D.R. & LU, K.H. 1959. A correlation and Path coefficient analysis of components of crested wheat grass seed productior. Agron. J. 51 : 515-8. FRIEND, D.J.C., HELSON, V.A. & FISHER, J.E. 1965. Changes in the leaf area ratio during growth of Marquis wheat, as affected by temperature and light intensity. Canad. J. Bot. 43 : 15-28. FRIEND, F.D.C. 1966. The effect of light and temperature on the growth of cereals pp. 181-99. The Growth of cereals and Grasses, Ed. by F.L. Milthorpe and J.D. Ivins, Butter worths London. HOWARD, A. 1924. Crop production in India. Oxp. Univ. Press, Bombay 100. MILLER, P.A, WILLIAMS, J.C., ROBINSON, H.F. & COMSTOCK, R.E. 1958. Estimate of genotypic and environmental variances and covariances in upland cotton and their implication in selection. Agron. J. 50 : 126-31. PATHAK, N.N. & NEMA, D.P. 1983. Gene action and heterosis in a spring wheat cross under high temperature and moisture stress conditions. Paper presented at the 6th International wheat Genetics symposium, Nov. 28-Dec. 3rd Kyoto, Japan. ROBINSON, H.F., COMSTOCK, R.E. & HARVEY, P.M. 1951 Genotypic and Pheotypic correlation in corn and their implication in selection. Agron. J. 43 : 283-7. SIKKA, S.M. & MAINI, N.S. 1962. Corrleation studies in some Punjab wheats Indian. J. Grent. Pl. Breed. 22(3) : 181-86. STIVASTAVA, S.N., SARKAR, D.K. & MALLICK, M.H. 1980. Association analysis in rainfed wheat Indian. J. Genet. Pl. Breed 40(3) : 512-14. SAHU, D.P. & PATNAIK, M.C. 1981. Variability correlation and path coefficient analysis in niger. Indian J. Agric. Sci 51(5) : 287-91. SISODIA, N.S. 1977. Photo-insensitivity in wheat breeding. Paper presented at the National seminar on Genetics and Wheat Improvement. Feb. 22-23, PAU Ludhiana. SISODIA, N.S., SINGH, K.P. & SHEOPURIA, R.R. 1978. Variability for high temperature tolerance in wheat. Proc. 5th Int. Wheat Genetics symposium New Delhi 217-24. VIRK, D.S. and S.S. BAHADUR. 1972. Path coefficient analysis of grain yield in wheat. (T. aestivum L.). Wheat Inf. Serv. 33 : 6-8. |
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