| Multiple correlation has been worked out between five yield components
and grain yield per plant. Multiple correlation (Table
2) was found to be 0.6392251 which indicated that about 71 percent of
total variability in grain yield was due to the variation in the four independent
variables. Highly significant multiple correlation coefficient was observed
from the mean squares. The pathways through which the four yield components operate to produce their phenotypic association with grain yield reveal direct and indirect contributions (Table 3) and are demonstrated diagrammatically in Fig. 1. The path coefficient analysis showed that the direct effect of spike length on grain yield was low and negative. The indirect effect via spikelets and spike yield was positive but very low in magnitude. Total correlation coefficient (0.4778) between spike length and grain yield was mainly due to its effect through seeds per spike (0.361158), which was high and positive and formed 75.59% of phenotypic correlation. This showed that selection for the character spike length would not be realized in increased grain yield (LARIK 1979) The direct effect of spikelets on grain yield was positive but not so pronounced. The indirect effect through spike length was low, whereas through seeds per spike was (0.4543601), which was highly positive and formed 66.82 percent of the total correlation coefficient and via spike yield (0.121235) was negligible. The total effect of spikelets on grain yield was 0.680 which was mainly due to its indirect effect through seeds per spike. Hence the spikelets can not be regarded as a reliable source of getting high yields in wheat. The direct effect of yield per spike on grain yield per plant was positive but nonsignificant (0.175703). Total correlation coefficient, 0.650, between grain yield per plant and grain yield per spike was mainly due to its indirect effect through seeds per spike. Therefore selection for spike yield cannot guarantee for high yields in wheat. In contemporary model of yield (WORLEY et al. 1976) seed is recognised as the basic unit of yield The direct effect of seeds per spike on grain yield was very high and significant (0.58455) and formed about 74.94 percent of total phenotypic correlation. The indirect effect through spike length was very low and negative, through spikelets per spike and spike yield was positive but not so pronounced. Total correlation coefficient 0.780 between grain yield per plant and seeds per spike was mainly due to its own direct effect which supports the hypothesis of LARIK (1979). However, indirect effect via spike length (-0.0569674) have somewhat deluded the direct effect. A number of complex and interlocking systems (WALTEN 1969), contribute to the expression of a quantitative character like yield. The high residual effect observed in the present studies (Fig. 1) suggest that the path coefficient obtained within the constraint of the construct do not reflect the influences of the second order components. It is clearly understood from the present study that the character of most influence on grain yield per plant was seeds per spike. This is also confirmed by SIDWELL et al (1976). SMOCEK (1977) also gave same idea for the character seeds per spike as reliable criterion for getting high yields in wheat plants. Literature Cited BHATT, M.W. 1973. Euphytica 22: 238-343. DEWEY, D.R. & K.H. LU 1959. Agron. Jour 51: 515-518. LARIK, A.S. 1978. Genetica Agraria 31: 237-244. LARIK, A.S. 1979. Wheat Inform. Serv. No. 50: 36-40. LYRENE, P.M. & H.L. SHANDS 1975. Crop Sci. 15: 361-363. RANDEY, S. & E.T. GITTON 1975. Crop Sci. 15: 353-356. SIDWELL, R.J.: E.L. SMITH & R.W. MCNEW. 1976. Crop Sci. 16(4): 650-54. SMOCEK, J. 1977. Cereal Res. Comm. 5(4): 439-49. SNEDECOR, G.W. 1956. Statistical methods, Ed. S, Iowa State College Press, Ammes U. S. A. 160-169. STEEL, G.D. & H. TORRIE. 1960. Principles and procedures of statisties. Mc Graw H Book Company, Inc 311, 2. VIRK, D.S. & M.M. VERMA 1972. Wheat Inform. Serv. 35: 11-14. WALTON, P.V. 1969. Can J. Plant Sci. 49: 587-596. SMITH, W. Jr., H. HARMON, Jr. RAMEY, D.C. HARRELL & T.W. CULP 1976. Crop. Sci. 16: 30-34. |
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