| In timely sowing, tillers/plant, grains/spike, 1000 grain weight, grain
weight/spike and days to maturity had directly contributed to increased
yield. Of these tillers/plant and grains/spike had higher values. However,
the indirect effect of grains/spike, grain weight/spike and harvest index
through tillers/plant was negative. Grains/spike, 1000 grain weight and
grain weight/spike contributed positively through each other except grains/spike
via 1000 grain weight. Days to flowering had negative direct effect. The partitioning of direct and indirect effects in late sown conditions evinced that harvest index, grains/spike and tillers/plant had high positive direct effect. The indirect effect of tillers/ plant was of low magnitude. However, grains/spike, harvest index, grain weight/spike and 1000 grain weight contributed positively towards yield through each other. Days to flowering and days to maturity had significant negative correlation with grain yield but their direct effect of low magnitude was positive. The present study thus revealed that tillers/plant and grain weight/spike were the most important yield contributing characters under the three dates of sowing. These results are in agreement with those of obtained by Paroda & Joshi (1970), Das (1976), Sharm & Ahmed (1978), Shrivastave et al. (1980). Paroda & Joshi (1970) reported that high positive correlation of 1000 grain weight and grains/spike with grain yield/plant was the result of high positive indirect effect of grain weight/spike. Grains/spike and 1000 grain weight in timely and late sowing and plant height in early sowing also showed high positive direct effect on grain yield in the present study. The indirect effect of tillers/plant in early sowing was of positive high magnitude whereas in late sowing it was of very low magnitude. Upadhyaya et al. (1979) while screening the varieties for thermoinsensitivity found that those varieties which did not flower quickly under the temperature influence but continue to tiller and take long time to flower give better yield under early sown conditions. The positive association between days to flowering and grain yield in early sowing and negative association in late sowing indicated that it could be possible to breed late flowering high yielding varieties for early sowing and vice verse for late sowing. Acknowledgement Authors are thankful to Director of Research, Gujarat Agricultural University for facilities. References DAS, P. K. 1976. Association of plant characters with grain yield in wheat as influenced by two sowing dates and its implications in selection. J. of the Society of experimental agriculturists 1(1): 11-16. DEWEY, D. R. and LU, K. H. 1959. A correlation and path coefficient analysis of components of crested wheat grass seed production. Agron. J. 51: 575-78. MILLER, P. A. WILLIAMS, J. C. and ROBINSON, H. F. 1958. Estimates of genotypic and environmental variances and covariances in upland cotton and their implication in selection. Agron. J. 50: 126-131. PARODA, R. S. and JOSHI, A. B. 1970. Correlation, path coefficient and their implication in discriminant function for selection in wheat (Triticum aestivum L.). Heredity 25: 383-392. SHARMA, J. C. and AHMED, ZIAUDDIN 1978. Indirect selection response in spring wheat. Indian J. Genet 28(3): 292-298. SHRIVASTAVA, S. N., SARKAR, D. K. and MALLICK, M. H. 1980. Association analysis in rainfed wheat. Indian J. Genet 40(3): 512-515. UPADHYAYA, Y. M., RUWALI, K. N. and MURTY, K. S. 1979. Evaluation of wheat germplasm for thermoinsensitivity Paper presented in the 18th All India wheat Research worker's Workshop held at B.A.U. Ranchi. |
| <-- Back |