| It will be of considerable interest to know the causes of heterosis in
grain yield. There can not be any gene system for yield per se and
the yield is an end product of the multiplicative interaction between the
yield components (WHITEHOUSE et al. 1958; GRAFIUS 1959). Hence it
would indicate that the heterosis for yield should be through heterosis
for yield components (SINGH & KANDOLA 1969). Accordingly, a clear picture
has emerged from this study that heterosis is present in all the four/three
components viz., grains/ear, ear weight, 1000-grain weight and flag leaf
area. Thus, it is obvious that increase in grain yield in three-way crosses
(as indicated earlier) are the result of increase in yield components. Thus, use of JNK-4w-184 with number of single crosses involving unadapted species and adapted durum cultivars appeared to have increased the potentiality of expression of some of the important yield components and ultimately the yield. Such a three-way combination of genotypes followed by judicious selection would help in introgressing the useful and diverse sources along with the proper agronomic base. Literature cited GRAFIUS, J.E. 1959. Agron. J., 51: 551-554. HAWKES, J.G. 1977. Euphytica. 26: 615-621. MOLL, R.H., W.S. SATHUANA and H.F. ROBINSON. 1962. Crop Sci., 2: 197-209. SINGH, K.B. and H.S. KANDOLA. 1969. Indian J. Genet., 29: 53-61. SINGH, K.B, and J.K. SINGH. 1971. Euphytica. 20: 586-590. WALSH, E.J. and R.E. ATKINS. 1973. Crop Sci., 13: 267-271. WHITEHOUSE, R.N.H., J.B. THOMPSON and D.V. RIBERIO. 1958. Euphytica. 7: 147-169. WILLIAMS, W. 1959. Nature. 184: 527-530. WILLIAMS, W. 1960. Heredity. 15: 327-328. |
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