| Heterosis in wheat (Triticum aestivum L.)
A.J. MALIK, S.M. SHEEDI and M.M. RAJPUR Department of Plant Breeding and Genetics Sind Agriculture University, Tandojam, Pakistan. Hetorosis, the increased vigor of F1 over the mid and better parents is the result of allelic or non-allelic interaction of genes under the influence of a particular environment. One of the most important developments in plant breeding of recent times has been the extension of the use of heterosis to many crop plants including wheat for increased yield. Continued attention has been given for the possible use of heterosis from intervarietal hybrids of wheat to advantages in yield and stability of performance for genetically diverse population. Recently, however, numerous investigators have engaged themsevles with new enthusiasm to determine heterosis in wheat. Many sicentists have established the fact that heterosis does occur with proper combination of parents. TSUNEWAKI (1970) reported heterosis for plant height in geographically & distantly related varieties, whereas, significant heterosis was reported by SINGH (1978) for plant height character. CHOWDHRY et al. (1972) reported significant heterosis for number of tillers per plant. Strongest heterosis for number of tillers per plant was reported by POPOVIC (1976). HRASKA (1975) reported heterosis for spike length, kernels per spike, and plant height exceeding 10 percent over the mid parental value and SINGH (1978) reported significant heterosis to mid and better parental value for this character. BITZER & FU (1972) reported heterosis for number of kernels per sike exceeding 5 percent over the better parent, whereas, positive and significant heterosis for this character was also reported by SINGH (1978). GRANT (1970) reported 25-36 percent increase in grain yield, whereas, SHABESKI (1970) reported heterosis exceeding 30-50 percent over the better parent in grain yield. HASSANAIEN et al. (1974) observed heterosis increasing 8-94 percent and 2-62 percent over the mid and better parental value respectively. CREGAN & BUSH (1978) reported 5 to 58 percent increase in grain yield over the mid parental value. Materials and Methods The experimental material used for the study comprised of ten wheat varieties viz: Pak 70, Chenab 70, C 591, C 273, H 23-42, LU 75, Mexi-pak 65, Cajemo, Tobari and Torum and ten crosses viz. (i) Pak 70 x Torim, (ii) Cajemo x Pak 70, (iii) Torim x C 591, (iv) H 23-42 x Tobari, (v) LU 75 x Chenab 70, (vi) LU 75 x Mexipak 65, (vii) LU 75 x C 293, (viii) Mexipak 65 x Chenab 70, (ix) Mexipak 65 x C 273 and (x) C 273 x Chenab 70. Hand crossing were made in 1977 and the F1 seed thus obtained was sown in the field alongwith their respective parents in the following year in randomized complete block design, one row for each line with three replications. The seeds were dibbled in rows three meters long and 30 centimeters apart. The distance between the two plants was kept at 20 centimeters. All cultural treatments were provided. Non-experimental border rows were also grown. A total of 10 plants from each cross and from each parental variety was taken for observation from each replication. The data on different plant characteristics was recorded in the following manner. |
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