| Production of male sterility and fertility restorer
analogues of Indian wheat varieties involving Triticum
timopheevi, Aegilops ovata
and Ae. caudata cytoplasms J. S. SINDHU and R. B. SINGH Dept. of Genetics and Plant Breeding, Faculty of Agriculture, B.H.U., Varanasi, India Earlier wheat could not be thought to be exploited for heterosis breeding because of an obvious barrier of its floral morphological framework which checks cross pollination. But, KIHARA'S discovery of cytoplasmic male sterility in 1951 suggested a mechanism by which cross pollination could be forced in this crop as well. This classical discovery gave an insight to wheat breeders all over the world. Later FUKASAWA'S (1959) discovery of male fertility restoration lead to researches on hybrid wheat in many countries. Extensive programmes are in progress to produce male sterile and fertility restorer lines of commercial cultivars. Success of hybrid wheat will depend upon (i) degree of heterosis (ii) stability of male sterile and fertility restorer lines and (iii) the cost of hybrid seed. Several studies have suggested considerable heterosis in wheat. Success of the male sterile and restorer lines will depend upon their stability and adaptability. Most of such of exotic lines are not quite suited to our conditions. Thus in order to be able to undertake any work on heterosis breeding in wheat we have to develop male sterile and fertility restorer lines in the existing distinct and diverse desirable indigenous wheat strains. With these considerations, in India the work of nucleus substitution to produce male sterile and fertility restorer analogues of local wheat varieties was started by us in October, 1970. Ten promising India wheat cultivars of diverse genetic origin viz. C. 306, K. 68, C. 591, N.P. 809. Lerma Rojo, Sonalika, Norteno, Sharbati Sonora, Kalyan Sona and Hira, were selected for the purpose. Production of male sterile analogues: Male sterile cytoplasm was transferred into the above mentioned ten wheat varieties from three different sources viz. Triticum timopheevi, Aegilops ovata and Ae. caudata. Table 1 shows the sources of male sterile cytoplasm and the Indian wheat cultivars with their important morphological characteristics, in which the male sterile analogues have been produced. The recipient varieties were used as pollinators to the above mentioned established male sterile lines. The F1s tested for pollen fertility and selfed seed set showed almost cent percent pollen sterility and no seed set in selfed heads. Subsequent backcrosses were made with the respective recipient varieties and in all the backcross generations data on pollen fertility and selfed seeds set were recorded. Only those plants which showed complete male sterility were used in backcrossing programme. To accelerate the pace of work, two crops were grown every year i.e., one in the normal season and the other as an offseason crop at hills. |
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