| Improved grain mutant in the wheat, variety Arjun (HD
2009) R.N. SAWHNEY, V.L. CHOPRA, H.R. MOHINDRO and Rajender KUMAR Division of Genetics Indian Agricultural Research Institute New Delhi-110012, India Experimental evidence has shown that induced mutagenesis technique is a very useful component of plant breeding methodology particularly when the objective of the exercise is limited and well defined and the character aimed to be improved or rectified is under simple genetic control. In this latter category are seed characteristics of cereals like grain colour, boldness and lusture. In this communication we report the development of a mutant line in the wheat variety, Arjun. Arjun is an improved, high yielding wheat variety officially released in 1973. The variety is characterized by a very high yield potential, wide adaptability and high degree of resistance to the fungal rust diseases. A short-coming in this variety is the tendency of its grain to mottle, some times heavily. This defect of grain mottling renders the grains of the variety to pricing disadvantage in the market. With the objective of removing the defect of grain mottling, we mutagenized seeds of Arjun with 0.02% Nitrosomethyl urea. In a population of about 30,000 plants in M2, vigorous selection was exercised for non-mottled grains. The plants with non-mottled grains produce improved average kernal weight, compared to the parental variety, Arjun. Fig. 1 shows comparison of the grains of the mutant culture and Arjun. The progenies of three mutant plants isolated in M2 were observed to segregate for the grain mottling characteristic for a few generations. Selection for grain non-mottled was therefore exercised over successive generations till three lines viz., M 354, M 360, and M 361, each derived from different M2 plants, were found fixed for non-mottled and improved grain weight. Care was taken that the selected grain mutants were phenotypically not distinguishable from the parent variety and had maintained their rust resistance so as not to unfavourably influence the varietal acceptability. The mutants were tested extensively for their yielding ability in comparison with both the parental variety and subsequently released varieties bred specifically for yield through conventional recombination breeding during the crop years 1977-78 and 1978-79 on experimental plots and on farmer's fields. Tables 1, 2 and 3 summarize data from these trials. It is seen that the mutant (M 354) compares well not only with the parent. HD 2009 but also with the three best checks (Table 1) in trials on farmer's fields in four Delhi villages. Similarly, the mutant M 360 has given yield performance comparable to HD 2009 and the recommended local check HD 2122 at eight locations in two Delhi villages (Table 2). Table 3 compares the yield of mutant cultures M 360 and M 361 at the Indian Agricultural Research Institute, New Delhi and at the Agricultural University's farm at Pantnagar in the state of Uttar Pradesh. The yield tests over locations and over years have convinced us that the better grain mutant cultures have retained the yield adoptability and rust resistant characteristics of the parental variety. |
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