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YIELD AND GROWTH RESPONSE OF RAPESEED (BRASSICA NAPUS L.) MUTANTS TO DIFFERENT SEEDING RATES AND Sowing dates

Syed Anwar Shah^1* and K. Rahman²

Abstract: The effect of various seeding rates and seeding dates on the agronomic performance of four rapeseed genotypes (three advanced mutants and one commercial variety) was studied for two consecutive years. The results showed that seeding rates did not affect plant height but influenced maturity significantly and plots seeded with 4 kg ha^-1 matured earlier than rest of the plots. Significant differences in mean values of rapeseed genotypes with respect to physiological maturity were also observed and RM-152-2 matured significantly earlier than rest of the entries. The yield data showed that only RM-182 significantly out yielded the check (Pak Cheen) at different seed rates. Also the yield tended to increase with an increase in seed rate up to 10 kg ha^-1, above which a slight decrease was noted. The lowest yields were obtained at the lowest seed rate. The interaction between the seed rates and genotypes was significant at P<0.05. The results of seeding date experiment revealed that plant height was reduced as sowing was delayed (except 15 October). The genotypes, however, did not differ significantly in plant height when averaged over sowing dates. They also did not differ significantly in days taken to maturity, nevertheless, plots sown early (on 15 September) matured earlier than other plots. It was also observed that delayed sowing beyond 25 October resulted in forced maturity, which adversely affected yield. The interaction of seeding dates and genotypes was significant at P<0.05. The yield results revealed that the highest yields were obtained in plots sown on 25 September and 5 October beyond that gradual reduction in yield was noted. The lowest yields were obtained from plots sown on 14 November, the last sowing date. All the mutants produced significantly higher yield than the check. Based on the results of these experiments over two years, it is concluded that seed rates and time of sowing had significant influence on yield and growth of rapeseed. A seed rate of 8 kg ha^-1 and sowing between 25 September and 15 October is, therefore, recommended for obtaining higher yields of rapeseed genotypes.

^1*Nuclear Institute for Agriculture and Biology (NIAB), P.O. Box 128, Jhang Road, Faisalabad, Pakistan

²Nuclear Institute for Food and Agriculture (NIFA), P.O. Box 446, Peshawar, Pakistan