Brassica oilseeds are the second most important source of vegetable oil in Pakistan. Due to the low priority attached to these crops in the past, no systematic breeding work was undertaken to develop improved varieties of rapeseed/mustard, resulting in a narrow genetic base of these crops. At the Nuclear Institute for Food and Agriculture (NIFA), gamma radiation was used to induce genetic variability in traits of economic importance thus diversifying the genetic base of indigenous/exotic cultivars of Brassica oilseeds. About 10,00015,000 dry seeds of oilseed rape (Brassica napus L.) cultivar Tower', having about 10% moisture, were irradiated at 1.0, 1.2 and 1.4 kGy gamma rays (60Co) in 1988. The treated seeds were planted directly in the field in isolation as Mi generation. Selection for desirable mutants was carried out in M2/M3 generations and a useful mutant, RM-152-2, was selected in M3. To speed up the breeding process two generations a year were raised, one at NIFA in winter and the other in summer at Hill Agricultural Research Station, Kaghan,. This shuttle breeding programme resulted in significant achievements in a short time span. The M5 mutants were tested in preliminary yield trials during 1990-91, at NIFA and mutant RM-152-2 significantly outyielded the parent variety and a commercial cultivar PR-7', by producing 2 t/ha grain yield, against 1.4 t/ha of control. This mutant was tested in advanced yield trials under irrigated as well as rainfed conditions during 1991-92. RM-152-2 again significantly outyielded the control cultivars under both environments and produced 1.8 and 1.67 t/ha yield of the control. Based on its excellent performance in these trials, RM-152-2 was assessed simultaneously in a multilocation yield trial in North West Frontier Province (NWFP), and in a 30-entry National Uniform Rapeseed Yield Trial (NURYT) for two consecutive years i.e. 1992-93 and 1993-94. In the multilocation trial in NWFP, RM-152-2 significantly outyielded the control cultivar at all locations in both years, producing 1.8 t/ha grain yield (Table 1). It is very clear that RM-152-2 significantly outyielded the control cultivars under both irrigated and rainfed conditions in both years. The mutant line produced 3rd highest yield of 1.62 t/ha (average of two years) amongst 30 entries (candidate varieties) consecutively for two years in the National trials. These results clearly indicated genetic stability of RM-152-2 over years and locations. RM-152-2 outclassed all the commercially grown cultivars by wide margins i.e. Pak chen'by 13.3% and DGL'by 5.2% (two non canola cultivars), and Shiralee'and Westar'(both canola type) by 10.2% and 18.4% respectively.
Brassica oilseeds are the second most important source of vegetable oil in Pakistan. Due to the low priority attached to these crops in the past, no systematic breeding work was undertaken to develop improved varieties of rapeseed/mustard, resulting in a narrow genetic base of these crops. At the Nuclear Institute for Food and Agriculture (NIFA), gamma radiation was used to induce genetic variability in traits of economic importance thus diversifying the genetic base of indigenous/exotic cultivars of Brassica oilseeds. About 10,00015,000 dry seeds of oilseed rape (Brassica napus L.) cultivar Tower', having about 10% moisture, were irradiated at 1.0, 1.2 and 1.4 kGy gamma rays (60Co) in 1988. The treated seeds were planted directly in the field in isolation as Mi generation. Selection for desirable mutants was carried out in M2/M3 generations and a useful mutant, RM-152-2, was selected in M3. To speed up the breeding process two generations a year were raised, one at NIFA in winter and the other in summer at Hill Agricultural Research Station, Kaghan,. This shuttle breeding programme resulted in significant achievements in a short time span. The M5 mutants were tested in preliminary yield trials during 1990-91, at NIFA and mutant RM-152-2 significantly outyielded the parent variety and a commercial cultivar PR-7', by producing 2 t/ha grain yield, against 1.4 t/ha of control. This mutant was tested in advanced yield trials under irrigated as well as rainfed conditions during 1991-92. RM-152-2 again significantly outyielded the control cultivars under both environments and produced 1.8 and 1.67 t/ha yield of the control. Based on its excellent performance in these trials, RM-152-2 was assessed simultaneously in a multilocation yield trial in North West Frontier Province (NWFP), and in a 30-entry National Uniform Rapeseed Yield Trial (NURYT) for two consecutive years i.e. 1992-93 and 1993-94. In the multilocation trial in NWFP, RM-152-2 significantly outyielded the control cultivar at all locations in both years, producing 1.8 t/ha grain yield (Table 1). It is very clear that RM-152-2 significantly outyielded the control cultivars under both irrigated and rainfed conditions in both years. The mutant line produced 3rd highest yield of 1.62 t/ha (average of two years) amongst 30 entries (candidate varieties) consecutively for two years in the National trials. These results clearly indicated genetic stability of RM-152-2 over years and locations. RM-152-2 outclassed all the commercially grown cultivars by wide margins i.e. Pak chen'by 13.3% and DGL'by 5.2% (two non canola cultivars), and Shiralee'and Westar'(both canola type) by 10.2% and 18.4% respectively.
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