Abstract: Morphological differences among the Brassica lines for all the characters were statistically significant. Among the lines, AY produced maximum yield and was closely followed by WL and AAR with lower but statistically similar trend. As expected these lines were also statistically higher in number of pods per main stalk, pod size and thousand grain weight. Present efforts were quite successful in determining the genetic potential of different lines for yield and its components and are recommended for further testing and if proved stable could be released as an improved variety(s).
Introduction
Yield is the ultimate objective in almost all crop improvement programs and in Brassica significant success has been reported on obtaining high yields in recent literature (Rawat and Ramadass, 1991; Fiaz and Siraj, 1995, Iram and Swati, 1995). Rape and mustard are well adapted to local environment, the per hectare yield is very low and not comparable to agriculturally advanced countries. The worldwide expansion in the production of oil producing crops in the past 50 years has been remarkable. Over all, from 1935 to 1986 it grew about three fold. During the same period production of edible vegetable oil quintupled and that of oilcake or meal increased six fold. Pakistan on the other hand is chronically deficient in the production of edible oil and this deficit is being continuously enlarged. The local production of edible oil from all crops is only sufficient to meet about one third of the domestic consumption, remaining being met through heavy imports. These imports are continuously increasing with an alarming rate of 13 percent annually. In addition to improving agronomic practices, high yielding varieties are needed to meet the edible oil crisis in the country. In present study, material selected from F8 through F9 generation of inter and intra specific crosses of Brassica was evaluated to identify lines with high yielding potential.
Materials and Methods
Fifteen Brassica lines developed from inter and intra specific crosses involving five parents of Brassica napus, two of Brassica juncea and one of Brassica carinata were used in this investigation. Parents included Kivi Salem, Westar, Altex, Ganyou-5, Marnoo, P53-48-2, LL-84 and Yellow Raya. The inter and intra specific crosses along with their designation are shown in Table 1.
The crosses were placed in two groups according to parental species: Brassica napus×Brassica napus (Intra specific), Brassica napus×Brassica juncea and Brassica napus×Brassica carinata (Inter specific). Each cross was assigned alphabetical numbers to facilitate the discussion and are referred by number rather than pedigree (Table 1). Parents were crossed in all possible combinations including reciprocals. The F2 through F8 bulked populations for each cross was produced at Peshawar and Kaghan, with no selection. Selection of desired plants was carried out in F8 and then in F9 and samples of seed of each cross was taken and used as source material for this study.
Parents and F10 yield trial was planted at Peshawar in the last week of September 1992. The experimental design was randomized complete block design with four replications. The plot size was 7×5 m consisting of 5 rows with 5 m length and spaced at 30 cm apart. Basal doses of nitrogen and phosphorus fertilizers were applied at the sowing time. Irrigation and other cultural practices were performed as recommended. The insecticides Malathion (20 ml/15 L) and Repcard (75 ml/12 L) were sprayed for the control of hairy caterpillar and cabbage butterfly, respectively.
Yellow raya was not germinated although it was resown after soaking in water, the reason may be that the seed was old and may had lost variability, however, it was present as one of the parent in certain lines. Harvesting was done in March for early maturing and in April for late maturing varieties. The data were recorded on plant height, pod-pod distance, No. of pods/main stalk, No. of secondary branches, pod length, 1000 seed weight, No. of seed/pod, pod-stem angle and yield/plot.
After harvesting, sun drying and threshing the grain yield per plot was recorded with the help of spring balance and then converted to yield per hectare by the following formula:
Seed yield/ha = yield per plot (kg)×10,000/plot size (m2)
Results and Discussion
Plant height is considered important in breeding for increased yield (Singh and Chowdhury, 1983). It was found to be very variable character among the genotypes studied. Maximum plant height was recorded for Brassica juncea, while the minimum for Kivi Salem.
| Table 1: | Number, parents and designation of the 15 crosses |
The WY showed maximum height among the lines, however, one of its parent Wester was not among the tallest genotypes which shows that recombination of genes may have influenced the character (Table 2). The line WL was next to WY in tallness after WY and it might have acquired genes from its parent LL-84. The minimum plant height among the lines was recorded for MG. Both of its parent Marnoo and Ganyou-5 were medium in height and their combination was even shorter which may be the result of transgressive segregation. Wide range of variation in plant height has also been reported by Villarreal-D et al. (1983) and Fiaz and Siraj (1995).
Number of pods/main stalk is another character contributing to yield. Similar to finding of Kumar and Yadav (1985), maximum No. of pods/main stalk among the parents were recorded by Westar followed by fairly good display by other parents of Brassica napes while marked decrease was observed for plants belonging to Brassica juncea. Wide variation among the parents of different species for this character could be attributed to their genetic potential. Among the lines, AS was on the top and even exceeded both of its parents in No. of pods (Table 2) which may be due to combination and expression of favorable genes. The lines WL, AP, LS and LW showed good No. of pods despite the fact that all of them had either LL-84 or P53-4L-2 in their pedigree which are known to be low pod bearing but in this case their effect may had been masked by the other parents. Variable trend among the genotypes for number of pods have also been reported by Ali (1985) and Iram and Swati (1995).
| Table 2: | Average data on plant height, number of pods/main stalk and number of branches of fifteen Brassica lines and their seven parents |
| Figures followed by different letters shows significant differences at 5 percent level of probability | |
| Table 3: | Average data on pod size, pod-pod distance and pod stem angle of 15 Brassica lines and their 7 parents |
| Figures followed by different letters shows significant differences at 5 percent level of probability | |
| Table 4: | Average data on number of seeds/pod, 1000 seed weight and yield of 15 Brassica lines and their seven parents |
| Figures followed by different letters shows significant differences at 5 percent level of probability | |
The number of secondary branches is a character of importance for its positive relationship with yield. The parents belonging to Brassica napus had generally more branches than Brassica juncea and maximum number were recorded for Ganoyu-5 and minimum for P53-48-2 whereas LL-84 was next to lowest (Table 2). The line AS exhibited highest number of branches among the lines which may be due to combination of favorable genes and expression of transgressive segregation and the same can be concluded for the line MS. Opposite results were obtained for LW which had LL-84 as its parent along with Westar. The size of pod is also considered an important contributing factor to yield. Among the parents, Kivi Salem had longest while Marnoo had shortest pods. Comparatively poor performing parents Wester and LL-84 when combined produced transgressive segregates with pods of maximum length (Table 3). Line GA, which was next to WL may have acquired this character from Ganyou-5 which had pod length similar to GA. The lowest pod length was recorded for AP, which showed faithful transmission of the character from parents to offspring as parents were also low in pod size. Variation for pod length in Brassica juncea which to some extent are in agreement with present findings. Whereas Fiaz and Siraj (1995) and Iram and Swati (1995) while working with selected Brassica lines found statistically similar sized pods. Among the parents, Kivi Salem showed maximum while P53-48-2 and LL-84 minimum pod-pod distance. The GS was on the top among lines as both of its parents had distant pods and the genes for this character seems to have fully expressed in GS. The line derived from a cross between LL-84 and Ganyou-5 exhibited shortest pod to pod distance which is possibly inherited by LL-84. The parent Ganyou-5 exhibited wider pod-stem angle while P53-48-2 and LL-84 were on the other extreme (Table 3). Among lines, AY had greater pod stem angle which may have contributed by Altex. Same can be concluded for WY, where Westar was placed among significantly upper edged parents. The minimum pod-stem angle was found in the line AAR, which may be due to the contribution made by the parent other than Altex.
The number of grain/pod is considered to be an important yield component (Singh and Chowdhury, 1983). Generally parents belonging to Brassica napus were high and Brassica juncea were low in number of seeds per pod. Among the lines, WS had maximum number grain/pod and exceeded both of its parents Wester and Kivi Salem (Table 4) suggesting that positive genes for the character may have been accumulated in the line. Similar results were recorded for AP, which could have been the result of influence made by P53-48-2. These conclusion are quite in agreement with Kumar and Yadav (1985) who reported that the least number of seeds/pod were possessed by Brassica juncea varieties and in disagreement with the finding of Iram and Swati (1995) who found some of the B. napus varieties as poor performer in seed/pod. 1000 seed weight is another important yield component. Among the parents, Westar had maximum 1000 seed weight followed by Altex, while the minimum value was recorded for P53-48-2. Among the lines, maximum value was recorded for GA, as both of its parents Ganyou-5 and Altex had highest values and may have inherited this potential to the line. The other significant lines were AAR, WL, AP, AY, GA and MS (Table 4). It is obvious from the results that Altex remained successful contributor whenever involved as one of the parent. The minimum value among the lines was recorded for WY although one of its parents westar had maximum 1000 grain weight but its expression may had been masked by Yellow Raya. However in AY the situation was reversed where Altex is seemed to have masked the effect of yellow Raya. Bhardwaj and Singh (1969) recorded range of variability in Brassica campestris. Yield is the ultimate objective of all breeding programs. The maximum yield among the parents was recorded for Ganyou-5 followed by Altex while P53-48-2 fell on the other extreme. Surprisingly mediocre parents Altex and Westar when involved in cross combination with yellow Raya and LL-84, respectively, produced highest yielding lines (Table 4) which could be the result of favorable gene combination. The lowest yield among the lines was recorded for GA selected from a cross between both parents high yielding. Findings of Villarreal-D et al. (1983) and Iram and Swati (1995) are in close agreement with the present result.