Abstract:
Edible oil is chief import of Pakistan. To overcome this problem, improved
cultivars requirement can not be over-emphasized. To achieve this goal, estimation of
genetic diversity has great value for a crop breeder for improving the crop and
producing high yielding varieties. In present studies, 114 accessions of Brassica
campestris L. and 25 accessions of Brassica napus L. were evaluated for 15 agro-
morphological and 6 seed quality traits for two years 2004-05 and 2005-06. Seed
storage proteins profile of all the accessions was estimated using SDS-PAGE.
Accessions with desirable traits were identified for exploitation in breeding program.
A six parent diallel was carried out to study inheritance mechanism of 15 agro-
morphological and 6 seed quality traits in Brassica napus L.
Among the accessions of Brassica campestris L., high variance was observed
for number of siliqua per plant followed by seed yield per plant, plant height, days to
flower initiation, number of siliqua per main inflorescence and glucosinolates content.
Significant positive association of seed yield with number of siliqua per main
inflorescence and number of siliqua per plant suggested that these traits are yield
contributing traits and must be selected for yield improvement. Cluster analysis
distributed the accessions into six clusters during 2005 and into five clusters during
2006. It was found that 7 and 5 principal components (PCs) with eigen values > 1
contributed 74.09% and 66.08% of total variation during 2005 and 2006, respectively.
Similarly, among Brassica napus L. accessions, high variance was also shown
by number of siliqua per plant, plant height, seed yield per plant, glucosinolates,
number of siliqua per main inflorescence, length of main inflorescence and oleic acid
content. Significant positive association of seed yield with number of siliqua per main
inflorescence and siliqua per plant revealed that these traits are really yield
contributing traits and must be selected in an effective breeding program for yield
improvement. Accessions were distributed into five clusters by cluster analysis during
2005 and into four clusters during 2006. Genetic variability was also studied using
principal component analysis and variables were considered simultaneously. It was
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found that 7 and 5 of 21 principal components with an eigen value higher than 1.0
exhibited 84.75% and 80.16% of the total variation during 2005 and 2006,
respectively.
All the 114 accessions of Brassica campestris L. were used for sodium dodecyl
sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis.
In total, 16
polypeptide bands were observed. Out of 16 protein bands, 12 (75%) were
polymorphic and 4 bands (25%) were monomorphic. Close relationship was observed
among most of the accessions except few.
Total seed proteins of all the 25 accessions of Brassica napus L. were analyzed
using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). In
total, 17 polypeptide bands were observed. Out of 17 protein bands, 10 (59%) were
polymorphic and 7 bands (41%) was monomorphic. Close relationship was observed
among most of the accessions.
Inheritance studies in Brassica napus L. were carried out following Hayman , s
Approach (Hayman, 1954 a) as advocated by Singh and Chaudhry (2004). Additive as
well as non additive variances were observed for yield and yield related traits. Over
dominance was observered for all characters except days to flower initiation, days to
flower completion and days to maturity.
In conclusion, germplasm exhibited wide genetic diversity for the studied
traits. Accessions with desirable traits (early maturity, higher yield potential, higher oil
content and low in erucic acid and gloucosinolates) were identified which can be used
for rapeseed improvement. Over dominance with additive as well as non additive
variance was found for most of the traits indicating the selection in later segregating
generation.