SELECTION OF F 2 PLANTS THROUGH SELECTION INDICES IN Brassica juncea (Linn.) CZERNJ. AND COSSON
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Date
2016
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Birsa Agricultural University, Kanke, Ranchi, Jharkhand
Abstract
Indian mustard [Brassica juncea(L.) Czern & Coss.] is one of the most important
oilseed crops of the country, and it occupies considerably large acerage among the
Brassica group of oilseed crops. The average productivity of rapeseed-mustard in
Jharkhand (642 kg/ha) needs to be increased as it is much below the national average
(1176kg/ha). This can be achieved through breeding high yielding varieties. The success of
any breeding programme in general and improvement of specific traits through selection in
particular, totally depends upon the genetic variability present in the genotypes of a
particular crop. The present experiment was carried out to construct various selection indices
from the different character combinations taking F2 population of 5 cross combination of
Indian mustard. Variability parameters, heritability, genetic advance, character association,
and selection index in the experimental materials have been estimated based on 10
quantitative traits.
A wide range of variability was observed for plant height, number of siliqua per
plant, seed yield per plant and number of secondary branches per plant in all the 5
segregating F2 population, whereas moderate to less variability as recorded for days to
first flowering, days to maturity and number of seeds per siliqua. However, narrow range
of variability could be observed for number of primary branches per plant, siliqua length
and 1000 seed weight.
Phenotypic coefficient of variations was higher in magnitude than the genotypic
coefficient of variations in respect of all the characters. High to moderate phenotypic
and genotypic co-efficient of variation (PCV & GCV) were recorded for number of
secondary branches per plant, seed yield per plant, number of siliqua per plant, number
of primary branches per plant, number of seeds per siliqua and 1000 seed weight.
However, lowest GCV and PCV as recorded for days to maturity for all five F2 cross
combinations.
The estimates of high to moderate heritability was recorded in number of siliqua
per plant, seed yield per plant, plant height, number of secondary branches per plant, days
to first flowering, 1000 seed weight, days to maturity, seeds per siliqua and siliqua length.
High heritability coupled with high genetic advance was observed for number of siliqua
per plant for all the five F2 cross combinations.
Correlations studies revealed that seed yield per plant had strong positive
association with plant height, number of primary and secondary branches per plant,
number of siliqua per plant, number of seeds per siliqua, and siliqua length for all the
five cross combination studied. On the other hand, days to flowering, days to maturity
and some extent 1000 seed weight were found to be non-significantly correlated with
seed yield per plant. Thus these characters have not been considered while constructing
selection index.
For construction of selection indices, the characters which had desirable
significant correlation with seed yield per plant were considered. Thus, a total 67
selection indices were constructed based on seven characters in all possible combination
with seed yield per plant. Among the single character index, number of siliqua per plant
exhibited higher genetic advance and relative efficiency over straight selection for seed
yield for all the cross combination.
Number of siliqua per plant showed higher expected genetic advance and relative
efficiency in percent, than those calculated for other character in all five cross
combination (CI, CII, CIII, CIV, CV) suggested that number of siliqua per plant proved
to be better index selection based on single character. High expected genetic advance as
well as selection efficiency was observed when this character was included in any
combination of characters in selection indices. In other words, selection efficiency
improved with an increase in number of characters in combination with yield and higher
value obtained when it includes the character number of siliqua per plant.
The study suggested that the superiority of selection based on index increase with
an increase in number of characters under selection. Hence, maximum gain was achieved
by taking all the seven characters simultaneously i.e. X7, X1, X2, X3, X4, X5 and X6 in
all cross combination.
In the present study, selection based on all the seven characters gave maximum
genetic gain and high efficiency for all the cross combination over straight selection for a
single character, but practically it is unmanageable to use in the selection exercise. So, it
is suggested to prefer the index which includes as minimum as possible the characters at
a time having high efficiency.
On the basis of selection index of 20 top ranked individual plants, it was found
that the plant number 49, 18. 40, 61, 30, 91, 21, 27, 98 54, 25, 71, 10, 84, 17, 11, 33, 35,
19 and 82 in F2 population of cross combination CI (Pusa Bold x PM 21) may be
selected for next generation as these plants had higher selection scores. Similarly, plant
number 11, 83, 8, 71, 91, 87,77, 76, 75, 25, 84, 12, 29, 68, 61, 22, 54, 7, 47 and 95 were
found better in terms of selection indices in F2 population of the cross combination CII
(NPJ 112 x PM 21). For cross combination CIII i.e. Shivani x BPR 543-2 plant number
98, 33, 99, 84, 56, 16, 11, 1, 78, 59, 83, 92, 31, 34, 19, 18, 75, 80,62, 6 were selected for
next generation advancement. The plant number 13, 47, 81, 12, 46, 45, 2, 87, 10, 41, 76,
5, 66, 86, 55, 91, 14, 100, 33 and 25 may be selected in F2 population of cross
combination CIV (NRCDR02 x RGN 73). For plant population of CV (BAUM 2007 x
PM 21) cross combination, the plant number 39, 26, 46, 5, 1, 95, 47, 36, 10, 31, 15, 65,
7, 16, 27, 14, 71, 57, 67 and45 may be selected to advance next generation.
Description
SELECTION OF F 2 PLANTS THROUGH SELECTION INDICES IN Brassica juncea (Linn.) CZERNJ. AND COSSON
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