MSc.

The project entitled “Generation mean analysis in yard long bean (Vigna
unguiculata subsp. sesquipedalis (L.) Verdcourt) for yield and quality” was carried out
at the Department of Vegetable Science, College of Agriculture, Vellayani, during
2017-2018, to study the inheritance and gene action of yield and quality in yard long
bean using generation mean analysis.
The six generations (P1 , P2 , F1 , F2 , BC1 and BC2 ) of two superior crosses of yard
long bean with high yield and quality characters viz. Cross 1 - VS 50 x VS 34
(Kakkamoola Local x Githika) and Cross 2 - VS 50 x VS 26 (Kakkamoola Local x
Vellayani Jyothika) were used for the study. The experiment was carried out in three
parts. In part I, two superior crosses of yard long bean with high yield and quality
characters, selected based on specific combining ability and per se performance from
the previous M.Sc. (Hort.) programme, were used. The seeds of the two hybrids were
produced in a crossing block. In part II, the two F1 hybrids were selfed to produce F2
progenies. Simultaneously, the F 1 hybrids were backcrossed with the female parent to
produce BC1 generation and the male parent to produce BC 2 generation. In part III, the
six generations (P1 , P2 , F1 , F2 , BC1 and BC2 ) of the two hybrids were evaluated in a
replicated field experiment using generation mean analysis.
The six generations of the two crosses were evaluated for vegetative and
flowering characters, yield and yield attributes and quality characters. Significa nt
difference was observed among the generations for most of the traits studied. Earliest
flowering was observed in F1 in both the crosses (50.00 days and 49.50 days in cross 1
and 2 respectively). Pod length and pod girth was maximum for P1 (65.99 cm and 3.11
cm respectively) in cross 1 and F 1 (68.56 cm and 3.57 cm respectively) in cross 2. The
highest pod weight was recorded by BC1 (47.22 g) and F2 (50.89 g) in cross 1 and 2
respectively. Maximum number of pods plant-1 was recorded in F1 (84.00) in cross 1
and BC2 (74.67) in cross 2. Highest number of seeds pod-1 was observed in F1 (22.33)
in cross 1 and BC 1 (20.33) in cross 2. Hundred seed weight was maximum for F1 in
both the crosses (17.05 g and 21.83 g in cross 1 and 2 respectively). The highest yield
was recorded by F1 in both the crosses (1210.51 g plant-1 and 1116.83 g plant-1 in cross
1 and 2 respectively). Among quality characters, highest pod protein content was
recorded by BC 1 in both the crosses (6.23 % and 6.27 % in cross 1 and 2 respectively)
and keeping quality by BC 2 in both the crosses (14.16 % weight loss and 16.88 %
weight loss in cross 1 and 2 respectively).
Predominance of dominance gene action was observed for most of the
characters in cross 1 (VS 50 x VS 34) viz., vine length at final harvest, primary branches
plant-1 , terminal and lateral leaf length, lateral leaf width, days to first flowering, pod
length, pod weight, pods plant-1 , yield, days to harvest, crop duration, pod protein and
keeping quality. Terminal leaf width and pod girth were controlled by additive gene
action whereas seeds pod-1 and hundred seed weight by dominance x dominance
interaction. In cross 2 (VS 50 x VS 26), characters such as terminal and lateral leaf
length and width, pod length, pod girth, pod weight, hundred seed weight and yield
were governed by dominance x dominance, vine length at final harvest, days to first
flowering, pods plant-1 , seeds pod-1 , days to harvest, crop duration, pod protein and
keeping quality by dominance and primary branches plant-1 by additive gene actions.
Incidence of spotted pod borer, aphids, leaf eating caterpillar, pod bug were observed
during the cropping period. Cowpea Aphid Borne Mosaic Virus (CABMV), fusarium
wilt, collar rot and web blight, cercospora leaf spot and rust were the diseases observed.
Predominance of dominance gene action pointed out the suitability of resorting
to heterosis breeding for the improvement of the trait. Presence of dominance x
dominance interaction suggested the use of hybridization followed by selection as the
appropriate breeding method. Simple selection procedure would be more rewarding for
improving the characters governed by additive type of gene effects. Duplicate type of
epistasis was observed for most of the traits studied, as shown by the opposite signs of
dominance (h) effect and dominance x dominance (l) type of interaction.