dc.description.abstract | Sesame in Kenya is mainly produced by peasant farmers.
Production has mainly been limited by poor soils, erratic
rainfall amounts, pest and disease attack, poor agronomic
practices and use of unimproved cultivars. This study was
thus conducted to determine the nature of gene action for
yield, yield components and other traits and the association
of componental characters with yield.
Nine sesame (Sesamum indicum L.) cultivars and their 36
F1 progeny were evaluated for yield per plant, capsules per
axil, branches per plant, days to 50% flowering, height to
first branch, 1000-seed weight, seeds per capsule, capsule
length, capsules per plant, height ~t maturity, height to
first capsule and locules per capsule in a diallel cross at
the University of Nairobi Dryland Field Station, Kibwezi in
1993. The experimental design was a randomised complete
block design with three replications. General and specific
combining abilities were determined by Griffing's (1956)
method 2, Modell.
Additive gene effects were more significant for days
to 50% flowering, height to first capsule and 1000-seed
weight. Non-additive gene effects were more conspicuous for
seeds per capsule, capsule length, capsules per plant and
height to first branch. SPS SIK 50/1 was the best general
combiner for yield per plant, 1000-seed weight and capsule
length. The crosses SPS SIK 114 x SPS SIK 111, SIK 131 x
SPS SIK 111, SIK 131 x SPS SIK 114, SIK 131 x SPS SIK 6 and
SPS SIK 50/1 x SPS SIK Z2 were the most promising, with high
specific combining ability for yield per plant, capsules per
plant, seeds per capsule, capsule length and 1000-seed
weight.
Yield heterosis of the F1 over the better-parent ranged
from -48.45% to 115.02%. Crosses involving SIK 131 showed
negative better-parent heterosis for capsules per- axil while
the rest of the crosses showed no heterosis. Crosses
involving SPS SIK 6 showed negative better-parent heterosis
for locules per capsule while the rest showed no heterosis.
All crosses except SPS SIK 6 x SPS SIK 111 showed a
reduction in height to first branch. The parental cultivars
SIK 131 and SPS SIK 004/1 were found to impart earliness to
their progeny.
Capsule length, 1000-seed weight, seeds per capsule and
capsules per plant were positively and significantly
correlated with yield per plant. From the path coefficient
analysis seeds per capsule, 1000-seed weight and capsules
per plant exerted the greatest direct influence on yield. | en |