Abstract:
Sorghum [Sorghum bicolor (L).Moench] is the leading crop in the arid and semiarid tropics, where
drought significantly affects crop production. The use of improved cultivar, in particular hybrid,
was found to be the major component as part of the integrated approach of extenuating the extreme
effect of drought. A line x tester analysis involving 32 hybrids that resulted from crossing among
eight lines and four testers along with two standard checks were studied for 16 characters to generate
information on combining ability, gene action and heterosis with respect to growth, phenological and
yield and yield components linked to drought tolerance. All 46 entries (32 F1s, 12 parents and 2
checks) were evaluated at drought prone area, Sirinka Agricultural Research Center Kobo trial site,
using randomized complete block design (RCBD) with three replications. AGROBASE 20 and SAS
version 9.1 were used for analysis of variance (ANOVA) as well as for GCA and SCA analysis. In the
analysis the total genotypic variances were partitioned into variation due to lines, testers and their
interaction. The GCA and SCA effects were significant for most of the characters studied. The SCA
effects were of greater magnitude than GCA effects, which showed greater manifestation of nonadditive gene effects. The ratio of SCA to GCA also revealed predominance of non additive gene
effects. Performances of M90950 and P-9529 among the CMS and PDL 984928, WSV 387 and ICSR
161 among the restorers were better for most of the traits. CMS lines P-851015, P-9532 and P-850341
and restorer ICSR 161 and WSV 387 were the best general combiners for most of the traits studied.
Mean grain yield of crosses was 3.63 t ha-1 with a range of 2.73 to 5.51 t ha-1. Cross combination P851015xWSV 387 gave the maximum grain yield 5.51 t ha-1. Not a single cross combination showed
consistent promising results for all traits, however, the cross combinations P-9532 x PDL 984928, P850341 x ICSR 161, P-851015 x WSV 387, P-9534 x WSV 387 and P- 851063 x WSV387 showed
higher specific combining effects for grain yield, number of green leaves per plant and other yield
components. Most of the crosses exhibited significant positive heterosis over the mid- parent and
standard check value for all traits, however, some of the crosses also depicted negative but desirable
heterosis for traits like days to 50% emergency, flowering, maturity and seedling vigor. Generally, this
study gave valuable information on the effect of gene action on the performance of crosses as well as
identified best general and specific combiners for drought tolerance. However, these should be
confirmed further over many locations and seasons.
