Assessment of Drought Tolerance, Earliness and Grain Yield in South Sudan Sorghum Germplasm and Icrisat Lines
Abstract
Sorghum production is highly constrained by drought stress in semi-arid tropics
leading to grain deficit, higher consumer food-commodity prices, food insecurity and
malnutrition. The goal of the current study was to identify sorghum genotypes
exhibiting genes for earliness and yield under drought stress conditions that could be
utilized in the development of superior sorghum synthetics for improved food and
nutritional security in drought prone areas of South Sudan. This study used sorghum
germplasm comprising 47 genotypes from South Sudan collection and 34 elite lines
drawn from ICRISAT-Nairobi‟s sorghum germplasm repository. The trails were laid
out in a 9 x 9 alpha square lattice in a well irrigated and non-irrigated conditions
Genotypes and water regimes had effects on days to flowering, staygreen scores, dry
leaf scores, waxy bloom, leaf area, leaf rolling, total leaf count and lodging implying
genetic diversity for the sorghum genotypes evaluated in this study. The superior lines
that outperformed the check variety (Kiboko local2) for earliness were Wote
collection1 (56 days), IESV 23010 DL (58 days), ZSV3 (60 days), Bizany (61 days)
and Tabat (61 days). However, there were yield penalties recorded among the
accessions wote collection1, Bizany, ZSV3 and Tabat. Thus, the accessions IESV
23010 DL would best serve as an ideal drought evading candidate with better
performance for grain yield. The sorghum genotype Olerere (12.82%) exhibited
staygreen trait while Omuhathi (76.23%) showed the highest senescence. Reduced
total leaf counts and net leaf area were observed among improved drought tolerant
lines namely IESV 92028 DL IESV 91111 DL, Mahube, IESV 92172 DL, Gwada and
IESV 23010 DL. The accessions that scored dense wax load under drought stress
condition were Gwada, ICSR 161, Mahube, AG8, IESV 91131 DL, IESV 91111 DL,
IESV 92028 DL and IESV 92172 DL and comprised of inbred lines drawn from
ICRISAT- Nairobi gene bank. The genotypes Lobuheti (50.65g), IESV 91131 DL
(46.52g), Lodoka1 (47.08g) and IESV 92172 DL (46.69g) showed superior field
weights as opposed to the check variety (Kiboko local1). Accession IESV 91131 DL
and IESV 92172 DL recorded high harvest index (3.13% and 6.86%) and threshing
percentage of 73.94% and 67.34%. Results of correlation analysis revealed that
panicle weight showed positive correlation with grain yield, harvest index, and
panicle width suggesting that these traits could be used as the basis for indirect
selection for high grain yield in sorghum breeding programs. There were significant
differences among the maternal and non-maternal effects implying that maternal
genes play a greater role in regulating maturity. There were higher predictability
ratios for days to flowering, panicle weight and grain weight suggesting that additive
genes play a bigger role than non-additive genes in conferring such traits. Negative
significant general combining ability effects (GCA) were noted for days to flowering
for parents ICSV 111 IN, B35 and Macia suggesting that these parents can be utilized
as donor parents when introgressing earliness triat. The parental lines Lodoka, Okabir
and Akuorachot with positive days to flowering implied lateness thus conferring the
late physiological maturity. The study identified parental lines, Macia and ICSV 111
IN as exhibiting positive and high GCA effects indicating that they are good
combiners for grain yield compared to parental lines B35, Okabir and Akuorachot
which showed inferiority with regards to grain weight. Parental lines Macia and ICSV
111 IN also showed positive GCA for 100-seed weight, suggesting that they are good
combiners for this trait and would therefore serve as good parental lines for the
development of commercial synthetics.
Publisher
University of Nairobi
Rights
Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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