By H. Shimelis* and M.D. Laing *Corresponding author: Shimelish@ukzn.ac.za

1. .{~ Variation and agronomic potential
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Limpopo province of South Africa
H. Shimel is and M.D. Laing
UNIVERSITY OF African C('ntrc for Crop hllpro,C'lI1rnl (ACel),
KWAZULU-NATAL School of Agricultural, Earth and Environmental Scienc('s, Univ(,Tsity of KwaZulu-Natal,
Prh'atc Bag XOI, Scottsville 3209, Republic or South Africa
ABSTRACT
.:. Drought remains a major limiting factor of potential crop production.
Limited water availability significantly reduces wheat production.
.:. Breeding for drought resistance under the prevailing environment would be a breakthrough.
Breeding drought tolerant wheat cultivars that produce higher yields and superior flour quality under marginal
.:. Different putative traits are available that consistently associated with higher grain yield under drought conditions.
rainfall conditions would be a major breakthrough. The objective of this study was to determine the genetic
.:. Drought is one of the major constraints of wheat production in South Africa.
variation and agronomic potential of 49 diverse wheat lines developed for semi·arid environments.
.:. Limpopo Province is characterized to have semi-arid environment that restricted wheat production.
Field evaluations were conducted using a partially balanced lattice design. with three replications.
.;. CIMMYT is developing candidate genotypes for semi-arid and unfavorable environments.
over two years in the Limpopo Province of South Africa. Significant differences (P50.05) were observed for
.:. Exploiting the genetic potential of the existing germ plasm for improved drought and heat resistance is important.
important agronomic traits, including days to heading (52.62 - 98.91 days), plant height (57.55 - 98.95
cm), tiller numbers (8 - 24 per plant), days to maturity (126 -147 days), spikelet length (5.33 -13 cm),
number of spikelet per spike(11 - 31), number of kernels per spike (8 - 46), hundred kernel weight (3.33 - 6.34 g) and
OBJECTIVES
yield (2.42 - 8.58 tlha). Semi-arid wheat accessions 336, 326, 302, 338 and 322 were identified as superior accessions, .:. To determine genetic variation and potential of semi·arid wheat germplasmfor yield and important agronomic
trails in Limpopo Province.
based on their relatively high yields and superior agronomic performances when compared to commercia l lines
marketed in the same region . The selected lines will be used for the strategic improvement of wheat for .'. Select suitable parents and Introgress traits into desirable genetic background todevelop drought and heat stress
, resistant cultivars.
drought-prone, and marginal regions of South Africa, and regions of Africa with similar environments.
MATERIALS & METHODS
.:. 49 diverse bread wheat lines used; 47 bred for semi-arid environments and two commercial local checks (SST822, SST825) included as comparative controls (Table 1) .
•:. Field experiments conducted (2007 and 2008) in Limpopo Province at the Experimental Farm of the University of Limpopo.
.;. Experiments were established using partially balanced lattice design (7 incomplete blocks, 3 replications)
.;. Data on yield and agronomic traits collected to select for early vs. terminal stress resistance
.:. Data analyzed using Agrobase Gen II and SAS Lattice procedure
Table 1. List and pedigree of 49 wheat lines used in the study
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an OI-vs· ....... 'OIt
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RESULTS & DISCUSSION
-:- Significant differences observed for important agronomic traits (Table 2).
-:- Considerable variations observed for days to heading (52.62 - 98.91 days), plant height (57.55 - 98.95 em), tiller numbers
(8 • 24 per plant), days to maturity (126 ·147 days), spikelet length (5.33 • 13 cm). number of spikelet per spike (11 ·31), number of kernels per spike (8 • 46),
hundred kernel weight (3.33 • 6.34 g) and yield (2.42 • 8.58 t/ha) (Table 3).
Table 4. Correlation coefficients for pair-wise association of nine
Table 2. Analysis of variance of agronomic traits among 49 lines
agronomic characters
of wheat tested under partially balanced
lattice design with seven Incomplete blocks and three replications.
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DF=degrees of freedom; MS=mean square; NS=non Significant.
• and" Signiflcanlly correlated at the 0.05 and 0.01 level, respectively
" •• denote significance differences at 0.05 and 0.01 probability levels, respectively.
-:- Lines 336, 326, 302, 338 and 322 were selected with rwlatlvely high yield and better agronomic perfonnanc. . when compared to commerdallocal checks (Table 3, Flgurw 1).
-:- The selected lines will be used In the strategic Improvement of wheat fOf' water limited and marginal environments In Limpopo Province and other similar environments
-:- Further evaluation and selection within various geographicallocaUon will be conducted 10 maximize adaptation and yield.
>0> Quality traits and controlled experiments (water deficient conditions) will be carried out.
>0> Other related sources of drought or heat shock realstant gerrnplasm will be Included.
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Figure 1. Rotated principal component scores and percent e)lplained
variance showing similarities among 49 entries of T. aest;vum
ACKNOWLEDGMENTS
The National Research Foundation (NRF) of South Africa and the Generation Challenge Program
(GCP) are sincerely thanked for financial assistance of the study.
CIMMYT Is acknowledged for providing the seml-arld wheat germplasm and awarding the conference travel grant to the first author.