Phenotypic Diversity and Associations of Some Potentially Drought‐responsive Characters in Durum Wheat

Abstract

Genetic improvement of crop plants for drought resistance is hindered by lack of information on variability and associations of drought‐response characters in breeding materials. We evaluated 3430 accessions in a world collection of durum wheat (Triticum turgidum L. var. durum) for 19 characters under severe moisture‐limiting field conditions at Swift Current, SK, Canada in 1984. Phenotypic diversity (H) and multicharacter associations were investigated in germplasm from nine durum wheat growing regions. The Middle East was one of the regions with a high level of diversity (H = 1.132). The rate of excised‐leaf water loss (RWL) was used as a possible indicator of drought resistance. Glaucousness, plant height, chlorotic leaf spots, days to flowering, and days to maturity were significantly associated with RWL in six to seven regions. The discrete multivariate log‐linear analysis involving these six characters revealed the first order (two‐character) and some second‐order (three‐character) associations. These five characters were chosen along with RWL as drought‐response characters that may be useful for establishing selection criteria for drought resistance. These results have important implications for developing durum wheat ideo‐types for high and stable production in drought‐prone environments.

Selection for Traits Associated With Drought Tolerance in Durum Wheat

“…The leaf samples were weighted (W1), wilted for 2 hour at 35oC, reweighed (W2), and oven-dried for 48 h at 70 o C to obtain dry weight (W3). The RWL was calculated using the following formula (Yang et al 1991):…”

CIFOR’s research programme on conservation of tropical forest genetic resources

“…Positive correlations between number of heterozygous allozyme loci and fitness-related traits have been reported (e.g., Ledig et al 1983;Linhart and Mitton 1985;Strauss 1986), but other studies showed either no or negative correlations (e.g., Bush et al 1987;Linhart et al 1989). The existence of gene co-adaptation in such studies can cause this inconsistency; for example, a fitness-related trait such as drought-response is controlled by a block of co-adapted gene complexes in some species (Yang et al 1991).…”

“…Similarly, there is a growing body of data on biochemical and molecular genetic variation, which is also underutilised. With the application of analytical techniques recently developed at the University of Alberta (e.g., Yang et al 1991, Yang et al 1996, quantitative and biochemical/molecular data can provide much more valuable information on population genetic structure, thus promoting the development of more effective conservation strategies, and the acceleration of genetic improvement programmes.…”

Characterization of sweet potato accessions in Malawi using morphological markers and farmers indigenous knowledge system (IKS)

“…The minimum value of the index was zero for a uniform population. The value of the index increases with increase within population variability and reaches maximum value when all phenotypic classes have equal frequencies (Yang et al, 1991). To test for the differences among pairs of Ĥ' values at P< 0.05, a t-statistic according to Jain et al (1975) was used as given by the formula:…”