PJB-2018-695
PHYSICAL AND CHEMICAL EVALUATION OF SOME LANDRACES AND IMPROVED TUNISIAN DURUM WHEAT GENOTYPES (TRITICUM DURUM L.)
SOUROUR AYED
Abstract
Variation in quality attributes of six Tunisian landraces and two improved durum wheat (Triticum durum L.) genotypes was determined by evaluating select physical (1000 kernel weight (TKW) and vitreousness) and chemical (protein, moisture, ash and falling number) characteristics. Analysis of variance (ANOVA) revealed significant differences among genotypes for all tested parameters. Landraces, when compared to improved genotypes, exhibited high TKW, indicating high milling yield potential (~5%). In addition, milled wheat of all landraces had a high protein (17.18-18.9% on a dry weight (DW) basis) and semolina (16.19-18.38% DM) content, which did not exceed 13.13% and 12.54%, respectively in the improved genotypes. The high falling number of milled samples (394-473.5 s) and of semolina (461-853.5 s) indicated extremely low amylolitic activity. The moisture content of semolina in landraces was conserved better than of the improved genotypes. Landraces had significantly higher mineral content (2.5% DM in milled wheat and 1.78% DM in semolina) than improved genotypes (< 1.73% and 1.09%), as assessed from ash content. Principal component analysis (PCA) explained 68.94% of total variability. From PCA, four landraces (Arbi, Biskri, Chili and Ouerd Bled), which showed the best physico-chemical characteristics, can be used as parents for improving the quality of durum wheat. A highly negative correlation (P < 0.01) existed for the degree of vitreousness (r = -0.93) and protein content of the milled wheat. Semolina protein content was also highly negatively correlated (P < 0.01) with the degree of vitreousness (r = -0.94) and the semolina moisture content (r = -0.72), but positively correlated with semolina extraction rate (r = 0.21) and higly correlated (P < 0.01) with ash content (r = 0.8). Therefore, semolina extraction rate and ash content could be used as selection criteria for improving the grain protein content in durum wheat.
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