Genetic advances in grain yield of durum wheat under low rainfall conditions
1999
Ben Amar, F. (INRAT, Boulifa (Tunisia). Station du Kef)
The seven most widely-adopted varieties of durum wheat (Triticum turgidum L. subsps. durum (Desf.) Husn.), released in Tunisia between 1960 and 1993, were evaluated for genetic gains in terms of grain yield and related characters in the semi-arid areas. They were grown in the 1993-97 seasons, on plots laid out in a randomized complete block design with three replications, and data recorded for the following characters: number of grains per spike, number of spikes per m2, plant height, vegetative period, days to maturity, plant biomass, thousand-kernel weight, and grain yield. Grain yields were found significantly and positively correlated with number of grains per spike and number of spikes per m2, and negatively correlated with vegetative period. But they were indirectly affected by plant height and days to heading through their significant and positive correation with vegetative periods. Thus, the number of grains per spike, the number of spikes per m2, the length of the vegetative period, plant height and days to heading were the major contributors to durum grain yield in the semi-arid regions. But regression analysis showed that as newer varieties were released in Tunisia, grain yields did not rise significantly in the semi-arid regions as they had in the sub-humid regions. The absence of significant gains in grain yield was reckoned to be because of lack of significant gains in terms of number of spikes per m2, plant height, and days to heading. Thus, the newer varieties did not outperform the older varieties for these characters in the semi-arid regions, indicating that they are not well-adapted to water-stress conditions
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