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  • Author or Editor: P. Monneveux x
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The objectives of this research were to assess the genotype × environment interaction and to identify barley (Hordeum vulgare L.) genotypes with high stability for grain yield, yield components, straw height, ear length, heading time, straw yield and harvest index. Eighteen barley breeding lines and one commercial cultivar were evaluated under field conditions during five growing seasons. The trials were carried out under both rainfed and irrigated conditions during the first four years and under rainfed conditions only during the last growing season. Stability studies showed significant differences between the environments for all the traits and between the genotypes for thousand-grain weight, heading time and ear length. The genotype × environment interaction was, however, not significant according to the Finlay-Wilkinson analysis. The analysis of correlations between the various traits showed the importance of selecting for earliness, high number of grains/ear, stem height and ear length in order to obtain acceptable grain yields under drought-stressed conditions.

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In the tropics, maize ( Zea mays L.) is often grown under low N conditions. Information on the respective role of N uptake and partitioning at anthesis in determining grain yield under low N is scarce. Senescence traits have been proposed as secondary traits to select for low N tolerance, but the stability of their association with yield under different environmental conditions has been rarely described. In the present study we analyzed the associations between grain yield, N uptake and partitioning at anthesis, dry matter matter partitioning, and senescence traits during two seaons in QPM (quality protein maize) hybrids. Association between grain yield and N uptake at anthesis, when found, was mainly explained by a close relationship between grain yield and above-ground biomass. No relationship was found between grain yield and N partitioning at anthesis. In both seasons grain yield was significantly positively associated with ear to above-ground biomass and ear to tassel weight ratios. The magnitude of the correlation between grain yield and senescence traits highly depended on climatic conditions.

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The relationships between leaf senescence, carbon isotope discrimination and yield performance were examined in durum wheat ( Triticum durum Desf.), in the high plains of Setif, eastern Algeria. Ten CIMMYT high-yielding cultivars were grown during two cropping seasons characterized by low rainfall (217 and 162 mm, respectively), freezing temperatures at heading stage and terminal heat stress. Senescence was assessed using numerical image analysis (NIA). Carbon isotope discrimination was analyzed in flag leaves at anthesis and grain at maturity. Senescence was significantly negatively correlated to grain yield in season 1, but not in season 2. There was no relationship between Δ and grain yield in both seasons. The absence of association between Δ and grain yield is likely to be due to a strong contribution of pre-anthesis assimilates to yield together with a sink limitation of yield.

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