ICARDA Annual Report 1998

Exploiting Genetic Variability in Wheat Landraces in Iran

Wheat crop in most of the highlands of WANA faces severe abiotic and biotic stresses. Research in these areas is relatively recent, and farmers still use old cultivars, or landraces, such as 'Sardari' in Iran, 'Local White' in Pakistan, and 'Achoure' and 'Kirik' in Turkey. Over the years, these landraces have adapted themselves well to their respective environments, but their yield is low and further threatened by new races and biotypes of plant pathogens and pests. A three-year study in Iran jointly conducted with ICARDA using 'Sardari', grown on more than half-a-million hectares in rainfed areas of western Iran, examined the possibility of improving the productivity of this landrace without sacrificing its genetic variability.
          Individual spikes of 'Sardari' were randomly picked in 1995 from a farmer's field in the Maragheh region of western Iran. They were increased as head rows in 1996 at the Dryland Agricultural Research Institute (DARI) in Maragheh. No selection was made, except for the elimination of a few heterogeneous families, leaving a total of 106 families that were evaluated in 1997 and 1998 for the following traits: reaction to cold, plant height, lodging, days to heading, reaction to yellow rust, number of tillers/plant, spike length, spikelets/spike, kernels/spike, spike color, seed color, 1000-kernel weight, protein content, and grain yield.
           Significant variation was observed among the 106 families for most of the traits. 'Sardari' is a winter mid-tall wheat cultivar, with white chaff and grain, and a weak straw. Its photothermal characteristics enable it to go dormant throughout the winter, grow actively in the spring, once the frost risk is over, and rapidly fill the grain, a major advantage in the dry highlands of WANA. However, it is very suscepti

ble to yellow rust (Puccinia striiformis f.sp. tritici) under favorable environmental conditions such as those of the early 1990s in WANA. It is moderately susceptible to severe cold.
          A relatively high frequency of yellow rust resistance or moderate resistance was unexpectedly observed among the 106 pure lines (Table 6). The variability among the landrace-derived lines was confirmed in field tests at Maragheh in Iran and Tel Hadya in Syria at both seedling and adult plant stages. This was unexpected as the mother 'Sardari' population is usually scored very susceptible (90S or higher) under favorable disease conditions, both in Iran and Syria.
             Divergence from the typical 'Sardari' type was also observed for most of the other traits. This within-landrace variability may explain the plasticity of such a population under variable growing conditions, a characteristic of the highlands and cold areas with a Mediterranean-type climate. Cluster analysis of the 106 families did not show a dominant type and there was no cluster that grouped all desirable types, i.e. yellow rust resistant, white kernelled, non-lodging, early, cold tolerant, and high yielding. Therefore, it seemed possible to take advantage of the desirable attributes identified in certain lines by intercrossing such lines or crossing them to other germplasm with complementary traits.The second procedure was applied by the breeders at DARI, and three new advanced lines were developed that possess the earliness of 'Sardari' and disease resistance and increased yield potential of other cultivars.
         The study suggested that wheat landraces such as 'Sardari' should not be discarded because of their disease susceptibility or low yield potential under certain conditions. Such populations should be preserved and simultaneously used to improve and develop new and diversified cultivars for different environments to avoid the erosion of genetic
variability.

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