Competition among four Ethiopian bread wheat cultivars and varying densities of Avena fatua L.: effects on nitrogen and phosphorus uptake and utilization
1997
Tanner, D.G. (CIMMYT/CIDA East African Cereals Program, Addis Abeba (Ethiopia)) | Giref Sahile
The effects of competition among four bread wheat (Triticum aestivum L.) cultivars and four wild oat (Avena fatua L.) densities on nitrogen and phosphorus uptake and utilization in grain and biomass were assessed in a field study in southeastern Ethiopia. Percent N in wheat grain and straw increased linearly in response to wild oat competition, while percent N in wild oat seed varied inversely with wild oat seed yield (i.e., in response to the competitiveness of wheat cultivars). Percent P did not vary in wild oat straw or grain; for wheat only straw P content varied among wheat cultivars. Total N uptake by the mixed canopy of wheat and wild oat varied among the wheat cultivars and increased linearly in response to wild oat density, while total P uptake only varied among wheat cultivars. The mean proportion of total N, total P and total biomass contained in the wild oat fraction was 30.5, 31.9 and 25.1 percent, respectively, indicating that wild oat was more successful than wheat at utilizing available soil N and P wheat N harvest index (NHI) varied among cultivars and decreased linearly in response to wild oat density. Wild oat NHI decreased linearly in response to increasing density. Wheat and wild oat P harvest index (PHI) followed similar trends. Wheat N use efficiency (NUE) varied among cultivars and decreased with wild oat density while wild oat NUE only varied among wheat cultivars. Wheat and wild oat P use efficiency (PUE) did not vary across either main factor. Cultivar by density interactions were non-significant for all parameters except percent N in wheat grain and wheat NUE.
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