Wild oats (Avena fatua L.) is one of the most widespread, noxious and harmful weeds in wheat. In order to quantify the impact of wild oats on wheat, two separate experiments were conducted at Agricultural Research Farm, NWFP Agricultural University Peshawar, Pakistan for two crop seasons i.e. 2004-05 and 2005-06. First experiment was concerned to find effect of wild oats populations and nitrogen levels on some agronomic and quality traits of wheat, while in the second experiment wild oats biotypes were subjected to different oats killers to find out the effect of herbicides on biotypes and the impact on wheat. The first experiment was laid out in Randomized Complete Block (RCB) design with split plot arrangement, having four replications. Three nitrogen levels (75, 100 and 125 kg ha-I) were kept in main plots while five wild oats densities (0, 10,20, 30, and 40 plants m-2) were assigned to the sub plots. The sub-plot size measured 5x 1 m2. The effect of nitrogen was not significant on different parameters of wheat and wild oats, while oats density and interaction of density with nitrogen levels were significant for all the parameters studied. The two year data revealed that less than one wild oats plant m-2 inflicted 1% reduction in wheat yield, while 30% reduction in yield was computed with the infestation of 16, 18 and 17 plants m-2 under 75, 100 and 125 N kg ha-I fertilizer regimes, respectively. It was further discovered that there existed a wild oats density related reduction in grain protein content. About one and a half wild oats plant m-2 reduced protein content by 1%, which is alarming in vegetable based diets like Pakistan. Judicious control measures for wild oats are recommended to be adopted for harvesting better quantity and quality of wheat.
The second experiment was laid out in Randomized Complete Block design with splitplot arrangement having three replications. The experiment comprised of four wild oats biotypes assigned to the main plots, while 3 herbicides Sencor 70WP, Isoproturon 500 EW and Affinity 50WDG (metribuzin, isoproturon and carfentrazone ethyl esterisoproturon) were kept in sub-plots. The Ghaznavi-98 wheat variety was seeded at the rate of 120 kg ha-I with sub-plot size of 5x 1m2. To avoid the risk of germination failure, three to five seeds of wild oats were seeded instead of a single seed and then thinning to one seedling hill-I and an ultimate density of 20 plant m-2. Data were recorded on tillers plant-1, wheat spikes m-2, wheat plant height at maturity (cm), wheat spike length (cm), wheat spikelets spike-I, number of grains spike-I, 1000 grain weight (g), biological yield (t ha-1(grain yield (t ha-I) and grain protein content (%). The analysis of data revealed that the main effects for biotypes were non-significant statistically for all the parameters studied, but the effect of herbicides and the interaction of herbicides with biotypes were significant statistically for all the traits except plant height at maturity and protein content (%) in wheat grain during 2004-05. For controlling wild oats biotypes, the herbicide Affinity proved to be the best treatment giving maximum grain yields (1.42 and 2.60 t ha-I) during two years study as against minimum grain yields (0.60 and 1.043 t ha-I) recorded in weedy check plots during 2004-05 and 2005-06, respectively. From our findings, it is concluded that herbicides may be applied cautiously to different biotypes of wild oats depending upon their susceptibility to various herbicides.