Studies on Competition Between Wheat (Triticunaestivuh L. Em. Thell.) and Wild Oats (Avena Spp.)

Abstract

Two experiments were carried out in the Kabete Field Station, Faculty of Agriculture, University of Nairobi to study the effect of wild oats (Avena spp.) in competition with short maturing "Kiboko” and long maturing "Kenya Bongo'’ varieties of wheat on well drained friable red clay soils. Two spacings of wheat, (10 x 2.5)cm and (10 .x 5.0) cm, were used and wild oats were planted between the rows after dehusking and soaking in tap water for forty eight (48) hours to enhance germination in both experiments. Experiment I was carried out in the short rains of 1970 without the benefit of fertilizer and wild oat populations were 0, 9, 10, 27 and 54 plants p^r m‘". Experiment II was carried out in the long rains of 1979 with adequate Diammonium phosphate fertilizer applied at the rate of 100 kg/ha before planting. In the first experiment, only the effect of wild oat competition on vegetative growth of "Kiboko” was examined due to bird damage to the grains. In addition to vegetative growth, the effect of competition on yield per plant and yield components of "Kenya Bongo” were also studied. The influence of both cropu on the vegetative growth of wild oats were examined in both experiments. The results of experiment I showed that height (xi) of wheat variety "Kiboko”, stem dry weight, number of tillers and leaves per plant were significantly depressed by increasing wild oat densities,whereas leaf dry weight and total dry weight per plant* though decreased with increasing wild oat densities, the reductions were not significant. The presence of the crop did not affect these vegetative components in 0 c a consistent trend in wild oats. In experiment II, the height of "Kenya Bongo" variety of wheat was significantly increased in the initial stages of growth and significantly depressed o *t the final harvest when wild oat densities increased. The number of tillers and gx-eeu leaves, item and leaf dry weight per plant were significantly depressed Ly the presence of wild oats. The ratio between green and senesced leaf was also significantly decreased as wild oat density increased. The number of fertile tillers, ear dry weight, number of grains and grain yield per plant were reduced by increases in wild oat population without affecting 1000 grain weight and grain weight per ear. Wild oats did not suffer any systemic trend in vegetative growth as result of competition from the crop. In both experiments the influence of wheat spacing was relatively minor. Although the • -(xid) parameters examined were increased at wider intra- row spacing, the number of tillers per plant was the only parameter significantly increased.