Effect of aqueous extracts of allelopathic plants on growth and biomass of wheat and weeds.
Weeds infestation is one of the yield limiting factors in Pakistan. Although chemical control of weeds is effective but may cause crop damage, resistance development of weeds and animal and human health problems. Therefore a field experiment was conducted at Agronomy Research Farm, The University of Agriculture, Peshawar-Pakistan to evaluate the effect of allelopathic plants water extract (Eucalyptus camaldulensis, Lantana camara, Parthenium hysterophorus and Sorghum halepense) and concentration of extracts (1:4, 1:5 and 1:6) on wheat and weed biomass during winter season 2015-16. The experiment was laid out in randomized complete block design using four replications. Plot size was 3 m × 1.8 m having 6 rows 30 cm apart. One control plot in each replication was maintained. The plant water extracts in respective concentrations were sprayed one week after sowing with knapsack sprayer. The results indicated that plots that received Sorghum halepense water extract resulted in lower weed density (43 m-2), fresh (102.4 g m-2) and dry (19.9 g m-2) weeds biomass. Similarly application of Sorghum halepense water extract in wheat crop increased emergence m-2 (89), leaf area tiller-1 (100.54 cm2), leaf area index (3.0), plant height (85.68 cm), biological yield (8717 kg ha-1) and harvest index (38.34%). Among different plant water extracts concentration of 1:4 remarkably reduced weeds density (35 m-2), fresh (74.6 g m-2) and dry (15.8 g m-2) weeds biomass, while application of different plant water extracts at 1:6 concentration produced maximum emergence m-2 (90), leaf area tiller-1 (102.26 cm2), leaf area index (3.1), plant height (89.03 cm), biological yield (9071 kg ha-1) and harvest index (38.31%). Thus spray of Sorghum halepense water extract at 1:6 concentration performed better and is recommended for weeds suppression and enhancing wheat biomass in the study area.