Journal of Research in Weed Science

Abstract A limiting factor in valerian production is weed interference so, the crop protection from weed is essential. Field experiments were conducted for two consecutive seasons (2014-2015) to evaluate different weed control methods on growth, yield, and oil quality of valerian in Iran. The experimental design was a randomized block with 7 treatment and 4 replicates. Treatments included untreated control, manual weeding, barley straw, sorghum straw, wheat, black plastic and post-emergence oxadiargyl. The lowest density and dry weight of weeds was related to the manual weeding treatment. Result showed that the maximum growth parameters of valerian were obtained from manual weeding treatment followed by black plastic, barely straw and sorghum straw reflecting superior weed control. Essential oil analyses indicated that bornyl acetate, valerenal, camphene and α-pinene were the most abundant constituents. These components on average represent 27.7, 14.7, 4.1 and 2.2% of the oils that were extracted from plant, respectively. Bornyl acetate, valerenal and camphene contents did not vary with the various studied treatments although there was a trend toward higher in manual weeding treatment. Overall finding of current experiments suggested that barely straw and sorghum straw are potential substitutes for manual weeding and black plastic mulch for weed control in valerian.

Abstract Smallholder farmers have challenges of weed control and mostly they use cultural control methods because chemical control with herbicides is usually costly. However, Lantana camara L. is known to be allelopathic to other plants hence a worthy candidate for biological control of weeds under cowpea production. A field study was conducted to determine the potential for L. camara to control weeds in cowpea at the University of Zambia Agricultural Experimentation Station. Leaves were harvested from two genotypes of L. camara (G1: Pink-flowered and G2: Orange-flowered genotypes) dried and pulverized to form a powder and applied at different rates (R0C: 0 kg ha^-1, R1: 100 kg ha^-1, R2: 200 kg ha^-1, R3: 400 kg ha^-1) using the following types of application: T0C: No application, T1: broadcasting, T2: incorporation in the soil and T3: spraying of soaked ground L. camara. The research was conducted at the University Of Zambia School Of Agricultural Sciences Field Station. The experiment was arranged in a split split-plot design with three replications. Weed population density and weed weight were reduced the most (38% and 12.5%, respectively) at the highest rate (R3: 400 kg ha^-1) of L. camara application. The cowpea grain yield was higher (P< 0.05) in fields treated with G1 (mean =876.90 kg ha^-1) than for G2 (mean =672.10 kg ha^-1). G1 increased cowpea grain yield by 36.04%. Lantana camara holds great potential to increase food security by reducing losses associated with weeds in cowpea.

Abstract Application of crop residues can be a good option for organic and sustainable weed management in rice. Consequently, the use of crop residues can suppress weed emergence and weed biomass. A study was conducted in two consecutive seasons firstly to optimize the mixture ratio to soil (v/v) of different crop residues on inhibition of common weed species and secondly to evaluate their performance on rice growth and yield. Among the crop residues used in this study sorghum was the most effective followed by mustard, barley, soybean, rice, wheat, triticale, maize, lentil and grasspea. The 50:50 (crop: soil, v/v) treatments incorporation rate of all crop residues suppressed the growth of all weed species in maximum level. The result revealed that broadleaf weed species were more susceptible to crop residues than grass weed species. In this respect, the highest growth inhibition (54.49%) was observed in controlling Monochoria vaginalis. Variety and rate of sorghum residues application significantly influenced weed growth and inhibition. A maximum increment in terms of plant height, dry weight and yield was observed due to sorghum 2.0 t ha^-1 residue applications. Considering yield and yield contributing characters, highest grain and straw yield was obtained from BRRI dhan29. All together, the result depicted that crop residues can effectively control weed along with enhancing growth and yield of rice and it can be successfully used in weed management program in rice.