Weed Management in Organic Horticulture by Cover Crop in Iran

Citrus (Citrus reticulata) is one of the most important horticultural plant in Iran and weed management throuth ecological methods such as cover crop is a proper option in orchard management practices. The experiment was designed as a split plot on the base of complete randomized block design with four replications in Mazandaran Province, Sari, Voushka county from 2010 to 2012. The main plots were methods of cover crop management (desiccated with glyphosate at 0.85 kg ai ha-1, mowed and incorporated with soil with rotivator that were done at the flowering stage), and the subplots were cover crop species [sainfoin (Onobrychis viciifolia), winter barely (Hordeum vulgare), triticale (×Triticosecale), sainfoin + barely and sainfoin + triticale] and one control treatment which was without cover crop. An important reduction of seedling emergence and total weed dry weight were observed in the plots with cover crop dessicated compared with the plots mowed or incorporated with soil. The optimum cover crop species for weed control was sainfoin + barely mixes because it had the highest biomass and lowered the amount of light reaching the soil surface and reduced soil temperature fluctuations, resulting in a reduction in weed seedling emergence. In addition weed suppression by it has been attributed in part to allelopathy. In both years there were no differences among treatments in tree yield but to maximize and sustain the output of an orchard, weeds in the tree row have to be controlled efficiently.