Journal of Forestry Research (2013) 24(3): 607-610 DOI 10.1007/s11676-013-0392-3 Effect of wood chip application on root growth of oak seedling and weed control in northern Iran Armin Mashayekhan  Seyed Mohammad Hojjati Received: 2012-01-30; Accepted: 2012-05-08 © Northeast Forestry University and Springer-Verlag Berlin Heidelberg 2013 Abstract: It was hypothesized that wood chips can serve as a mulch to improve the growth of young trees by facilitating the development of their root systems, inhibiting weed germination, and suppressing weed growth. The present study was carried out in Ghorogh Nursery, Golestan Northern Iran, in order to investigate the impact of wood chips applica- tion on root growth of oak (Quercus castaneifolia) seedlings and control of weed. A three centimeter wood chip layer was used on the soil surface as the mulch treatment with bare soil as the control. The number of new roots, the length of exciting roots and the density of weeds were meas- ured after 5 and 12 weeks. Results showed that wood chip application had significant positive effect on the length of excising roots after 5 and 12 weeks compared with control seedlings. Also, weeds were reduced to near zero levels in treated plot. Our findings suggested that wood chip layer on the soil surface in the nursery can conserve soil moisture and prevent nutrient leaching from the rooting zone as well as diminish weed growth which consequently lead to production of high quality seedling. Key Words: Mulch; root growth; Quercus castaneifolia; weed control; Ghorogh Nursery; Golestan Province; Iran Introduction A nursery is a place where plants are raised with special care until they are ready or large enough for transplanting into the field (Munjuga 2006). The purpose of a nursery is to produce good quality trees seedlings which are healthy, uniform, and capable of quick field establishment (Munjuga 2006). Forest nursery managers are aware of the significance of weed losses in Iranian nurseries. Weeds directly affect the quantity and quality The online version is available at http://www.springerlink.com Armin mashayekhan ( )  Seyed Mohammad Hojjati Sari Agricultural Sciences and Natural Resources University, Sari- P.O.B: 737, Iran. Email: Mashaykhan@yahoo.com ; s.hojati@sanru.ac.ir ; s_m_hodjati@yahoo.com Corresponding editor: Hu Yanbo of forest seedlings and can indirectly cause losses by reducing the length of roots and shoots and thus reduce field survival. Since control of nursery weed is necessary. Weeding is one of the tasks necessary in the nursery. Weeding is usually done 5-6 times to eliminate weeds in the nursery by workers. If you use an herbicide, seedling can be destroying due to the sensitivity of the seedling in the nursery. Seedling preservation of physical injury caused by weeding on one hand, high labor cost and free use of wood residual from the sawmill industry in Iran on the other hand, are the economical reasons for using wood chip in weed control. Application of organic mulch is one effective way to improve the soil condition for root growth and weed control (Iles 2001; Takeda et al. 2005; Strahan 2007; Igbokve 2007). Wood chips encourage root development and suppress weed via im- proving soil moisture and temperature, shading and also adding valuable organic matter to the soil (Iles 2001; Percival and Evan- gelos 2006; Wilen et al. 2011). The active organic molecules have been shown to enhance the growth of seedling roots through promotion of adventitious roots on several plant species and highly beneficial in the weed control (Blunden and Woods 1969; Finnie and Vanstaden 1985; Pattison 1994; Walsh 1997; Scott Green 2001). Long term investigation showed that mulch- ing with wood chips increased soil moisture, root growth and used to suppress weeds (Herms et al. 2001). Mulches are used in urban forestry (Duryea et al. 1999) and to lesser extent in wild land forestry (Flint and childs 1987; Vincent and Davies 2003; Geyer et al. 2006) in order to inhibit weed germination and sup- press weed growth, prevent water loss from the soil by evapora- tion, and reduce erosion (Lopushinsky and Beebe 1979; Walker and McLaughlin 1989; McDonald and Helgerson 1990; Gupta 1991; Mayhead 1992; Truax and Gagnon 1993; Haywood et al. 1997) which in turn improves plant growth and survival (Greenly and Rakow 1995; Davies 1988; Chaar et al. 2008). The root den- sity of mature little leaf linden, green ash, sugar maple and red maple trees were greater under mulch than in bare soil (Herms et al. 2001). They stated that turf grass compete for nutrients with seedling roots. Competition with turf grass for soil moisture be- comes especially problematic for seedlings during drought peri- ods. Conversely, mulches are commonly used to suppress weeds. SHORT COMMUNICATION