Effect of weed control on growth and performance of four nursery-grown conifer species

This research was conducted on the survival, growth, biomass and vitality status of Arizona cypress (Cupressus arizonica var. arizonica Green.), Medite cypress (C. sempervirens var. horizantalis), Brutia pine (Pinus brutia Ten.) and Aleppo pine (P. halepensis Mill.) seedlings subjected to weeding as well as various combinations of organic matter and leaf litter use at Koloudeh nursery, Amol city (north of Iran).). Seeds were planted in plastic pots in a randomized block design with four replications. Two weeding treatments of 10-day (W1) and 20-day (W2) intervals and different treatments include soil 1) control soil 2) control soil+ manure (1:1), 3) control soil + decomposed litter (1:1), 4) control soil + manure + decomposed litter (1:1:1) were applied. The results obtained for each species seedlings following first growing season indicated better response of W1 compare to W2 for most of the characteristics include growth, biomass, vitality and performance. C. sempervirens in no. four soil treatment with 10 day weeding interval, showed the optimal rate of all studies traits. Decreased competition, increased light, nutrient availability could be attributed to shorter weeding interval and successful seedling establishment. Therefore, weed control applied at shorter interval (10-day) during the first growing year combined with fertile soil is recommended.