Date of planting and seeding rate effects on quantitative and qualitative characteristics of turnip in agro forestry compared to mono cropping systems

Agroforestry is one the aspects of sustainable agriculture in which multiple cropping of perennial trees in mixture with crops guarantees the environmental، economical and social sustainability in rural communities. High demands for forage in Northern provinces of Iran lead to agroforestry in citrus orchards as a potential mean for forage production through agroforestry systems. This research was conducted to determine the best planting date and seeding rate of turnip in agroforestry and mono cropping systems. The treatments were arranged as split factorial based on a completely randomized block design with three replications. The cropping systems (agroforestry and mono cropping) were assigned to the main plots and the factorial combinations of planting dates (March 10th، March 25th، and April 9th) and seeding rates (1، 2، and 4 kg seed ha-1) were randomly assigned to the subplots. The results of the experiment showed that as the seeding rate increased to 4 kg. ha-1، a significant increase (by 5%) in total forage production was observed in both cropping systems. A decreasing trend in forage production was observed in latter planting dates for both cropping systems; however، this decrement in mono cropping was more severe than agroforestry system. In later planting dates the water soluble carbohydrates and forage dry matter digestibility increased but ADF decreased. The results of this experiment indicated a great potential for forage production in citrus orchards of the northern provinces of the country through agroforestry systems.