Effects of Soil moisture content and Urea fertilizer on survival, growth and some physiological attributes of Mediteranian cypress seedling

This study conducted with the purpose of investigating the response of Mediteranian cypress seedling to changes of moisture and nitrogen nutrition status in the soil, given the importance of in this species seedling production and forestation practices in dry and semi dry environments of the couuntry. For this purpose, 270 healthy and uniform seedlings of Cupressus horizontalis L. prepared, and examined under 6 soil moisture content (100, 75, 50, 25, 15 and 10 percent of field capacity) and 3 levels of urea fertilizer, including Control, Low and High concentration respectively with 0, 75 and 150 mg/kg urea, using a two way factorial experiment with 3 replications based on randomized complete block design for 5 months (from May to November). The results showed that more than 82.2% of seedlings survived until 25% field capacity (FC) in Control (no fertilizer) treatment. Survival of seedlings in 15% and 10% FC under the effect of Urea fertilizer, especially under HN treatment, was gained 100% and 66.7% respectively. Regardless of Urea, reduction of soil moisture content, specially in 50% and 25% FC, significantly decreased characteristics of stem length growth, biomass of different parts, quality index (QI) and physiological properties (photosynthetic area, relative water content and total chlorophyll) of seedlings. However, increase of Urea fertilizer, increased survival, biomass of different parts of seedlings, physiological properties, WUE, Total Chlorophyll, and QI of seedlings. Therefore, it is suggested that in order to produce C. horizontalis seedlings, soil moisture content should not drop under 50% FC; Otherwise, the use of Urea fertilizer is necessary with the aim of improving growth, quality and water use efficiency of seedlings.