Evaluating Effect of Different Nitrogen Application Managements on Yield and Some Quality Traits of Strawberry

In order to evaluate the effect of nitrogen rates and application times on yield and some quality characteristics of strawberry cultivar Queen Elisa in the perennial harvesting system, a field experiment was conducted at Grizeh Station in Sanandaj District, Iran, from September 2011 to 2013. Treatments included four rates of nitrogen (N0, N50, N100, and N150 kg N. ha-1 from urea) and four application times: T1=Total nitrogen in spring (two weeks before flowering), T2=Total nitrogen in spring (one day after the last harvest), T3=Total nitrogen at the beginning of September, and T4=Application of nitrogen in three equal installments at times T1, T2, and T3. Experiment was conducted with three replications as a factorial in a randomized complete block design. The results of analysis of variance showed that the effect of year on yield, TSS, pH, acidity, and dry matter of fruit was significant (p<1%). The main effects of nitrogen rates and application time on yield, dry matter, and TSS of fruit were significant (p<1%). The interaction effect of year and application time on fruit yield was significant (p<1%). The interaction effect of application time and nitrogen rates on fruit yield was significant (p< 5%) and on dry matter and TSS of fruit at p<1%. The highest fruit yield was obtained in N150 treatment and T4 application time of 629 g. plant-1 followed by fruit yield in N150 T3, N100 T4, and N100 T3, respectively, while N150 and N100 at T2 were not significantly different from the control. The effects of different nitrogen rates and application times of nitrogen on chlorophyll index and leaf nitrogen concentration were significant (p<1%). With increasing nitrogen rates, its concentration in the leaves increased. There was a strong positive correlation between nitrogen concentration in leaves and leaf chlorophyll index. Nitrogen rates and application times had no effect on titratable acidity and pH of fruit. By application of 100 kg N.ha-1 in three equal installments at T4, the highest yield, TSS, and fruit dry matter were obtained.