Determination of optimum N and P fertilization levels for dry flower yield and essential oil percentage in autumn-grown German chamomile (Matricaria chamomilla) in Jiroft, Iran

In order to determine the most appropriate N and P fertilization levels for flower yield and essential oil percentage of German chamomile, a field study was carried out in Jiroft, Iran as a factorial experiment based on a randomized complete block design with three replications in which the factors were pure N from urea source (46%) at four levels of 25, 50, 75 and 100 kg.ha-1 and pure P from superphosphate triple source at four levels of 25, 50, 75 and 100 kg.ha-1. Results showed that different levels of N and P and their interaction significantly affected essential oil percentage, essential oil yield per ha and flower number per plant at 1% probability level. Auxiliary branch number was significantly affected by N fertilization level at 5% probability level and by P fertilization level at 1% probability level. N fertilization significantly impacted dry flower yield per ha at 1% and 5-flower dry weight at 5% probability level. Also, P fertilization level significantly impacted the former at 5% and the latter at 1% probability level. In order to realize the maximum essential oil yield per ha, it is recommended to use fertilization level of 75 kg N.ha-1 + 25 kg P.ha-1.