ارزیابی عملکرد، اجزای عملکرد، ویژگی‌های کیفی و میزان نور دریافتی گیاه دارویی بابونه آلمانی در کشت تلفیقی با درختان صنوبر

Background and Objectives: Many medicinal plants grow under the canopy of forest trees and are shade-tolerant, so agroforestry can be a suitable and practical strategy for promoting their cultivation and conservation. The agroforestry system is one of the land use systems that affects the soil's physical, chemical and dynamic properties and maintains agricultural sustainability. Little research has been conducted on the productivity of agroforestry systems, especially with medicinal and aromatic plants under a poplar-based Silvi-medicinal system. Accordingly, in the present study, the growth rate, yield, and yield components of chamomile in pure and mixed cultivation with poplar were compared under Karaj conditions.



Materials and Methods: This study was conducted for five consecutive years from 2017 to 2021 to evaluate the yield and essential oil of the medicinal plant German chamomile (Matricaria recutita L.) in an intercropping crop with poplar trees. Chamomile medicinal plant was planted in late autumn 2017 in the Alborz Research Station farm, between the rows of uniform seedlings of poplar (Populus euramericana clone of 92/40). Seedlings of Populus were planted in March 2017 at a distance of 3 m × 4 m. The statistical design of this research was a paired t-test with 2 treatments (chamomile with poplar and chamomile monoculture) in three experimental plots and 6 replications in each plot. Chamomile seeds were sown in five rows with a length of 21 m and 50 cm among rows and 10 cm in rows at a depth of 2 cm of soil, and then field irrigated immediately. During each growing season, poplar seedlings were irrigated once a week until late November, and chamomile plants until early September (before seed maturity). Then, variables of yield and yield components of chamomile, chlorophyll, and carotenoid concentrations, essential oil (%) and essential oil yield, percentage of tree shade density each year, and soil carbon content at two different depths by measuring the percentage of organic carbon and the apparent specific gravity of the soil in the final year were calculated.



Results: The results showed that the variables of plant height, number of flowers per plant, flower diameter, seed yield, and number of main stems showed statistically significant differences in all years studied and in the first and second years, the highest amount of these variables was in intercropped cultivation compared to sole cultivation. The amounts of chlorophyll a, chlorophyll b, and total chlorophyll in the second and third years of harvest were higher in sole cultivation than in intercropped cultivation. A comparison of means showed that intercropped cultivation had the highest essential oil (%) in the first year with 0.78% and the lowest essential oil (%) in the third year with 0.41% due to the decrease in mount of light intercepted. The intercropped crop had the highest essential oil yield in the first year with 451.02 kg ha-1 and the lowest essential oil yield in the third year with 116.03 kg ha-1. In the third year of harvest, the amount of light intercepted during the growing months in the intercropped crop was greatly reduced, so that the density of shading created by poplar trees on the chamomile crop was calculated to be 64.5%. The main effect of cultivation type and soil depth and the interaction between these two factors on the rate of soil organic carbon content was significant, and the highest amount was obtained in intercropping at a depth of 30-60 cm.