Response of German Chamomile Landraces to the Geographical Orientations of Sowing Rows under Low Irrigation and Saline Soil Condition

The German chamomile (Matricaria chamomilla L.) is an annual herb from the Asteraceae family. This plant has many medicinal uses. Chamazulene, α-bisabolone oxide A and b-farnesene are part of essential oil components of German chamomile. Chamomile causes the chamomile essential oil to turn blue color. Chamazulene is the most important part of chamomile essential oil. Chamazulene has many therapeutic properties, including lowering total cholesterol and triglycerides and generally having a high anti-concentration effect of lipoprotein (Hyperlipidemia) in the blood. Most plants are more vulnerable in the early stages of growth. Within a region with adverse climatic conditions, microclimate can make more survival possible for the plants. In very warm and dry areas, in furrow sowing condition, seeds sowing in the bed of furrow in the different geographical orientations causes the formation of microclimates, especially in short plants and at the germination and seedling stages. For example, salt accumulation on the ridge and reducing soil salt in the bed of furrowimprove growth conditionsand on the other hand, shading the ridge on the furrow, by reducing the time of sunlight shining on the furrow bed reduces soil temperature and evapotranspiration in early stages of seedling growth. The geographical orientations of the sowing can affect the shading period time of the ridgeon bedfurrow.

Under low irrigation and saline-sodic soil condition (At a depth of 0 to 30 cm, with an average electrical conductivity of 7.7 dS.m-1, pH 7.7, silty clay soil texture, 1% organic matter and with an altitude of 22 meters above sea level), a field experiment conducted in a factorial based on a randomized complete block design with three replications in Khuzestan Agricultural Sciences and Natural Resources University (North East of Ahvaz, 2016-2017). The experimental treatments were included the geographical orientations of sowing rows (control (nonlinear flat sowing) and orientations of sowing rows in the North-South, East-West, North East-South West, North West-South East) and chamomile landraces (Ahvaz, Isfahan, and Shiraz).The traits that were studied included: plant height, diameter of main stem, light extinction coefficient, capitule diameter, dry weight of 10 inflorescences, number of flowers per plant, number of stems per plant, dry inflorescence yield, essential oil percentage, essential oil yield, biological yield, percentage of chamazulene, α-Bisabolone oxide A and b-Farnesene in essential oil .

Experimental factors had no significant effect on dry weight of 10 inflorescences and capitule diameter. The lowest light extinction coefficient was observed in nonlinear flat sowing. The landraces had no significant effect on main stem diameter but the effect of geographical orientations of sowing rows were significant. The lowest and highest diameter of main stem were obtained from nonlinear flat sowing, respectively. The main effect of geographical orientations of sowing rows and interaction of populations and geographical orientations of sowing rows on number of stems per plant were significant. The highest number of stems per plant (15.2) was obtained from Shiraz landrace and northwest-southeast geographical orientation but the lowest number of stems per plant was in Shiraz landrace and nonlinear flat sowing (8.7). In both the highest and the lowest number of stems per plant, the landrace of Shiraz was common, this indicates a high effect of geographical orientations of sowing rows on this trait. The highest and the lowest of number of flowers per plant was observed in Isfahan landrace in north-south orientation (78.5) and Shiraz landrace and nonlinear flat sowing (49.5), respectively. The highest number of flowers per plant, dry inflorescence yield, and the highest biological yield were obtained from Isfahan landrace in the north-south, north-south and north west-south east orientations, respectively. The highest essential oil percentage was obtained from the Isfahan landrace (East-West orientation). The lowest and highest yield of essential oil was observed in Isfahan landrace and in nonlinear flat sowing and east-west direction, respectively, which increased by 221%. Isfahan landrace received different signals due to different climatic conditions (Ahwaz) compared to the main region (Isfahan) and this increased the percentage and yield of essential oil even more than native landrace (Ahwaz population). The highest percentage of chamazulene, b-Farnesene, and α-bisabolone oxide were shown in the Ahwaz (north-south), Shiraz (south west-north east) and Isfahan (north to south) landraces, respectively.

Isfahan non-native landrace had higher biological yield (northwest-southeast orientation) and essential oil percentage (east-west orientation) and essential oil yield (east-west orientation) than Shiraz and Ahwaz native landraces. Generally, row sowing in the furrow and in a suitable geographical orientation can be a low-cost method to increase crop productivity.