Introduction: The dragon's head, with the scientific name Lallemantia sp, is one of the medicinal plants of the mint family (Lamiaceae). Dragon's head is a plant that has various uses due to its medicinal and industrial properties as well as its use in agriculture. This plant is used in sustainable agriculture in arid and semi-arid regions of Iran. Drought is one of the most important issues in the cultivation of medicinal plants in arid and semi-arid conditions. Because one of the factors that may have a significant adverse effect on plant growth is water scarcity. In contrast, the ability of plant species to tolerate water deficit and wet conditions varies, and this characteristic is usually used to identify drought-tolerant species. Dragon’s head ability to produce in dry conditions shows the flexibility and adaptability of this plant in drought stress conditions. In summary, weather conditions greatly impact the production and effectiveness of medicinal plants by affecting the levels of active substances. Changes in sowing dates influence plant density and water availability during growth. Effective irrigation planning, considering factors like water use efficiency, seed yield, and overall water utilization, is crucial for maximizing plant growth and economic performance. By considering weather conditions, adjusting sowing dates, and implementing efficient water management strategies, farmers can enhance water use efficiency, economic performance, and the overall quality of medicinal plant production. Considering the lack of information about the response of different dragon head species in autumn and spring sowing under arid and semi-arid conditions, the present study was conducted to investigate the effect of sowing date on yield and quantitative and qualitative traits of dragon's head (L. iberica) and lady's mantle (L. royleana) in dry and semi-dry conditions.
Materials and Methods: To investigate the effect of planting date on the yield, quantitative and qualitative traits of the dragon’s head (L. royleana and L. iberica) under dryland condition, a factorial experiment was conducted in the form of a randomized complete block design in three replications. The first factor was two types of Lallemantia (L. royleana and L. iberica), and the second factor was the planting date (November 29 and March 8, respectively, as autumn and spring sowing).
Results and Discussion: The results showed that the simple effect of species on the thousand seed weight at the 5% probability level, number of sub-branches was significant, mucilage percentage and mucilage yield at the 1% probability level. So, the number of sub-branches and mucilage percentage in L. royleana increased by 121.7% and 88.6%, respectively, compared to L. iberica. Also, by examining the simple effect of sowing date (autumn and spring), the number of sub-branches increased at the 5% probability level. Plant height, seed yield, biological yield, harvest index, mucilage yield, and water use efficiency increased at the 1% probability level at the autumn sowing date compared to the spring sowing date. In this regard, grain yield and water use efficiency on the autumn sowing date showed an increase of 125.8% and 126.6%, respectively, compared to the spring sowing date. In addition, the mucilage yield and harvest index in the autumn sowing of L. royleana were 271.3% and 36.6% higher, respectively, than the spring sowing of L. iberica.
Conclusions: In general, the sowing date of 29 November (autumn sowing) due to the length of the season, favorable temperature, humidity, and sufficient rainfall compared to 8 March (spring sowing) can be considered suitable for both (L. royleana and L. iberica) dragon's head species under dryland condition. In addition, considering the soil salinity conditions in this study and the increase in mucilage of L. royleana species compared to the L. iberica species, it is necessary to carry out additional research in field condition.