Evaluate the effect of drought stress on the quantity and quality of medicinal plant populations Balangu (Lallemantia royleana Benth.)

Introduction: With the advancement of science and the world's attention to the harmful effects of chemicals and synthetic materials, world again turned to the use of herbal products, so it is said twenty-first century, a century medicinal plants (Amanzadeh et al., 2011).Lallemantia royleana is a member of Lamiaceae family. This family is one of the largest and most distinctive flowering plants (Zargari, 1980).Balangu seed is a good source of polysaccharides, fibre, oil and protein and has some medicinal, nutritional and human health properties (Naghibi et al. 2005; Razavi and Karazhiyan 2009). Drought is one of the major abiotic stresses that severely affect and reduce the yield and productivity of food crops worldwide up to 70% (Akram et al., 2013). The response of plants to drought stress is complex and involves changes in their morphology, physiology and metabolism (Sairam and Srivastava, 2001). Therefore, the objective of this research was to study evaluate the effect of drought stressthe quantity and quality of medicinalplant Bulangu population. Materials and methods: In the research experimental field of medicinal plants the Shahed University, during the 2014-2015 cropping season. This experiment was a split plot arrangement based on randomized complete block design (RCBD) with three replications. Three drought stress levels which include -3.5, -6.5, and -9.5 atm of soil water potential as the main factor levels, while five Bulangu population which include Esfahann3, Esfahann5, Esfahann6, Esfahann7 and Kordestan were arranged to sub plots. The site is located at latitude of 35°34´E, longitude 51°8´N, with an altitude of 1190 m above the sea level and its precipitation rate was 216 mm throughout the experimental period.‎Studied traits were determined according to the following protocols: Soluble sugars (Paquin and lechasseur, 1979), Mucilage percentage (Ghasemi Dehkordi, 2002), Inflation factor (Asgharpour and Rezvani Moghaddam, 2002), and Oil yield (Rasti et al., 2012). The RWC (relative water content) was determined according to Levitt 1990. All calculations were performed using the SAS software, version 9.1 and means were compared using Duncan’s range test at P=0.05. Results and discussion: Climate change is causing more frequent and intense periods of drought as overall rainfall levels decline. Dry areas cover more than 40% of the world’s land surface and are home to 2.5 billion people; one-third of the global population. Drought is currently one of the main constraints that prevent crop plants from expressing their full genetic potential. Drought had a significant effect on grain yield, biological yield, harvest index, soluble sugars, mucilage percentage, Inflation factor, RWC (relative water content) and oil yield. Drought was no significant effect on oil percentage.The results of this study demonstrate that increased drought reduced grain yield. Crop yield response to water efficiency in different stages of plant growth and water use throughout the growing season (Igbadun et al., 2006). The E3 population with the highest grain yield of (312.77 kg/ha) and oil yield of (86.7 kg/ha) in moisture potential -9.5 atm.Drought reduces the amount of soluble sugars. This results compatiblity with the results Abbaszadeh et al. (2007) in (Melissa officinalis).The effects of the interaction of E5 and E3 populations in the highest and lowest mucilage percentage mild stress into account. According to the study looks population Esfahan3, is to drought stress resistant population. Conclusions: It can be generally concluded that, drought stress atmosphere -9.5 atm decreases the quantitative and qualitative characteristics of medicinalplant Bulangu population. The Esfahan3 population has the highest grain yield and oil yield. According to the study looks population Esfahan3, is to drought stress resistant population. Results comparisons of traits in populations Balangu average suggests that most of these changes may be due to their genotype.