The effect of low irrigation regime on biomarkers of two local variety of ajwain (Trachyspermum ammi )

Deficit irrigation is one of the new ways to reduce the effects of drought stress because crops can be supplied with available water in a controlled manner throughout the growing season. In order to investigate the effects of deficit irrigation on two local variety of ajwain, a factorial experiment was conducted based on a randomized complete block design with three replications in 2017 in the Research Farm of University of Birjand, Iran. The factors included three levels of soil moisture deficit (SMD: 50, 75 and 100 percent of field capacity), and two landraces of ajwain (Birjand and Sistan). Vegetative traits including plant height, leaf area and weight, yield components and quantitative and qualitative yield were measured. Resutls revealed that a reduction in the irrigation level, from 100 to 50% of field capacity, caused the grain yield, essential oil yield, biological yield, seed weight and number of umbels per plant to be reduced significantly. Sistan landrace had a higher chlorophyll a and b and carotenoid contents than Birjand, which may reflect an increase in the special leaf area (increased thickness) of Sistan landrace. Two landraces showed a different response to reduced irrigation. The growth characteristics and quantitative and qualitative yields of Sistan landrace were less affected by low irrigation levels, compared to Birjand landrace. In general, it can be said that the local variety of Sistan has a better compatability with deficit irrigation; however there was no significant difference between grain yield and essential oil yield of these two landraces.