Effect of Partial Root Zone Drying on the Quantitative Traits of (Thymus vulgaris L.)

Considering the limited water resources in arid and semi-arid climate of Iran, deficit irrigation is one of the strategies for efficient use of water and increasing water use efficiency in agricultural districts. In order to study the effects of deficit irrigation on the quantitative traits of Thymus vulgaris L., an experiment was conducted in Kerman Municipality seedling production station in 2016. The experimental treatments were arranged as randomized complete block design with three replications. The irrigation regimes consisted of full irrigation (FI-100), regulated deficit (RDI75% and RDI55%) and partial root zone drying irrigation (PRD75% and PRD55%). The results showed that the highest herbage dry weight (1670.6 kg/ha) and leaf area index in different stages of growth were produced by full irrigation treatment, while no significant difference between this treatment and PRD75 was observed. Also, the highest number of shoots (64.4) and plant height (39.4 cm) were produced by full irrigation treatment and there was significant difference between this treatment and other treatments. However, the highest water use efficiency (0.66 kg/m3), root fresh weight (4.5 g), root depth (15.8 cm) and root volume (2.8 cm3 per plant) appeared in PRD75. Therefore, 75 percent water replacement in partial root zone drying irrigation treatments, in addition to saving water consumption, provides better use of soil moisture and sunlight. Thus, this treatment can be considered as suitable approach to cope with the water crisis and achieve a sustainable agriculture.