Phenological, yield, essential oil yield and oil content of cumin accessions as affected by irrigation regimes

Cumin (Cuminum Cyminum L.) is cultivated in arid and semi-arid regions where drought is a common problem, thus developing irrigation programs to minimize yield and quality reduction in this area is needed. Therefore, plant height, yield components (number of branches/plant, number of umbels/plant, number of umbellets/plant, seed numbers/umble and1000 seed weight), seed and essential oil yields, aerial parts essential oil content and seed oil content of four cumin accession were determined under 70, 150 and 200 mm irrigation regime based on evaporation of class A pan during 2011and 2012 in Isfahan, Iran. Seed and essential oil yields, number of irrigation per year and seed oil yield decreased, while annual water used and irrigation water use efficiency increased as drought level increased. Aerial essential oil content was not affected by severe but increased under moderate drought stresses. However, there was interaction between irrigation regime and accession and based on 40% or less reduction in seed yield, Isfahan and Khour could be cultivated under 70-200 mm, while Nishapur and Yazd could be planted under 70-150 mm irrigation regimes. Furthermore, based on 30% or less reduction in essential oil yield, Isfahan, Khour and Nishapur could be planted under 70-200 mm while Yazd could be planted under 70 mm irrigation regimes for essential oil yield production. Whereas, for both seed and essential oil yields production, Yazd under 70 mm, Isfahan under 150 and Khour under 200 mm irrigation regimes were the most productive accessions, thus recommended for cultivation under these conditions. The results suggested that cumin is a drought tolerant species, but its water requirement depends on genotypes and purpose of cultivation.