Evaluation the effect of deficit irrigation on growth indices of Petunia (Petunia hybrida L.), Coneflower (Rudbeckia fulgida L.), Blanket flower (Gaillardia grandiflora L.), Marigold (Tagetes patula L.)

In order to investigate the effect of different irrigation levels of deficit irrigation on growth indices of Petunia (Petunia hybrida L.), Coneflower (Rudbeckia fulgida L.), Blanket flower (Gaillardia grandiflora L.), Marigold (Tagetes patula L.), a pot experiment was conducted in a research greenhouse in Mashhad, on 2016. This experiment was carried out as a factorial experiment based on completely randomized design with three replications. The treatments were different irrigation levels (100% field capacity (control), 75% field capacity, 50% field capacity, 25% field capacity) and 4 flower species (Petunia, Coneflower, Blanket flower, Marigold). In this experiment, irrigation treatements were selected so that plants were exposed to non-stress conditions, moderate stress, moderate stress and severe stress. Application of irrigation stress was done using weighted method. Recorded Traits were leaf area index (LAI), plant height, number of flowers, flower mean diameter, flower fresh and dry weigh, leaf fresh and dry weight, lateral branche number, lateral branche fresh and dry weight, root fresh and dry weight, root height, bud number, bud fresh and dry weight, stem diameter, shoot fresh and dry weight. Results showed that different species and different irrigation treatements and their interactions had significant effect on the traits (p<1%). Comparison of different plant species characteristics showed that coneflower was the most resistant species in terms of plant height, root fresh weight and flower number. In terms of root length, the most resistant species was petunia and marigolod and blanket flower were sensitive. About the number of lateral branches, blanket flower was resistant and coneflower was sensitive. Also, coneflower was resistant and petunia and blanket flower was sensitive in terms of flower number. In terms of mean flower diameter, resistant species was petunia and marigold, blanketflower and coneflower were susceptible.