Difference in drought resistance among three Brassica species at different growing stages and application of zeolite

One of the factors limiting the growth of crops is water deficit. A split plot factorial experiment was conducted in Qazvin (Iran) to determine the effects of water deficit stress on three Brassica species at different growing stages and application of zeolite in 2010–12 growing seasons. In these experiments factorial combination of different levels of water deficit stress (regular irrigation (I₀), withholding irrigation from flowering stage to end of plant life cycle (I1), and withholding irrigation from pod stage to end of plant life cycle (I₂) and zeolite were applied (0 and 10 t.ha⁻¹), in main plot units, and different species (B. napus, B. rapa and B. junceu) were placed in sub plot units. Results showed that interactions among water deficit stress and different species, different water deficit stress and two zeolite amounts were significant for number of branches per plant, length of main, sub and total plant pod, and seed oil yield. Application of zeolite in all water deficit regimes increased the seed oil percent and seed oil yield and in interaction between these two factors, \ without zeolite reduced the seed oil yield, in comparison to I₀and zeolite application.