Evaluation of changes in fatty acid profile, grain, and oil yield of Carthamus tinctorius L. in response to foliar application of polyamine compounds under deficit irrigation conditions

Abstract

Safflower is an oilseed plant rich source of omega 3 and 6 whose fatty acids composition may be affected by water deficit stress. Thus, filed experiments were conducted in Tehran, Iran during 2017 and 2018 growing seasons to investigate the influence of foliar application polyamines on fatty acid compositions and agronomic traits under deficit irrigation stress as a split plot with four replications. The studied treatments included irrigation at two levels of normal irrigation (I1, 50 %) and deficit irrigation at flowering stage (I2, 75 %) (irrigation after depletion of 50 % and 75 % moisture of field capacity, respectively) as the main plot and foliar application treatments at 10 levels included (water foliar application or control, foliar application putrescine, spermidine and spermine each in concentrations (50, 100, 200 μmol L−1)) as the subplot. Foliar application of putrescine under I2 enhanced grain and oil yield by 721.7 and 120.7 kg ha-1, respectively, on average in the two years of experiment compared with the control treatment. The total polyunsaturated and unsaturated fatty acids (∑PUFA and ∑UFA), UFA (omega 3 and 6), ratio of ∑PUFA to saturated fatty acids (∑SFA), harvest index and oil content rose under I2 conditions in both years of the experiment with spermine foliar application. Foliar application of putrescine also increased omega 6, ∑PUFA and ∑UFA under I1 conditions in both years. The results of this experiment indicate that foliar application of polyamines can improve grain and oil yield and quality of fatty acids of safflower under irrigation regimes.