Biochemical and morphological response of Carrizo citrange and Volkameriana rootstocks to putrescine and water stress

Water stress is one of the most important problems that limit the cultivation of crops in arid and semi-arid regions of Iran. In this study, the effect of putrescine was studied on one-year-old seedlings of both Carrizo citrange (Citrus sinensis Osb. × Poncirus trifoliate Raf.) and Volkameriana (Citrus volkameriana) grown in containers, under water stress. A factorial experiment based on a completely randomized design was set up using putrescine at three concentrations of 0, 1, and 2 mM on seedlings under 0.3 field capacity. Results showed that foliar application of putrescine increased root and shoot growth and total plant biomass in both seedling rootstocks. Putrescine significantly reduced the root diameter, which was due to an increased percentage of fine roots. Moreover, the application of putrescine significantly increased the relative water content, proline, and soluble sugars content, but reduced the electrolyte leakage. Although the growth rate and total plant biomass had been decreased under water stress, putrescine application limited the downward effects of water stress in both mentioned seedlings.