Hayward kiwifruits and Plant Growth Regulators: Detection and effects in post-harvest studied by Magnetic Resonance Imaging and Scanning Electron Microscopy

We used Magnetic Resonance Imaging spectroscopy to reveal the use of two Plant Growth Regulators (PGRs), i.e. cytokinin and auxin, on Hayward kiwifruits, at any stage of cultivation, and post-harvest ripening and storage. The internal morphology was non-destructively determined in order to depict structural features related to hormones treatments and we found that T ₂-weighted MRI images showed different internal tissue organisations depending upon the use and the type of PGR. Transverse relaxation times allowed the recognition of cytokinin-treated samples, whilst image analysis was used to identify auxin-treated kiwifruits. We also exploited the post-harvest conditions, i.e. normal refrigeration and controlled atmosphere, on PGRs treated kiwifruits, and found that auxin shortened the shelf-life, with normal refrigeration exerting a stronger effect. The kiwifruit pulp was also investigated by means of Scanning Electron Microscopy, highlighting significant differences at a cellular level amongst treatments, in terms of pore size and vacuoles number, both probably playing a fundamental role in the evaporation activity.