The impact of foliar dikegulac and Asahi SL sprays on the shoot production of highbush blueberry nursery plants

The aim of the present study was to assess the usefulness of dikegulac (2,3:4,6-di-O-isopropylidene-α-Lxylo-2-hexulofuranosonic acid) and Asahi SL (sodium ortho- and para-nitrophenolate, sodium 5-nitroguaiacolate) in production of highbush blueberry nursery plants. The experiment was carried out on three cultivars of highbush blueberry: ‘Bluecrop’, ‘Brigitta blue’ and ‘Darrow’. Pot plants were treated two times with dikegulac (0.1%) or/and Asahi SL (0.2%) foliar sprays in the late spring. The reaction of blueberry clones to the tested chemicals was different. Dikegulac-treated plants developed significantly more shoots making them a good and efficient source of cuttings when using the traditional propagation. Dikegulac limited the shoot elongation of two studied cultivars (‘Bluecrop’, ‘Darrow’). It also reduced the size of leaf blades but generally did not change the fluorescence and the relative content of chlorophyll. The influence of dikegulac in the applied dose was much stronger than the impact of nitrophenolates. The application of Asahi SL, alone or together with dikegulac, did not give any spectacular and advantageous effects.