Lilium morphology, physiology, anatomy and postharvest flower quality in response to plant growth regulators

Plant growth regulators (PGRs) are chemical compounds that can potentially stimulate cut flowers growth and development and play key regulatory roles in plant responses to the surrounding environment. The aim of this study was to assess how the application of five PGRs; 6-Benzylaminopurine (BA, cytokinins), indole-3acetic acid (IAA, auxins), gibberellic acid (GA3, Gibberellins), Ethephon (ethylene stimulant, stem retardant) and Ancymidol (stem retardant) affected plant morpho-physiology, leaf and stem anatomy, yield and flower quality of lily (Lilium pound elegans cvs. MayTime and Fangio). Two experiments were carried out; in the first experiment, PGR stimulants (BA, IAA, GA3) were applied at rates of 50 and 200 mg l-1 on days 30 and 40 (vegetative stage). The results showed that BA and GA3 at 50 mg l-1 significantly increased leaf area in 'Fangio' by 44 %-69 %. In addition, BA, IAA and GA3 at lower rate (50 mg l-1) significantly increased flower number per stem ('Fangio' 29 %-47 %; 'Maytime' 20 %-70 %), and vase life ('Fangio', 16 %-32 %; 'Maytime' 17 %-18 %). In terms of anatomy, BA at both rates (50 and 200 mg l-1) increased leaf thickness while GA3 at 50 mg l-1 increased the total number of vascular bundles in the stem, compared to control untreated ones. The cultivar 'Maytime' had higher leaf area (200 %), plant height (73 %), number of days to flowering (49 %), brightness or lightness color L* (106 %), lower number of flowers per stem (43 %), and shorter vase life (21 %) than 'Fangio'. In the second experiment, both lily cultivars received two foliar sprays of growth retardants; Ancymidol at rates of 50 and 200 mg l-1 and Ethephon at 50 and 500 mg l-1. Ancymidol at 50 mg l-1 was effective in reducing stem elongation by 23 % to 41 % without adverse side effects on leaf and flower quality. In fact, lilies plants treated with Ancymidol at 50 mg l-1 had similar leaf area, chlorophyll content, photosynthesis rate, stomatal conductance, transpiration, flower diameter, number per stem and vase life to that of control nontreated plants. On the other hand, reduced stem length (28 %-53 %) resulted from Ethephon application was associated with 67 % to 100 % flower abortion across lily cultivars. Overall, this study revealed that foliar application of PGRs (BA, GA3 and IAA) at a rate of 50 mg l-1 hold promise for improving flower quality of lily cultivars, specifically, flower numbers per stem and vase life. In addition, 50 mg l-1 of Ancymidol is efficient in producing compact plants while maintaining leaf and flower quality components.(c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.