337 Proc. VII th IS on Kiwifruit Eds.: G. Costa and A.R. Ferguson Acta Hort. 913, ISHS 2011 Use of Plant Bioregulators in Kiwifruit Production G. Costa 1 , F. Spinelli 1 , A. Soto 1 , S. Nardozza 1 , L. Asteggiano 2 and G. Vittone 2 1 Department of Fruit Tree and Woody Plant Sciences, Bologna University, Italy 2 CReSO, Consorzio di Ricerca e Sperimentazione per l’Ortofrutticoltura Piemontese, Cuneo, Italy Keywords: nursery, open field, pre-harvest, post-harvest, JA, ABA, disease control Abstract In kiwifruit, plant bioregulators (PBRs) have found several applications. In nursery, auxin containing compounds (NAA and IBA) are used to enhance root formation in woody and herbaceous cuttings; in micropropagation techniques, auxins are routinely used to promote root formation and cytokinins to induce shoots proliferation. In field conditions, the application might start very early in the season. During dormancy, dormancy breaking agents (Dormex, Hi-cane, Citokin and Armobreak) are used to overcome lack of chilling requirements enhancing bud break and fertility. Therefore, after blooming, auxins, gibberellins (Triclopir, Spray Dunger Global) and cytokinins (forchlorfenuron) are used to affect fruit morphogenesis. Recently, other new PBRs, such as jasmonates, were tested in kiwifruit to affect flesh colour in fruits of Actinidia chinensis, and to reduce water use in both A. chinensis and deliciosa, such as abscisic acid. In post-harvest conditions, the use of molecules able to interfere with ethylene biosynthesis, such as 1-MCP, are suggested to prolong fruit storage and shelf-life. INTRODUCTION In kiwifruit plant bioregulators (PBRs) have been proposed for several uses from the plant propagation to the field application up to post-harvest. In the nursery, synthetic auxins are used to stimulate cutting root formation. In open field conditions, starting from the dormancy period in January-February, ‘dormancy breaking agents’ (DBA) are used to overcome the lack of chilling requirement in the climatic areas characterized by warm winter temperatures. In open field conditions, several bioregulators, like cytokinin (CK), auxin and gibberellins (GA) are used to increase fruit morphogenesis. Other chemicals belong to a class arbitrarily named “biostimulant” (Phytagro, Benefit, etc) showed similar effect. Recently new PBRs (i.e. jasmonic acid, abscisic acid) were tested on both kiwifruit specie Actinidia deliciosa and A. chinensis cultivars to enhance fruit quality (flesh colour intensity and soluble solids content) and to reduce water use. Finally, in post-harvest conditions, some preliminary trials indicated that the use of 1-MCP can ameliorate the performance of the fruits during storage and controlling, to some extent, the appearance of some post-harvest diseases, such as Botrytis cinerea. NURSERY Several PBRs belonging to hormones promoters are used for plant propagation. Synthetic auxins, such as alfa-naphthalenacetic acid (NAA) and indol butirric acid (IBA) are used to affect root formation of the woody cuttings and of the herbaceous cutting while, auxins and CKs are mainly used in the micropropagation techniques. In the first case, both NAA an IBA synthetic auxins are used to increase cutting root formation. This technique is routinely done in the nursery and the application consists in dipping the basal part of the cutting in a liquid solution for few second (5 to 10) or in a powder preparation containing the active ingredient. The chemical in a powder preparation has a fixed concentration (2%) while when the active ingredient is dissolved in a liquid solution, the concentration ranges from 1000 up to 5/6000 ppm (Biasi et al., 1990). Researches carried out on ‘Hayward’ cuttings showed a better efficacy for NAA formulates than IBA on the woody plant material on increasing both root number and quality without stimulating an excessive callus proliferation, which, instead, was normally induced by IBA. However,