Improved clonal approaches to growing black locust (Robinia pseudoacacia L.) in Hungary: a case study

Black locust (Robinia pseudoacacia L.) was introduced to Hungary about 300 years ago and at present it covers approximately 23 per cent of the forested lands (465 000 ha). It has been well adapted for growth in a wide variety of ecological conditions and planted throughout the world from temperate to subtropical areas. It is fast growing, excellent coppicing, drought tolerant, has high survival rates and yield as well as very hard durable wood (Rédei et al. 2002). Due to its symbiosis with the nitrogen fixing bacteria, Rhizobium sp. black locust is capable of colonising very low nutrient substrates. Black locust is also a promising tree species for short rotation forestry (SRF) including energy plantations (Rédei et al. 2002, 2008). Besides Hungary black locust breeding and improvement is undertaken in the United States (Bongarten et al. 1991, 1992), Greece (Dini-Papanastasi & Panetsos 2000), Germany (Liesebach et al. 2004, Böhm et al. 2011), Slovakia (Chalupa 1992), Poland (Kraszkiewicz 2013), Turkey (Dengiz et al. 2010), India (Sharma 2000), China (Dunlun et al. 1995) and South Korea (Lee et al. 2007). Brown (1980) was the first to report a successful in vitro method for mass production of black locust. Enescu & Jucan (1985) started experiments in Romania with similar results. Balla & Vértesy in 1985 had the first success in the sterile production of some Hungarian state-approved black locust cultivars. Balla et al. (1998) published the improvement of the acclimatization results of micropropagated black locust using symbiotic microorganisms which have proved to be successful in the field of mass clonal micropropagation (Rédei et al. 2002). Finally, a summary on black locust micropogation techniques was published by Jain et al. (2007). In this paper a field trial established with micropropagated black locust clones is evaluated with special regard to their propagation technique and juvenile growth.