# Allelopathic Activity of Leaf Wastes of _Lriodendron tulipifera_ for Sustainable Management
## 1 Introduction  
_Lriodendron tulipifera_ L., belonging to the Magnoliaceae family, is a hardwood tree and grows to 25-40 m in height as well as to 1-2 m in trunk diameter. The alternate simple leaves are palmately lobed and grow up to 10-15 cm long and wide [1, 2]. The species is native to eastern North America and was introduced to many other countries under temperate climate conditions in Europe and East Asia [3, 4, 5]. _L. tulipifera_ grows along residential streets as shade trees and in parks as well as gardens as ornamental trees [6, 7, 8]. _L. tulipifera_ is also valuable as a nectar source for honey production. A 20-year-old tree of _L. tulipifera_ was recorded to produce 3.6 kg of nectar in one season, which is equivalent to 1.8 kg of honey [6]. Since _L. tulipifera_ grows rapidly and has tall and straight trunks, its timber is commercially valuable [2, 3, 9]. The average dry weight of the timber is 455 kg per m\({}^{3}\) (hardness, 2400 N) [9], and the wood of _L. tulipifera_ is used in a wide range of products, such as furniture, interior finishing, and plywood [10, 11, 12]. However, logging operations of _L. tulipifera_ from tree plantations create a great amount of industrial waste, such as leaves, branches, bark, and stumps. It was recorded that 80% of total tree biomass went to waste during logging operations [13]. Minimizing waste may contribute to the sustainability of timber production systems and reducing the environmental impact [14, 15]. The development of possible applications for the waste from timber processing and the minimization of the environmental impact are two tasks to be completed for future timberproduction systems. Several options of the usage of \(L\). _tulipifera_ waste from logging operations have been investigated, such as charcoal and bio-oil from the wood waste [13; 16], solid fuel from the sawdust [17], and bioethanol from the branches and wood [18; 19]. In addition, \(L\). _tulipifera_ is a deciduous tree species, and its fallen leaves accumulate on the streets and grounds in parks and gardens in the autumn, where they are grown as shade and ornamental trees. These fallen leaves need to be organized at a high expense [20]. However, the utilization methods of leaf waste from logging operations and fallen leaves from residential areas have not yet been investigated. The bark of \(L\). _tulipifera_ has been used by Native Americans as an antipyretic for the treatment of malaria [21; 22; 23; 24]. Pharmaceutical investigations have shown that \(L\). _tulipifera_ bark contains several secondary metabolites, such as alkaloids and lignans [25]. Its wood, roots, and leaves have also been reported to contain many secondary metabolites, such as alkaloids, terpen, flavonones, lignans, and steroids, and some of them have shown pharmacological activity [23; 24; 26; 27; 28; 29; 30; 31]. Although the allebotatic activity of these identified compounds in \(L\). _tulipifera_ has not yet been investigated, some of these compounds may work as allebotatic agents. Allebotathy is the chemical interaction between donor and receiver plants, and donor plants can release certain secondary metabolites, defined as allelochemicals, to their neighboring environments [32; 33; 34; 35]. Allelochemicals affect the germination, growth, development, and regeneration of plant species nearby, including weed plant species, and most allelochemicals show inhibitory effects [36; 37; 38; 39]. Therefore, allebotatic plants and their tissues, which contain allelochemicals, can potentially be applied for weed control purposes. Some allebotatic plants have shown excellent weed control ability when these plants were incorporated into the soil as soil additives and when their extracts were applied to weeds as a foliar spray [40; 41; 42; 43]. Weed infestation causes significant problems in agricultural production [44; 45; 46]. However, there is no available information on the allebotathy of \(L\). _tulipifera_ leaves in the literature. The objective of this research was to develop a possible application of \(L\).