Germination Capacity in Culture Medium of Prosopis Laevigata Seeds in the Presence of Copper Sulphate

Copper is a nutrient and traceable metal of prokaryotes and eukaryotes, since it is required in certain concentrations for metabolic functions (Navarrete et al, 2011), specifically, it acts as a cofactor in several enzymes and is required in several physiological processes (Auld, 2001;Cuyperset al., 2002; Nanda and Agrawal, 2016), and activates enzymes such as catalase, hydrogenase and cytochrome oxidase, also stimulates chlorophyll formation, intervenes in carbohydrate metabolism and oxidative processes, stimulates fixation of nitrogen and seed germination,(Yruela, 2005, 2009; Jeleaet al., 2016). In addition, this element can influence each stage of plants cycle of life and their sensitivity to metals (Liu et al., 2005; Muccifona and Bellani, 2013).

Copper despite being an essential nutrient for plants, in high dose concentrations of 200 mg kg-1 is toxic for their development, Leucaenaleucocephala, it specially affects corn production. Which is one of the most important crops in Mexico. Chromium also, in high doses of 200 mg kg-1affects the health of plants, although it was phytoextracted in a lower proportion than copper (Gardezi, 2007). However, copper is a pollutant among heavy metals in the environment (Zappala et al., 2013), essential for plants in low concentrations, but toxic when these are high (Hattabet al., 2009; Hattab et al., 2010). Increase use of fungicides and pesticides allows accumulation of copper in soil (Yruela, 2005; Muccifona and Bellani, 2013; Jelea et al., 2016) triggered by various anthropogenic activities that include industry, agriculture, mining, transportation, urbanization, among others (Haque et al., 2009). Copper stress can inhibit seed germination and subsequently plant growth (Nanda and Agrawal, 2016). Complete germination is a critical step since it requires activation of a complex regulatory system, which is controlled by intrinsic and extrinsic factors (Belwall et al., 2015). Reinoso et al., (2000), cited by Rios-Gomez et al., (2010), found that germination is the most sensitive phase in P. farcta, P. strombulifera and P. flexulosa, since germination process begins with rapid water absorption (phase I), followed by an embryo expansion (phase II) and radicle germination(phase III). Germination and dormancy are influenced by environmental generic Jfactors to maximize long-term survival of seeds in many species (Koornneef et al.,2002; Belwall et al., 2015).

Therefore, the objective of this study was to examine the role of copperas a germination stimulator as well as its inhibitory effects of germination of mesquite (Prosopislaevigata) seeds, depending on concentration of CuS0 .5H 0solutionsused. The 4 2 variables studied were daily and accumulative germination, average germination time, germination rate and anhydrous weight of mesquite seeds. Mesquite has a variety of uses such as energy source, from firewood and coal; other important uses are elaboration of posts for fences, parquet, handicrafts, boards and planks, food for cattle, flour for human consumption, production of rubber and medicine (Solis, 1997); Prieto-Ruiz et al., 2013). In addition, its ecological importance lies in its ability to fix atmospheric nitrogen, which enriches soil around it and promotes the contribution of nutrients (Quiñonez-Gutiérrez et al., 2013). Finally, according to what was established by Clemens et al., (2002), these trees are ideal in phytoremediation projects since they have multiple uses and can adapt to particular environmental conditions in their habitat. An example is their conditioning to sites with high concentrations of heavy metals and contribution as a defense against herbivores and pathogens (Boyd and Martens, 1998; Martens and Boyd, 2002; Tolra et al., 2001; Barceló and Poschenrleder, 2003).