Chitosan seed soaking: germination and growth of Coriandrum sativum and Solanum lycopersicum

• ¹ Escola Superior de Turismo e Tecnologia do Mar, Biotechnology, Portugal

The world´s growing food demand poses as a major concern on agriculture resources. In order to meet the demand resulting from demographic studies, it is extremely important to improve the production technologies in order to achieve high agricultural productivity. Proper fertilization and efficient pests control in cultures are required to obtain a high quality production. In order to improve crop resistance against temperature fluctuations and diseases, several strategies have been tested, such as seed coating (Omolehin et al., 2005). Although current practices effectively enhance germination and reduce losses, the conventional seed coating agents are not the best alternative, since it relies on chemical fertilizers and pesticides addition to the soil, leading to environmental costs. In addition, pests may develop resistance against them, which implies the use of increasingly larger amounts to be efficient (Altieri and Nicholls, 2003). Therefore, there is an increasing demand for safer and more eco-friendly alternatives. Chitosan is a cationic polysaccharide produced by the alkaline N-deacetylation of chitin. The positive charge of chitosan confers numerous and unique physiological and biological properties with great potential in a wide range of industries, such as water treatment, food processing, medicine and pharmacology (Rinaudo, 2004). Furthermore, chitosan have been recognized as a product to enhance crop production due to its bioactivities: biodegradability, growth stimulation and seed germination, increasing nutrient uptake, reducing oxidative stress, increasing in chlorophyll content, photosynthetic and chloroplast enlargement in the leaves, antifungal, antiviral and antibacterial properties (Hadrami et al., 2010; Hadwiger, 2004). Therefore, it can be used as foliar spraying, seed coating, seedling root dipping; soil enrichment or as supplement into plant tissue media (Pichyangkura, R., Chadchawan, 2015). In this context, our aim was to study the effects of chitosan, extracted from marine resources, on biophysical characteristics commonly farmed tomato and coriander species, Solanum lycopersicum and Coriandrum sativum, respectively. For that we have used medium and lower molecular weight chitosan with and without acetic acid and ascorbic acid. The crops were all treated at the same conditions, in a greenhouse with controlled temperature (T=24ºC), aeration and photoperiod (12h:12h light:dark). Preliminary results showed for both species an enhancing of germination rates of seeds soaked with chitosan when compared to control seeds (without chitosan). Furthermore, growth measurements also showed differences between chitosan treatments and remaining conditions.