Abstract Currently the use of nanotechnology is revolutionizing agricultural production. Copper nanoparticles have been shown to influence the growth and development of different plant species, in addition to operating as stress resistance inducers. The objective of the present research was to evaluate the response in growth and yield, as well as the activation of the defense system of tomato plants. The treatments evaluated were a complex of polyvinyl alcohol-chitosan-copper nanoparticles (PVA-Cts-nCu), another complex of PVA-Cts and an absolute control (T0). The treatments were applied via foliar in tomato plants under greenhouse conditions. During the crop cycle, agronomic variables were determined, and the activity of enzymes related to stress tolerance such as β-1,3 glucanase, chitinase and phenylalanine ammonia lyase (PAL), as well as the expression of the PR1 gene. The PVA-Cts-nCu complex increased yield, number of fruits, average fruit weight, aerial fresh weight and root fresh weight, in addition, it promoted the defense system by increasing the PAL enzyme activity, as well as the overexpression of the PR1 gene.

Resumen Actualmente el uso de la nanotecnología está revolucionando la producción agrícola. Se ha demostrado que las nanopartículas de cobre tienen un efecto en el crecimiento y desarrollo de las diferentes especies vegetales, además de operar como inductores de resistencia al estrés. El objetivo del presente trabajo fue evaluar la respuesta en el crecimiento y rendimiento, así como la activación del sistema de defensa de plantas de tomate. Los tratamientos evaluados fueron un complejo de alcohol polivinílico-quitosán-nanopartículas de cobre (PVA-Cts-nCu), otro complejo de PVA-Cts y un testigo absoluto (T0). Los tratamientos se aplicaron vía foliar en plantas de tomate bajo condiciones de invernadero. Durante el ciclo del cultivo, se determinaron variables agronómicas, y la actividad de enzimas relacionadas a la tolerancia a estrés como β-1,3 glucanasa, quitinasa y fenilalanina amonio liasa (PAL), así como la expresión del gen PR1. El complejo PVA-Cts-nCu incrementó el rendimiento, número de frutos, peso promedio de fruto, peso fresco aéreo y peso fresco de la raíz, además, promovió el sistema de defensa mediante el aumento en la actividad enzimática PAL, así como la sobreexpresión del gen PR1.

A atividade antimicrobiana de quitosana e complexos interpolieletrolíticos hidrossoluvéis de poli(ácido acrílico)-quitosana foi estudada. Quitosanas de dois diferentes pesos moleculares foram testados em diferentes concentrações, 0,5 a 5 g • L-1, como agentes antimicrobianos nas P. aeruginosa e P. oleovorans. Em ambos os casos, obteu-se a melhor inibição microbiana com a concentração de 5 g • L-1, no entanto os complexos interpolieletrolíticos de poli (ácido acrílico)-quitosana com composição φ = 2 apresentaram maior atividade antibacteriana do que os dois quitosans na concentração de 0,5 g • L-1. O complexo NPEC2 foi mais eficaz do que as quitosanas, sendo que o resultado pode ser atribuído ao número de moles dos grupos aminos da quitosana e aos grupos carboxílicos dos complexos de poli(ácido acrílico).

The antimicrobial activity of chitosan and water soluble interpolyelectrolyte complexes of poly(acrylic acid)-chitosan was studied. Chitosans of two different molecular weights were tested at different concentration for 0.5 to 5 g·L-1 as antimicrobial agents against P. aeruginosa and P. oleovorans. In both cases, the best microbial inhibition was obtained with the concentration of 5 g·L-1. However, the interpolyelectrolyte complexes of poly(acrylic acid)-chitosan with composition φ =2 produced higher antibacterial activity than the two chitosans at the concentration of 0.5 g·L-1. The NPEC2 complex was more effective than chitosans. This could be attributed to the number of moles of the amino groups of chitosan and the carboxylic acid groups of the interpolyelectrolyte complexes poly(acrylic acid).