Efeitos da interação entre fontes de nitrogênio e a percepção de etileno no metabolismo, crescimento e produção de plantas de tomateiro

Abstract

Nitrogen (N) is the nutrient that most limits the growth and productivity of agricultural crops. Ethylene is a phytohormone that plays an important role in the integration of events related to plant growth and development. Although some degree of interaction between N and ethylene has already been demonstrated, further details of the physiology of plants under conditions of nutritional stress due to variation in the N source and alteration in the metabolism of this hormone are still scarce. In the present work, tomato plants (Solanum lycopersicum L. cv. Micro-Tom, wild type - WT) were used as control, and its hormonal mutant Never ripe (Nr), which is insensitive to ethylene, grown in nutrient solution with different sources of N (ammonium - NH4+ and nitrate - NO3-) and a mixture between the two sources, in a factorial 2 (genotypes) x 3 (N sources). In order to understand the interaction between sources of N and the perception of ethylene, parameters of growth, photosynthesis, levels of biochemical markers, levels of total N and concentrations of NH4+ and NO3- were evaluated during the experiment. The growth parameters were significantly altered in relation to the plants treated with 100% NH4+ and 100% NO3- in Nr, which better assimilated these N sources, with increased growth and production compared to WT. As for photosynthesis parameters, mainly in photochemistry, photosystem damage occurs when control plants are subjected to 100% NH4+; on the other hand, Nr in relation to the WT genotype showed a clear tolerance to this nutritional stress. Several differences were found in the biochemical parameters in relation to the plants treated with NH4+ and NO3- sources, in interaction with the hormonal alteration, justifying that the mutant shows its greater productivity and growth using the 100% NO3- source. The data found here confirm that tomato plants have a higher production response at 100% NO3-; however, it is also evident how alterations in the perception of ethylene allow the plant to better assimilate this element in both sources.