Formação de mudas de goiabeira irrigadas com águas de diferentes natureza catiônica e ácido saliclico.

Abstract

The northeastern semi-arid region has stood out each year for the production of fruit trees, among them the guava tree, which is a species of great economic and nutritional potential, being rich in several vitamins and mineral salts. However, water sources in the region commonly have high levels of dissolved salts that, when used for irrigation, can cause deleterious effects on plants. Thus, the objective of this work was to evaluate gas exchange, growth, phytomass and quality of guava seedlings as a function of the cationic nature of the water used in irrigation and foliar application of salicylic acid. To evaluate the morphophysiology and quality of guava seedlings as a function of irrigation with water of different cationic natures and foliar application of salicylic acid. The experiment was carried out in a greenhouse, belonging to the Centro de Ciências e Tecnologia Agroalimentar, located in the municipality of Pombal, PB, using a randomized block design, in a 6 × 4 factorial scheme, with six cationic compositions of irrigation water [S1 – Witness (supply water); S2 - Na+; S3 - Ca2+; S4 - Na++Ca2+; S5 – Mg2+ and S6 - Na++Ca2++Mg2+], associated with four concentrations of salicylic acid (0; 1.3; 2.6 and 3.9 mM), with 3 replicates and 2 plants per plot. The plants referring to the control (S1) were irrigated with water with an electrical conductivity (ECw) of 0.3 dS m-1, while for the other treatments (S2; S3; S4; S5 and S6) an ECw of 4.3 was used dS m-1, consisting of different cations, in the form of chloride. In the seedling formation phase, the guava tree was sensitive to calcium water, resulting in a marked decrease in plant growth. Stomatal conductance, transpiration and phytomass accumulation of guava seedlings were more affected by variation in electrical conductivity compared to the cationic nature of water. Salicylic acid at concentrations of 2.9 and 1.9 mM increased stomatal conductance and stem dry mass, respectively, in guava seedlings. Water with an ECw of 4.3 dS m-1 allowed the formation of guava seedlings with acceptable quality for transplanting in the field, regardless of the cationic nature of the water.