Doses e modo de aplicação de hidrogel para desenvolvimento inicial de espécie arbórea nativa

Abstract

The semi-arid region is in an edaphoclimatic scenario which leads into challenges concerning the development of plants. Regarding forest species, fundamental to afforestation and reforestation, the water deficit is compromising since the development of seedlings. With the aim of reducing the impacts of the water scarcity, it is crucial to utilize technologies such as superabsorbent polymers (hydrogel). These materials, when approaching the water, expand and retain humidity, indicating a potential to retain and supply water to plants gradually through its application into soil. Despite the increasing of utilization of polymers in the first sector, there is, nonetheless, the questioning over the dosage and proper application method of hydrogel resulting in a better initial development of Sabiá seedlings (Mimosa caesalpiniaefolia). The experiment has been conducted into a greenhouse with completely randomized design, with factorial arrangement 2 x 5 + 1 with 4 repetitions, totalizing 44 experimental units formed by vases containing 2.5 kg of soil. The first treatment factor has been constituted of two methods of application of the polymer Forth Gel ® (incorporated or applied into the pit); the second treatment factor has been constituted of five dosages of polymer (0.4; 0.8; 1.6; 3.2; 6.4 grams/vase, correspondent to 0.02; 0.03; 0.06; 0.13; 0.26% m/m) and the additional treatment with no application of polymer. The humidity of the soil has been maintained to 70% of its field capacity during the entire experiment, through weighing and daily irrigations. During 60 days as of the sowing, it was obtained data concerning the total water volume under evapotranspiration by vase and development of seedlings. 60 days upon the sowing, it was evaluated the gas exchanges, biomass, root attributes, noduling and accumulation of nitrogen in the plants. The data which did not correspond to normality of BOX-COX has been transformed. An analysis of variance (ANOVA) has been performed, a linear regression to the dosages and a Tukey test A 5% significance level was adopted to the application method. The dosage of hydrogel 6.4 g/vase (0,26% m/m) in the pit has promotes 3.9 L of water evapotranspirated, 1.18 times lower than the volume observed regarding the treatment with hydrogel incorporated and 1.33 times lower than the observed regarding the additional treatment of type control. The results of development of seedlings, root attributes and nitrogen accumulation indicate that the absence of the polymer or the application incorporated of 0.4g/vase 0.02% m/m) has been more favorable to the seedlings. The gas exchanges have indicated the incorporated application has been more favorable to the performance of the seedlings. The application of hydrogel incorporated into the soil in the smallest dosages or non-application of the polymer have led to a better metabolism and growth of the seedlings of M. caesalpiniaefolia. Therefore, the application of the superabsorbent polymer incorporated into the soil has favored the development of the seedling of M. caesalpiniaefolia, in comparison to the localized application. The dosage of hydrogel recommended by the producer was not the most suitable for seedlings of sabiá, it is recommended, hence, the use of a 0.4 g/vase dosage (0.02% m/m) or the non-application of the product.