Silicato e calcário para o capim-ipyporã submetido ao regime hídrico controlado: características agronômicas e enzimáticas

Abstract

Silicon (Si), a beneficial element, can act to reduce abiotic stresses caused by drought, increase the tolerance of plants to water stress, in this sense, the objective of this work was to evaluate the agronomic and enzymatic characteristics of ipyporã grass with the use of calcium and magnesium silicate and limestone subjected to water regimes. The experiment was carried out in a greenhouse located at the Faculty of Agricultural Sciences of the Universidade Federal da Grande Dourados (FCA/UFGD) from July 2019 to November 2020. The experimental design was a randomized block in a factorial 5 x 2 with 4 repetitions, of which: five water regimes with water reposition based on field sources (CC) (30, 40, 50, 60 and 70% of CC), with two soil acidity correctives (calcium and magnesium silicate and dolomitic limestone) mandatory to raise base saturation to 70%. Three harvets were made and carried out as evaluations of agronomic characteristics (dry matter productivity of the aerial part - MSPA, counting the number of leaves and profiles and measures of plant height), determining the SPAD value, specifying the concentration of silicon in the plants) and enzymatic evaluations (total proteins (PT leaves), glucanase (GLU), guaiacol peroxidase (GPX), superoxide dismutase (SOD), lipid peroxidation (PxL) and catalase (CAT)). The silicate provided a greater number of leaves and plant height for the first harvest and, plant height and MPSA for the third harvest. The CC of 60 and 70% were better for agronomic characteristics. The enzymatic activity was higher with the use of limestone for the first and third harvests, however for the second harvest, it was higher with the silicate. For CC with respect to enzyme activity, the values were quite variable. The correction of the soil with calcium and magnesium silicate for some harvests provided a greater number of tillers, leaves, plant height and MSPA, as well as reduced the activity of enzymes related to oxidative stress. Although the silicon concentration does not differ between the correctives, the silicon conferred greater tolerance to water stress on the plants of the ipyporã grass. Water replenishments based on 60 and 70% CC were the ones that showed the highest values of agronomic characteristics and had divergent values between cuts in relation to enzyme activity. Therefore, further studies under field conditions are needed to prove the beneficial effect of silicon in reducing damage caused by water stress in forage grasses.