Potencial hídrico em plantas de soja sob diferentes níveis de compactação

Abstract

Plants are in constant change of their physiological state in order to adapt to the restrictions imposed by the soil condition to which they are inserted. The field compaction occurs by mechanical means or animal trampling, alters the physical properties of the soil and increases its density and decreases its porosity, leading to a reduction of the infiltration and ramification of the roots, caused by excessive soil resistance to penetration and poor aeration, causing limitations on the water potential available to the plants, reflecting on the productive potential of the culture. In this way, this work aims to evaluate the water potential and development of soybean plants, cultivated in typical Dystrophic Red Latosol, under different levels of compaction. The experiment was conducted in a greenhouse in the Pato Branco - PR's campus of UTFPR, in a randomized block design (DBA). This work used four levels of compression, performed manually, being them: 1,0 Mg m-3 (T1); 1,15 Mg m-3 (T2); 1,25 Mg m-3 (T3); 1,35 Mg m-3 (T4). The work also used PVC tubes of 10 x 80cm (diameter/height), lined with plastic. One seed of the NS4823RR, Nidera® cultivar was sown per tube, and irrigated accordingly to the culture's needs. After sowing, every 7 days to the 56th day, the plants height (AP) and the number of leaves where monitored. On the 56th day, were evaluated the water potential (Ψ), the fresh mass of the aerial part (MFPA) and the fresh mass of the root (FMR); the dry mass of the aerial part (MSPA) and the dry mass of the root (MSR); and the length of the compacted layer (CCC). The data was submitted to analysis of variance and averages comparison by the Tukey test, with 1% error probability, using the Minitab software. There were no significant differences in the AP variables at 7, 14, 21, 42 49 and 56 DAS and NF, Ψ, MFR, MSR, MSPA for none of the treatments. For the AP (28 and 35 DAS) there was a significant difference only between treatments T1 and T4, in which plants submitted to T1 treatment obtained a higher size. The CCC of the treatment T1 and T2 differed significantly from the others, showing smaller length of the compressed layer. As for the MFPA variable, the treatments T1 and T2 showed higher production of fresh mass in comparison with the others, due to better plant development. These results are due to the low levels of compaction affected by the manual compression, allied to the maintenance of the irrigation through the whole period of conduction of the experiment.