Efeito da adubação fosfatada no desenvolvimento inicial da Cultivar BRS KURUMI (Pennisetum purpureum Schum)

Abstract

The BRS Kurumi is a clone of elephant grass, which presents vegetative propagation, perennial cycle and low stature, is characterized by the formation of clumps in the semi-open format, green leaves and stems, short internodes, stands out for its high potential for fodder production (30 t/ha/year of DM), high nutritional value (18 and 20% of crude protein and digestibility between 68 and 70%), high leaf/stem ratio and ease of management. The objective of this study was to evaluate the initial development of the BRS Kurumi cultivar (Pennisetum purpureum Schum), with different concentrations of phosphate fertilization. The experiment was developed between the months of October/2022 and January 2023, in the Vitrine of Technologies of Embrapa, located in the Agricultural Exposition Park “Luiz Lorenço de Souza”, in the municipality of Parintins - AM, with the planting of the stalks performed in 60 polyethylene pots, with 10 kg of soil in each pot. The soil used was collected from the Showcase area, where chemical analysis was performed to determine the amount of lime to be added to raise the base saturation to 55% and the amount of phosphorus in the soil to define the levels of phosphorus to be used. The experimental design was entirely randomized (DIC), with five levels of P2O5 (0, 15, 30, 45 and 60 mg/dm³), with twelve repetitions, totaling sixty sampling units. Thirty days after planting, the following response variables were analyzed: aboveground fresh mass (MFPA), root fresh mass (MFR), aboveground dry mass (MSPA), root dry mass (MSR), MFPA/MFR and MSPA/MSR ratios, root length (CR), aboveground length (CPA), stem length (CC), number of emitted leaves (QTF) and number of tillers (QTP). After the measurements, the plant material was taken to an oven at 55º C for 72 hours to determine the dry mass of the aboveground part (ADM) and the roots (RMS). In the analysis of variance the PROC MIXED procedure of the statistical software SAS (Statistical Analysis System) was used and the Tukey test was employed for multiple comparison of means at 5% probability level. It was found that the response variables CC, CPA, QTP, MFPA, MSPA and MSR showed increasing linear effect (P<0.05) as a function of increasing levels of phosphorus evaluated. On the other hand, no significant differences were found in the variables CR, QTF, MFR, and in the MFPA/MFR and MSPA/MSR ratios as a function of the phosphorus doses. The initial growth of the elephant grass cultivar BRS Kurumi was influenced by the levels of P2O5 evaluated. It was found that most of the variables analyzed showed better growth performance at the level of 30 mg P2O5/dm3 applied to the soil.