Phytometric and Productive Characteristics of Safflower Submitted to Phosphate Fertilization in the Oxisol of the Brazilian Cerrado

Abstract

The safflower ( Carthamus tinctorius L.), in particular, has been soaring in significance as an alternative for oil and biodiesel production. In this context, the goal of this study was to assess the influence exerted by phosphate fertilization on the phytometric and productive characteristics of the safflower raised on the Oxisol of the Cerrado. The experiment was performed in a greenhouse, using pots of 3 dm ^-3 in volume. Adopting the completely randomized design, five doses of phosphorus (P 2 O 5 : 0, 90, 180, 360 and 540 mg·dm ^-3 ) and six replicates were included. The following variables were estimated, viz., number of leaves, plant height, and stem diameter, besides chlorophyll index (SPAD index), number of chapters and shoot dry matter. Barring the shoot dry matter and number of chapters, all the other variables were evaluated on days 30 and 45 after the plants were transplanted. Data were submitted to analysis of variance at 1 % , 5 % and 10% probabilities, and regression analysis, at 1 % and 5% probabilities, respectively. All the variables revealed significant differences and adjustments to the linear regression model (P < 0.1), excepting the SPAD index on day 30 after the plant emergence which was adjusted to the quadratic regression model. The highest findings of 24.47 for leaf number, 34.97 cm for plant height, 3.76 mm for stem diameter, 64 . 76 for chlorophyll index, 5 units for the number of chapters and 3.45 g for dry shoot mass were recorded in response to the highest phosphorus dose in the experimental range (P 2 O 5 : 540 mg·dm ^-3 ). Phosphate fertilization was observed to affect the phytometric characteristics and boost the development of the safflower plants cultivated in the Cerrado Oxisol, substantiating that safflower could be a viable cash crop that can be established in the Brazilian Cerrado.