ABSTRACT
Chia (Salvia hispanica) is an annual oilseed crop of high nutritional value. This study aimed to analyze the performance of chia plants sown at different times and grown under different phosphorus rates. The experiment was conducted under field conditions at the Experimental Farm of the State University of Maringá, Umuarama, Brazil. Treatments were arranged in a randomized split-plot design with three replications. Phosphorus fertilizer was applied at the time of sowing at rates of 0, 40, 80, or 120 kg P2O5 ha-1. Seeds were sown on four dates at 14-day intervals, starting on March 21, 2017, for the first crop and March 29, 2018, for the second crop. Plant population density, raceme number, shoot dry matter yield, thousand seed weight, seed yield, and seed oil content were determined. It was observed that the end of March is the borderline for chia cultivation, because the low temperature and rainfall conditions occurring after this period compromise chia growth. The best phosphorous rate for chia growth was 80-120 kg ha-1, which led to optimum vegetative parameters.
ABSTRACT
The search for vegetal species regarding effectiveness in the phytoremediation of soils is of great importance, mainly in function of the great environmental problems, such as soil contamination with heavy metals, the necessity of producing more food, among others that mankind face today. This work aimed (i) to evaluate phytoremediation capacity of Crambe abyssinica Hochst and its growth in soil artificially contaminated with Cd and Pb, and (ii) to evaluate the possible impacts of crambe cultivation in contaminated soil conditions, in order to evaluate, to test, and to question the Brazilian CONAMA 420, providing important information that can be useful for governmental and environmental purposes. Two simultaneous experiments were developed, one for each metal. The soils were contaminated with salts of CdCl2 and PbCl2H2O in five doses based on the investigation values (IV) of CONAMA Resolution 420, resulting in 0; 1.5; 3; 9 and 30 mg kg-1 for Cd and 33; 90; 180; 540 and 1800 mg kg-1 for Pb. Gaseous exchange, development, nutritional composition and production of plant components, as well as phytoavailability of metals, were evaluated. The contamination with metals reduced photosynthesis, increased breathing as well as leading to a negative effect on the mineral nutrition and productivity in general; Plants cultivated in soil with Cd presented higher phytoavailability when compared to those cultivated in the Pb conditions, being found metals in all parts of the crambe plants from 1.5 mg kg- 1 of Cd in the soil; and Pb was retained only in roots, not being translocated in the plant. Cd showed higher phytoavailability, being found in all parts of the plant and Pb was retained only in the roots. Cd showed a higher phytoavailability when compared to Pb, also being found in all parts of crambe plants from dose 1.5 mg kg-1 of Cd in soil, which is an environmental problem, since in these concentrations the cultivation of crops is allowed by Brazilian legislation CONAMA 420.
