Adubação fosfatada e características de sementes de amaranto produzidas no sul do Brasil

Abstract

Amaranthus cruentus is a species considered pseudocereal belonging to the family Amaranthaceae, possessing desirable agronomic characteristics capable of becoming an option of cultivating the off season in the southern region of the country. However, there is no information in the literature about its production. In view of the above, the objective of this work was to evaluate the effects of phosphate fertilization and interrelations of the agronomic and physiological characteristics of amaranth seeds (Chapter I); to evaluate the physiological quality of amaranth seeds through electrical conductivity and accelerated aging (Chapter II); and to assess the physical characteristics of pseudocereal seeds (Chapter III). Based on the results obtained it is possible to conclude that the Amaranthus cruentus species expresses variability to the morphological attributes, yield components and seed quality produced in relation to the use of phosphate fertilization. Doses comprising 100 to 200 kg ha-1 of P2O5 tend to potentiate plant height, dry biomass accumulation, yield, germination and vigor of the seeds produced. Plants with greater stature and accumulation of biomass increase the proportion of photosynthetic pigments, being these determinants for the production and quality of seeds produced of amaranth in the extreme south of Brazil. Regarding the physiological quality of the seeds, the accelerated aging test at 41 ° C in the 72-h period with the use of unsaturated NaCl salt solution is efficient in the classification of amaranth seed lots at vigor levels. The electrical conductivity test conducted in the eight - hour period with 25 mL of water and 100 seeds allowed the classification of lots of amaranth seeds as to the physiological potential. Regarding the physical characteristics the results for the water content of 13.1% of amaranth the porosity results were, respectively, 35.5% and the slope angle of 25 ° amaranth. The length, width and thickness were 0.825mm, 1.287mm and 1.389mm for amaranth seeds. Sphericity was 93% for amaranth seed. When the electrical property was evaluated, the permissivity values were 3.26 in amaranth. The specific mass and weight of one thousand amaranth seeds were 804.7 kg.m-³ and 0.78g.