congresos y reuniones científicas
Silica production and phenological stages in soybean, wheat and maize crops developed in soils from Pampean region, Argentina
Conferencia; 7th International Conference on Silicon in Agriculture; 2017
Amorphous silica biomineralizations (silicophytoliths) constitute a significant source of silicon to the soil-plant-atmosphere system, since they dissolve faster than silicate minerals. The knowledge of the silica production of plant communities in an specific area is essential for the comprehension of Si cycle in this environment. Pampas region, in Argentina, is a vast area where the intensification of land use by agriculture caused negative effects on the soils, and also has modified and replaced the natural vegetation. In order to understand how this agricultural practices affect the terrestrial silicon cycle, we aimed to analyze the silica content/production in three of the most important crops developed in pampean region, and its relation with phenological stages. We selected vegetative and reproductive organs from at least nine individuals of three crops (soybean, maize and wheat) in three phenological stages, cultivated in fields from SE Pampean region. Biomass production was also calculated from each crop. Plants were subjected to calcination technique (Labouriau, 1983), and silica content was calculated as dry weight. The potential input of amorphous silica in each stage of each crop was calculated as kg/ha. Silicophytoliths obtained after the calcination technique were described under optical and electronic microscopes, and related to anatomy. Silica content in soybean ranged between 0.9-3.1% (% dry weight), depending on the type of organ and stage, and it was higher in the final developing stage. The highest silica content was observed in leaves from the last phenological stage. The potential input of amorphous silica was higher in the two last developing stages (1.01, 25.2 y 14.29 Kg/ha). In wheat, silica content ranged between 2.9-13.8%. The highest contents were observed in leaves (13.8%) and inflorescences (13.3%) from the last phenological stage. The potential input of amorphous silica increased toward the last stage (26.76, 105.01 and 737.9 kg/ha). In maize, silica content ranged between 0.9-10.5%, depending on the organ and stage, and it increased in the last phenological stages. The organ with higher silica content was the leaf in the last stage (10.5%). Silica calculated as kg/ha increased toward last stages (0.13, 240.7, 215.8 kg/ha). In the three crops, the principal tissue that became silicified was the epidermis, along with xylem. The morphologies of silicophytoliths observed were first described in soybean, and coincides with previous research in wheat and maize. Silica content was higher in wheat and maize (Poaceae) in comparison with soybean (Dicotyledon), and increased in the last developing stages, as it was expected. The results obtained in this work constitute the first data of silica content in crops from Argentina.