Interaction between water stress and nitrogen availability on gas exchange and secondary metabolism in plants of Amaranthus cruentus L.

Abstract

Amaranthus is a plant of great economic value because both its leaves and seeds can be used as food, but little is known in Brazilian agriculture. Its leaves and seeds are rich in protein, vitamins and minerals. In countries where it is grown, the leaves are consumed as vegetables and their seeds used as cereal or processed into flour and used in the bakery and biscuits industry, resulting in more nutritious food.Water availability is a primary factor limiting productivity of cultures by affecting various physiological processes. Although Amaranthus is often described as a water-tolerant plant, significant reduction in the photosynthetic rate was observed under water stress conditions. Nutrient availability is the primary factor limiting nutrient uptake and crop yield. Inorganic and organic fertilizers are widely used in agriculture to increase crop productivity in order to meet the growing demand for food by the expanding population. Among the mineral nutrients, nitrogen stands out as an essential constituent of amino acids, nucleic acids and proteins, as well as being part of the photosynthetic apparatus.The elucidation of the effects of water availability in the culture of Amaranthus is of great importance to agriculture. In this sense, the aim of this project is to evaluate the nature of the changes induced by the variation in the availability of water and nitrogen and their interactions in the production of biomass, photosynthetic characteristics and leaf chemical composition. The chemical changes in the leaves will be evaluated by determining the levels of photosynthetic pigments, phenolic compounds,proline, total nitrogen, nitrate and ammonium. Moreover, it will be evaluated the ability ofplants to recover from the water stress after 24 h of rehydration. (AU)