Potassium (85Rb) and water use efficiency by sugarcane genotypes

• Grant number: 13/24372-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2014
• End date: November 30, 2014
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: José Lavres Junior
• Grantee: Nícolas Braga Casarin
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The efficient use of natural resources such as water and nutrients required to plant development is the main key to the development of agriculture with low energy cost and environmental safety. The objective of this project is to evaluate the morphological attributes of the root system (total root length and total root surface), the K (rubidium, 85Rb) and water use efficiencies in two sugar cane genotypes (SP83-2847 tolerant; SP90-3414 sensitive to water stress) affected by the K deficiency and water stress, as well. In addition, the following hypotheses are: 1) K supply to the genotypes grown under drought stress may contribute to minimize the effects of lack of water; and 2) the water-use-efficiency (WUE) represents the direct effect of the potassium-utilization-efficiency (KUtE), which means, the higher biomass per unit of water taken up by the plant is the result of the highest internal K-use. The project will consist of two experiments, which in turn the experiment (I) will be carried out in pots containing nutrient solution, using the experimental design of randomized complete block with treatments arranged in a 2 x 2 factorial scheme (two concentrations of K in the solution x two varieties). The experiment (II) will be held in pots containing soil, using the experimental design of randomized complete block with treatments arranged in a factorial scheme 4 x 2 x 2 (four K rates; two varieties x two water supplies), which in both experiments contain five repetitions. In experiment (I) the K kinetics parameters (Km , Vmax and Cmin) of 85Rb as related to two levels of K (high and low) in the nutrient will be assayed; as well as the efficiencies of absorption and use of K (85Rb). In experiment (II), we are evaluating the photosynthetic parameters of the plants subjected to different K and water supplies, the activity of nitrate reductase, as well as to evaluating K and water use efficiency and the yield of plant tops and root dry matter.