Competition between weeds and sunflower

• Grant number: 10/18899-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): February 01, 2011
• Effective date (End): January 31, 2012
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Patrícia Andrea Monquero
• Grantee: Izabela Orzari
• Host Institution: Centro de Ciências Agrárias (CCA). Universidade Federal de São Carlos (UFSCAR). Araras , SP, Brazil

Abstract

Two experiments will be conducted at the Center for Agrarian Sciences, Federal University of São Carlos, Araras-SP, to evaluate the effects of different periods of weed interference on yield and nutrient accumulation in sunflower cultivation. In the first part, which will be made in the field, the experimental design is a randomized block design with four replications. Interference periods consist of maintaining the culture in the presence and absence of weeds for 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 days after emergence (DAE) of culture (total cycle). The weed community existing in the experimental area will be identified by determining the density and dry weight of weeds in each plot. At the end of the experiment will be given the yield and the periods of cohabitation. In the second experiment in a green house will evaluate interference effects of three weed species in the relative content (RC) of macro and micronutrients, dry weight of shoots of sunflower plants. The weeds will be chosen on the basis of an experiment (the ones that have higher density). Sunflower seeds are sown in pots containing 10 L of substrate. After crop emergence will be sowing weeds in six densities (0, 1, 2, 3, 4 and 5 plants per pot). The periods of cohabitation shall be determined by the development of weeds, ie, coexistence will be closed when the weeds entering the reproductive phase. During this period the analysis will be made of the leaf crop and weeds to determine the relative content of P, K, Ca, Mg, S, Zn, Cu, Mn and Fe, B, N.