Integrated control of Striga hermonthica (Del.) Benth. in Burkina Faso through host plant resistance, biocontrol and fertilizers

A two-year field study investigated integrated management of Striga hermonthica on sorghum through host crop resistance, biocontrol (Fusarium oxysporum isolate 34-FO), and fertilizer application. The experiment was conducted in a field with natural Striga infestation at Kouaré Research Station in Fada N’Gourma, Burkina Faso. Treatments combining sorghum resistance with Fusarium inoculum and N-fertilizer or manure significantly reduced emerged Striga plant number, plant vigour and dry biomass of Striga and the area under the Striga number progress curve (ASNPC) in 2002, as compared to the control. Integrated Striga Management (ISM) plots fertilized with urea, urea plus growth medium or urea plus manure associated with Fusarium inoculum resulted in improved sorghum grain yield of at least 15% in 2001 and of at least 97% in 2002. Economic analysis showed that the combination of sorghum resistance with fungal inoculum or urea at 200 kg ha-1 allowed for a significant financial profit in sorghum production. The results suggest that to reduce Striga infestation below economic threshold, ISM treatments should be consistently applied for several years without expecting very high returns.Keywords: Striga hermonthica, integrated control, Fusarium inoculum, Sorghum resistance, fertilization, Burkina Fas

π-π stacking tackled with density functional theory

Through comparison with ab initio reference data, we have evaluated the performance of various density functionals for describing π-π interactions as a function of the geometry between two stacked benzenes or benzene analogs, between two stacked DNA bases, and between two stacked Watson–Crick pairs. Our main purpose is to find a robust and computationally efficient density functional to be used specifically and only for describing π-π stacking interactions in DNA and other biological molecules in the framework of our recently developed QM/QM approach "QUILD". In line with previous studies, most standard density functionals recover, at best, only part of the favorable stacking interactions. An exception is the new KT1 functional, which correctly yields bound π-stacked structures. Surprisingly, a similarly good performance is achieved with the computationally very robust and efficient local density approximation (LDA). Furthermore, we show that classical electrostatic interactions determine the shape and depth of the π-π stacking potential energy surface