Controlling indeterminacy in short season lentil by cultivar choice and nitrogen management

Western Canada is a major area of lentil (Lens culinaris Medik.) production and global export, specializing in short season production. In cool or wet years lentil often fails to mature within the 115-d growing season. In the absence of a determinate cultivar, our goal was to test whether current cultivars could mature earlier and without a yield penalty by managing N fertility practices. Eight cultivars of lentil were grown in Saskatchewan during 2006 and 2007 under three N fertility treatments: 50 kg N ha(-1), Rhizobium inoculant, and an uninoculated control. Measurements included days to maturity, yield, aboveground biomass (DW), plant total N content, and N-2 fixation. Lentil yielded 1900 kg ha(-1), 2120 kg ha(-1) and 2070 kg ha(-1) in control, fertilized, and inoculated treatments, respectively. The N treatments did not affect days to maturity or harvest index (HI). Yield and N-2 fixation were unaffected by the N treatments except in drought, where yield was smallest in the control and N-2 fixation was smallest in the fertilized treatment. Cultivars CDC Milestone, CDC Red Rider and CDC Rouleau had comparable yield and matured earlier than large-seeded cultivars. demonstrating that growing a recently released small-seeded cultivar gave earlier maturity than N fertility management. Results did not demonstrate any advantage from applying N fertilizer to hasten maturity, to increase HI or yield compared to the current practice of relying on N2 fixation from proper inoculation. Biological N-2 fixation is a sustainable and more economical means of supplying N to the lentil crop without the need to apply N fertilizer, particularly with high yielding early maturing cultivars. (C) 2012 Elsevier B.V. All rights reserved.