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

Abstract

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: 50kgNha−1, Rhizobium inoculant, and an uninoculated control. Measurements included days to maturity, yield, aboveground biomass (DW), plant total N content, and N2 fixation. Lentil yielded 1900kgha−1, 2120kgha−1 and 2070kgha−1 in control, fertilized, and inoculated treatments, respectively. The N treatments did not affect days to maturity or harvest index (HI). Yield and N2 fixation were unaffected by the N treatments except in drought, where yield was smallest in the control and N2 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 N2 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.