SEED YIELD RESPONSES OF THREE GRASSES TO POST-HARVEST STUBBLE REMOVAL

Abstract

The effect of post-harvest stubble removal dates upon the succeeding year’s seed yield of timothy (Phleum pratense L. ’Climax’), orchardgrass (Dactylis glomerata L. ’Frode’), and smooth bromegrass (Bromus inermis Leyss. ’Saratoga’) was investigated over four harvest years. The stubble was removed each year on 15 Aug., 15 Sept., 15 Oct., 15 Aug. and 15 Sept., 10 Apr., or left uncut. The experiments were conducted under conditions of adequate soil fertility. No stubble removal treatments increased the seed production of timothy. Orchardgrass seed yields were increased by all fall removal treatments but responded best to the 15 Aug. removal. Bromegrass responded to all stubble removal treatments but produced its highest seed yield from the 15 Oct. treatment. Seed yields declined with successive years until year 5 when timothy, and particularly orchardgrass, produced a yield increase. The interaction for years × stubble removal dates was significant only for bromegrass seed yield. Seed yield was highly correlated with panicle number in all species, with weight of seed in 25 panicles in timothy and bromegrass, and with 200-seed weight in timothy.