Winter Survival and Stand Density Effects on Canola Performance in North Dakota.

Proper stand density is important for achieving optimum yield of summer and winter annual grain crops and is influenced by many factors during stand establishment. A major difference between the two growth types is the winter survival component associated with winter annual crops and the impact this has on subsequent spring stands. The study objective was to evaluate winter canola survival and stand density influence on crop performance. Winter canola genotypes were screened from fall of 2002 to present in a RCBD replicated field study conducted at the Prosper research site 24 km northwest of Fargo, ND. Winter canola genotypes (20 to 50) were seeded in August and September each fall at 5.6 kg/ha into standing hard red spring wheat stubble approximately 25 cm tall. Plots consist of 6 rows each spaced 30 cm apart and 7.6 m in length sown with a six-row plot drill with double-disk openers and twin-vee packer wheels. Traits evaluated include fall stand, winter survival, spring stand, flowering, plant height and lodging, seed yield, test weight, and oil content. Mean genotype fall stand establishment was greater than 80% each year, but mean genotype winter survival, recorded the following spring ranged from 0 to 98%. Among the 11 years of genotype screening (i.) the trial was abandoned three years because of near zero winter survival and no seed yield, (ii.) seed yield was poor one year, (iii.) seed yield was fair two years, (iv.) seed yield was good three years, and (v.) seed yield was exceptional two years. Mean genotype spring stands associated with zero, poor, fair, good, and exceptional seasonal yields ranged from 0 to 5%, 10 to 64%, 13 to 63%, 47 to 98%, and 67 to 97%, respectively. Adequate spring stands, approximately 50% or greater based on this study, are important for good yield performance however, genotypes respond differently in their ability to compensate for low and non-uniform stands.