Winter canola dry matter and nutrient accumulation and partitioning and yield formation in northeast Kansas

Abstract

Winter canola (Brassica napus L.) in the southern Great Plains offers producers an opportunity to diversify their cropping systems and take advantage of several beneficial aspects of canola. One of the obvious benefits is seed yield. However, due to the indeterminate nature of canola and its ability to adapt to growing conditions, it has been difficult to gain an understanding of dry matter (DM) accumulation, nutrient accumulation, and yield formation. This research was done in an attempt to improve knowledge and understanding of winter canola growth and development in northeast Kansas. Two samplings and two experiments were conducted in Manhattan, Kansas from the spring of 2017 to spring of 2019. Biomass samples were collected along with other potential yield formation data throughout the winter canola growing season. The two samplings (2016-17 and 2017-18) did not have treatment factors. The first experiment (2017-18) had one treatment factor with two levels of plant density. The second experiment (2018-19) had two treatment factors of variety and plant density with two levels each. The first objective of this research was to determine the pattern of dry matter accumulation and partitioning throughout the growing season of winter canola in northeast Kansas at both high and low plant populations, and with open-pollinated (OP) varieties that were bred in Kansas. Plant DM increased quickly and steadily through bolt and the beginning of pod fill. The accumulation rate slowed by the middle of pod fill. Dry matter peaked during ripening in all of the studies. At the end of the season there was 36 to 50% of the DM in vegetative material, 25 to 33% in pod material, and 24 to 34% in the seed. There was generally more DM accumulated in the high plant density than the low density, except in one experiment at harvest when the low density had greater DM than the high density. The varieties accumulated DM similarly to each other. The second objective was to determine the pattern of nutrient accumulation and partitioning throughout the growing season for winter canola in northeast Kansas at high and low plant populations and with OP varieties. Plant nutrient accumulation generally followed the same trend as the DM accumulation. For nitrogen, 17 to 40% of nitrogen at the end of the season was in vegetative, 13 to 17% in pod, and 44 to 66% in seed material. For phosphorus, 14 to 36% of phosphorus at the end of the season was in vegetative, 7 to 32% in pod, and 35 to 78% in seed material. For potassium, 42 to 50% of potassium at the end of the season was in vegetative, 30 to 37% in pod, and 13 to 26% in seed material. For sulfur, 25 to 37% of sulfur at the end of the season was in vegetative, 35 to 49% in pod, and 21 to 32% in seed material. For iron, 15 to 45% of sulfur at the end of the season was in vegetative, 20 to 27% in pod, and 28 to 65% in seed material. The third objective of this research was to identify yield formation factors that contribute to yield and are potentially useful indicators in predicting yield. Plant DM, seed DM, plant height, and pod count on the main raceme were the most highly correlated measurements to yield at the most sampling dates out of the identified potential yield indicators. For those factors with high correlation values, there were several sampling dates with an r² value of 0.5 or above. Determining a pattern of DM accumulation and nutrient accumulation and identifying factors that drive yield formation has contributed to the understanding of winter canola growth and development.