Winter Wheat Cropping System Response to Seed Treatments, Seed Size, and Sowing Density

Abstract

Poor stand establishment resulting in lower yield is a major constraint to expanding winter wheat (Triticum aestivum L.) across western Canada. To address this issue, we conducted a study totaling 26 site‐years over three growing seasons (2011–2013) to observe crop responses to system manipulations involving seeding rate (200 and 400 seeds m−2), seed size as a proxy for plant vigor (light/thin, moderate, heavy/plump), and a dual fungicide/insecticide seed treatment, on crop establishment, yield, and seed quality. Fall and spring plant density was about 10 plants m−2 greater for heavy seed vs. light seed. Seed treatment improved fall and spring plant density slightly more than 10 plants m−2. The dual seed treatment improved yield and test weight for thin seed size. Hypothesized weakest agronomic systems (low seeding rate and untreated, light seed) that often included the 200 seeds m−2 seeding rate were the poorest performing (suboptimal responses and highly variable) systems; however, a favorable response to seed treatments allowed for partial compensation and grain yield comparable to systems with high seeding rates. Greater instability was generally observed in weak systems irrespective of seed treatment. The economic advantage of the seed treatment was more apparent with thinner winter wheat stands as it resulted in greater gross (CAN+$31 ha−1) and net (+$22 ha−1) returns. This study reaffirms the importance of a strong and integrated agronomic system and indicates seed treatments can help offset weak systems comprised of poor stand establishment and lower yield performance.Core Ideas Poor stand establishment resulting in lower yield is a major constraint to expanding winter wheat acreage across western Canada. Hypothesized weakest agronomic systems (low seeding rate and untreated, light seed) that often included the 200 seeds m−2 seeding rate were the poorest performing (sub‐optimal responses and highly variable) systems; however, a favorable response to seed treatments allowed for partial compensation and grain yield comparable to systems with high seeding rates. Winter wheat crop establishment and grain yield results indicated that producers that intentionally use low seeding rate should use a dual fungicide/insecticidal seed treatment; however, the inherent variability is not entirely overcome with seed treatment. Inclusion of a dual fungicide/insecticide seed treatment provided the highest gross returns for both levels of sowing density; however, the added input cost of the seed treatment relative to the magnitude of change for grain yield reduced overall net returns at the 400 seeds m−2 seeding rate compared to the check (–$11 ha−1). This study reaffirms the importance of a strong and integrated agronomic system and indicates seed treatments can help offset weak systems that tend to have poor stand establishment and lower yield performance.

Winter Wheat Yields Are Increased by Seed Treatment and Fall‐Applied Fungicide

“…In the current study, only certified seed with germination levels of >90%, and little or no infection with F. graminearum was used. In a companion study by Beres et al (2016) the same dual fungicide/ insecticidal seed treatment, as used in the current study, increased winter wheat fall and spring plant density as well as winter survival. They also reported that the same combination seed treatment, increased grain yield and net returns, especially when a lower seeding rate was used (Beres et al, 2016).…”

“…In a companion study by Beres et al (2016) the same dual fungicide/ insecticidal seed treatment, as used in the current study, increased winter wheat fall and spring plant density as well as winter survival. They also reported that the same combination seed treatment, increased grain yield and net returns, especially when a lower seeding rate was used (Beres et al, 2016). Fall-applied foliar fungicide (prothioconazole) reduced leaf disease severity at GS 83 and improved grain yield, and weakly affected grain protein concentration (P < 0.10), and net returns (Table 5).…”

“…2), which is typical for crop production in the Prairies. Trends are summarized in the companion paper to this study (Beres et al, 2016). Briefly, eastern Prairie locations tended to be cooler during the winter months than more westerly locations.…”

“…To study the integrated role of seed treatments combined with fall-applied foliar fungicides, the following hypothesis was established: seed treatments can improve winter wheat establishment and productivity, and fall-applied foliar fungicides may further improve crop health, yield components, and competitiveness. A companion paper addresses how the integration of seed treatment, seed lot vigor (seed size), and sowing density can be manipulated to enhance winter wheat production systems (Beres et al, 2016).…”

Grain yield and competitive ability against weeds in modern and heritage common wheat cultivars are differently influenced by sowing density

“…Sowing density and, consequently, crop density is an important factor in determining the competitive ability of cereals against weeds (Doll et al, 1995;Kristensen et al, 2008) as well as the expression of their grain yield potential (Beavers et al, 2008;Beres et al, 2016;Li et al, 2016). The crop density to grain yield relationship is not directly proportional.…”