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Bruce Burdick
1109 S. Birch St.
Albany, MO 64402
660-726-5610
Email: BurdickB@missouri.edu

Hundley-Whaley Center phone
660-726-3698

PROGRESS REPORT ON SOYBEAN PERFORMANCE IN NORTH MISSOURI AS INFLUENCED BY MATURITY CLASSIFICATION AND PLANTING DATE

Situation: Leading companies in identity preserved soybean variety development are putting most of their developmental effort into soybean varieties that are considered to be early maturing for north Missouri producers. If north Missouri producers are to benefit from enhanced value trait development they will have two options. One option would be to convince companies to develop the value traits in Maturity Group 3, or early 4, soybean varieties. The other option would be to produce earlier maturing soybeans. If the latter option were adopted done, the question would then be, "How well will early maturing soybean varieties perform in relation to full-season varieties in north Missouri?"

Objective: To determine the soybean performance of early maturing soybeans in comparison to conventional maturing varieties commonly produced in north Missouri

Methods: The second year of a three-year study to fulfill the objective stated above was conducted at the Hundley-Whaley Farm at Albany, Missouri. The study was to compare the yield of ten soybean maturity groups. The maturity groups were 0.8, 1.6, 1.9, 2.3, 2.6, 3.1, 3.6, 4.1, 4.4 and 5.0. This differs from the seven varieties tested in 2001 with varieties ranging in maturity from 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 & 4.5. Two companies (Asgrow and Merschman) supplied seed falling within the desired maturity groups.

Two planting dates were used in the study. They were planned for May 1 and June 1. Wet spring weather conditions delayed the first planting to May 28 with the second planting date delayed to June 14. The soybean seed was counted at the rate of 150,000 seeds per acre and planted with a John Deere 30" wide row planter equipped with cone planting units.

The study was designed as a split-block with six replications. One block was used for the May planted soybeans, with the second block used for the June planted soybeans. Plot size was 10' wide by 25' long. Row width was 30" and the two middle rows of the four row plot was harvested for data.

In 2002, weed control was planned as total post glyphosate applied as needed since all of the soybean varieties in the test were Roundup Ready.

Variety maturity was visually noted and harvest was made as soon as possible after each variety was mature. The soybeans were harvested with an MF 8 plot combine. The actual harvest dates for 2002 were September 11 & 18 and October 1, 8 & 16. The early maturing varieties were harvested first and the fuller season varieties were harvested last.

The weather for 2002 could be characterized as wet early in the planting season, followed by a very dry summer. Rainfall in August exceeded 3" and this favored the later planting, especially the later planting of the early maturing varieties. Fuller season varieties were less affected by planting date than early season varieties.

Results: All soybean lines in the study were Roundup Ready^TM, therefore glyphosate was applied as needed throughout the growing season for weed control. The plots were nearly weed free at the end of the season. Some late-emerging shattercane plants were scattered throughout the plot area, but these were estimated to be non- competitive to the soybeans.

The yield data for 2002 is shown in Table and Figure 1. A highly significant yield difference between the early maturing varieties and the late-season varieties was observed within the May 28 planting date. The 0.8 maturing variety, Asgrow 0801, yielded over 30 bu/acre less than the maturity group 4.4 variety, Merschman Denver.

Figure 1: 2002 Hundley-Whaley Farm

Figure 3 (Merschman varieties - 2002 data averaged over two planting dates)

Figure 4 (Asgrow varieties - 2002 data averaged over two planting dates)

Figures 3 and 4 graphically illustrate soybean yields in relation to different maturity group varieties provided by the two seed companies which were in the test. The trend for higher soybean yield with longer maturity varieties was expressed regardless of the company providing the genetics.

Performance data for 2001 is shown below in Table 2 and Figure 5. Yield data from the May 23 planting showed no significant yield difference between the early maturing Mars (1.5) and the late maturing Denver (4.5) soybean varieties. More variability was observed in the performance of the June 13 planted soybeans. The early maturing soybean varieties performed significantly less than they did when planted early.

Figure 5: 2001 Hundley-Whaley Farm

Conclusion: In 2001, soybean maturity group did not play a significant roll in soybean seed yield performance when the soybeans were planted on May 23. The later planted (June 13) soybeans exhibited more seed yield variability, and the earlier maturing varieties did not produce yields as high as the fuller season varieties.

The yield data obtained from the 2002 study were quite different than 2001. The early maturing soybean varieties performed significantly less than the full-season soybean varieties planted at the earliest planting date (May 28). Fewer differences were evident in the performance of the different maturity groups planted on June 14, with the trend of fuller season soybeans yielding higher than early maturing varieties.