Methods of Estimating Developmental Periods in Soybean1
- Orlando Agudelo,
- D. E. Green and
- Richard Shibles2
Three methods of characterizing the duration of developmental stages in two soybean [Glycine max (L.) Merr.) populations were evaluated in the field in 1982. The major objective was to compare the three methods for estimates of the duration of developmental periods, especially days to beginning seed-filling and the seed-filling period. Methods used were the Fehr and Caviness method, a first-flowering- node method, and a similar-node method. In the first-flowering- node method, all notes were taken on the first node to begin flowering. In the similar-node method, notes were taken on nodes of plants of lines from each stem-termination group that began flowering on the same day. The lines evaluated were from two crosses between ‘Harosoy-63’, a daylength-sensitive and previously widely used cultivar, and two daylength-insensitive plant introductions, ‘Shinsei’ (PI317.336) and a selection from ‘Kitami Shiro’ (PI317.334B). A comparison of lines in two stem termination types, determinate and indeterminate, was made for days to certain stages of development by using the three methods of characterization. The three methods were equal in differentiating among lines within a given stem-termination type for stages Rl, R5, and R7 and for duration of the flowering, seed-filling, and reproductive periods. The Fehr and Caviness method estimated the determinate lines to be earlier in reaching the beginning seed-filling stage and, thus, to have a longer seed-filling period than the first-flowering-node and similar-node methods. The best method of characterizing developmental stages of the soybean lines would depend on the genetic material being studied and the information desired. The first-flowering-node and similar-node methods may be best if lines with different stem-termination types are being compared because they are based on the reproductive development at one node.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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