Growth Parameters and Their Use in Predicting Seed Yield in Soybeans (seed-Filling Period, Glycine Max)

39 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986.Previous research has demonstrated a positive relationship between seed-filling period (SFP) and seed yield in soybean Glycine max (L.) Merrill . Two studies were conducted to (1) predict the gain in seed yield by selection for SFP and (2) to determine which growth parameters are most important to seed yield among breeding lines that differ in their yield-SFP relationship. The experimental design was a randomized complete block of replicated field plots in 1984 and 1985 at Urbana, Illinois on a Flanagan silt loam (Aquic Argiudoll).In the first study, two populations (containing 131 and 89 F(,2)-derived lines) were replicated twice and evaluated in the F(,3) and F(,4) generations. Yield and SFP (measured as the difference between reproductive growth stages R1, R4, R5, R7, and R8) were estimated on single row plots. Genotypic correlations between yield and SFP were low. Heritabilities, estimated by the regression of offspring (F(,4) generation lines) on parent (F(,3) generation lines) were higher for yield than for SFP. Direct selection for yield was predicted to be substantially more effective than indirect selection in all cases.In the second study, eight experimental lines were selected to represent four yield-SFP categories: long SFP with high yield, long SFP with low yield, short SFP with high yield, and short SFP with low yield. Observations taken in six replications included SFP, seed yield, harvest indices for dry matter and N, total flowers, total pods at three stages (pod 5 mm long, pod containing a seed 3 mm long, and mature pod), and total N and dry matter at the beginning and end of SFP. Early flowering was related to SFP, but not to yield. Total N in the plant at the end of SFP was related to yield, but not SFP. Total N in the plant at the end of SFP, total N and dry matter assimilated during SFP, harvest indices for N and dry matter, and seed yield were related.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD