The regression analysis between the estimated CSDL values for the 10 cultivars showed a very close agreement between the values solved in North Carolina compared with values solved independently in Georgia ([r.
2] of the regression analysis was not as high as for CSDL (0.
These results suggest that less confidence should be placed on the repeatability of the solved cultivar traits that affect seed yield (X1 and X2) compared with the cultivar traits that control the individual phases of the life cycle (FLSD and SDPM) and the CSDL.
Third, the CSDL can cause faster or slower actual progress despite a long or short SDPM and SFDUR, thus absolute relationship to SFDUR should not be expected.
The regression analysis between the CSDL coefficients estimated for Georgia on the basis of only 3 yr of data from 1992 to 1994 (Table 9) and those estimated on the basis of the whole data set from 1987 to 1996 (Table 5) showed a very close agreement ([r.
Regarding the transportability of cultivar coefficient estimates in different environments, we identified the CSDL as the most reliably estimated cultivar trait.
Parameter Definition Units CSDL Critical short day length below h which reproductive development progresses with no daylength effect.
For each cultivar, CSDL and PPSEN were allowed to change within the range of values for [+ or -] 2 maturity groups since the assignments of the cultivars to specific groups should not necessarily limit the range of the search.
R1PPO decreases CSDL by a given number of hours, making plant development more sensitive to photoperiod after anthesis.
Optimized CSDL values for most MG VII cultivars were within the typical MG range and were generally smaller than the values for MG V and VI as expected (Table 7).
Abbreviations: CSDL, critical short daylength; DOY, day of year; GE, genotype x environment; RMSE, root mean square error; SLPF, soil fertility factor.