During 1994 and 1995 field investigations has been provided in order to examine photoperiod reaction of soybean plants various maturity groups, and duration of some growth stages dependence from daylength and temperature. Four commercial soybean varieties created in Scientific Institute of Field and Vegetable Crops, Novi Sad were tested: Ranka, Panonka, Balkan and Vojvođanka. The trial was set according to RCBD method in 4 replications, with 7 planting dates. The following traits were tested: grain yield (t/ha), harvest index, 1000 grain mass (g), vegetative and reproductive stage duration (days), sum of bioclimate temperatures during vegetative and reproductive stage (°C) and vegetative and reproductive photoperiod (hours). Analysis of variance for three factor design was applied, and interdependance of examined traits was established using correlation coefficients. Principal component’s analysis was applied in order to reduce entity of group data, and those results were statistically solved by path – coefficient analysis.

It has been established that photopheriodism in soybeans expresses primarilly through changes in growth stages duration. Due to shorter daylenths in late planting days, growth stages are also shorter, and yields are lower. Variability of grain yield mostly due to variety x environment interactions (69.19 %), than environmental factors and errors (25.83 %), while to genetic differences between varieties only 4.98 %. Achieved results could be used as base for examination of adaptability and stability of varieties grown in our agroeclogical conditions, and also in future work in soybean breeding.

Keywords: soybean, variety, photoperiodism, variability, path – coefficient analysis

A copy of thesis is field in the Library of the Faculty of Agriculture, University of Novi Sad (contains 54 pages, 30 tables, 3 graphs, 1 figure, originally in Serbian with summary on English)