EFFECTS OF LOW-TEMPERATURE TREATMENT AT SEEDLING STAGE ON SOYBEAN GROWTH, DEVELOPMENT AND FINAL YIELD

The after effect of continuous and variable chilling temperatures acti ng periodically for 7 days at, seedling stage (day/night: 2/2 degrees C, 5/5 degrees C, 15/2 degrees C, 15/5 degrees C, 15/15 degrees C and control-22/18 degrees C) on growth, development and final yield of soy bean cultivar Polan and Progres were investigated. The temperature dec rease lengthened the duration of the vegetation period before flowerin g for both cultivars, which allowed compensation for the reduced-as an effect of chilling-rate of daily increments in the leaf area and the dry weight of the aboveground parts of the plants. The most important symptom of chilling treatment was a considerable increase in the numbe r of axillary branches after flowering, which caused an increase in th e dry weight of plants. The subsequent reaction of the growth of leave s to chilling at seedling stage was, after flowering, variety dependen t. The area of leaves bigger at Polan or similar to control at Progres ensured good seed filling in an increased number of pods developed on axillary branches. Chill-induced delay in plants development allowed the avoidance of low temperature occurring during flowering in this ex periment. This chilling during flowering was one of the reasons of wor se-pod setting and reduction of seeds per pod number at control plants .