Effects of low temperature treatment at seedling stage on soybean growth, development and final yield

The after effect of continuous and variable chilling temperatures acting 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 soybean cultivar Polan and Progres were investigated. The temperature decrease lengthened the duration of the vegetation period before flowering 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 number of axillary branches after flowering, which caused an increase in the dry weight of plants. The subsequent reaction of the growth of leaves to chilling at seedling stage was, after flowering, variety dependent. 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 experiment. This chilling during flowering was one of the reasons of worse-pod setting and reduction of seeds per pod number at control plants.