EFFECT OF TEMPERATURE STRESS AND WATER SHORTAGE ON THOUSAND GRAIN WEIGHT OF SELECTED WINTER WHEAT VARIETIES

The aim of the presented study was to assess the effect of high temperatures and water shortage during anthesis on thousand grain weight (TGW) of two winter wheat varieties (Tobak and Pannonia). In addition, numbers of grains per spike were also assessed. The six growth chambers were used to simulate heat stress conditions within following gradient of temperature maxima: 26 degrees C (control chamber), 29, 32, 35, 38 and 41 degrees C. The relative humidity (RH) course and photosynthetically active radiation (PAR) intensity were controlled via protocols. Additionally, drought stressed (dry) and well-watered (wet) treatments were established within each growth chamber. The plants were removed from the growth chambers after 14 days and they were left until a full maturity, exposed to actual weather conditions. The TGW at 14% moisture were evaluated for particular treatments within both winter wheat varieties. TGW was generally more affected by high temperatures under drought stress than in well-watered conditions. The results revealed that Pannonia TGW was much more affected by the water deficiency in combination with high temperature (particularly 38 and 41 degrees C) than Tobak TGW.