Effect of temperature treatments on growth stages and yield of rice varieties in greenhouse

In order to study of temperature treatment on growth of rice crop, a green house experiment was carried out at deputy of rice research institute of Iran. Treatment’s included varieties in 5 levels (Tarom, Fajr, Shirudi, Dilam and Line 843) as main factors and 2 levels of temperature treatment. (16 & 32°c) along with 4 levels of growth stages (mid-tillering utile maximum tillering, stem elongation, bootingflowering and grain filling) were considered as two sub factors. Only two seedlings were planted in each pot and all of them were kept in normal temperature then they were kept in 16°c for 15 days then they were transferred to 32°c place. After each stage, morphological characters of plant height, tiller number, leaf area, leaf, stem and total dry weight per hill were measured. Yield and yield components of hill was measured in physiological maturity stage. The decrease of temperature from 3 to 16°c causes the decrease of morphological characters of plant height, tiller number, leaf area, leaf, stem and total dry weight up to, 17, 56, 39 and 38 percent, respectively. In different growth stage in relation to temperature stress in the middle tillering stage until the appearance of young panicle lowest yield was obtained because of decrease in morphological characters and panicle number and length. The most sensitive variety in relation to temperature stress is the 843 line with the most percentage of decreasing of yield (% 20.64) and the most tolerance in relation to temperature stress is the variety of Shirudi with the least percentage of decreasing of yield (% 11.01). The most amount of yield was obtained in the variety of Dilam with temperature stress in grain filling stage (30.68 g in hill) and the lowest amount in the variety was Tarom in the mid-tillering utile the appearance of young panicle stage (16.57 g in hill) because of decreasing the panicle number in hill and less number of grain in panicle. The mount of final yield decreasing in 16°c in relation to 32°c was 19.6 percent.