تاثير جنستين بر روي رشد و نمو سه گونه يونجه يكساله تحت تنش دماي پايين خاك

The Effect of Gensteine on Growth and Development of Three Annual Medics Under Low Soil Temperatures Stress

To study the effects of different concentrations of gensteine on growth and morphology of annual medics under 5 °C root- zone, an experiment was carried out under controlled conditions of growth chamber with 25/20°C day/night air temperature. Three annual medic species (Medicago polymorpha cv. Santiago, Medicago radiata cv. Radiata, and Medicago rigidula cv. Rigidula), which are adapted from cold and temperate conditions were used. Gensteine concentations with 5 levels: 0, 10, 20, 30 and 40 micromol per litre were used. Experimental design was based on factorial in randomized complete blocks design with three replications. Result showed that there was a singnificant difference between species in respect to dry matter and yield components, M rigidula had the highest leaf, stem and root dry matter, plant hight, root length, leaf and stem- to root ratio, leaf to stem ratio, leaf surface and yield compared with other species. The result showed that in 5°C gensteine had a significant effect on yield and yield components of annual medic species. Increasing in gensteine concentration led to increasing in plant height, root length, dry matter of root, leaf and stem, allocation of higher dry matter to aerial parts of plant, number of brunch, stem and leaf node and leaf surface area of annual medic species. Interaction effect of species and gensteine showed that M rigidula cultivar in 20 micro mol gensteine per litre in respect to root length, dry matter of root, stem and leaf, rate of leaf and stem to root, rate of leaf to stem, leaf number, leaf surface and node number was better than other species. M rigidula in low root-zone temperature had better growth and development in 20 micro mol gensteine per litre, so this treatment is more suitable for ley-farming system in cold and temperate regions. Also cereal- pasture rotation system in the regions with low soil temperature about 5°C will be successful if gesteine is applied. In these regions, cereal- legume ley farming system can be a suitable alternative for cereal- fallow systems.