اثرت دماي منطقه ريشه بر روي صفات مرفولوژيكي يونجه يك ساله

The effects of root zone temperature on morphological characters of annual medics

In order to study the effect of low root zone temperature (RZT) on growth and development of some annual Medicago species, an experiment was conducted in control growth chamber. In this experiment, three species of annual medics namely Medicago polymorpha, M. radiata, and M rigidula that suppose to be adapted with cold and temperate zones were used. Root zone temperatures at four levels including 5, I0, 15 and 20C° were considered. The experimental plan was factorial in base of randomize complete design with four replications. Result showed that the annual Medicago species had significant difference for producing dry matter and yield components. The species of M polymorpha and M rigidula had more leaf, stem and root dry matter and leaf area than M radiata. Therefore these species may be better for ley- farming system in cold and temperate zones. Also the result showed that root zone temperature at 5C° had effectively deceasing the growth of the annual medics. In conclusion, application of ley-farming system is not successful in zone that soil temperature is lower than 5C°. Therefore, in zones that soil temperature is more than 10C°, annual medics have normal growth and produced suitable growth. In these regions lay-farming system (cereal-legume rotation) can be replaced with fallow-cereal rotation.