application of seed equilibrium moisture curves in agro physics

the water relations play a fundamental role in seed comprehension of biology. in order to describe the process of drying and the effect on water activity, which controls biological change in storage, a sound knowledge of the relationship between equilibrium moisture content (emc) and water activity/equilibrium relative humidity (erh) is essential. the relationship between the total moisture content and water activity of the food, over a range of values, at a constant temperature and under equilibrium conditions, yields a moisture sorption isotherm when expressed graphically. this isotherm curve can be obtained in one of two ways; adsorption or desorption. the establishment and the mathematical description of the moisture sorption isotherms could help the food engineers to design these processing equipments. here there are many researches on seeds of plant and some foods. in all researches seeds or foods has one or more mathematical models for describing of the moisture sorption isotherms. however, in all seeds or foods the equilibrium moisture contents increased with an increase in the water activity at any particular temperature and decreased with increase in temperature at constant water activity. the researches have suggested that the water potential of the seed or seed structures provides a better indicator of the seed water status than water content