Abstract:
Evapotranspiration is an important component of the hydrologic cycle. Water works as the medium of absorption and transport of nutrients from the soil, plays important role in plant photosynthetic process, is medium of transport of metabolites, and forms part of structure of the plant tissues. Evapotranspiration is the basic process that governs the state and movement of water in the Soil-Plant-
Atmospheric continuum (SPAC). It is itself controlled by availability
of water in the root zone soil, plant characteristics including transport
resistances at various stages in the SPAC, and atmospheric
evaporative demand, As time after irrigation or rainfall proceeds,
water from the crop root zone continously depletes, resulting in the
stress condition in the root zone. Due to stress, several plant
functions like photosynthesis, cell division and enlargement, nutrient
uptake, and thus growth and development processes are affected
resulting in to reduction in the otherwise realizable yield. Therefore
it is essential to keep the root zone well supplied with water by
resorting to irrigation. To qualify water status which determines
the irrigation needs of a crop, it is desirable that the component of evapotranspiration is adequately quantified so that crops are irrigated at appropriate time before stress conditions may develop affecting the yield.
