Effects of Drought Stress on Physiological Characteristics and Yield of Maize in The Presence of a Shallow Water Table in Ahvaz Climatic Conditions

In this research, in order to study the effect of deficit irrigation on the physiological indexes of maize (single cross 704), an experiment in randomized complete block design with three replicate, was performed in the experimental field of Shahid Chamran university during the year 2013.The Irrigation treatments included 100, 75 and 50 percent of the maize water requirement that was calculated through the evapotranspiration of the reference plant (grass). Volumetric lysimeter were used for the cultivation and the depth of the groundwater table was held at 70 centimeters from the soil surface. A lysimeter with complete irrigation and without the presence of water table was used as control treatment. The amount of the physiological indexes was measured 60,74 and 88 days after sowing for Determination of Stomatal conductance, photosynthesis speed and chlorophyll's density. The results showed that with increasing of water stress, the amount of the physiological indexes decreased. The maximum and minimum amount of chlorophyll's density was 55.38 and 39.66, obtained from the treatments with 100 and 50 percent of maize water requirement irrigation, respectively. The maximum and minimum amount of Stomatal conductance and photosynthesis speed obtained from treatments with 100 and 50 percent of maize water requirement irrigation, respectively. The alteration process of these three indexes during the infancy showed that from the eighth week after the cultivation till the end of the maize infancy the maize petal loophole conduction, photosynthesis velocity and the chlorophyll's density will decrease. also, the results showed that the maximum maize biomass was 4.63 ton/ha obtained from the treatment with 100 percent of maize water requirement irrigation and the minimum maize biomass was 3.72 ton/ha obtained from the treatment with 50 percent of maize water requirement irrigation.