Salinity and fertility stresses modify K_s and readily available water coefficients in maize (case study: Qazvin region)

Abstract

Field stresses such as salinity and fertility stresses affect on stomatal resistance and evapotranspiration (ET). But the effects of these stresses were ignored in the determination of ET and irrigation requirement. The present study investigated evapotranspiration (ET) and available moisture for maize SC 704 under salinity and fertility stresses. Treatments of saline water were 0.5 $\left( {{\text{S}}_{0} } \right)$, 2.1 $\left( {{\text{S}}_{1} } \right)$, 3.5 $\left( {{\text{S}}_{2} } \right)$, and 5.7 $\left( {{\text{S}}_{3} } \right){ }$ dS m⁻¹. Four nitrogen fertilization levels of 100% $\left( {{\text{N}}_{0} } \right)$, 75% $\left( {{\text{N}}_{1} } \right)$, 50% $\left( {{\text{N}}_{2} } \right)$ and 25% $\left( {{\text{N}}_{3} } \right)$ based on fertilizer tests were consumed. Irrigation times were determined based on stomatal resistance measurement. The results showed that stresses increased the stomatal resistance. ET stress coefficients (K_s) were measured between 0.63 and 1 in 2017 and between 0.62 and 1 in 2018. Polynomial function had the best performance in estimating of K_s coefficients. Also, the range of the RAW (readily available water) for stressed and control plants was estimated at 42% to 66.5% in 2017 and 41.5% to 67% in 2018. Results showed that linear and exponential models performed well in estimating of RAW. An accurate estimation of ET and RAW made irrigation schedule more accurate. Due to reduced ET and plant water uptake in salinity and fertility stresses, the volume of irrigation water can be reduced relative to standard conditions. This will lead to reduce water use and water footprint.