The impact of Deficit Irrigation and Salinity Stress on Physiological Parameters and Yield of Bell Pepper in Greenhouse by Smart Drip Irrigation system

Soil moisture control and salinity control are important management components to reduce water consumption and improve the quality and quantity of the products in greenhouses. An experiment was conducted in order to determine the effect of deficit irrigation and salinity stress on physiological characteristics and yield of bell pepper in the greenhouse during winter and spring 2013-2014, in the greenhouse of Ferdowsi University of Mashhad. The smart drip irrigation system is used to irrigate the bell pepper. For this purpose, plant moisture is detected by humidity sensors "REC-P55" embedded in pots. The necessary commands and instruction were given to the controller to connect or disconnect irrigation. The irrigation treatments were applied to include 100% (I1), 85% (I2) and 70% (I3) of water requirement as well as three levels of salinity in the amount of 1/2 (S1), 3 (S2) and 6 (S3) dS/m, and with three replications in a factorial experiment in a completely randomized design. The results have shown a very significant effect (%1) of salinity and deficit irrigation on yield, fruit number and fruit weight. Although the interaction of salinity and deficit irrigation on fruit yield at 5% level, but it did not have a significant effect on the number of fruit. In other words, the low number of fruits cannot be the cause of a reduced performance. But a decrease in the number of fruit can reduce the average weight of the fruit. With increasing salinity and lack of irrigation, the leaf chlorophyll has fallen leaf chlorophyll. Salinity and irrigation practices on the leaf stomatal conductance, did not show significant differences between treatments . However, with increasing salinity and lowering irrigation its amount has been dropped. The amount of used water has dropped due to low irrigation and salinity. The use of smart irrigation systems has led to remarkable water save. The results have shown that fresh and dry weight, leaves and roots, as well as the percentage of water content in the roots and leaves have fallen, due to the effects of limited irrigation and salinity.