Introduction:
Intensive and controlled greenhouse cultivation can be effective to some extent in improving food security. Greenhouses have a distinct advantage due to their ability to support continuous crop production throughout the year, resulting in increased productivity, especially when compared with open-field cultivation. Water is one of the main and influential inputs on food production and security, and it should be used optimally to achieve high productivity and efficiency. Determining the optimal amount of water requirement and the performance of each crop provides valuable guidance for planners to increase the food security factor. Water shortage is also a significant threat to the agricultural sector. Determining irrigation scheduling is effective in enhancing the production of agricultural products, especially greenhouse crops. Appropriate knowledge of water consumption and the water use efficiency of various crops, including tomatoes and bell peppers, can effectively assist planners and officials at the regional and national levels in optimizing the production of various greenhouse crops throughout the seasons.
 Methods:
This research was conducted in the Kakulak greenhouse complex located in Shahrekord city, Iran, during 2022-2023 cropping season. Cultivation was carried out in two greenhouses in the autumn of 2023,  simultaneously with cultivation in the corresponding control greenhouses. Each crop (bell pepper and tomato) was planted in one greenhouse with three replicates, each replicate consisting of three pots. A grass lysimeter and an evaporation pan (class A) were installed in each greenhouse, and another evaporation pan was placed outside the greenhouse. Bell pepper seeds were sown in seedling trays using a culture medium and were transferred to the pot environment after about five weeks. Crop management practices (irrigation, weed removal, spraying, fertilization, pruning, measuring the height and number of fruits per plant) and harvesting were carried out during the cultivation period. Irrigation was typically performed daily. Fertilization and pesticide application of the pots were the same the greenhouse schedule. Daily recorded data included: volume of water added to the pots, the grass lysimeter volume of drained water, volume of water evaporated from the evaporation pans inside and outside the greenhouses, the temperature parameters, the instantaneous and maximum, and minimum daily relative humidity inside and outside the greenhouse and the amount of light intensity inside the greenhouse. In addition, the volume of water consumed in the bell pepper greenhouse was measured using a two-inch meter. Actual evapotranspiration (the amount of water consumed by the plant) was calculated and estimated using the water balance equation and considered for the desired crops. Water use efficiency index (WUE) was also calculated as a function of the yield of each crop (kilograms per hectare) and the amount of water used (cubic meters per hectare).
 Conclusion:
In order to increase the food security factor, considering the challenges and tensions caused by the shortage of water resources globally and in Iran use of high-yield intensive cropping systems such as greenhouses cultivation, is essential. Development of greenhouses cultivation, due to higher productivity (lower water consumption and increased yield per unit area), can partially help solve the problems of water stress. According the results of the current research on water requirements and water use efficiency of tomatoes and bell peppers in greenhouses, the bell pepper crop consumed 4993 cubic meters per hectare of water during the growing season (341 days), with a yield and production of 115634 kilograms per hectare and a water use productivity index of 23.56 kilograms per cubic meter. The ratio of water used for bell pepper production to grass evapotranspiration and transpiration was 52.1 percent, and to the amount of evaporation from a class A evaporation pan was 58.31 percent. The tomato crop with 165-days growing season, water consumption of 2844 cubic meters per hectare, yield of 89191 kg per hectare, with a water use efficiency index of 31.36 kg per cubic meter was obtained. The irrigation hydromodule of both crops, considering the water requirement of pad and fan, was 0.45 liters per second per hectare. Future reaearch is suggested with focus on scaling these finding to larger greenhouse systems. Additionally, investigating the impact of varying greenhouse use across diverse agricultural contexts. These advancements could support local policymakers and farmers in developing resilint food production systems while conserving critical water resources.