A Comparative Study on Lettuce Seed Germination Rates Conventional and Smart Greenhouses using Internet of Things Technology

Abstract

This research aims to develop a smart greenhouse using Internet of Things (IoT) technology and to compare its efficiency with a conventional greenhouse. It is an engineering research and development project applying the ESP32 microcontroller to collect data from sensors to measure air temperature/humidity, soil moisture, and light intensity. These sensors’data are used to control the on-off of water pumps’operation based on soil moisture values and to operate the mist spraying system according to the specified temperature. The data is saved on the cloud, and users can track and set settings via smartphones. Three types of lettuce seeds: Red Oak, Green Oak, and Frillice Iceberg were cultivated simultaneously in both the smart and conventional greenhouses. The smart greenhouse was found to function properly under the defined conditions. The misting system reduced the average internal temperature by 3°C compared to the conventional greenhouse. The watering system can maintain soil moisture within a 32%–43% range which is a more suitable and stable range than the conventional greenhouse, which ranged from 28%–48%. Comparisons revealed that lettuce grown in the smart greenhouse had higher and more consistent seed germination percentages and germination index, with a mean germination time of 4.32 days. Seedlings in the smart greenhouse exhibited a 21.5% higher average growth rate than those in the conventional greenhouse and showed lower relative variation. In conclusion, the developed smart greenhouse proved effective in controlling environmental conditions and enhancing the germination rate and growth of lettuce compared to a conventional greenhouse.