Evaluation of the Control of Environmental Variables in a Pine Seedling Greenhouse

Abstract

The objective of the research was to evaluate the control of environmental variables that allows obtaining a favorable environment inside a greenhouse for the development of Pinus radiata seedlings. A controller was implemented inside the greenhouse to maintain the variables in preset ranges: temperature from 19.0ºC to 25.0ºC; soil humidity from 50% to 100%; ambient humidity from 70% to 90% and illumination at levels greater than 450 lux. The control algorithm was implemented in the PIC 18F4550 microcontroller, as control actuators were used: a fan-exhaust fan and air heater for temperature; solenoid valves for soil and ambient humidity; LED lamps for illumination. As a result, the environmental variables controller, when tested for 24 hours for 10 days, maintained on average: temperature at 21.54ºC; soil humidity at 75.09%; relative humidity at 79.32% and illumination in the absence of sunlight at 451.62 lux. Likewise, it was found that the DQI of Pinus radiata seedlings of the average control group was 0.433 and the experimental group had an average DQI of 0.571; when evaluating the normalized DQI for both groups, a significant difference greater than 5% was obtained, with the t-test for two-tailed independent samples, with the p-value = 0.002, which is less than the significance level alpha = 0.05. Therefore, it is concluded that the controller generated a favorable environment for the development of the Pinus radiata seedlings of the experimental group, having a high possibility of survival when transferred to the final field.