Multi-factor coupling regulation of greenhouse environment based on comprehensive growth of cherry tomato seedlings

Abstract

Environmental regulation based on crops can ensure efficient and high-quality production. However, environmental factors, such as temperature, air humidity, and light intensity, promote and restrict production during the crop growth, while complex compensation effects and feedback paths exist among these factors. In order to accurately and efficiently control the greenhouse environment for the growth of cherry tomato seedlings, a design of composite quadratic orthogonal regressive rotation with three factors and five levels was adopted. Experimental variables included temperature, relative humidity (RH), and photosynthetically active radiation (PAR). We established the response models of growth indicators (seedling index, dry matter accumulation, net photosynthetic rate, transpiration rate and chlorophyll content) to environmental multiple factors. The analytic hierarchy process (AHP) and entropy weight method were introduced to weight five indicators, and the game theory-based combined weighting method was subsequently used to obtain the final weight of each indicator. A comprehensive growth evaluation system for cherry tomato seedlings was established based on Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), and the response model of comprehensive growth to environment multi-factor was established according to evaluation values. Also, the synergistic regulation of the environmental factors was analyzed. Results demonstrated that the optimum environment for the seedling index is consistent with that of dry matter accumulation, but different from those of other growth indicators. Furthermore, the greatest combined weight was determined for the seedling index (0.327), while chlorophyll content ranked bottom (0.118). Enhancing photosynthetically active radiation was not able to significantly promote the growth of tomato under low temperatures and humidity. Based on our results, for medium levels of photosynthetically active radiation, increasing relative humidity rather than temperature is suggested for the promotion of tomato growth during the seedling. In addition, the optimal environmental factor combination for comprehensive growth of cherry tomato seeding was a temperature of 27.6 °C, an RH of 76.1% and PAR of 396.3 μmol•m − 2•s − 1. Our results can be applied to the environmental management of greenhouse cherry tomato seedlings and can also improve energy efficiency of environmental control.