Physiological and Growth Characteristics of Tomato Seedlings in Response to Low Root-zone Temperature

Abstract

Root-zone temperature (RZT) is an indispensable environmental factor for the proper growth and development of plants. Low RZT is one of the major limitations for agricultural production during cold seasons. In this study, the physiological responses of tomato seedlings to low RZT stress (10 °C) and its recovery were investigated with hydroponic cultivation in an artificial climate-controlled chamber. The stress reaction of tomato seedlings was evaluated by combining various indexes, including photosynthesis, chlorophyll fluorescence, root activity, hydrogen peroxide, and antioxidants. The results showed that low RZT adversely affected root activity, and in response to the limited root-source water and mineral elements, supply for shoot metabolism, leaf photosynthesis, and chlorophyll fluorescence were negatively influenced, which led to inhibited leaf area development and biomass accumulation. Hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline accumulated with the time of low RZT stress. When restored to normal temperature (∼20 °C), the physiological parameters recovered to a certain degree, although most parameters were not at a similar level with the control. In crop production during cold seasons, it is necessary to improve the RZT to achieve high quality and yield production.