Overnight warming negatively impacts growth and reproduction in Brassica rapa

Abstract

Temperature plays a central role in plant growth and development. As global warming has increased, heat stress has become an increasingly pressing issue that influences plant growth, reproduction, and crop yield. One-hundred and thirty Brassica rapa plants were examined in this experiment to investigate the effects of overnight warming on temperate species. It was hypothesized that the elevated overnight temperature would have significant effects on the plant growth, reproduction, and seed viability of B. rapa. The B. rapa seeds were measured as two groups: a control group with conditions of 27°C for 14 daytime hours and 20°C for 10 overnight hours, and an experimental group with conditions of 27°C for 14 daytime hours and 24°C for 10 overnight hours. Weekly, stem height, width, chlorophyll content, and leaf area were measured for growth variables. A count of buds, flowers, and seed pods were obtained weekly beginning in the second week. Aboveground biomass was harvested to determine productivity for vegetative and reproductive plant products. Results showed plants grown with an elevated overnight temperature were shorter, had narrower stems, shorter leaves and produced less aboveground biomass compared to the control plants. Experimental plants produced wider leaves with a higher chlorophyll content, more flowers and created seeds with a greater average seed biomass than the control plants. There was no difference in germinability between the control and experimental groups. Results suggest differential physiological responses of growth and reproductive organs in response to stress associated with warmer overnight temperatures.