Submitted to: Photosynthetica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/12/2013
Publication Date: 6/1/2014
Citation: Singh, S., Reddy, K.R., Reddy, V., Gao, W. 2014. Maize (Zea mays L.) growth and developmental responses to temperature and UV-B interactions. Photosynthetica. 52(2):262-271. Interpretive Summary: The total amount of UV-B radiation has been increased in the recent past causing harmful effects on plants and animals. The extreme temperature events (high or low) are also expected to be more frequent due to the changes in global climatic conditions. Maize (corn) is an important crop grown worldwide for food, bio-fuel, and animal feed. UV-B radiation caused reduction in maize growths at all temperatures. A combination of high temperature with high UV-B radiation was more harmful to maize growth than any of these factors alone. The results suggested that maize growth and development are highly sensitive to both current and projected UV-B radiations and it will be more harmful to maize at high temperature. This work will advance our current understanding with regards to the impact of these environmental stress factors on maize crops and aide to the further research designed to predict responses of the agronomic crops under future climate scenarios.
Technical Abstract: Plant response to the combination of two or more abiotic stresses is different than its response to same stresses singly. The interaction among stresses will have a profound impact on plants under current and projected changes in climatic conditions. The response of maize (Zea mays L.) photosynthesis, growth and development processes were examined under controlled environments in sunlight plant growth chambers. Plants were grown at three levels of each, day/night temperature (24/16 °C, 30/22 °C and 36/28 °C) and UV-B radiation (0, 5, and 10 kJ m-2 d-1) and their combinations from 4 days after emergence to 43 days under optimum nutrient and water conditions. An increase in plant height, leaf area, node number and dry weight were observed as temperature increased. However, UV-B radiation negatively affected these processes by reducing the rates of stem elongation, leaf area expansion and dry matter accumulation. On average maximum photosynthesis and quantum efficiency was observed at 30/22 °C. UV-B radiation affected leaf photosynthetic mostly at early stage of growth in both younger and older leaves. Although, UV-B stimulated biosynthesis of ultraviolet absorbing compounds (phenolics) at a given temperature, higher temperatures tend to suppress accumulation of these compounds. Plant exposed to UV-B radiation produced more leaf epicuticular waxes except at 24/16 °C temperature treatment. The results suggested that maize growth and development, especially stem elongation and leaf area expansion, are highly sensitive to current and projected UV-B radiations, and temperature will play a important role in the magnitude and direction of the UV-B mediated responses.