Abstract
Maize (Zea mays L.) is the most important food and feed crop grown under diverse soil and climatic conditions. Among the cereals, demand for maize is increasing year after year, but fluctuation in climatic conditions especially the temperature extremes is the current and future threat in maize cultivation. Each degree Celsius increase in global mean temperature causes yield reduction up to 7.4 per cent in maize. The high temperature stress impact at the reproductive stage affects grain filling rate and duration. Adaptation of maize crop to future warmer climatic conditions requires a better understanding of physiological responses to elevated temperatures. With this view, a pot culture experiment was conducted at the Department of Crop Physiology, TNAU, Coimbatore during the summer season of 2020. Two maize inbreds viz., UMI 1230 and CBM-DL- 322 were taken for the study and exposed to high temperature stress treatments viz., T1 - ambient, T2 - ambient+4°C and T3 - ambient+6°C (44°C) for 10 days during the reproductive stage to assess the changes in biochemical and yield traits. The ambient+4ºC treatment revealed that the maize inbred line CBM-DL-322 recorded lower malondialdehyde content with over production of antioxidant enzyme activity (superoxide dismutase, catalase and ascorbate peroxidase). Cob weight and seed set parentage showed a negative correlation with both elevated temperatures. It is concluded that the maize inbreds line CBM-DL- 322 performed better at an elevated temperature at ambient+4°C and recorded more cob weight (57.09g) compared to UMI 1230 inbred (43.56g).
Highlights
Global climate change leads to adverse effects on agricultural productivity
The ambient+4oC treatment revealed that the maize inbred line CBM-DL-322 recorded lower malondialdehyde content with over production of antioxidant enzyme activity
At the reproductive stage (52 DAE), maize plants were transferred to a growth chamber (Open Top Chamber-OTC) where the high temperature stress was imposed for 10 days in a closed environment
Summary
Global climate change leads to adverse effects on agricultural productivity. Temperature extremes severely affect crop yields when occur during the reproductive stage. According to the IPCC - 2018, if current rates of global warming continue, global temperatures will rise by 1.5 degrees Celsius between 2030 and 2052. Mikhaylov et al (2020) reported that in the last 100 years, the earth’s global temperature has increased by 0.5-1 degrees Celsius. According to Raza et al (2019), over the last few centuries, changes in climatic conditions such as temperature and rainfall patterns had a significant impact on the morphology and physiology of a wide range of crop species and so it can generate excess energy in high temperatures, but a larger increase in temperature reduces plant growth and photosynthesis rate
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