Diurnal Temperature Amplitude Alters Physiological and Biochemical Response of Maize during the Vegetative Stage.

Diurnal temperature amplitude alters physiological and biochemical response of Maize during the vegetative stage

John Sunoj V.S.*, Kyle J. Shroyer, Krishna Jagadish S.V. and Prasad P.V.V.

Latest IPCC reports indicate increase in mean day time temperature with greater tendency of narrowing the diurnal temperature amplitude, mainly driven by rapid increase in night time temperature. Higher day and night temperature are shown to induce significant negative impact during growth and development, but limited studies have focused on diurnal temperature amplitude. Hence, the major objective of our studies was to ascertain the effect of diurnal temperature amplitude changes (with the same daily average temperature) on physiological and biochemical changes during the vegetative growth of maize.  A maize hybrid (DKC47-27RIB) was grown in controlled environment chambers at two mean day time temperature treatments (30°C and 35°C) with three different combinations of amplitude resulting in a difference of 2°C, 10°C and 18°C. After 40 days, significant changes were observed in night time respiration, plant height, total leaf area and total dry matter accumulation. Interestingly, the sugar and the starch content changed in accordance with the variation in night respiration. A linear increase was observed in plant height, total leaf area and total dry matter accumulation as the diurnal amplitude increased, while the night respiration had a decreasing trend as the amplitude increased. The total sugars, non-reducing sugars and starch also showed a linear increase with increasing temperature amplitude. However, there was no significant change observed in photosynthesis, photochemical efficiency and chlorophyll content. A strong negative correlation was found between night respiration and total dry matter accumulation, leaf area, reducing sugars and starch. The results implies that night time respiration drives the negative impact on maize growth with narrow temperature amplitude as a result on increasing nigh time temperature.