Paper Critique on Sensitivity of Photosynthesis in a C4 Plant, Maize, To Heat Stress

Paper Critique on Sensitivity of Photosynthesis in a C4 Plant, Maize, To Heat Stress
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Paper Critique on Sensitivity of Photosynthesis in a C4 Plant, Maize, To Heat Stress
Summary
Abstract
The objective of the study titled “sensitivity of photosynthesis in a C4 plant, maize to heat stress” is focusing on investigating the sensitivity of the elements of photosynthesis parameters of maize, a C4 plant to high and stressful levels of temperature. The authors reveal that the inhibition of net photosynthesis of a leaf is at temperatures beyond 38°C (Yamori, Hikosaka, & Way, 2014). Furthermore, the inhibition is much harsher when there is a rapid rise in temperature unlike during the time of a gradual rise in temperature. The increase in the rate of transpiration is progressive with the temperature of the leaf (Yamori, Hikosaka, & Way, 2014). This is an indicator that there is no relationship between inhibition of photosynthesis and the closure of stomata pores. There is a rise of the non-photochemical fluorescence quenching when the temperature of the leaf was more than 30°C. This indicates that there is an increase in the thylakoid energies even at a temperature that there is no inhibition of the net photosynthesis (Crafts-Brandner, & Salvucci, 2002).
In comparison with the absorption of carbon dioxide, the important quantum product of the second photosystem has some comparative insensitivity to leaf temperatures up to 45°C. The activation status of phosphoenolpyruvate carboxylase reduces a little bit at leaf temperatures beyond 40°C. The activeness of pyruvate phosphate dikinase stays unresponsive to temperatures up until 45°C. The activity status of Rubisco declines at temperatures more than 32.5°C having almost a total lack of activity at a temperature of 45°C. According to Crafts-Brandner, and Salvucci (2002), the inactivation of Rubisco remains the basic limitation on the rate of net photosynthesis of the maize leaf as the temperatures inclined to levels higher than 30°C.
Introduction
Photosynthesis is in most cases a major determining factor of the productivity of a plant and in this case the maize. Temperature has an impact on the initial growth as well as the yield of a crop. Low temperatures may affect the photosynthesis rate of a maize plant. The photosynthetic output of a plant relies on the level of temperature. There have been frequent examinations of the sensitivity of plants to photosynthesis. However, researches concerning the impacts of high temperature on C4 photosynthetic breakdown are rare. The hypothesis of the study is such that high temperature might make Rubisco inactivated and result in a limitation of the net photosynthesis in the same way just like in C3 plants. Nevertheless, according to literature reviews, it appeared realistic that heat stress may also affect some particular processes, for instance, the fixation of carbon dioxide by an enzyme known as the phosphoenolpyruvate carboxylase. In addition, it might influence the Calvin cycle and the shuttling of the maize plant acids from the mesophyll to the package sheath cells. The aim of the research focuses on investigating the effect of heat stress on the processes related to photosynthesis. This objective is realistic and the results will be a reflection of the effect of heat stress on plants. The processes likely to remain affected by heat stress include Rubisco activation, pyruvate phosphate dikinase, PSII stability and activities of phosphoenolpyruvate carboxylase in the leaves of a maize plant. The study provides a report of the process that is most sensitive to heat in a maize species (Crafts-Brandner, & Salvucci, 2002). The article has evidently used a review of literature that is recent and most relevant to the title of the article.
Results
The net photosynthesis in maize demonstrates a wide-ranging temperature most favorable between 28°C and 37.5°C. The inhibition of the net photosynthesis is after the temperature reaches higher than 37.5°C and the comparative inhibition is much more is cases whereby there is a rapid rise in temperature in comparison to a situation of gradual increase (Crafts-Brandner, & Salvucci, 2002). An increase in the level of CO2 above normal does not cause any alteration to the temperature reaction of net photosynthesis. Depending on the reports for species of different plants, the inhibition of net photosynthesis through heat stress lacks a link with the closure of stomata. As evident, the progressive increase in the rate of transpiration enhances the ability of the stomata to conduct more heat, which leads to an increase in the temperature of a leaf.


To some extent, the non-photochemical fluorescence quenching has some sensitivity to leaf temperatures with a noticeable increase happening from 32.5°C to 37.5°C. This is before the visible heat inhibition of the net photosynthesis and a progressive rise in temperature up to 45°C. In comparison to the non-photochemical fluorescence quenching, the optimal output of PSII there is a relative insensitivity to leaf temperatures up until 42.5°C (Crafts-Brandner, & Salvucci, 2002).


Heat stress has an effect on the activation of Rubisco in C3 plants, which may be due to the enzyme activas...