Photosynthetic pigments and gas exchange in castor bean under conditions of above the optimal temperature and high CO2

The castor bean plant, a Euphorbiaceae oil seed C3-metabolism rustic and drought-resistant plant, is cultivated in a wide range of environments due to its good adaptive capacity. However, given the current environmental changes, many biochemical and physiological impacts may affect the productivity of important crops, such as castor bean. This work aimed to evaluate the impacts of the castor bean gas exchange in response to high temperature and increased CO2 concentration. Our experiment was conducted in a phytotron located at Embrapa Algodão in 2010. We adopted a completely randomized design, with four treatments in a factorial combination of two temperatures (30/20 and 37/30°C) and two CO2 levels (400 and 800 (mol L-1); four replications were performed, obtained in five surveys over the growth cycle, for a total of 80 sample units. An infrared gas analyzer (IRGA - Infra Red Gas Analyzer) was used for the quantification of the photosynthetic rate, stomatal conductance and transpiration. An increase in the atmospheric CO2 concentration and temperature negatively affected the physiology of the castor bean plants, decreasing the net rate of photosynthesis, transpiration and stomatal conductance.

蓖麻作为大戟科（Euphorbiaceae）油籽作物，属于C3代谢类型，兼具抗逆性与耐旱性，因其良好的环境适应能力，可在广泛的生境中栽培。然而，在当前全球环境变化的背景下，诸多生物化学与生理层面的影响因素可能威胁包括蓖麻在内的重要作物的产量。本研究旨在评估高温与CO₂浓度升高对蓖麻气体交换过程的影响。本实验于2010年在巴西农业研究公司棉花研究所（Embrapa Algodão）的人工气候室（phytotron）中开展。实验采用完全随机设计，设置4个处理组合，由2个温度梯度（30/20℃与37/30℃）与2个CO₂浓度水平（400与800 mol·L⁻¹）构成；共设置4次重复，在整个生长周期内开展5次采样调查，最终共计获得80个样本单元。本研究采用红外气体分析仪（IRGA - Infra Red Gas Analyzer）测定光合速率、气孔导度与蒸腾速率。大气CO₂浓度升高与温度升高均会对蓖麻植株的生理状态产生负面影响，降低其净光合速率、蒸腾速率与气孔导度。