Title: Effects of Drought Stress on Photosynthetic Characteristics of Maize Hybrids at Seedling Stage
Abstract: Maintaining active photosynthesis is very important for crops to adapt drought stress. The electron transport chain and stomatal conductance are important in photosynthesis. Limited data are available on their combined responses to drought stress in maize. In this paper, the effects of drought stress on photosynthetic characteristics in maize hybrids Shaandan 609 and Zhengdan 958 at seedling stage were investigated. The results showed that the CO2 assimilation(Pn), stomatal conductance(Gs) and intercellular CO2 concentration(Ci) decreased during drought stress, showing the decreased photosynthesis due to stomatal factor. During moderate and severe drought stress, down-regulation in net CO2 fixation(Pn) was primarily mediated through non-stomatal limitation. The OJIP transients and other associated biophysical parameters elucidated the events of photoacclimatory changes in photosystem II(PSII) with progressive increase of drought stress, and the K-bands appeared in the stage of extreme drought severity indicating the imbalance between the electrons at the acceptor and donor sides of PSII, which suggested the oxygen-evolving complex(OEC) and electron transport were inhibited. In conclusion, the moderate and severe drought stress mainly damages the electron transfer from the plastoquinone(PQ) pool to the PSI terminal acceptors; this, along with constraints to both stomatal and non-stomatal components of photosynthesis, limits carbon assimilation. There are differences in cultivars with the response of PSII activity to drought stress.
Publication Year: 2015
Publication Date: 2015-01-01
Language: en
Type: article
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