PJB-2018-1041
The physiological responses of Nouelia insignis towards drought and low temperature
Zhining Xia and Yanling Zheng
Abstract
Climate change was increased the frequency and magnitude of drought events in southwest China, particularly in winter and spring. However, the effects of drought and low temperature on physiological characteristics of the endangered Nouelia insignis whose natural regeneration is poor are not clear. Seedlings subjected to each drought treatment (achievement by withholding irrigation for 0, 5 and 9 d, respectively) were randomly divided into three groups and treated at 25, 5 and -5 °C for 1.5 h, respectively. Leaf relative water content, effective quantum yield of PSII-Y(II), photochemical quenching coefficient (qp) and electron transport rate (ETR) decreased significantly and superoxide dismutase (SOD) activity increased significantly with the duration of withholding water. Pigment content, malondialdehyde (MDA) content, peroxidase (POD) activity and proline content increased significantly and maximum quantum yield of photosystem II (Fv/Fm) decreased significantly for seedlings subjected to severe drought. Y(II), qP and ETR decreased with the duration of withholding water for seedlings treated at 5 and -5°C. Fv/Fm, Y(II), qp and ETR decreased significantly, by 26.02%, 35.90%, 27.37% and 37.33%, respectively and MDA content increased significantly by 26.19% for seedlings subjected to -5°C. Fv/Fm of drought-stressed seedlings recovered to the original level after 2 d of recovery but that of freezing-treated seedlings did not recover which decreased with the duration of withholding water. In conclusion, photosynthetic activities and membrane of N. insignis were negatively affected by both severe drought and freezing temperature and the seedlings were more tolerant to drought than freezing temperature which might be due to the increased activities of antioxidant enzymes and accumulation of some osmolytes. Additionally, tolerance of N. insignis to low temperature was not enhanced by pretreatment of seedlings with drought and even diminished after being subjected to severe drought. Therefore, extreme drought and low temperature, particularly their combination, might be the important factors which limited natural regeneration of N. insignis.
To Cite this article:
Xia, Z. and Y. Zheng. 2020. The physiological responses of Nouelia insignis towards drought and low temperature. Pak. J. Bot., 52(4): DOI: http://dx.doi.org/10.30848/PJB2020-4(28)
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