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Pak. J. Bot., 47(6): 2069-2075, 2015.

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Physiological and Photosynthesis Response of Popcorn Inbred Seedlings to Waterlogging Stress

MIN ZHU, JI WANG, FENGHAI LI^*AND ZHENSHENG SHI^*

Department of Agronomy, Specialty Corn Institute, Shenyang Agricultural University, 110866 Shenyang, Liaoning Province, P.R. China

^*Corresponding authors e-mail: 58692710@qq.com; xiaozhu211211@163.com; Tel: +8602488421178

Abstract: Waterlogging is one of the most severe global problems, which affects crop growth and yield worldwide, especially in the low-lying rainfed areas, and irrigated and heavy rainfall environment. Our objective was to study the physiological and photosynthetic characteristics of two popcorn genotypes under waterlogging conditions. The experiment was carried out in pots with two contrasting inbred lines differing in waterlogging tolerance: Q5 (tolerant) and Q10 (sensitive). Leaf gas exchange, oxidative stress, and chlorophyll (Chl) fluorescence were measured at 0, 2, 4, and 6d in the control and waterlogged plants. A decrease in net photosynthesis, stomatal conductance, and transpiration was observed in both genotypes. The waterlogging-sensitive plants showed reduced chlorophyll fluorescence, chlorophyll content and increased activity of peroxidase and polyphenol oxidase. Response curves for the relationship between photosynthetically active radiation (PAR) and net photosynthetic rate (P_N) for waterlogged plants were similar in both genotypes. The different physiological and photosynthetic response in the two popcorn inbred lines might be responsible for higher tolerance of Q5 than Q10. These results suggest that Q5 popcorn inbred lines are a source of genetic diversity for important traits such as P_N and WUE.

Key words: Popcorn, Waterlogging, Physiology, Photosynthsis, Chlorophyll content, Chlorophyll fluorescence.

Abbreviations: AQY-apparent quantum yield; Chl-chlorophyll; E-transpiration; F_v/F_m-maximal quantum yield of PS II; g_s-stomatal conductance; L_s-light saturation point; L_c-light compensation point; PAR-photosynthetically active radiation; P_max-maximal photosynthetic rate; P_N-net photosynthetic rate; WUE-water-use efficiency; Φ_PSⅡ-effective quantum yield of PSII photochemistry.