Chin J Plant Ecol ›› 2006, Vol. 30 ›› Issue (3): 472-478.DOI: 10.17521/cjpe.2006.0063

• Original article • Previous Articles     Next Articles

EFFECTS OF Pb POLLUTION ON PHOTOSYNTHETIC CHARACTERISTICS, QUALITY, AND YIELD OF TOBACCO LEAVES

MA Xin-Ming(), LI Chun-Ming, YUAN Zu-Li, XIONG Shu-Ping   

  1. College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China
  • Accepted:2006-01-17 Published:2006-05-30

Abstract:

In order to examine the effects of Pb pollution on photosynthesis, quality, and yield of tobacco cultivar, pot experiment was carried out at the Research Station of Henan Agricultural University during 2002-2004. Cultivar of `Yunyan 85' was treated with seven concentration levels of Pb2+ (0, 150, 300, 450, 600, 750 and 1 000 mg·kg-1) applied with (CH3COO)2Pb after transplanting. Twenty leaves were saved after topping. The net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), and stomatal conductance (Gs) of three identical functional leaves from the same position were measured during rosette, budding, and harvest stages respectively using a Li-6400 Portable Photosynthesis System. Maximal fluorescence (Fm),fixed fluorescence (Fo), and steady fluorescence (Fs) were determined in the dark (for 30 min) and maximal fluorescence in the light (Fm') with a Hansatech FMS2 photo-fluorometer. PSⅡ activity (Fv/Fo), PSⅡ maximum light energy transformation (Fv/Fm), chemical quenching coefficient (qP), non-photochemical quenching coefficient (NPQ), apparent photosynthetic electron transport rate(ETR), and the ratio of photochemical quantum yield of PSII (ФPSⅡ) were calculated.The reductive sugar, total N, nicotine, Kalium contents of tobacco leaves and yield per plant were investigated.

The results showed that Pn, Gs, and Ci occurred at the Pb concentrations of 300 mg·kg-1 in budding stage and the Pb concentrations up to 150 mg·kg-1 in rosette and harvest stages. Fv/Fo, Fv/Fm, qP, NPQ, ETR, and ФPSⅡ decreased with increasing Pb concentrations, resulting in declining ability of photosynthetic pigments assimilating light, photosynthetic light use efficiency, and Pn of tobacco leaves. Higher Pb concentrations led to increases in the ratios of reductive sugar/nicotine (9.52-11.96) and total-N/nicotine (1.05-1.23), which are used as the quality indexes of tobacco leaves, above the standards (7 and 1) of high quality of tobacco leaves, and then deteriorated the fragrance of tobacco leaves.

Key words: Pb pollution, Tobacco, Photosynthetic characteristics, Quality, Yield