Differences in calcium uptake and accumulation by Chinese cabbage (Brassica campestris L. ssp. pekinensis) cultivars under stress conditions

Uptake and translocation of Ca2+ by plant roots have been showed to be inhibited by osmotic stress. To assess the different response of six Chinese cabbage cultivars, a hydroponics culture system was employed, using NaCl (EC at 5 and 10 mS/cm) and PEG (at -0.3Pa and -1.0Pa). Under salt and osmotic stresses, accumulation of Ca in all the tested cultivars declined significantly. The most sensitive cultivar was Tianjingqingmaye, with a Ca content being 21.05% of the NaCl free control in 5 mS/cm NaCl solution and 6.32% in 10 mS/cm NaCl solution one day after treatment, respectively. The most insensitive cultivar was Chengqing 2. with a Ca content being 66.70% of the control in 5 mS/cm NaCl solution one day after treatment, and 49.45% in 10 mS/cm solution respectively. The latter cultivar contained 3 times and 8 times Ca of that in the former cultivar in 5 mS/cm and 10 mS/cm NaCl solution respectively. In PEG treated plants, Tianjingqingmaye was most affected with a Ca content 80.15% lower than that of the zero PEG control in -0.3 Pa PEG solution and 94.68% lower than that of control in -1.0 Pa PEG. The least affected cultivar, Zhaoshou 5 has a Ca content only 27.50% lower than that of the control in -0.3 Pa PEG solution, and 45.78% lower than that of the control in 1.0 Pa PEG solution. The difference between these two cultivars in Ca accumulation ability under osmotic stress was 2-3 times.