Low root/shoot (R/S) biomass ratio can be an indicator of low cadmium accumulation in the shoot of Chinese flowering cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) cultivars
Chinese flowering cabbage is a commonly consumed vegetable that accumulates Cd easily from Cd-contaminated soils. Cultivations of low-Cd cultivars are promising strategies for food safety, but low-Cd-accumulating mechanisms are not fully elucidated. To address this issue, 37 cultivars were screened to identify high- and low-Cd cultivars upon exposure to sewage-irrigated garden soil pretreated with different Cd concentrations (1.81, 2.90, and 3.70 mg kg−1dry soil). The results showed that shoot Cd concentrations differed among the cultivars by maximum degrees of 2.67-, 3.71-, and 3.00-fold under control and treatments, respectively. Soil-pot trial and hydroponic trial found no significant difference in Cd and Ca mobilization, uptake, and transport ability by root per weight between high- and low-Cd cultivars. Interestingly, a stable R/S ratio difference among cultivars (p < 0.01) was observed, and the cultivar variation of Cd accumulation in shoots was mainly dependent on their R/S ratios. R/S ratio was also statistically positively associated with Cd and Ca accumulation in high- and low-Cd cultivars (p < 0.05), both in soil and hydroponics culture. This was mainly due to the lower root biomass of low-Cd cultivars resulted in lower total release of root exudates, lower total Cd and Ca mobilization in rhizosphere soil, and lower total Cd and Ca uptake and transport. The higher shoot biomass of low-Cd cultivars also has dilution effects on Cd concentration in shoot. Overall, low R/S ratio may be regarded as a direct and efficient indicator of low Cd accumulation in the shoot of Chinese flowering cabbage. These findings provided the possibilities to screening low-Cd cultivars using their R/S ratio.
KeywordsLow-Cd cultivars R/S biomass ratio Cd mobilization Cd uptake and translocation Ca channel
The authors are grateful to the National Key Research Project of China (No.2017YFD0801305), the National Natural Science Foundation of China (No. 41371321), and the Department of Science and Technology of Guangdong Province, China (No. 2017A010105005) for their financial support.
- Dai KJ, Shen YX, Zhou WJ, Deng Y, Liu WY (2005) Mechanism of Pinus yunnanensis seedlings root response to phosphorus deficiency under controlled conditions. Acta Ecol Sin 25:2423–2426Google Scholar
- Dar MI, Green ID, Naikoo MI, Khan FA, Ansari AA, Lone MI (2017) Assessment of biotransfer and bioaccumulation of cadmium, lead and zinc from fly ash amended soil in mustard-aphid-beetle food chain. Sci Total Environ 584:1221-1229Google Scholar
- Lu K (1999) Analytical methods of agricultural chemistry in soil. Agricultural science and Technology Press of China. Beijing, ChinaGoogle Scholar
- Sheng RL, Tong HY, Chai C, Huang SZ (2010) Effect of NaCl stress on seedling growth of different cultivars of Stevia rebaudiana. J Plant Resour Environ 19:60–67 (in Chinese) Google Scholar
- Stritsis C, Steingrobe B, Claassen N (2012) Shoot cadmium concentration of soil‐grown plants as related to their root properties.J Plant Nutr Soil Sci 175:456–465Google Scholar
- Sun J, Ma B, Lu X (2017) Grazing enhances soil nutrient effects: trade-offs between aboveground and belowground biomass in alpine grasslands of the Tibetan plateau. Land Degrad Dev 29:770Google Scholar
- Welch RM, Hart JJ, Norvell WA, Sullivan LA, Kochian LV (1999) Effects of nutrient solution zinc activity on net uptake, translocation, and root export of cadmium and zinc by separated sections of intact durum wheat (Triticum turgidum L. var durum) seedling roots. Plant Soil 208:243–250CrossRefGoogle Scholar
- Xu ZM, Tan XQ, Mei XQ, Li QS, Zhou C, Wang LL, Ye HJ, Yang P (2018) Low-cd tomato cultivars ( Solanum lycopersicum L.) screened in non-saline soils also accumulated low Cd, Zn, and Cu in heavy metal-polluted saline soils. Environ Sci Pollut Res 25:27439–27450Google Scholar
- Ye J, Yan C, Liu J, Lu H, Liu T, Song Z (2012) Effects of silicon on the distribution of cadmium compartmentation in root tips of Kandelia obovata (S., L.) Yong. J Food Agric Environ 162:369–373Google Scholar
- Zong LG, Sun JK, Shen QY, Zhang XP (2007) Impacts of cadmium and lead pollution in soil on leaf vegetables growth and toxic-symptoms. Asian J Ecotoxicol 2:63-68 (in Chinese) Google Scholar