Effects of Hydroxyapatite on Growth and Quality of Potato ( Solanum tuberosum L.) in Cd Polluted Soil
羟基磷灰石对Cd污染土壤中马铃薯生长及品质的影响

A pot experiment was conducted in a glasshouse to study effects of hydroxyapatite amending Cd polluted soil on growth and quality of potato (Solanum tuberosum L.). In the experiment, 3 levels of Cd pollution (0, 5, and 10 mg·kg-1) and 6 levels of hydroxyapatite application (0, 4, 8, 10, 16, and 30 g·kg-1) in soil were prepared to plant 2 potato varieties (Zhongshusanhao and Daxiyang in Chinese system). The results showed that Cd pollution in soil resulted in decrease in yield per plant of potato; for example, in the soils with 5 and 10 mg·kg-1 of Cd, the yield per plant decreased 24%-31% and 41%-45%, respectively. Applying hydroxyapatite to Cd pollution could greatly increase yield per plant of potato. Compared to the soil without hydroxyapatite, 10 or 30 g·kg-1 hydroxyapatite added to the soil with 5 or 10 mg·kg-1 of Cd increased 17%-39% or 45%-58% in yield per plant. Due to hydroxyapatite amending Cd polluted soil, chlorophyll contents in leaves and superoxide dismutase (SOD) activities in tubers enhanced and malondialdehyde (MDA) contents in tubers declined apparently. Meanwhile, quality of potato tubers was obviously improved, such as increase in vitamin C contents, starch contents, and protein contents in potato tubers. With hydroxyapatite applying from 0 to 30 g·kg-1, Cd contents in potato tubers deceased from 0.87-0.95 mg·kg-1 to 0.13-0.21 mg·kg-1 by 78%-85% in the soils with 5 mg·kg-1 of Cd, and from 1.86-1.93 mg·kg-1 to 0.52-0.65 mg·kg-1 by 66%-72% in the soils with 10 mg·kg-1 of Cd. The experiment indicated that the mechanism of hydroxyapatite alleviating soil Cd toxicity main included rising soil pH values, reducing effective Cd contents in soil, and Ca from hydroxyapatite blocking soil Cd moving to potato. However, ability of hydroxyapatite alleviating soil Cd toxicity was limited, and excessive hydroxyapatite to soil exhibited stress effects on growth and quality of potato. In the Cd polluted soils with proper hydroxyapatite, growth and quality of Zhongshusanhao were better than those of Daxiyang, indicating different responses of various potato varieties to environment amelioration.