|
Lead is one of the major pollutants in the soil, not only cause crop growth inhibition, lower production, but also accumulate easily in plants. Particularly the lead accumulation of underground organ are more. Silicon has a fixed effect on a variety of heavy metals, reduce plant the amount of lead absorption enrichment in plant, and strengthen the plant resistance and increase crops yield remarkably. Ginger （Zingiber officinale Rosc.） is one of the main export vegetables to the rhizome in China, roots easily absorb environmental pollutants, which accumulate in the roots and affect product safety. In this view, hydroponic culture and pot experiments were used to study the lead on ginger growth, yield and the impact of product safety, as well as the absorption and accumulation of lead in ginger and discussed the physiological mechanisms for studying the silicon alleviation of lead poisoning of ginger. The main results were as follows:1. Soil lead levels less than 250 mg·kg-1 had no significant effect on ginger growth. But with the lead content increased, the ginger plant growth was significantly reduced. When they were 500 and 1000 mg·kg-1, the single plant yield decreased by 18.06% and 33.25% compared with control, respectively. However, under the conditions of hydroponic culture, the lower lead concentration showed significant inhibitory effect. When they were100, 250 and 500 mg·L-1, fresh weight of ginger rhizome reduced by 18.90%, 25.07% and 40.04%, respectively.2. The Pb content of different organs of ginger were both significantly increased with the growing and higher soil Pb contents and the Pb content of roots was higher, followed by rhizomes, that of stems, leaves was less. When the soil Pb content was 250 mg·kg-1, the Pb content of ginger rhizome was 0.261 mg·kg-1, which did not exceed the state maximum allowable limit, while the soil Pb contents were 500 and 1000 mg·kg-1, respectively, the rhizome Pb contents were 175.67% and 495.33% more than national standard, respectively.3. Hydroponic experiments showed that MDA content of the ginger root and leaf were significantly increased, short lead stress SOD, POD, CAT and APX activities of ginger root and leaf increased, but with the stress time, in addition to SOD, others were significantly decreased and of enzyme activities of the roots drop considerably. With 250 mg·L-1Pb stress for 30 d, POD, CAT and APX activities of the roots, were reduced by 18.65%, 42.14%, 56.70% compared with control, respectively,.4. Silicon fertilizer in soil could alleviate the stress of lead on the ginger, significantly promoted the growth of ginger, increased production, reduced lead accumulation in the ginger rhizome, improved product safety. Under 500 mg·kg-1Pb stress, silicon fertilizer for the amount were 1,2 g·kg-1, plant height increased 16.67% and 11.99%, yield increased by 33.23% and 43.60% compared with non-silicon treatment. The lead content of rhizome were 0.225 and 0.071 mg·kg-1 decreased by 72.79% and 91.41% than non-silicon treatment.5. Ginger in lead concentration 250 mg·L-1cultured 30 d, whose root, stem, leaf and rhizome fresh weight were reduced by 19.85%, 21.42%, 22.89% and 18.96% compared with control, while adding 1.5 mmol·L-1Si, only 4.90%, 12.35%, 18.17% and 11.53% lower than the control. When treated by adding silicon and hydroponic, ginger root, stem, leaves and rhizome of the lead content were 58.92%, 55.74%, 69.82% and 58.27% than non-silicon treatment, respectively.6. Under hydroponic ginger 250 mg·L-1lead stress conditions, adding 1.5 mmol·L-1Si significantly showed alleviation effect. Such as treated by silicon for the 10 d, MDA content of ginger root, leaf decreased by 32.87% and 30.43%, CAT and APX activities of root, leaf increased by 153.44%, 40.79% and 57.29%, 60.96%, root activity increased by 54.74%, total chlorophyll content of leaves and photosynthetic rate increased 7.51% and 207.50%, respectively.
|