Impacts of Copper on Rice Growth and Yield as Affected by Pig Manure
A pot experiment was conducted to investigate the impacts of copper (Cu) on rice growth and yield grown in artificially Cu-contaminated paddy soil amended with 0%, 1% and 3% manure. Results showed that low level of Cu (i.e. 200 mg·kg−1) at 0% and 1% manure increased number of tillers significantly, while high levels of Cu (i.e. 600 and 800 mg·kg−1) caused significant reduction. Addition of 3% manure significantly decreased number of tillers at 100 and 800 mg·kg−1 of Cu but increased obviously at 200 and 400 mg·kg−1. The average grain yield decreased along with increasing Cu levels at 0% manure and 30%∼72% reduction was observed at 400∼800 mg·kg−1. Grain yield was increased by 1% manure at 100, 200 and 400 mg·kg−1 but decreased by 38% and 41% at 600 and 800 mg·kg−1 compared to the control. In contrast to 0% and 1% manure, average grain yield for 3% manure was lowest at 100 and 200 mg·kg−1, while it was highest at 600 mg·kg−1 compared to the corresponding control. Concentrations of Cu in rice grains increased with the increase of soil Cu levels at 0% manure, whereas application of 1% and 3% manure substantially decreased Cu contents in the grains and the effect of 3% manure was more remarkable. The results also showed that manure application decreased the amount of DTPAextractable Cu and reduced Cu bioavailability, which resulted in the reduction of Cu uptake by rice.
KeywordsPaddy rice Copper Pig manure DTPA-extractable Cu
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