不同沼液施用量对水稻生长、产量及重金属含量的影响

摘要

为探讨沼液在水稻上的适宜用量用法,以规模化养殖场猪粪尿发酵的沼液作为肥源,以当地常规化学施肥为对照,研究不同沼液用量对水稻生长、产量、重金属含量等的影响.结果表明:当沼液总施用量低于750 t·hm-2时,水稻株高有增加趋势,同时分蘖能力提高;当沼液总施用量大于750 t·hm-2时,株高不再增加且分蘖能力显著(P<0.05)下降.施用沼液对叶片荧光强度影响较小,但不合适的沼液适用量下会对净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)等光合特性产生抑制作用.与传统化肥处理相比较,施用沼液显著(P<0.05)降低了水稻结实率、穗实粒数、千粒重等,但能提高总穗数,沼液施用量600 t·hm-2时,水稻产量及其构成表现最好.沼液施用使水稻秸秆中汞、铬、铜、砷等重金属含量均有不同程度增加,存在一定的重金属风险,但籽粒中重金属含量未见增加,且符合中国食品中重金属限量标准(GB 2762—2012),不存在重金属超标风险.综合来看,沼液总施用量600 t·hm-2(基肥:追肥=1:1)较为适宜.%To investigate the appropriate application rate and method of biogas slurry on rice , the pig manure from large-scale farms was fermented as fertilizer in the experiment to study the effects of different application rate of bio -gas slurry on rice growth , yield and heavy metals concentrations .It was shown that when the total amount of biogas slurry was below 750 t· hm-2 , the height and tillering ability of rice were improved , while the height no longer in-creased and tillering ability significantly ( P<0.05 ) decreased when the application amount was above 750 t· hm-2 . The application of biogas slurry had little effect on the fluorescence intensity of rice leaf , but inhibited the photosyn-thetic intensity , such as net photosynthesis rate , stomatal conductance , transpiration rate .Compared with conven-tional fertilizer treatment , the biogas slurry treatments significantly ( P <0.05 ) decreased rice seed setting rate , filled grain number per panicle and 1000-grain weight , yet increased the total spike number .The application rate of 600 t· hm-2 was appropriate to improve rice yield and its components .However , the biogas slurry treatments had po-tential risks for heavy metals accumulation in rice straw , as the contents of heavy metals such as Hg , Cr, Cu, As were increased in rice straw compared with conventional fertilizer .But, this risk was not found in grains .Further-more, the contents of heavy metals in grain had no significant changes and were all met with the national standard of GB 2762-2012.In general, the application of 600 t· hm-2 biogas slurry (basic fertilizer:topdressing=1:1) was ap-propriate for rice production .