不同水平阿散酸粪肥对水稻生长发育及砷积累的影响

Enrichment amounts of arsanilic acid in livestock manure affect plant growth development and alter accumulation profiles of arsenic in rice

【目的】饲料添加剂阿散酸是一种有机砷制剂,在动物肠道内吸收较少,绝大部分以原形随粪便排出体外。阿散酸中的砷可以随施用粪肥进入农田,对作物生长发育产生不利影响,并影响人类健康。本文研究了阿散酸进入土壤后,其所含砷在作物体内的迁移和积累,为粪肥合理施用提供依据。【方法】以水稻进行了盆栽模拟试验,供试土壤为褐土。将含有一定量阿散酸的动物粪便与供试土混匀,制成含阿散酸分别为30、75和150 mg/kg的试验用土样,按照每公顷22000 kg施用量,以无阿散酸污染的动物粪便为对照。在水稻分蘖期和开花期取样,分为根、茎、叶,成熟期样品分为根、茎、叶、稻壳和糙米,测定砷的含量和积累量。【结果】1)与对照相比,30~150 mg/kg阿散酸各处理水稻根系长度、单株根数和株高无显著差异,150 mg/kg处理无效分蘖显著增加(P<0.05),75 mg/kg和150 mg/kg处理稻米产量显著降低(P<0.05);2)与对照相比,阿散酸各处理水稻分蘖期、开花期和成熟期根、茎和叶中砷含量显著增加(P<0.05);与30 mg/kg阿散酸处理相比,150mg/kg处理分蘖期、开花期和成熟期水稻根中砷含量显著增加了40.51%、46.25%和53.1%(P<0.05),开花期和成熟期茎和叶中砷含量显著增加了56.1%、30.9%和86.7%(P<0.05)、61.75%(P<0.05);阿散酸各处理水稻根中砷含量均在开花期达到最高,成熟期下降,阿散酸含量≤75 mg/kg时,水稻茎和叶中砷含量在开花期达到最高,成熟期下降,阿散酸添加量为150 mg/kg时,水稻茎和叶中砷含量为成熟期>开花期>分蘖期。3)与对照相比,阿散酸处理籽粒砷含量显著增加(P<0.05);与30 mg/kg阿散酸相比,75 mg/kg处理米糠和糙米中砷含量显著增加了138.5%和126.1%(P<0.05),150 mg/kg处理颖壳、米糠、糙米和精米砷含量显著增加了24.6%、165.7%、158.7%和125.0%(P<0.05)。【结论】在褐土中施用含阿散酸非堆沤粪肥时,当阿散酸含量≥75mg/kg时即对水稻产生毒害作用,并增加可食部砷污染风险,建议土壤阿散酸污染不得高于该值。

[Objectives]Arsanilic acid （AA） has been widely applied as feeding stuff additives in livestock and poultry breeding. These organic arsenic compounds are not easily absorbed in the intestinal system of animals, and usually excrete with manure in an original form. Therefore, application of such manures exerts negative effects on crop growth and development, and endangering human health through food chains.[Methods]A pot experiment was conducted using rice and cinnamon soil as tested materials. A certain amounts of arsanilic acid were added into dry manures, and then the manures were applied in rate of 22 t/hm2 into soils to make treatments of arsanilic acid levels of 0, 30, 75 and 150 mg/kg in soils, with soil applying no arsanilic acid polluted manure as control. The plant samples at tillering and flowering stages were divided into roots, stems and leaves, and the samples at maturating stage were divided into roots, stems, leaves, husks, brown and polished rice, the arsenic contents and cumulative amounts were analyzed.[Results]Compared with the control, the root length, root number per plant and plant height were not significantly affected in treatments of AA 30-150 mg/kg, the ineffective tillers were significantly increased at AA 150 mg/kg, the grain yields were significantly decreased at the AA 75 and 150 mg/kg. The shoot biomass in the treatment of AA 150 mg/kg was remarkably higher than those in AA 0 and 30 mg/kg （P 〈 0.05）, and the number of ineffective tillers in the treatment of AA 150 mg/kg was significantly increased （P 〈 0.05）. The arsenic contents in rice roots, stems and leaves of all the AA treatments were significantly increased at all the sampling stages （P 〈 0.05）. Compared with AA 30 mg/kg, the arsenic contents in rice roots in AA 150 mg/kg were significantly increased by 40.5% at tillering stage, 46.2% at flowering, and 53.1% at mature stage （P 〈 0.05）, respectively; the arsenic contents in stems and leaves in AA 150 mg/kg were significantly increased by 56.1% and 30.9% at flowering stage, 86.7% and 61.8% at mature period （P 〈 0.05）, respectively. The arsenic content in rice roots in AA treatments exhibited the highest enrichment at flowering stage, and started decreasing at mature stage. When the AA level was ≤ 75 mg/kg, the arsenic content in rice stems and leaves reached the highest at flowering stage and declined at mature stage. When AA treatment was 150 mg/kg, the arsenic contents in rice stems and leaves at maturity stage were the highest, and then were at flowering and tillering stages in turn. Relative to the control, the arsenic contents in rice grain of all AA treatments were significantly increased （P 〈 0.05）. Compared with AA 30 mg/kg, the arsenic contents in husks and brown rice in AA 75 mg/kg were significantly increased by 138.5% and 126.1%, respectively, and the those in glumes, rice husk, brown and polished rice in AA 150 mg/kg were significantly increased by 24.6%, 165.7%, 158.7% and 125.0%, respectively.[Conclusions]When applying compost containing arsanilic acid, the application levels of arsanilic acid in soil should be controlled not exceeding 75 mg/kg in cinnamon soil, otherwise will trigger toxic detriment to rice, and increase the risk of arsenic pollution in edible grain.