【作者】 常思敏；

【导师】 马新明；

【作者基本信息】 河南农业大学 ， 作物栽培学与耕作学， 2006， 博士

【摘要】 砷是土壤中污染最严重的重金属之一。研究砷毒害对烤烟碳、氮代谢和产量、品质的影响及其在烟草体内的积累情况,探索减少土壤中砷对烤烟毒害的有效途径,在预防或减少砷对烟草产量和经济损失、最大可能地保护烟农利益和吸食者的健康等方面具有重要的理论和现实意义。为此,2004-2005年以云烟85为供试品种,采用400 mm×340 mm的聚乙烯花盆在河南农业大学科教园区进行了3个盆栽试验。1)砷毒害试验:以砷酸钠（Na₃AsO₄·12H₂O）为污染源,按纯砷含量计算,2004年设置0（CK）,5,20,40,60,100,200,400 mg·kg^-18个处理,2005年设置0（CK）,5,20,40,60 mg·kg^-15个处理。2)铁减害试验:以硫酸亚铁（FeSO₄·7H₂O）为土壤添加剂,按纯铁含量计算,设置0,200,400,600,800 mg·kg^-15个处理,各处理均加入纯砷50 mg·kg^-1。3)黄腐酸减害试验:以95%的黄腐酸（FA）为土壤添加剂,设置0,200,400,600,800 mg·kg^-15个处理,各处理均加入纯砷50 mg·kg^-1。系统地研究了砷对烤烟全生育期碳、氮代谢及其过程、生长发育、产量和品质的影响,以及烤烟对砷的吸收、积累和分配情况,并探讨了铁和黄腐酸在这些方面的减害效应。1砷对烤烟碳氮代谢及其产量、品质的影响砷严重影响了烤烟的碳代谢。砷降低了烤烟整个生育期的叶绿素含量、光合速率、蔗糖合成酶（SS,合成方向）活性和现蕾以后的蔗糖磷酸合成酶（SPS）活性,提高了全生育期的SS（分解方向）活性和可溶性糖含量,因而抑制了碳的同化和蔗糖的合成,促进了蔗糖的分解,不利于碳向积累方向转化。同时,砷降低了团棵期和采收期的可溶性淀粉酶（SSS）活性,提高了全生育期的腺苷二磷酸葡萄糖焦磷酸化酶（ADPG-PPase）活性,增加了团棵期和现蕾期淀粉的积累,又降低了采收期的淀粉含量,从而导致了碳积累代谢的紊乱,最终造成碳积累的减少。砷毒害对烤烟的氮代谢有显著影响。砷降低了整个生育期的硝酸还原酶（NR）活性,抑制了烤烟对硝态氮（NO₃^--N）的同化:提高了全生育期的谷氨酰胺合成酶（GS）活性,增强了烤烟对铵态氮（NH₄⁺-N）的同化。砷提高了全生育期的谷氨酸—丙酮酸转氨酶（GPT）活性和天冬酰胺酶（asparaginase,ASG）活性,以及现蕾以后的游离氨基酸含量,使烤烟的氮转化代谢表现旺盛。与此同时,砷引起了烤烟生育前期的蛋白质含量降低,随着生育进程的推进,又引起中、后期的蛋白质含量增加,最终导致烤烟蛋白质的积累,但使整个生育期的烟碱含量降低。砷抑制了烤烟的生长发育,导致其生育时期延迟,叶片数和叶面积减少,株高和产量降低,同时,砷造成了烤烟产值、均价和上中等烟比例降低,使其经济性状变差,总糖、还原糖、总氮、蛋白质含量提高,烟碱和K⁺,Ca²⁺,Mg²⁺,C1^-含量降低,糖氮比、糖碱比、氮碱比等比例失调,因而降低了烤烟的商品价值和化学品质。本研究的结果还表明,当土壤中的砷含量达到100 mg·kg^-1时,烤烟的生长发育受到严重抑制,已没有生产价值,当达到200mg·kg^-1以上时,烤烟不能成活,使烤烟减产10%的土壤施砷量阈值为16.89 mg·kg^-1。若以食品中砷含量≤0.5 mg·kg^-1为参照,下、中、上部叶和中部叶燃烧后烟气中要求的土壤施砷量阈值分别为2.63,6.56,13.91和12.90 mg·kg^-1。土壤中施砷可增加烤烟对砷的吸收和积累,且土壤中施砷越多,烤烟吸收也越多。与之相反,施砷可降低烤烟由地下部向地上部运输砷的能力,土壤中砷含量越高,其向地上部的运输能力越低。砷被烤烟吸收后,能分布在作物的各个部位。砷在烤烟植株中的分布、积累规律为根＞下部叶＞茎＞中部叶＞上部叶。中部叶燃烧后,有39.58%的砷残留在灰分中,有60.42%随烟气被吸烟者吸收或扩散到空气中。2铁对砷毒害烤烟碳氮代谢、产量和品质的影响土壤中施用硫酸亚铁可减轻砷对烤烟碳代谢的毒害。叶绿素含量和光合速率的提高,说明铁明显改善了其全生育期的碳同化能力。SS（合成方向）活性和SPS活性的提高、SS（分解方向）活性和可溶性糖含量的降低,有利于蔗糖合成和向碳积累方向的转化,抑制了砷造成的碳转化代谢旺盛问题。虽然烤烟前期或中期的淀粉含量、团棵期的SSS活性和现蕾期的ADPG-PPase活性降低,不利于碳的积累,但这些指标在生育后期的表现说明碳积累得到明显改善。铁能提高砷毒害烤烟的NR活性,降低其GS活性,促进了NO₃^--N的同化,抑制了砷毒害造成的NH₄^--N的同化。现蕾以后GPT活性和游离氨基酸含量、全生育期的ASG活性的降低说明铁抑制了氮转化代谢的旺盛问题。铁提高了全生育期烟碱的合成能力,但增加了生育中后期的蛋白质含量。铁可改善砷毒害烤烟全生育期的生长发育状况,导致其株高、叶片数、叶面积增加,且对生育中、后期的影响大于前期,并能极显著地提高其产量。铁对砷毒害烤烟的品质有利有弊。铁可造成砷毒害烤烟的总糖含量、还原糖含量、糖氮比、糖碱比和氮碱比的降低,使砷毒害烤烟的烟气酸性减少,受焦油危害的可能性减小,安全性得到改善。土壤中铁含量较高(≥600 mg·kg^-1)时烟碱含量的提高,可改善其劲头,但总氮和蛋白质含量的提高会增加烤烟的刺激性,当土壤中铁含量较低(≤400 mg·kg^-1)时,总氮和蛋白质含量的降低则有利于其刺激性和香气质的改善,但烟碱含量降低。K⁺含量的增加有利于燃烧性,但Cl^-含量的增加则不利于此方面性状的改善。施铁可增加砷在土壤中的残留率,降低烤烟对砷的吸收和单株含砷量,以及各部位叶片砷的含量,致使烤烟的富集系数和烟灰、烟气中的砷含量减少,但铁能提高砷在烤烟体内的位移系数,因而相对地增加了单株地上部含砷量。铁还可导致不同部位叶片之间的砷含量存在差异,各处理均表现出以下规律性:根＞茎＞下部叶＞中部叶＞上部叶。同时,铁可造成砷毒害烤烟对铁的吸收减少,但造成单株地上部含铁量和位移系数增加,促进了铁向砷毒害烤烟地上部的迁移,致使其地上部的铁积累增加。铁还影响砷毒害烤烟中铁在各部位的分布,随着施铁量的增加,根、茎中铁含量降低,而下部叶、中部叶和上部叶的铁含量均明显提高。同一施铁处理各部位铁的分布均为:根＞下部叶＞中部叶＞上部叶＞茎。3 FA对砷毒害烤烟碳氮代谢、产量和品质的影响适量的FA可提高砷毒害烤烟全生育期的叶绿素含量和光合速率,增强其碳同化能力,但造成了碳转化和积累代谢的紊乱。虽然不适当的施用量和适当的施用量在生育前期均不利于碳转化和积累,但随着生育进程的推进,适量的黄腐酸施用量最终能改善砷毒害烤烟的碳转化和积累,造成了对产量形成有利的影响。FA提高了砷毒害烤烟的NR活性,降低了GS活性,改善了NO₃^--N的同化能力,抑制了NH₄⁺-N的同化。不同的FA施用量对氮转化代谢的砷毒害影响不同。适量的黄腐酸施用量在生育前期也协同砷的毒害,但随着生育进程的推进,适量的黄腐酸施用量最终能抑制氮转化代谢的旺盛问题。FA降低砷毒害烤烟团棵期的蛋白质含量,提高现蕾以后的蛋白质含量和全生育期的烟碱含量。适量的FA可改善砷毒害烤烟的生长发育状况,导致其株高、叶片数、叶面积增加,提高其产量。FA处理与相应的化学成分及其协调性之间也没有必然的相关性,但FA600处理能使砷毒害烤烟的总糖、还原糖、蛋白质含量和糖碱比、氮碱比、糖氮比降低,烟碱、K⁺含量提高,显著改善其化学成分及其协调性,提高了砷毒害烤烟的化学品质。土壤中施用适量的FA可增加砷在土壤中的残留率,降低烤烟对砷的吸收和单株含砷量,致使烤烟的富集系数和烟灰、烟气中的砷含量减少,但FA能提高砷在烤烟体内的位移系数,因而相对地增加了单株地上部含砷量。FA还能降低烤烟各部位砷的分布,影响烤烟各部位砷的含量,同一FA处理不同部位叶片之间的砷含量存在差异,各处理均表现出以下规律性:根＞下部叶＞茎＞中部叶＞上部叶。不同FA处理对烤烟砷含量的也有显著影响,但以FA600的烤烟砷含量为最低。本试验条件下,以土壤中施用600 mg·kg^-1的FA减轻砷毒害的效果最好。更多还原

【Abstract】 Abstract:Arsenic,a high toxic heavy metal,was one of the most serious contaminants in soil and a potential threat to crops growth and human health.Therefore,it was very important to study effects of arsenic toxicity and on metabolism of carbon and nitrogen in flue-cured tobacco and on its yield and quality,and to study toxicity-alleviating effects of iron and folvic acid.In order to prevent or decrease losses of tobacco yield incurring economic losses,and to increase benefits of growers and health of smokers as much as possible,3 experiments were conducted on the farm of Henan Agricultural University,Zhengzhou,China.With Yunyan 85 planted in plastic pots（400 mm in diameter and 340 mm in height）in 2004 and 2005.The first experiment was carried out at eight levels arsenic toxicity:0（CK）,5,20,40,60,100,200 and 400 mg·kg^-1[added to sodium arsenate（Na₃AsO₄·12H₂O）]in 2004 and at five levels of 0（CK）,5,20,40,and 60 mg·kg^-1in 2005 to determine effects of arsenic toxicity on growth,development,yield,and quality of flue-cured tobacco,and to determine the critical content of arsenic in soil.The second experiment carded out with 50 mg·kg^-1of arsenic toxicity（added to sodium arsenic）:with ferrous sulphate of 0, 200,400,600,800 mg·kg^-1in 2005 to study the effects of iron on alleviation of arsenic toxicity. The third experiment was carried out with 50 mg·kg^-1of arsenic toxicity with 0,200,400,600, 800 mg·kg^-1（added to 95%fulvic acid）in 2005,to study the effects of fulvic acid on alleviation of arsenic toxicity in flue-cured tobacco.Effects of arsenic toxicity on metabolism of carbon and nitrogen in flue-cured tobacco and on yield and qualityArsenic toxicity significantly affected on carbon metabolism during the whole growing period.Chlorophyll content,photosynthetic rate and sucrose synthetase（SS,synthetic direction） activity during the growing period as well as activity of sucrose phosphate synthetase（SPS）after budding stage all decreased.But activity of sucrose synthetase（decomposition direction）and content of soluble sugar during the growing period increased.This suggested that assimilation of carbon and synthesis of sucrose in flue-cured tobacco be inhibited,and decomposition of sucrose be accelerated as a result of arsenic toxicity,which was not favorable for carbon transformation. The results also indicated that activity of soluble starch synthetase（SSS）at rosette stage and harvest stage,and accumulation of starch at harvest stage were inhibited,SSS activity at budding stage,activity of adenosine diphosphoglucose pyrophosphorylase（ADPG-PPase）during the growing period,and starch content at rosette stage and budding stage all increased by arsenic toxicity.Therefore,arsenic toxicity caused the disarray of metabolism of accumulated carbon and the decrease of starch content during the last part of the whole growing period.Arsenic toxicity also significantly affected on nitrogen metabolism in flue-cured tobacco.On one hand,activity of nitrate-reductase（NR）during the growing period was reduced:And on the other activity of glutamine synthetase（GS）during the growing period was increased.These indicated that assimilation of NO₃^--N was inhibited but that of NH₄⁺-h+-N was enhanced by arsenic toxicity.The results also showed that activity both of glutamate-pyruvate transaminase（GPT）and asparaginase（ASG）during the growing period,and content of free amino acids after the budding stage were increased,indicating that arsenic toxicity led to exuberance of transformation metabolism in flue-cured tobacco.In the meantime,compared with those in CK,protein content during the early growing stage and nicotine during the growing period decreased,however protein content increased during the middle and last growing stages.Arsenic toxicity inhibited growth and development of flue-cured tobacco.It delayed the growing process,and decreased leaves,leaf area,plant height,and yield.Besides,it decreased economic properties such as output value per plant,average price,and ratio of high level,and chemical quality properties such as increase in total sugar,reduced sugar,total nitrogen,and nicotine.It also decreased content of potassium,calcium,magnesium,and chlorine.Therefore,it resulted in disproportion of sugar-nitrogen,nitrogen-nicotine,sugar-nicotine,and potassiumchlorine. And hence,arsenic induced decrease both in economic and in chemical value.The results also showed that when flue-cured tobacco was planted in soil added to 100 mg·kg^-1of arsenic, flue-cured tobacco was so affected that there was no production value.When soil was added to more than 200 mg·kg^-1of arsenic,flue-cured tobacco could not grow.When soil was added to 16.89 mg·kg^-1of arsenic,yield was decreased by 10%.Arsenic content in leaves increased with arsenic addition in soil.After cutters were burned at 300 temperatures,only 39.58%of accumulated arsenic remained in ash,and the remaining was away with smoke.The arsenic residues in lower leaves,cutters,upper leaves and smoke of cutters was less than those specified in food hygienic standard when the critical content of arsenic in soil was 2.63,6.56,13.91,and 12.90 mg·kg^-1,respectively.The arsenic in soil increased content of arsenic in flue-cured tobacco.And the higher content of arsenic in soil,the higher content of arsenic in the plant.On the contrary,the arsenic in soil decreased the plant’s ability to transfer arsenic from root to shoots.The higher there was content of arsenic in soil,the lower there was ability to transfer arsenic of the plant.Arsenic could be distributed in every organs of the plant.Accumulation of arsenic in flue-cured tobacco was frist from roots,to lower leaves,to stalks,to cutters,and then to upper leaves.Residues of arsenic in ash were 39.58%,the remaining（60.42%）were inbreathed by smokers or entered into the air.Effects of iron on metabolism of carbon and nitrogen,yield,and quality of arsenic-toxicated flue-cured tobaccoArsenic toxicity to carbon metabolism in flue-cured tobacco was alleviated by application of ferrous sulphate in soil.The increase both in chlorophyll content and in photosynthetic rate indicated that iron improved assimilation of carbon in arsenic-toxicated flue-cured tobacco during the whole growing period.Iron also increased activity of sucrose synthetase（SS,synthetic direction）and sucrose phosphate synthetase（SPS）,and decreased activity of sucrose synthetase （decomposition direction）and soluble sugar content,which not only helped to synthesization of sucrose and transformation to carbon accumulation,but also inhibited exuberance of transformed-carbon metabolism caused by arsenic toxicity.Although soluble starch synthetase （SSS）activity at rosette stage,adenosine diphosphoglucose pyrophosphorylase（ADPG-PPase） activity at budding stage,and accumulation of starch both at rosette and at budding stage were inhibited,which decreased accumulation of carbon,accumulation of carbon was increased in late growing.The increase in nitrate-reductase（NR）activity and the decrease in glutamine synthetase activity（GS）during the whole growing period indicated that iron improved assimilation of NO₃^--N and inhibited assimilation of NH₄⁺-N in flue-cured tobacco toxicated by arsenic.In the meantime,decrease in free amino acids content,glutamate-pyruvate transaminase（GPT）activity after budding stage,and in asparaginase（ASG）activity during the whole growing period showed that iron inhibited exuberance of transformed-nitrogen metabolism as a result of arsenic toxicity. The result also indicated that iron increased nicotine content during the growing period,but protein content only increased by iron during the middle and late stages.Iron increased leaves,leaf area,and plant height in arsenic-toxicated flue-cured tobacco during the growing period,and hence it improved plant growth and development and remarkably increased yield.Iron decreased content of total sugar,reduced sugar,ratios of sugar-nitrogen, sugar-nicotine and nitrogen-nicotine,and thus it resulted in decrease in acidity in smoke and possibility of tar damage to smoker.When iron content was 600 mg·kg^-1or higher in soil,nicotine content was increased in arsenic-toxicated flue-cured tobacco.However,increase both in total nitrogen content and in protein content strengthened stimulation of cigarettes.When iron content was 400 mg·kg^-1or lower in soil,decrease both in total nitrogen content and in protein content improved stimulation and fragrance of cigarette,while nicotine content was decreased.Increase in potassium content was helpful to burning ability of cigarettes,but not to chlorine content. However,iron could either improve or worsen chemical quality of arsenic-toxicated flue-cured tobaccot.Residues of arsenic in soil were increased by iron.Absorption of arsenic by flue-cured tobacco and arsenic contents in plant and in leaves in different plant positions were decreased,and bioaccumulation factor（BCF）and arsenic content both in ash and smoke were also decreased,but translocation factor（TF）in plant and arsenic content in shoots were increased.There was difference of arsenic content in the five organs of the plant.Arsenic accumulation order in flue-cured tobacco leaves was roots＞stems＞lower leaves＞cutters＞upper leaves.In the meantime, because of iron application,absorption of iron by arsenic-toxicatecd flue-cured tobaccowas decreased,but iron content in shoots and translocation factor（TF）were increased.Accumulation order of iron in flue-cured tobacco leaves was roots＞lower leaves＞cutters＞upper leaves＞stems.Effects of fulvic acid on metabolism of carbon and nitrogen,yield and quality in arsenic-toxicated flue-cured tobaccoReasonable content of fulvic acid improved assimilation of carbon in arsenic-toxicated flue-cured tobacco.Although unreasonable content of fulvic acid in soil enhanced arsenic toxicity in carbon transform metabolism,and caused disarray of carbon metabolism during the early growing period,reasonable content of fulvic acid could finally improve transformation and accumulation of carbon during plant growth and development.Different contents of fulvic acid had different effects on nitrogen metabolism in arsenic-toxicated flue-cured tobacco,reasonable content of fulvic acid enhanced arsenic toxicity during the early growing period,but finally improved NO₃^--N assimilation and inhibited NH₄⁺-N assimilation and transformation of nitrogen during the process of growing and development. Fulvic acid increased protein content after budding stage and nicotine content during the whole period,but decreased protein content at rosette stage.Reasonable content of fulvic acid improved the growth and development of arsenic-toxicated flue-cured tobacco,affecting leaves,leaf area,and plant height.Therefore,the yield was significantly improved.There was not an interrelationship between fulvic acid application in soil and chemical compositions and their coordination arsenic-toxicated flue-cured tobacco,but application rate of fulvic acid of 600 mg·kg^-1in soil decreased content of total sugar,reduced sugar, total nitrogen,protein,and ratios of sugar to nitrogen,nitrogen to nicotine,sugar to nicotine,and increased content of nicotine and potassium.Therefore chemical quality of arsenic-toxicated flue-cured tobacco was improved by fulvic acid application at a rate of 600 mg·kg^-1.Resedues of arsenic in soil were increased by reasonable application of fulvic acid,but the absorption of arsenic by flue-cured tobacco and arsenic content in the plant were decreased. Bioaccumulation factor（BCF）and arsenic content in ashes and smoke were also decreased,but translocation factor（TF）of the plant and arsenic content in shoots were increased.There was difference in arsenic contents in the five parts of plant.The accumulation order of arsenic in flue-cured tobacco plant was roots＞lower leaves＞stems＞cutters＞upper leaves.The best treatment of fulvic acid in the experiment was 600 mg·kg^-1.更多还原