【作者】 吴花；

【导师】 李伏生；

【作者基本信息】 广西大学 ， 蔬菜学， 2007， 硕士

【摘要】 人类不合理活动造成镉等重金属在土壤中大量富积，致使蔬菜等农产品中镉严重超标，进而污染食物链，危害人类健康；锌则是蔬菜生长发育必需的微量元素。本文主要研究不同氮肥形态（铵态氮和硝态氮）及其配比（NH₄／NO₃，％／％）对植株产量和品质、土壤pH和镉和锌形态及其生物有效性的影响。试验1以菠菜为材料，设不同外源镉浓度和氮肥形态2个因子；试验2以苋菜为材料，设不同外源镉浓度和NH₄／NO₃配比2个因子；试验3以菠菜为材料，设不同外源镉浓度、外源锌浓度和NH₄／NO₃配比3个因子。主要研究结果如下：1．施NO₃^--N有利于菠菜和苋菜的生长，全部施加NO₃^--N肥时菠菜单株生物量最大，苋菜在NH₄／NO₃比例为25／75时单株生物量最大，全部施NO₃^--N肥较NH₄／NO₃比例为25／75处理略低。而高浓度镉抑制菠菜和苋菜的生长，与不添加镉处理相比，试验1、2和3镉浓度为5mg.kg^-1的单株鲜重分别降低30.7％～90.5％、6.5～11.5％和26.4％～39.4％。但添加一定量的锌对菠菜生长有促进作用，提高菠菜单株鲜重。2．随着NO₃^--N比例的提高，菠菜和苋菜硝酸盐含量均增加。但当添加20mg.kg^-1锌处理，则抑制菠菜体内硝酸盐的积累，体内硝酸盐下降90.98～235.08 mg.kg^-1。3．不同NH₄／NO₃配比对菠菜Vc含量有一定的影响。单施NO₃^--N处理的菠菜Vc含量比单施NH₄⁺-N处理要高。4．不同NH₄／NO₃配比对土壤中pH值的影响明显。与施NH₄⁺-N处理相比，试验1、2和3施NO₃^--N处理土壤pH值分别增加0.23～0.36，0.84～0.99，1.38～1.80个单位。5．土壤pH值是影响土壤镉和锌形态及其生物有效性的主要因素。随着NO₃^--N比例的提高，土壤pH增加，水溶交换态镉和锌含量和植株对镉和锌的吸收均降低，而碳酸盐结合态镉和锌含量则增加。6．随着外源镉（锌）浓度的增加，植株对镉（锌）的吸收明显提高。镉与锌共存时，随着外源镉浓度的增加，植株对锌的吸收明显下降。反之，当锌浓度高时，植株对镉的吸收显著下降，这表明镉与锌之间有明显的拮抗作用。因此可以通过选择适宜的肥料形态影响土壤中镉和锌形态及生物有效性，减轻镉的污染和增加锌的吸收，保障农产品营养和安全。更多还原

【Abstract】 More accumulatation of Cd in soil caused by unreasonable actions results inover-standard Cd concentration in vegetable, even polluts food chains, and thenendangers our health. But Zn is an essential microelement for vegetable growth. In thisthesis, spinach and amaranthanus as plant materials were applied to study the effect ofdifferent form of N fertilizer （ammonium and nitrate） and its ratios （NH₄/NO₃, %/%） onsoil pH, vegetable yield and quality, soil Cd and Zn forms and bioavailability. Twofactors, i.e. Cd levels and N forms were designed for Experiment 1; two factors, i.e. Cdlevels and ammonium and nitrate ratios （NH₄/NO₃, %/%） were designed for Experiment2; three factors, i.e. Cd levels and ammonium and nitrate ratios （NH₄/NO₃, %/%） andZn levels were designed for Experiment 3. The main result are outlined as following:1. Fresh weight of spinach or amaranthanus reduced with the increase of Cdconcentration in soil, indicating that high Cd concentration restrained growth of spinachor amaranthanus. Compared to no Cd added soil, the highest Cd concentration(5mg.kg^-1) in soil reduced fresh weight of spinach and amaranthanus by 30.7-90.5%,6.5-11.5%.and 26.4-39.4% for experimental 1, 2 and 3, respectively. Applied NO₃^--N canaccelerate the growth of spinach or amaranthanus. Fresh weight of spinach was thegreatest when applied only NO₃^—N. Fresh weight of amaranthanus was greatest whenNH₄/NO₃ ratio was 25/75, but fresh weight in only NO₃^—N treatment was lower thanthat of 25/75 ratio for NH₄/NO₃. In addition, added appropriate Zn can also increasefresh weight of spinach.2. Nitrate content in spinach and amaranthanus increased with increased NO₃^--Nproportion. But added Zn (20mg.kg^-1) treatment reduced the nitrate accumulation in spinach.3. Different NH₄/NO₃ ratio affected Vc content in vegetable to some extent. Vccontent of spinach in only NO₃^--N treatment was higher than that of only NH4⁺-Ntreatment.4. Different NH₄/NO₃ ratio influencd soil pH obviously. Compared to only NH4⁺-Ntreatment, only NO₃^--N treatment increased 0.23-0.36, 0.84～0.99, 1.38～1.80 pH unit forexperimeantal 1, 2 and 3, respectively.5. Soil pH is an important factor affecting soil Cd and Zn forms and bioavailability.With the enhancement of NO₃^--N proportion, soil pH increased, contents of watersoluble and exchangeable Cd and Zn in soil and absorption of Cd and Zn by plant（spinach and amaranthanus） reduced significantly, but carbonate bond-Cd andcarbonate bond-Zn increased.6. With increased Cd （Zn） concentration in soil, Cd （Zn） uptake increased obviously.When Cd and Zn coexisted, Zn （Cd） uptake decreased with the increasing of Cd （Zn）concentration, indicating that there were significant antagonism between Cd and Zn.Therefore, selecting appropriate fertilizer form can affect the form andbioavailability of soil Cd and Zn, and then reduce Cd pollution and increase Znabsorption, so as to insure nutrition and safety of agricultural products.更多还原