【作者】 赖涛；

【导师】 沈其荣；

【作者基本信息】 南京农业大学 ， 植物营养学， 2006， 博士

【摘要】 有机肥料投入不足及质量下降制约着我国有机食品、绿色食品的发展。本论文以草莓为研究对象，通过不同种类商品有机氮肥及其与无机氮肥配合施用，设置了5个处理，分别是有机肥A(OFA)，有机肥B(OFB)、有机无机复配肥(OIF)，无机肥尿素(UN)和不施肥处理(CK)，以研究：1)不同形态氮肥施用条件下土壤硝态氮、铵态氮和微生物量氮的动态变化；2)不同形态氮肥施用对草莓根冠干物质累积及根系形态变化的影响；3)不同形态氮肥施用对草莓氮素吸收分配的影响：4)不同形态氮肥施用条件下草莓植株内源激素的变化；5)不同肥料氮素施用下草莓根系形态变化的发生机理。旨在揭示不同形态氮肥施用下根系形态变化的发生机制及其对植株生长、果实产量和品质的影响。研究结果表明：1．在肥料一次性作基肥施用条件下，氮肥对草莓苗期根系生长产生抑制作用，并且无机氮肥(UN)和有机无机复配氮肥(OIF)还抑制苗期植株地上部分的生长，这种抑制作用会持续到初果期；而施用商品有机肥(OFA和OFB)有利于草莓地上部生物量的持续增加，它们对根系生长抑制的持续时间不长，并很快转为促进作用。在移栽60天后，OFA和OFB地上部干物质比对照增加85.9％和35.2％，而OIF和UN两个处理比对照减少了12.1％和1.2％。2．全生育期干物质累积高峰出现在草莓移栽后134d-175d。施肥对草莓根冠生物量及其累积速率产生影响，使根冠占植株总量的比例和根冠比发生改变。草莓根冠比呈现出苗期升高，始花期后降低的趋势，草莓全生育期中根冠比“高-低-高”的总变化趋势有利于植株生育中后期冠层生物量累积的增加和果实成熟末期根系生理活性的保持，有机肥料施用正好能使植株根冠比呈现出这一特征。3．施肥有利于促进植物氮素吸收，提高氮素积累速率，促进氮素向果实中分配。施肥处理后氮素的日均积累量平均为10.8mg／株，而不施肥处理仅为5.1mg／株。在果实采收末期，不同处理草莓各器官的氮素分配趋势均为：果实＞茎和叶柄＞叶片＞根系。施用纯有机肥(OFA和OFB)，果实中吸收的氮素达到植株吸收总量的一半，分别占53.5％和51.7％，无机氮肥处理(UN)和有机无机复混肥处理(OIF)的果实氮素分配率较少，分别为46.1％和39.8％。4．在氮素养分等量施用条件下，施用OFA和OFB促进草莓产量的增加，而UN和OIF施用引起产量降低。表明草莓是一种不宜将无机氮料作为基肥一次性施用的水果型植物。施氮有利于提高草莓品质及商品果率，施用纯有机肥处理，糖酸比提高23.7-28.7％，与对照呈显著差异，而无机尿素和有机无机复配肥处理的增加幅度小于14.2％，与对照的差异不显著。5．氮肥施用不同程度地提高草莓叶片叶绿素含量SPAD值。不同时期的草莓植株特定部位叶片SPAD值分别与同时期全氮含量存在着显著线形正相关，相关系数介于0.8107与0.8531之间，倒二叶(靠近心叶)的相关系数更高。这种关系的存在为草莓叶片氮素营养状况的无损诊断提供了理论依据。6．本试验条件下，施氮对草莓移栽初期的根系伸长有抑制作用，其中无机氮肥影响程度较重，有机氮肥影响程度较轻，而有机肥料施用有助于草莓移栽中后期(60-90天)根系的伸长；施肥同样也降低草莓苗期根系比根长(sRL)，但影响程度随时间推进而逐渐减小。根系直径与SRL变化趋势相反，二者存在极显著的线性负相关，由此导致UN与OIF处理细根比例相对较大。7．在草莓移栽初期，植株侧根数量和侧根密度受施肥影响显著，OFA与OFB的影响小于UN和OIF。移栽60天后，OFA和OFB处理的草莓其每株侧根数量比对照分别增加8.9％和20.5％，而OIF与UN处理的侧根数量依然低于对照；同时期的侧根密度亦以有机肥处理(OFA和OFB)大于尿素和有机无机复配肥处理(OIF和UN)，增加幅度为17.9％～57.3％。另外，OFA与OFB处理显著提高了生长60d的植株根系表面积和体积。说明有机氮肥较无机氮肥及有机无机复配肥更能诱导草莓侧根的发生，增加植株根系养分吸收面积。8．施肥可以显著提高土壤铵态氮和硝态氮含量，土壤微生物量氮含量的高低主要与施用的有机物料C／N比有关。在草莓全生育期，OFA、OFB和OIF处理的土壤有效氮平均含量分别较UN降低49.3％、79.9％和28.7％，而土壤微生物量氮平均含量却分别提高91.2％、83.0％和68.2％。说明虽然有机肥(OFA和OFB)和有机无机复配肥(OIF)的供氮能力低于尿素(UN)，但它们比无机肥更能促进微生物对土壤氮的固持，提高土壤对氮素的“缓冲”能力，改善土壤供氮性能。9．在草莓移栽初期(20d)，施肥区根系及叶片中内源IAA和ABA含量显著高于对照，而移栽60天时。OFA和OFB处理的根和叶片中IAA和ABA含量却显著低于对照，同时期UN和OIF处理的根和叶片中IAA和ABA含量均高于有机肥处理．施肥显著提高草莓苗期根和叶片中iPAs的含量，施用含有无机氮的肥料处理(UN和OIF)的提高程度大于施用纯有机肥料处理。另外，施肥能显著降低草莓内源生长素／细胞分裂素IAA／iPAs比值，并且施用含有无机氮的肥料处理(UN和OIF)的比值降低程度大于施用纯有机肥料处理。10．土壤硝态氮、铵态氮和有效氮与根系形态参数(根生物量、根直径、根尖数、侧根数量、总根长、主根长度、比根长和侧根密度)之间存在着良好的相关性，它们相关程度达到显著水平以上项次的顺序为：硝态氮(8项)＞有效氮(7项)＞铵态氮(5项)。其中土壤氮素有效养分与根直径是正相关，其它均为负相关。不同施肥处理植株的根直径、侧根数量和侧根密度总平均值与土壤氮素有效养分总平均值之间的相关关系可以更好地用二次曲线回归方程来表达。11．草莓植株内源IAA和iPAs含量与根系形态指标参数之间有着较好的线性相关关系，除根系分枝度外，内源IAA水平与其它根系指标呈极显著相关，相关系数介于0.6941和0.9253之间。根系中内源iPAs含量与根系形态指标参数的相关性较IAA稍差，只与根系生物量、根直径、总根长、主根长度和比根长呈极显著线性相关(P＜0.01)，未发现内源ABA含量与草莓根系形态参数之间存在相关关系。12．土壤氮素养分的改变和植株内源激素的差异都对草莓苗期根系形态建成有着重要的影响。有两种机制可能存在于氮肥施用调控草莓根系形态变化过程中：内源激素诱导机制与供氮诱导机制(硝酸盐诱导的基因调控机制)。由植株内源激素含量和土壤硝态氮含量与根系形态参数的相关程度(相关系数大小)推测，内源激素对根系形态建成的诱导机制占主导地位，而后者占次要地位。草莓施氮根系形态的变化可能是2种机制共同作用的结果。综上所述，由于草莓苗期生长量较少，土壤中较少的氮素完全能满足植株幼苗生长的养分需要，供氮(即便是有机氮)都可能给移栽初期根系生长造成负面影响。然而，草莓生长过程中不同肥料氮素释放速率存在差异，有机肥料的氮素释放过程基本与植物需求过程相吻合，有助于草莓生长后期根生物量、根尖数、侧根数量、总根长、主根长度、比根长和侧根密度等根系参数的提高。不同形态氮肥施用显著影响土壤氮素有效养分状况和植物生理状况，在草莓根系结构调控中，植株内源激素和土壤硝态氮起着关键作用。同时有机氮肥施用通过提高土壤硝铵比值优化植株生长过程中的根冠比，显著提高草莓果实的产量和品质。更多还原

【Abstract】 Application of commercial organic fertilizers is very important for theproduction of green foods and organic foods. Strawberry and different fertilizercombinations were used in this experiment. Treatments included organic fertilizer A（OFA）, organic fertilizer B （OFB）, organic-inorganic compound fertilizer （OIF）,chemical fertilizers only （UN） and no amending （CK）. The aim of this research was tocompare the influences of different fertilizer applications on 1) Dynamics of soilNO₃^--N, NH₄⁺-N and microbial biomass N; 2) Strawberry root and shoot biomassaccumulation; 3) Root growth and development; 4) Nitrogen （N） uptake anddistribution in strawberry; 5) Changes of plant endogenous hormones and the relatedroot morphology; 6) Yield and quality of strawberry fruit.The results obtained are listed as follows.1. Fertilizer applications inhibited root growth of strawberry during very seedlingstage. Furthermore, UN and OIF application inhibited shoot growth until early fruitstage whereas application of organic N fertilizers （OFA and OFB） had a continuousincrease effect on shoot biomass after they decreased root growth for a very short timeduring the seedling stage. Root dry biomasses in OFA and OFB treatments were85.9% and 35.2% higher than that in CK, while they were decreased by 12.1% and1.2% in OIF and UN treatments 60 days after strawberry seedlings were transplanted,respectively.2. Highest accumulation of root and shoot biomass were found during 134～175days after transplanting. Fertilizer application affected root biomass, shoot biomassand their accumulation rate in a different way and thus, the ratio of root and shootbiomass to total biomass and root/shoot were changed. Root/shoot ratio increased atseeding stage, and then decreased after early flowering stage. The "high-low-high"variation tendency of root/shoot ratios during the whole growth period wasbenefitablc to strawberry biomass accumulation in middle-late growth stages, and toroot physiological activities during lateral fruit mature period. This variation tendencycould be obtained by application of organic fertilizers（OFA and OFB）.3. Fertilizer application improved N uptake by plants, thus increasing N accumulation in plants and N distribution in fruits. Average accumulation of N perday was 10.8 mg/plant in N fertilizationtreatment, and 5.1mg/plant in CK. N distribution in different organs of alltreatments at the end of fruiting season was in the order of fruit＞stem and petiole＞root. The N accumulated in fruit with organic fertilizers treatments （OFA and OFB）accounted for half of the total N taken up by strawberry plants, namely 53.5% and51.7%, while those with inorganic fertilizer （UN） or Organic-inorganic fertilizertreatments （OIF） were only 46.1% and 39.8% of the total N absorbed, respectively.4. In terms of equal N application, the yields of strawberry was increased byOFA and OFB, but decreased by UN and OIF. This was mainly caused by too muchinorganic N present in the soils not suitable for strawberry growth. Fertilizerapplication could improve strawberry quality. Sugar/acid ratio of the strawberry, forexample, was increased by 23.7-28.7% in organic fertilizer application treatmentwhile it was increased only 14.2% in inorganic fertilizer treatment.5. There was significantly positively linear dependence between SPAD values ofstrawberry leaves on specific node in different stages and the total N in plant with thesame stage. The correlation coefficient values varied from 0.8107 to 0.8531.Therefore, non-destructive testing of N nutrient situation would be facilitated by thelinear dependence.6. Root growth was inhibited after fertilizer application in the initial stage ofstrawberry transplanting and it was more strongly affected by inorganic N fertilizerapplication. N fertilizer application also decreased the specific root length （SRL） ofseedling stage but the effects disappeared soon with strawberry growth. There was anegative relationship between root diameter and SRL, which resulted in a big value offine roots in UN and OIF treatments.7. In the initial stage after transplanting, lateral root number and lateral rootdensity of strawberry plants were evidently affected by fertilization. Sixty days aftertransplanting, the lateral root number of strawberry in OFA and OFB treatment wereincreased by 8.9% and 20.5% compared with CK, respectively, whist those of UN andOIF treatments were still less than CK. Lateral root density of strawberry in OFA andOFB treatment were 17.9% to 57.3% higher than those of UN and OIF treatments. Inaddition, root surface area and volume of strawberry 60 days after transplanting weresignificantly increased by the application of OFA and OFB. These results showed thatthe development of lateral root was effectively induced by organic N fertilizer and thus, root surface area for nutrients uptake of strawberry were elevated.8. Fertilizer application significantly increased soil NO₃^--N and NH₄⁺-N and themicrobial biomass N mainly depended on the C/N of organic matters applied in soil.The soil available N of OFA, OFB and OIF treated soil were decreased by 49.2%,79.9% and 28.7%, respectively but the average microbial biomass N were increasedby 91.2%, 83.0% and 68.2%, respectively, compared with CK in the whole growthperiod of strawberry plants. The study indicated that the content of mineral N inorganic fertilizer （OFA and OFB） and organic-inorganic fertilizer （OIF） treatmentswas less than that of urea N （UN） but application of organic fertilizers could facilitateimmobilization of soil N by soil microbes and increase soil N supply bufferingcapacity, which was very useful to the gowth of strawberry plant.9. Contents of endogenous IAA and ABA in leaves and roots in fertilization sitesduring the initial stages （20 days after transplanting） were significantly higher thanthose in CK. However, at 60 days after transplanting, the contents of IAA and ABA inleaves and roots in OFA and OFB treatments were lower than those in UN and OIFtreatments. Fertilization significantly increased the content of iPAs in leaves and rootsof strawberry seedlings and UN and OIF application had higher iPAs content than OFtreatments. In addition, the ratio of endogenous IAA/iPAs was significantly decreasedby fertilizer applications and UN and OIF had a more effect than OF.10. There were significant correlations between the contents of soil available Nand root morphological characteristics （root biomass, root diameter, root tips, lateralroot number, total root length, length of adventitious root, specific root length （SRL）and lateral root density）. Among them, positive correlation was only found betweensoil available N and root diameter. The correlation between the average content of soilavailable N and root diameter, lateral root number and lateral root density withdifferent treatments could be quantified finely by quadratic regression equation.11. Better linear correlation was found between root morphologicalcharacteristics and the contents of endogenous IAA and iPAs in strawberry. Therewere significant correlations between the contents of endogenous IAA and otherindexes of roots except degree of branching with the correlation coefficient rangedfrom 0.6941 to 0.9253. The content of endogenous iPAs was not as good as thecontent of endogenous IAA correlating to root morphological characteristics, and thesignificantly negative correlations were only found between the content ofendogenous iPAs and root biomass, root diameter, total root length, length of adventitious root and specific root length （P＜0.01）. No correlation was found amongthe content of endogenous ABA and root morphological characteristics.12. The changes of soil N nutrient and the differences in endogenous hormone inplants all greatly affected root formation during strawberry seedling stage. Theremight be two mechanisms for N to modulate strawberry root formation: the inducedmechanism by endogenous hormones and the induced mechanism by N supply （generegulation by nitrate-N supply）. According to the correlations between rootmorphological characteristics and the contents of endogenous hormone in strawberryand soil nitrate-N, it could be deduced that endogenous hormone is the dominatingfactor to induce the root formation.In conclusion, strawberry plants grow slowly at seedling stage, so a soil with lowmineral N content could supply enough N for their growth. Too much mineral Nsupply could restrict root growth. However, application of pure organic fertilizerscould help the increase of root biomass, root tips, lateral root number, total root length,length of adventitious root, specific root length and lateral root density at lateralseedling stages. The changes of endogenous hormones and nitrate-N played importantroles in the modulation of root formation for strawberry plants. The application of Nfertilizers significantly affected the status of soil available N and plant growth; theroot to shoot ratio was optimized in the course of plant growth with the application ofOFA and OFB by increasing the ratio of nitrate-N to arnmonium-N in soil, which wasfavorable to improvement of yield and quality of strawberry fruit.更多还原