连续施石灰对作物生长及其养分吸收的影响

在浙江金华由红色粘土发育的酸性水稻土上,对稻—稻—大麦连续,次施石灰的试验结果表明,适量地施石灰可使大麦增产2—3倍,而水稻的反应一般不明显。对土壤和作物的测定显示,大麦增产的原因主要与石灰提高土壤pH,消除铝的毒害,提高磷肥有效性,促进根系发育,并显著增强大麦对磷、钾等养分吸收有关。但施石灰反而降低了水稻对磷素的吸收。因此,石灰一般宜用于大麦等旱作物。从产量、经济效益、消除铝毒及养分有效性诸因素综合考虑,对大麦的石灰用量以中和土壤pH至6.0左右为宜。但不论何种作物,连续大量地施石灰都是极不可取的。     

秸秆腐解产物阻控红壤复酸化促进玉米生长

【目的】秸秆腐解产物具有改善土壤酸度、提高土壤抗酸化能力等作用。研究不同秸秆腐解产物对红壤复酸化的阻控效果及对作物生长的促进作用，为有效阻控酸性土壤复酸化提供新思路。【方法】供试土壤为花岗岩和玄武岩发育的赤红壤(pH 4.75)和砖红壤(pH 5.02)，处理土壤样品为分别添加2%的水稻和豌豆秸秆腐解产物(RSD、PSD)，对照为两类型土壤中添加Ca(OH)₂至pH分别与RSD和PSD相同(RCK、PCK)，共8个样品。在黑暗处培养30天，用于盆栽试验处理。盆栽试验作物为玉米，在玉米收获后，分析土壤酸度、阳离子交换量、有机质、有效养分含量、微生物多样性，以及玉米植株地上部、根系生长和养分吸收量。【结果】赤红壤上RSD、RCK、PSD、PCK处理玉米收获后土壤的pH较播种前分别下降了0.11、0.60、0.92、1.04个单位，RCK、PSD、PCK处理的降幅达到显著水平；砖红壤上RSD处理玉米收获后的土壤pH较播种前升高了0.22个单位，而RCK、PSD、PCK处理分别下降了0.13、0.16、0.36个单位，PSD、PCK处理的降幅达到显著水平。在赤红壤上，4个...     

间作模式下作物根系与坡耕地红壤抗蚀性的关系

通过径流小区试验,结合土壤理化性质分析和根系指标测定,研究了玉米单作、大豆单作以及玉米/大豆间作模式下,不同作物根系特性与坡耕地红壤抗蚀性的关系。结果表明,玉米/大豆间作模式在改善土壤理化性质、提高红壤质地和结构方面优于玉米或大豆单作,玉米/大豆间作模式在0—10,10—20,20—30cm土层的含根量、根系表面积、根系体积、根尖数和根长较玉米单作或大豆单作均有提高,其中0—10cm土层范围内差异显著;玉米/大豆间作模式较玉米单作模式在根量、根系表面积、根系体积和根长分别提高了80.95%,50.93%,90.30%和77.99%,较大豆单作模式分别提高了58.70%,73.36%,123.05%和149.27%;在20—30cm土层范围内,间作模式根长较玉米单作模式提高了150.48%,较大豆单作模式提高了206.94%;不同种植模式下,土壤抗蚀性指数在10—20cm土层差异不显著,在0—10cm和20—30cm土层之间差异显著;不同深度土层范围内,间作模式土粒抵抗分散能力均最强;在间作模式下,同期土壤流失量较单作减少,土壤流失量与作物根系量、根系表面积、总根长、根系体积和根尖数呈显著负相关。玉米大豆间作可以通过改善根系特征,提高土壤有机质含量,进而提高土抗蚀性。     

电动模拟土壤酸化及其交换性离子组成变化

土壤酸化及其环境效应研究是土壤环境领域的重要内容。自行设计了模拟土壤酸化的电动装置,该装置由直流电源、反应槽、石墨电极组成,并采用四种不同类型土壤,研究了电动模拟土壤酸化后土壤pH、交换性酸和交换性阳离子组成的变化。实验结果显示,经电动处理后土壤pH发生明显变化,土壤pH由阳极到阴极逐渐升高,pH变幅为水稻土燥红土红壤赤红壤,水稻土的pH变化比红壤更为明显;土壤交换性H+和Al~(3+)含量在阳极附近最高,交换性Al~(3+)占交换性酸总量达65%以上;交换性Ca~(2+)、Mg~(2+)、K~+和Na~+表现出离阳极越远,含量越大的规律,其中交换性Ca~(2+)和Mg~(2+)在模拟酸化后含量变化较大,而交换性K~+和Na~+的变化幅度相对较小。结果表明,电动处理可快速获得不同pH梯度的土壤样品,并模拟了土壤酸化过程中的阳离子迁移过程,是模拟土壤酸化及其效应研究的有效方法。     

造纸污泥堆肥农用对酸性土壤性质影响研究

通过玉米盆栽试验,研究了添加富含铝盐的造纸污泥堆肥对酸性赤红壤理化性质的影响。结果表明,添加造纸污泥堆肥能有效减缓土壤酸化,增加土壤有机质和有效磷含量,提高土壤质量;同时添加堆肥的各处理土壤中的总酸溶性铝和总单核铝浓度在盆栽初期较CK有显著增加,并随堆肥用量的增加而增加,但随着玉米生长时间推移,各处理（除了CK）总酸溶性铝和总单核铝浓度明显下降,在盆栽结束时各处理总酸溶性铝浓度均低于原赤红壤中总酸溶性铝浓度,可见造纸污泥堆肥农用不会对酸性土壤形成活性铝累积问题。     

不同土壤的还原状况对铁镉形态转化和水稻吸收的影响

采用土壤-蛭石联合培养,以填充蛭石的网袋模拟根际,置于红壤、水稻土、盐土中后淹水栽培水稻13 d.试验结果表明,水稻栽培期问,红壤、水稻土、盐土pH变化范围分别为6.05 ～6.78、6.47 ～7.33、6.42 ～7.44;有机质处理下,除红壤根际pH明显升高外,其余土壤根际和非根际pH均有所下降.各土壤对照根际Eh保持在233 ～ 385 mV;有机质处理使根际Eh下降,同时也导致除盐土外的非根际Eh上升.土壤还原溶解Fe与蛭石吸附Fe的90％以上均米自铁锰氧化物结合态铁(Oxide-Fe)组分,与溶液Eh、pe+ pH均有显著相关性,表明两表面同为Fe的氧化还原反应,但方向相反.水稻根表Fe膜的形成与根际氧化还原状况有关,在对照根际(高Eh)环境下,根表Fe含量随pH升高而降低,在有机质处理根际(低Eh)环境下则随pH升高而升高;在红壤中,根表Fe膜阻碍Fe的吸收,在水稻土和盐土中,根表Fe膜促进Fe吸收.根表Cd含量与根内Cd、地上部Cd有显著正相关;在红壤中,根表Fe膜阻碍了水稻Cd的吸附和吸收;水稻土和盐土中,根表Fe膜促进了水稻Cd的吸附和吸收.     

不同调理剂对酸性土壤降酸效果及大麦幼苗生长的影响

采用土壤培养及盆栽试验研究5种调理剂(生石灰、油菜秸秆、有机肥、钾硅肥、土壤改良剂,用量均为1.8 g/kg)对酸性土壤(pH值3.9)酸度指标和大麦幼苗生长的影响。土壤培养试验结果表明,施用生石灰、有机肥和钾硅肥均能明显提高土壤pH值,降低土壤交换性酸总量、交换性H+和交换性铝含量。其中以生石灰降酸效果最好,到培养第90 d,相比于对照处理提高了0.66个单位,土壤交换性铝含量减少了2.01 cmol/kg;其次是有机肥和钾硅肥处理,pH值较对照处理分别提高了0.14和0.15,土壤交换性铝含量分别降低了0.23和0.19cmol/kg;油菜秸秆和土壤改良剂处理从酸度指标来看,与对照并没有显著差异。大麦幼苗盆栽试验结果表明,与对照相比,生石灰、油菜秸秆、有机肥、钾硅肥和土壤改良剂处理的大麦幼苗地上部生物量分别增加71.5%、24.1%、27.6%、28.2%、24.7%,大麦株高、根长、根系总表面积和根系活力均显著高于对照处理,根系平均直径减少,有利于养分和水分的吸收。综合结果表明,不同类型的调理剂对酸性土壤的降酸效果不尽相同,其中以生石灰效果最好,秸秆处理尽管没有有效降低土壤酸度但仍可明显促进作物生长,因此也可用作酸性土壤的改良物质,在实际生产中应因地制宜应用各种调节物质来促进作物生长。     

不同作物根茬对土壤酸度的影响

通过室内培养试验,研究了添加大豆、玉米、谷子、花生、高粱5种根茬后对土壤酸度的影响。结果表明,培养结束时,添加5种作物根茬均显著提高了土壤pH值,高粱根茬降低土壤pH值的效果最好;添加5种作物根茬后的土壤交换性酸、交换性Al 3+含量均显著低于对照,高粱根茬对交换性酸降低效果最好。添加根茬后土壤有机质相对于对照组均有显著提升(P0.05),其中高粱根茬的土壤有机质含量优于其他处理组;添加高粱根茬土壤的酸碱滴定S形曲线最为平缓,添加大豆根茬土壤酸碱滴定曲线坡度最大,但均优于对照组。相关性分析表明,影响土壤酸度的主要因素是交换性钙、阳离子交换量和盐基饱和度,影响添加作物根茬后土壤缓冲容量的主要因素是土壤有机质含量;缓解土壤酸化,添加高粱根茬效果最好。     

水稻根际中铁的形态转化

本文以熟化红壤性水稻土、淀浆白土、红壤和赤红壤为样品,研究了植稻后根际中铁的形态转化.结果表明,两种水稻土根际中无定形氧化铁、游离氧化铁、络合态铁、土壤中氧化铁的活化度及两种红壤上根际中的络合态铁均低于非根际土;而两种红壤上其余各项在根际内外分布趋势均与水稻土相反.用穆斯堡尔谱仪分析表明,所有根际土与非根际土相比,四极矩分裂增大,内磁场下降,说明根际中氧化铁被活化.同时,水稻土上根际中Fe²⁺增多,赤红壤中根际出现新矿物磁赤铁矿.根际中铁被活化,可能会影响根际中重金属等污染物的吸附和解吸特性、植物的铁素营养及对其它养分的吸收.     

施用白云石对酸性黄红壤作物产量及化学性质的影响

白云石改良酸性黄红壤三年定位试验结果表明:酸性黄红壤施用白云石可以降低土壤交换性铝的含量,提高土壤pH值和交换性钙、镁的含量,显著提高作物产量,且有明显的后效。第1—6季作物分别增产10.8%~13.4%、21.5%~48.6%、9.4%~16.2%、10.9%~44.6%、7.9%~22.0%和6.6%~29.8%。白云石施用量为600kg hm-2时,降酸作用可维持3季作物以上;白云石施用量为2500 kg hm-2时,降酸作用可维持6季作物以上。     

Root Growth,Nutrient Uptake,and Nutrient-Use Efficiency by Roots of Tropical Legume Cover Crops as Influenced by Phosphorus Fertilization

Roots are important organs that supply water and nutrients to growing plants. Data related to root growth and nutrient uptake by tropical legume cover crops are limited. The objective of this study was to evaluate root growth of tropical legume cover crops and nutrient uptake and use efficiency under different phosphorus (P) levels. The P levels used were 0 (low), 100 (medium), and 200 (high) mg kg^?1 of soil, and five cover crops were evaluated. Root dry weight, maximum root length, and specific root length were significantly influenced by P and cover crop treatments. Maximum values of these root growth parameters were achieved with the addition of 100 mg P kg^?1 soil. The P?×?cover crops interactions for all the macro- and micronutrients, except manganese (Mn), were significant, indicating variation in uptake pattern of these nutrients by cover crops with the variation in P rates. Overall, uptake pattern of macronutrients was in the order of nitrogen (N) > calcium (Ca) > potassium (K) > magnesium (Mg) > P and micronutrient uptake pattern was in the order of iron (Fe) > Mn > zinc (Zn) > copper (Cu). Cover crops which produced maximum root dry weight also accumulated greater amount of nutrients, including N, compared to cover crops, which produced lower root dry weight. Greater uptake of N compared to other nutrients by cover crops indicated that use of cover crops in the cropping systems could reduce loss of nitrate (NO₃ ^?) from soil–plant systems. Increase in root length and root dry weight with the addition of P can improve nutrient uptake from the soil and lessen loss of macro- and micronutrients from the soil–plant systems.     

Root growth,nutrient uptake and use efficiency by roots of tropical legume cover crops as influenced by phosphorus fertilization

The root is an important organ which supplies water and nutrients to growing plants. Data related to root growth and nutrient uptake by tropical legume cover crops are limited. The objective of this study was to evaluate root growth of tropical legume cover crops and nutrient uptake and use efficiency under different phosphorus (P) levels. The P levels used were 0 (low), 100 (medium) and 200 (high) mg kg^?1 of soil and 5 cover crops were evaluated. Root dry weight, maximum root length, specific root length were significantly influenced by P and cover crop treatments. Maximum values of these root growth parameters were achieved with the addition of 100 mg P kg^?1 soil. The P X cover crops interaction for all the macro and micronutrients, except manganese (Mn) was significant, indicating variation in uptake pattern of these nutrients by cover crops with the variation in P rates. Overall, uptake pattern of macronutrients was in the order of nitrogen>calcium>potassium>magnesium>phosphorus (N > Ca > K > Mg > P) and micronutrient uptake pattern was in the order of iron>manganese>zinc>copper (Fe > Mn > Zn > Cu). Cover crops which produced maximum root dry weight also accumulated higher amount of nutrients, including N compared to cover crops which produced lower root dry weight. Higher uptake of N compared to other nutrients by cover crops indicated that use of cover crops in the cropping systems can reduce loss of nitrate (NO₃^?) from soil-plant systems. Increase in root length and root dry weight with the addition of P can improve nutrient uptake from the soil and less loss of macro and micronutrients from the soil-plant systems.     

Growth of Tropical Legume Cover Crops as Influenced by Nitrogen Fertilization and Rhizobia

Tropical legume cover crops are important components in cropping systems because of their role in improving soil quality. Information is limited on the influence of nitrogen (N) fertilization on growth of tropical legume cover crops grown on Oxisols. A greenhouse experiment was conducted to evaluate the influence of N fertilization with or without rhizobial inoculation on growth and shoot efficiency index of 10 important tropical cover crops. Nitrogen treatment were (i) 0 mg N kg^?1 (control or N₀), (ii) 0 mg N kg^?1 + inoculation with Bradyrhizobial strains (N₁), (iii) 100 mg N kg^?1 + inoculation with Bradyrhizobial strains (N₂), and (iv) 200 mg N kg^?1 of soil (N₃). The N?×?cover crops interactions were significant for shoot dry weight, root dry weight, maximal root length, and specific root length, indicating that cover crop performance varied with varying N rates and inoculation treatments. Shoot dry weight is considered an important growth trait in cover crops and, overall, maximal shoot dry weight was produced at 100 mg N kg^?1 + inoculation treatment. Based on shoot dry-weight efficiency index, cover crops were classified as efficient, moderately efficient, and inefficient in N-use efficiency. Overall, the efficient cover crops were lablab, gray velvet bean, jack bean, and black velvet bean and inefficient cover crops were pueraria, calopo, crotalaria, smooth crotalaria, and showy crotalaria. Pigeonpea was classified as moderately efficient in producing shoot dry weight.     

Arbuscular mycorrhizal dependency of different plant species and cultivars

The degree of plant growth change associated with arbuscular mycorrhizal (AM) colonization is expressed as mycorrhizal dependency (MD). In this review, previous reports on the differences in MD among plant species or cultivars were surveyed, and the factors affecting the differences are discussed. Mean values of MD were 44% for field crops (37 species), 56% for forage crops (46 species), 70% for wild grasses and forbs (140 species), 79% for trees (26 species), and 56% for all plants (250 species), indicating that the cultivated plant species showed a lower MD than the wild plant species. MD was negatively correlated with root morphological characteristics such as root length, root dry weight, root hair length, density of root hairs, the ability of roots to acquire phosphate from soil, and the phosphorus utilization efficiency of the host plant. Inoculation of arbuscular mycorrhizal fungi (AMF) for low input systems should be carried out in considering differences in MD.     

不同铁效率玉米品种苗期适应低铁胁迫的根系特征与铁积累差异

  【目的】  石灰性土壤高pH和高重碳酸盐含量严重影响土壤中有效铁含量,导致作物缺铁黄化、减产,铁高效玉米品种的推广应用是实现石灰性土壤玉米高产稳产的重要途径。 本研究探讨不同铁效率玉米品种适应低铁胁迫的根系特征与铁积累差异,旨在为铁高效玉米品种的推广应用提供科学依据。  【方法】  试验以铁高效玉米品种正红2号 (ZH2)、正大619 (ZD619) 和铁低效玉米品种川单418 (CD418)、先玉508 (XY508) 为材料,设置极低铁处理 (Fe0,Fe浓度为0 μmol/L)、低铁处理 (Fe10,Fe浓度为10 μmol/L) 和正常供铁 (Fe100,Fe浓度为100 μmol/L) 3个处理,通过砂培试验,研究不同铁效率玉米品种适应低铁胁迫的根系形态特征、干物质重、铁积累及铁吸收利用差异。  【结果】  低铁胁迫下,玉米幼苗的根干重、单株干重、铁积累量、根系相对铁吸收效率均显著降低,而根冠比与铁素生理效率均显著升高,且随胁迫程度的增加变幅加大;总根长、根表面积、根体积和根直径则表现出明显的品种差异,与正常铁处理 (Fe100)相比,低铁处理下铁低效品种的总根长、根表面积和根体积显著降低,根直径显著增加,而铁高效品种的总根长和根表面积差异不显著,根体积显著增加,根直径在极低铁处理(Fe0)下显著降低,低铁处理 (Fe10)下差异不显著;铁高效品种总根长、根表面积、根体积、根干重、单株干物重、铁积累量和根系铁吸收效率的降幅及根冠比的增幅均明显低于铁低效品种,而铁生理效率的增幅高于铁低效品种。相关性分析结果表明,玉米幼苗铁积累量与总根长、根表面积、根体积和根干重均呈显著正相关,而与根冠比呈负相关,其中与总根长 (R2 = 0.8546) 和根表面积 (R2 = 0.8983) 相关性最强。  【结论】  与铁低效玉米品种相比,铁高效玉米品种低铁胁迫下具有较优的总根长、根表面积及较高的根系铁吸收效率与铁生理效率,促进了其对铁的高效吸收与利用,提高了其对低铁环境的适应能力。     

The role of phosphorus sources on root diameter,root length and root dry matter of barley (Hordeum vulgare L.)

Roots are the main plant organs that supply nutrients, water, hormones and physical support for the plant. Phosphorus (P) is one of the most limiting and important elements in root growth and crop production. The aims of this study were to investigate the effects of different sources of phosphorus treatments on root growth (root length, diameter and dry matter) of barley. The two glasshouse pot experiments results showed that under P deficiency, the weight of dry root significantly decreased and the total root length of whole plant significantly increased with decrease of root diameter. Our results suggested that soil fertility and root structure are widely recognized as important role of the soil community and plant growth, the root structure and root extension can directly and indirectly affected by soil fertility and specially P nutrient of the soil. Accordingly, root characteristics can determine the circumstance of plant growth and crop production.     

ROOT GROWTH OF UPLAND RICE GENOTYPES AS INFLUENCED BY NITROGEN FERTILIZATION

The plant root system is an important organ which supplies water and nutrients to growing plants. Information is limited on influence of nitrogen fertilization on upland rice root growth. A greenhouse experiment was conducted to evaluate influence of nitrogen (N) fertilization on growth of root system of 20 upland rice genotypes. The N rate used was 0 mg kg^?1(low) and 300 mg kg^?1(high) of soil. Nitrogen X genotype interactions for root length and root dry weight were highly significant (P < 0.01), indicating that differences among genotypes were not consistent at two N rates. Overall, greater root length, root dry weight and tops-roots ration were obtained at an N fertilization rate of 300 mg kg^?1compared with the 0 mg N kg^?1soil. However, genotypes differ significantly in root length, root dry weight and top-root ratio. Nitrogen fertilization produced fine roots and more root hairs compared with absence of N fertilizer treatment. Based on root dry weight efficiency index (RDWEI) for N use efficiency, 70% genotypes were classified as efficient, 15% were classified as moderately efficient and 15% were classified as inefficient. Root dry weight efficiency index trait can be incorporated in upland rice for improving water and nutrient efficiency in favor of higher yields.     

Differential responses of sericea lespedeza to aluminum stress

Toxic levels of aluminum can cause severe yield reductions in many crop species, but sericea lespedeza [Lespedeza cuneata (Dum.‐Cours.) G. Don] has demonstrated considerable tolerance. Aluminum tolerances of six sericea lespedeza cultivars (Am 312, Appalow, AU Lotan, Interstate, Interstate 76, Serala) representing a broad genetic base were evaluated in a Monmouth soil [26.2% Al saturation (pH 4.8) vs. 2.8% Al saturation (pH 5.7)] and in nutrient solutions (0 vs 111 μM Al; pH 4.5). The soil and nutrient culture studies were harvested 30 and 27 d after seeding, respectively.

Aluminum stress did not reduce root and shoot growth significantly, nor were the pooled Al stress x cultivar interactions significant. Cultivars differed significantly in mean shoot and root vigor in nutrient solutions but not in soil. R‐esponses in soil were only weakly correlated with responses in nutrient solutions. Am 312 and Appalow had the lowest relative weight values (dry weight stressed/dry weight unstressed) in both media and Interstate and Interstate 76 the highest. Interstate 76 exhibited a significant positive response (5% level) to Al when evaluated in nutrient solutions.     

Variation of morpho-physiological traits in geographically diverse pigeonpea [Cajanus cajan (L.) Millsp] germplasm under different phosphorus conditions

Genotypic variation for morpho-physiological parameters, phosphorus (P) content and root acid phosphatase activity was studied in 52 pigeonpea genotypes. Data related to shoot (length, dry weight, number of leaves, and leaf area), root (volume, length, dry weight, area, perimeter, and number of root tips), acid phosphatase activity, and P content (root, stem, and leaf) were recorded at 60 days after sowing (DAS). The P use efficient genotypes showed high root length, root area, root perimeter, root dry weight, P content in leaves, and root to shoot dry weight ratio under the P not added condition. Significant variation was found among genotypes for root- and shoot-associated characteristics under both P treatments. The P use efficient genotypes with improved root morphological phenes have potential to acquire and utilize more P from immobile soil bound P sources may be of additional factor for increasing efficiency of acquisition and utilization of supplied P fertilizer.     

Copper-Use Efficiency in Dry Bean Genotypes

Copper (Cu) is an essential micronutrients and its deficiency has been reported in many crops including dry bean. A greenhouse experiment was conducted to evaluate thirty dry bean genotypes (G) for Cu-use efficiency. The Cu levels used were low (natural soil level) and adequate [10 mg Cu kg^?1 soil, applied with copper sulfate (24 percent Cu)]. Straw yield, seed yield, number of pods per plant, seed per pod, seed harvest index (SHI), maximum root length (MRL), and root dry weight (RDW) were significantly affected by Cu and genotype treatments. The Cu × G interactions were also significant for these traits, indicating variation in genotype responses with the variation in Cu levels. Based on seed yield efficiency index (SYEI), genotypes were grouped in three classes: Cu efficient, moderately Cu efficient, and Cu inefficient. Fifty-three percent of the genotypes were classified as efficient, 40 percent were classified as moderately efficient, and 7 percent were classified as inefficient in Cu-use efficiency.