EARLY DIAGNOSIS OF BORON DEFICIENCY IN CHESTNUT

This study aims to identify an alternative plant tissue to be used in the early diagnosis of boron (B) deficiency in chestnut (Castanea sativa Mill.). A B-deficient orchard was selected, and 16 trees were submitted to two levels of B fertilization. When flowers were in bloom, the following tissues were sampled: leaves, androgynous catkins and flowers. There was a significant increase in B content in plant tissues due to B application. In July, the highest B content was observed in flowers in B0, but leaves had the greatest content in B1. Boron content in the tissues collected in July was positively correlated with B contents in leaves sampled in September. Foliar B concentrations, irrespective of the sampling period, were correlated with chestnut productivity, while the other tissues did not. These results suggest that the leaves, sampled in bloom, were the most efficient tissue for the early diagnosis of B deficiency.     

RELATIONSHIP OF IRON-MANGANESE TOXICITY DISORDER IN MARIGOLD TO MANGANESE AND MAGNESIUM NUTRITION

The iron-manganese (Fe-Mn) disorder in marigold (Tagetes erecta L.) is related to high Mn and low magnesium (Mg) in leaves. Three solution-culture experiments with marigold were conducted in a greenhouse. One investigated Mn and the disorder. Based on dry matter production, 4.5 mg Mn/L was the toxicity concentration and gave 880 mg Mn g^?1 dry weight in new leaves and 1200 in old leaves. Manganese above 4.5 mg L^?1 produced bronzed speckles on leaves. A second experiment investigated Mg and the disorder. Based on dry matter production, 10 mg Mg L^?1 was the deficiency concentration and gave 1.5% Mg in the shoots. Symptoms of Mg deficiency did not resemble those of the disorder. A third experiment investigated Mn and Mg. Leaf chlorosis appeared at 2.5 mg Mn L^?1 with the lowest supply of Mg. These experiments suggest that Mn supply is related to the disorder but increasing Mg does not alleviate the problem.     

THE INFLUENCE OF MAGNESIUM AND OF EASILY WEATHERED MINERALS ON HYDRAULIC CONDUCTIVITY CHANGES IN A SODIC SOIL

Exchangeable Mg appears to have no specific effect on soil hydraulic conductivity of A and C horizons of a sodic sandy loam soil (montmorillonite and kaolinite clay minerals) leached with solutions which cause clay swelling to be the dominant mechanism reducing conductivity (SAR < 20, electrolyte concentration 10 meq per litre). There is some evidence of a specific effect when these soils are subsequently leached with water which causes clay dispersion to become important. Fresh loess in the A horizon dissolves in percolating rainwater, causing difficulties in the replication of experiments. It seems to give a small degree of ‘self protection’ to soil structure, a property likely to be operating in other soils affected by recent loess deposits.     

EFFECT OF BORON-DOPED GOETHITE ON SOIL ACIDITY,DIFFERENT FORMS OF MANGANESE IN RED SOIL AND THE GROWTH OF RAPE (BRASSICA NAPUS L.) SEEDLINGS

Rape (Brassica napus L.) seedling pot experiments were performed with a red soil treated with goethite which had boron (B) either adsorbed (ad-B-goethite) or occluded (oc-B-goethite). Soil acidity, different forms of manganese in the soils and different elements content of the rape seedlings were determined. It was found that the addition of boron-containing goethite to the soils resulted in increased rape growth, elevated soil pH and decreased exchangeable acidity. Compared with the control, boron-containing goethite elevated the content of exchangeable manganese (Mn) (EXC-Mn), organic matter bound Mn (OM-Mn), reducible oxide Mn (RO-Mn) and residual Mn (RES-Mn) which were difficult to use for plant. Low labile organic matter was significantly correlated with easily reducible oxide Mn (ERO-Mn) (P < 0.01) and RO-Mn (P < 0.05). Middle organic matter and soil pH was significantly (P < 0.05) correlated with RES-Mn. Stepwise regression was used to select the combination of variables that best estimates shoot and root dry weight of rape seedling. Among them, soil pH, EXC-Mn, OM-Mn, RO-Mn and RES-Mn significantly influenced the dry weight of rape seedlings. The addition of boron-containing goethite improved the uptake of iron (Fe), calcium (Ca), magnesium (Mg), and copper (Cu) element and decreased the uptake of Mn and zinc (Zn) element in rape seedling. The results suggested that boron-containing goethite could provide a better soil acidity environment for plant growth; it was also an important agent increasing a part of manganese difficult to use for plant and reducing the activity of soil manganese, which was beneficial to altering rape seedling growth.     

缺镁对龙眼光合产物生产和分配的影响

缺镁对龙眼 (DimocarpusLonganaLour.)光合产物的生产和分配有明显的影响。缺镁胁迫下 ,龙眼叶片单位面积和单位重量的叶绿素、类胡萝卜素含量均降低 ,光合速率下降 ,叶绿体亚显微结构发生明显的改变 ,叶绿体中可见有大量的淀粉粒。随着缺镁胁迫程度的加重 ,14 C -光合产物在标记叶中的滞留量增加 ,输出率降低。叶片非还原糖、淀粉含量增加 ,茎秆、根系的非还原糖尤其是淀粉含量降低。本文还就缺镁影响龙眼光合产物生产和分配的机理进行了讨论     

青藏高原东北部边缘区栗钙土的历史演变

本文根据土壤¹⁴C、孢粉和物理化学分析资料,探讨了青藏高原东北部边缘区栗钙土的成土环境和历史演变过程及其主要理化性质。(1)晚更新世晚期栗钙土已有发育,集中形成于全新世中期和晚期。(2)成土期草本孢粉占90%左右,仅有少量木本花粉出现。(3)栗钙土的剖面结构由现代土壤和不同时代的古土壤构成。(4)土壤矿物风化弱,腐殖质化程度低。     

冀北高原草甸栗钙土春小麦中化肥氮去向的研究

在冀北高原张北县的草甸栗钙土上，采用＾１５Ｎ质量平衡法和微气象学技术，对春小麦中氮肥的去向，以及氨挥发进行了田间原位观测。试验中的氮肥用量为Ｎ４．８３ｋｇ／亩，１／３作基肥、２／３作追肥。基肥随播种施入，追肥于拔节期撤施，随即灌水。结果表明，小麦回收、土壤残留和损失的肥料氮各占施入氮量的３７．８％－４８．３％、３３．８％－４０．４％和１４．３％－２５．４％。其中，尿素作基肥与作追肥的处理之间，其氮     

辐照板栗保鲜技术研究

低剂量 ( 0 2 5kGy)γ射线辐照板栗可以控制害虫繁殖、抑制板栗发芽。板栗贮藏于 2～ 4℃冷柜中 45d其保鲜效果可达 91 1 % ,用井岗霉素等抑菌剂处理后再辐照 ,其 60d贮藏保鲜效果为 92 0 %以上     

辐照对板栗胚芽细胞结构的影响

本研究试图通过电子显微镜观察γ辐射对板栗胚芽细胞的损伤程度 ,结果发现辐照对胚芽中淀粉影响较为明显 ,0 5kGy以下处理时对胚芽淀粉无明显影响 ,1kGy处理淀粉粒边缘开始部分糊化 ,6kGy以上剂量辐照糊化较为明显。与此相对应 ,板栗种子淀粉的粘度也随辐照剂量的增加而逐渐下降。另外观察到胚芽细胞壁随辐照剂量的增加而逐渐变薄     

GROWTH AND IRON-MANGANESE RELATIONSHIPS IN DRY BEAN AS AFFECTED BY FOLIAR AND SOIL APPLICATIONS OF IRON AND MANGANESE IN A CALCAREOUS SOIL

Manganese (Mn) deficiency may be induced by adding large quantities of iron (Fe), provided that soil manganese is marginally deficient. Results of a greenhouse study showed that iron soil application did not influence shoot dry matter yield of dry bean due to the fact that the iron:manganese ratio in aerial parts of dry bean was higher than 0.4. A foliar spray of 2% iron sulfate significantly reduced it probably due to the high level of shoot iron and iron:manganese ratio greater than 4. Iron application decreased concentration/uptake of shoot manganese due to the iron-manganese antagonistic relationships. Mangenese soil application is not an effective method in correction of manganese deficiency induced by iron fertilizers. Iron did not affect root manganese uptake, indicating that manganese absorption was not affected by iron application. Both manganese/iron soil tests are recommended in calcareous soils with manganese soil test in marginal range.     

栗钙土水肥耦合效应的田间研究

高寒半干旱栗钙土农田水肥耦合效应明显。供水量为250～450mm 条件下,氮磷合理配施改善了地上部生物学性状,促进了地下部根系发育;供水350mmN120P90处理0～40mm 根重密度最高,达1.317mg/cm3 , P45较N60根重密度增加0.067～0.375mg/cm3。供水为150mm的干旱年型,水分是限制作物生产的主导因素,而供水250～450mm年型主导因素则是土壤营养不足。供水量350mm N120P90处理作物水分利用效率最高,可达7.27kg/(mmhm2), N60P90氮肥利用率最高,子粒和植株分别为48.18%和88.17%,N120P45磷肥利用率最高,子粒和植株分别为21.13%和30.42%。水肥合理耦合有效地提高了作物产量和水肥利用率。     

NITROGEN SOURCE AND MANGANESE APPLICATION EFFECTS ON MANGANESE DYNAMICS IN THE RHIZOSPHERE OF WHEAT CULTIVARS GROWN ON MANGANESE-DEFICIENT SOILS

To study the effect of two different nitrogen (N) sources and manganese application on root-shoot relations and manganese (Mn) dynamics in the rhizosphere of two wheat cultivars, a screen house experiment was conducted using manganese-deficient soil. Significantly higher root length (RL), root surface area, shoot dry weight (SDW), root length density, and manganese uptake were recorded in calcium nitrate supplied plants of cultivar ‘WH 542’ when applied with calcium nitrate along with manganese rather than ammonium sulfate. Cultivar ‘PD W274’ produced 72% of the maximum RL and 77% of the maximum SDW under similar conditions. Results indicated that cultivar ‘WH 542’ was more manganese efficient than ‘PD W274’ and calcium nitrate was a better source of nitrogen than ammonium sulfate. However, maximum shoot manganese content was recorded in ammonium sulfate supplied plants, which was due to depletion of manganese at root surface to a lower value, causing higher concentration gradient and hence higher manganese influx to root.     

缺锰和多锰对番茄产量及风味品质的影响

通过设置不同的硫酸锰浓度并测定不同供锰水平下番茄的产量及与果实风味品质相关的指标,研究了缺锰和多锰对番茄产量和品质的影响。结果表明,无论缺锰还是多锰处理,番茄叶片叶绿素含量和产量都显著下降,叶绿素含量分别为正常处理的57.31%和61.50%,产量为58.25%和68.35%;叶片POD和SOD活性降低,以缺锰处理较为显著;缺锰和多锰处理的MDA含量分别高于对照71.07%和40.71%。缺锰和多锰处理导致果实的酸度分别增加37.4%和40.1%,可溶性固型物含量降低17.51%和13.19%,两者较正常锰处理均差异达到显著水平,Vc含量降低31.94%和9.45%;此外,2种处理果实中的活性物质番茄红素含量均下降34%左右,总酚和总黄酮含量下降30%~35%,总抗氧化力也明显降低,而且果实的芳香物质种类也少于正常处理。说明适宜的锰浓度是保证番茄高产、优质的重要因素。     

农业生产中的铁锰平衡问题

本文根据对菠萝和水稻的研究,论述了土壤和植物体内铁与锰的关系,认为在植物体内铁与锰的比例应保持一个平衡的关系。如果锰多铁少、比例失调,作物的正常生长将受到危害。     

土壤水分状况对物质移动及作物生长的影响

水分状况不仅影响水稻土的发生性质,也影响水稻土生态系统的生产力.当稻田灌水量满足蒸发,蒸腾和渗漏需要时,水稻可获高产;如水分过多,反不利于水稻生长.太湖与华南等大面积种植双季稻地区,多因地势低平,土质粘重,土壤排水不良,引起了次生潜育作用,出现青泥层,致使三麦常受渍害,水稻迟发.从而削弱了水稻土生态系统功能的发挥.     

水解聚丙烯腈对土壤氮磷影响的初步研究

水解聚丙烯腈是一种土壤结构改良剂,它具有大量的活性功能基,如羧基(-COOH),胺基(-NH₂),酰胺基(-CONH₂)等等.这些活性功能基在溶液中离解,产生剩余价键,使聚合物离解成具有许多活性点的带电荷的离子.这种具有大量活性功能基的土壤结构改良剂,在土壤介质这一分散系统中,引起土壤胶体和金属离子发生一系列复杂的化学、物理化学、胶体化学变化和力学作用,使分散的土粒形成具有水稳性团粒结构的土壤,使土壤容重降低,土壤总孔隙度增加,有效地防止土壤板结龟裂^[2,3],对作物出苗和根系发育有良好的作用^[6].     

粘土夹层对地下水上升运行的影响

我国华北平原土壤质地情况比较复杂,壤土剖面中,在不同部位上往往有不同厚度的粘土层^[6]。土壤中水盐运行的情况密切受土壤质地和地下水位的影响^[5]。如土壤剖面中有粘土夹层,它将在很大程度上影响剖面中水分的分布和运行。     

辐照对板栗冷藏后期生理的影响

板栗经过0.5kGy低剂量辐照处理和0℃~4℃低温贮藏,能取得良好的贮藏效果。辐照后的板栗经过8个月的冷藏后保持较高的水分、糖、淀粉含量,能保持较好的质量品质。     

青藏高原的隆起对高山土壤形成的影响

素有“世界屋脊”之称的青藏高原是地球上最年青的大高原,也是一个独特的土壤区域.本文主要论述青藏高原的隆起对高山土壤形成的影响,对本区主要土壤类型和区域特征也有所讨论,意欲对高山土壤的发生、分类和土壤区划提供一些资料.