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1.
Phosphorus (P) cycles rapidly in lowland tropical forest soils, but the process have been proven difficult to quantify. Recently it was demonstrated that valuable data on soil P transformations can be derived from the natural abundance of stable oxygen isotopes in phosphate (δ18OP). Here, we measured the δ18OP of soils that had received long-term nutrient additions (P, nitrogen, and potassium) or litter manipulations in lowland tropical forest in Panama and performed controlled incubations of fresh soils amended with a single pulse of P. To detect whether δ18OP values measured in the incubations apply also for soils in the field, we examined the δ18OP values after rewetting dry soils. In the incubations, resin-P δ18OP values converged to ∼3.5‰ above the expected isotopic equilibrium with soil water. This contrasts with extra-tropical soils in which the δ18OP of resin-P matches the expected equilibrium with soil water. Identical above-equilibrium resin-P δ18OP values were also found in field soils that did not receive P additions or extra litter. We suggest that the 3.5‰ above-equilibrium δ18OP values reflect a steady state between microbial uptake of phosphate (which enriches the remaining phosphate with the heavier isotopologues) and the release of isotopically equilibrated cell internal phosphate back to the soil. We also found that soil nutrient status affected the microbial turnover rate because in soils that had received chronic P addition, the original δ18OP signature of the fertilizer was preserved for at least eight weeks, indicating that the off-equilibrium δ18OP values produced during microbial phosphate turnover was not imprinted in these soils. Overall, our results demonstrate that ongoing microbial turnover of phosphate mediates its biological availability in lowland tropical soils. 相似文献
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为确定甘肃高寒雨养区燕麦(Avena sativa)种子生产中磷肥最佳用量,提高肥料利用效率,试验在氮肥(尿素)用量75 kg·hm-2的固定水平下,设计4个磷肥(P2O5)水平(0(CK),65(C1),100(C2),135(C3)kg·hm-2),对各磷肥水平下干草产量、种子产量和相关性状的变化进行了研究。结果表明:施用磷肥使燕麦的株高、茎粗、分蘖和干草产量均有提高,灌浆期C1,C2,C3干草产量较CK依次提高13.85%,25.96%,22.65%,干草产量与磷肥水平显著正相关(相关系数0.91);施用磷肥提高了燕麦的有效分蘖数、主穗长,显著提高主穗粒数、穗粒重、千粒重、种子产量和秸秆产量,C1,C2,C3种子产量较CK依次提高12.37%,16.72%,14.38%,种子产量与磷肥水平显著正相关... 相似文献
4.
利用32P示踪研究马铃薯(合作-88)对磷素营养的吸收及分布规律 总被引:1,自引:0,他引:1
应用3 2 P研究“合作 88”马铃薯对磷素营养的吸收和分布规律 ,结果显示 :马铃薯对磷素营养的吸收率随植株的生长而增加。吸收率与栽培生长时间呈显著正相关。磷素主要分布为茎 >根 >叶 ,随生育期茎中含量相对增加 ,而叶中含量相对减少 ,根的不变。 相似文献
5.
植物对磷饥饿的反应研究进展 总被引:4,自引:0,他引:4
磷是构成生命的重要元素之一,也是土壤中有效性最低的一种营养元素。我国是世界上最大的小麦生产国。但是我国耕地中有59%的土壤缺磷。农作物的产量常受到缺磷的影响而受损。土壤缺磷并不是土壤中总磷量低,而是土壤中可供植物直接吸收利用的有效态磷含量低。植物在磷饥饿时会发生各种各样的变化,以尽最大可能满足自身对磷的需求。植物对缺磷的反应是一个复杂的网络过程。大约有100多个基因参与了植物对缺磷的反应。其中主要的有磷转运蛋白基因、核糖核酸酶基因、磷酸酶基因等。植物在吸收外界的磷的过程中磷转运蛋白发挥了重要作用。植物磷转运蛋白基因按照序列相似性可以划分为H+/Pi共转运家族(Pht1家族)和Na+/Pi共转运家族(Pht2家族)。按照吸收动力学的标准可以分为高亲和力磷转运蛋白和低亲和力磷转运蛋白两种。磷饥饿时植物对磷吸收能力的增强的原因之一是增加了磷转运蛋白分子的合成数目。目前尽管人们对植物吸收磷的理解已经有了长足的进步,但是在植物对磷的具体调控机制、磷的跨液泡膜运输等重要方面仍然没有明确的结果。 相似文献
6.
棉花不同品种叶片和纤维中蔗糖磷酸合成酶活性变化
及其与糖含量的关系 总被引:5,自引:0,他引:5
利用山农棕02、丰抗6号、中棉45 3个品种在大田栽培的条件下,研究了叶片和纤维中蔗糖磷酸合成酶活性的变化及与糖含量的关系。结果表明,在3个品种的叶片和纤维中,蔗糖磷酸合成酶活性均出现双峰,在开花当天最高,花后18d次之,整体呈下降趋势;与此同时可溶性总糖和蔗糖的含量变化以及光合速率的变化也成相似的变化。3个品种中,丰抗6号蔗糖磷酸合成酶活性和含糖量最高,中棉45次之,山农棕02最低。3个品种的相应观测指标之间均呈极显著差异。 相似文献
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《Plant Production Science》2013,16(2):194-201
AbstractGreater species diversity in natural ecosystems increases plant biomass production and stability. Intercropping is an agricultural practice that aims to accrue the benefits of species diversity by growing two or more species simultaneously in the same space. Functional group diversity is considered important for enhancing the beneficial effects of species diversity, but most previous intercropping studies used combinations of only two functional groups. Thus, we used three green manure species from different functional groups: sorghum (Sorghum bicolor (L.) Moench.), a C4 grass; crotalaria (Crotalaria juncea L.), a legume; and sunflower (Helianthus annuus L.), a forb. We examined the effects of intercropping on biomass, nutrient uptake, and their stability using a proportional replacement series in a field experiment for three years with four trials. The aboveground biomass was higher with dual and triple-component intercrops compared with sole crops; however, there were no superior effects of triple-component intercropping over dual-component intercropping. There were also no clear advantages of intercropping in terms of the nutrient uptake amount and stability. 相似文献
9.
HPLC法测定磷酸替米考星可溶性粉中磷酸替米考星的含量 总被引:1,自引:0,他引:1
建立了HPLC法测定磷酸替米考星可溶性粉中磷酸替米考星的含量。色谱条件:用十八烷基硅烷键合硅胶为填充剂;以水-乙腈-磷酸二丁胺缓冲液-四氢呋喃(805:115:25:55)为流动相;流速每分钟1.0ml;检测波长280nm。替米考星在0.0516mg/ml~1.032mg/ml范围内,线性关系良好(r=0.9999,n=6),平均回收率为98.5%,RSD为2.0%。本研究所建立的方法专属性强、方法简便、准确,可用于磷酸替米考星可溶性粉的质量控制。 相似文献
10.
Yoram Barak Eddie Cytryn Iliya Gelfand Michael Krom Jaap van Rijn 《Aquaculture (Amsterdam, Netherlands)》2003,220(1-4):313-326
Phosphorus dynamics were examined in a prototype, zero-discharge, marine-recirculating system. Operation of the system without discharge of water and sludge was enabled by recirculation of effluent water through two separate treatment loops. Surface water from the fish basin was pumped over a trickling filter in one loop, while bottom-water was recirculated through a sedimentation basin followed by a fluidized bed reactor in the other treatment loop. Ammonia oxidation to nitrate in the trickling filter and organic matter digestion together with nitrate reduction in the sedimentation basin and fluidized bed reactor were the main biological features of this treatment system. Orthophosphate concentrations did not exceed 15 mg PO4–P/l in the culture water during more than 1 year of system operation. Much of the phosphorus was retained within the sedimentation basin and fluidized bed reactor. In these treatment stages, the phosphorus content of organic matter was as high as 17.5% and 19%, respectively. High concentrations of total phosphorus and low concentrations of soluble orthophosphate were measured in the initial stages of sedimentation under oxic and anoxic conditions, suggesting that most of the phosphorus was associated with organic matter. Depletion of oxygen and nitrate in the sludge layers of the sedimentation basin coincided with sulfate reduction to sulfide and a release of soluble orthophosphate. The observed phosphorus dynamics in this marine system supported findings from previous studies in which it was demonstrated that denitrifiers underlie phosphorus immobilization under these conditions. 相似文献