排序方式: 共有9条查询结果,搜索用时 46 毫秒
1
1.
目的 研究陕西关中冬小麦/夏玉米区土壤磷素分布特征及近30年农田土壤有效磷变化,对维持和提高土壤质量和土地生产力,合理施磷和减磷增效具有重要意义。方法 利用2011年在陕西关中平原冬小麦/夏玉米种植区选择的10个典型县、区采集的458个土壤样本,通过与1980年土壤普查土壤有效磷含量数据的比对,分析近30年来陕西关中农田耕层土壤有效磷的变化及当前土壤磷库分布特征。结果 30年来该区农田耕层土壤有效磷含量整体呈显著上升,宝鸡市、咸阳市和渭南市的平均有效磷含量分别为26.09、27.50和21.53 mg·kg -1,与第二次土壤普查有效磷含量结果相比,增幅分别达334.83%、276.71%和231.23%。高有效磷等级地块的比例均有大幅度增加,其中以有效磷含量15-30 mg·kg -1的增幅最大,有效磷含量<10 mg·kg -1的降幅最大。有效磷和无机磷总量分布呈现出西部(宝鸡市)和中部(咸阳市)高于东部(渭南市),而有机磷含量则相反。当前关中地区大面积土壤有效磷含量高于农学阈值,可满足作物高产时的磷素供应。同时,宝鸡、咸阳市土壤有效磷含量>37 mg·kg -1 的累积分布概率超过20%,水溶性磷含量>2 mg·kg -1 的累积分布概率超过22%,存在较高的水环境污染风险。 结论 长期集约化高强度种植条件下含磷肥料的过量施用显著提高了土壤有效磷含量。从保护环境和合理利用有限的磷资源角度考虑,应合理调控磷肥施用,做到因土施肥,因需供肥。 相似文献
2.
【目的】在土壤Olsen-P和全磷含量基本接近但土壤有机碳水平呈梯度的陕西省关中平原塿土上,研究有机碳对土壤各形态无机磷有效性及其形态转化的影响,为合理培肥土壤,有效利用土壤累积态磷提供理论依据。【方法】采集并选取了陕西省关中平原小麦-玉米种植体系下塿土Olsen-P含量相近(平均含量范围17.41—18.72 mg·kg-1),不同有机碳水平(有机碳平均含量分别为6.38、8.34、10.17、11.95、13.64和15.74 g·kg-1)的土壤样品,采用蒋柏藩-顾益初改进的Chang和Jackson的石灰性土壤无机磷分级方法分别对土壤中各磷组分(二钙磷(Ca2-P)、八钙磷(Ca8-P)、铝结合态磷(Al-P)、铁结合态磷(Fe-P)、闭蓄态磷(O-P)和十钙磷(Ca10-P))含量进行测定。【结果】在陕西关中平原小麦-玉米种植区塿土中,有机碳对土壤各形态磷素水平及形态转化起重要作用。随着有机碳含量的增加,土壤中Ca2-P、Ca8-P、Al-P、Fe-P、O-P、缓效磷库(Ca8-P、Al-P和Fe-P)和难利用磷库(O-P和Ca10-P)含量均显著增加(P≤0.05),Ca10-P相对稳定。有机碳含量与土壤活性磷库(Ca2-P)、缓效磷库(主要为Al-P)的相对含量(占无机磷总量的比例)呈极显著正相关关系,与难利用磷库(主要是Ca10-P)呈极显著负相关关系。土壤Olsen-P含量与难利用磷库含量呈显著正相关关系。【结论】在Olsen-P相近,全磷也基本相似的条件下,土壤有机碳促进了土壤中难溶态磷酸盐向缓效态磷库和活性态磷库的转化,提高了有效磷源占无机磷总量的比例,从而提高了土壤磷素有效性。研究结果表明可通过合理的措施培肥土壤,从而有效地促进土壤累积态磷的活化利用。 相似文献
3.
Integrated tool for microsatellite isolation and validation from the reference genome and their application in the study of breeding turnover in an endangered avian population 下载免费PDF全文
Zhenzhen LIN Josephine D'URBAN‐JACKSON Andrew DIXON Batbayar BOLD Jiliang XU Xiangjiang ZHAN 《Integrative zoology》2018,13(5):553-568
Accurate individual identification is required to estimate survival rates in avian populations. For endangered species, non‐invasive methods of obtaining individual identification, such as using molted feathers as a source of DNA for microsatellite markers, are preferred because of less disturbance, easy sample preparation and high efficiency. With the availability of many avian genomes, a few pipelines isolating genome‐wide microsatellites have been published, but it is still a challenge to isolate microsatellites from the reference genome efficiently. Here, we have developed an integrated tool comprising a bioinformatic pipeline and experimental procedures for microsatellite isolation and validation based on the reference genome. We have identified over 95 000 microsatellite loci and established a system comprising 10 highly polymorphic markers (PIC value: 0.49–0.93, mean: 0.79) for an endangered species, saker falcon (Falco cherrug). These markers (except 1) were successfully amplified in 126 molted feathers, exhibiting high amplification success rates (83.9–99.7%), high quality index (0.90–0.97) and low allelic dropout rates (1–9.5%). To further assess the efficiency of this marker system in a population study, we identified individual sakers using these molted feathers (adult) and 146 plucked feathers (offspring). The use of parent and offspring samples enabled us to infer the genotype of missing samples (N = 28), and all adult genotypes were used to ascertain that breeding turnover is a useful proxy for survival estimation in sakers. Our study presents a cost‐effective tool for microsatellite isolation based on publicly available reference genomes and demonstrates the power of this tool in estimating key parameters of avian population dynamics. 相似文献
4.
冬小麦?夏玉米体系磷效率对塿土磷素肥力的响应 总被引:2,自引:2,他引:0
5.
Characteristics of Soil Phosphorus in Winter Wheat/Summer Maize Cropping in Shaanxi Guanzhong Plain 总被引:1,自引:0,他引:1
LIU Lin JI BingJie LI RuoNan BATBAYAR Javkhlan ZHANG ShuLan YANG XueYun 《中国农业科学》2019,52(21):3878-3889
6.
7.
8.
等有机质 土有效磷和无机磷形态的关系 总被引:4,自引:0,他引:4
目的 在有机质含量相同的土壤上探讨土壤无机磷组分对有效磷的贡献,为合理的磷肥管理提供决策依据。方法 采集并筛选陕西关中平原冬小麦-夏玉米种植区
土有机质含量相近(10.03-10.68 g·kg -1),有效磷含量梯度(平均分别为10.73、18.06、20.61、24.01、30.73、43.69和58.58 mg·kg -1)的土壤样品,采用蒋柏藩-顾益初改进的Chang和Jackson无机磷分级方法进行磷组分测定。 结果 西北冬小麦-夏玉米种植区耕层土壤的无机磷以钙磷为主,约占无机磷总量的66.67%,其中磷酸二钙(Ca2-P),磷酸八钙(Ca8-P)和磷灰石(Ca10-P)分别占2.80%、16.80%和47.09%;铝结合的磷酸盐(Al-P),铁结合的磷酸盐(Fe-P)和闭蓄态磷酸盐(O-P)分别占16.28%、5.23%和11.81%。随着Ca2-P、Ca8-P、Ca10-P、Al-P、Fe-P和O-P含量的增加,Olsen P呈显著线性增加;磷活化系数(土壤有效磷与全磷之比,PAC)与Ca2-P、Ca8-P、Al-P、Fe-P和O-P呈显著线性正相关关系。通径分析结果表明,该区域土壤无机磷对土壤有效磷(Olsen P)的贡献依次为Ca2-P(0.974)>Al-P(0.186)>Ca8-P(0.182)>Fe-P(0.150)>Ca10-P(0.007)>O-P(-0.074),各形态无机磷对磷活化系数(PAC)的贡献为:Ca2-P(0.768)>Al-P(0.082)>Ca8-P(0.071)>Fe-P(-0.018)>Ca10-P(-0.055)>O-P(-0.388),与土壤磷组分对有效磷的贡献大体一致。逐步回归分析结果表明,Ca2-P和Ca8-P对Olsen P贡献最大,但仅Ca2-P对PAC的贡献最大。结论 在有机质相同或相近条件下,Ca2-P是陕西关中平原小麦-玉米种植区
土最有效的磷源。土壤磷有效性的提高主要通过增加高有效性的磷形态比(例如Ca2-P)和缓效磷形态(如Ca8-P、Al-P),降低土壤中有效性极低的Ca10-P的比例来实现的。由此看来,关中平原长期施用磷肥土壤磷仍主要以有效性相对较高的磷素形态存在。 相似文献
9.
Altangerel K Battsetseg B Battur B Sivakumar T Batmagnai E Javkhlan G Tuvshintulga B Igarashi I Matsumoto K Inokuma H Yokoyama N 《Veterinary parasitology》2011,182(2-4):343-348
In the present study, we have surveyed the presence of a bovine Theileria protozoan, Theileria orientalis, in Mongolian cattle and engorging tick populations from selected provinces and districts in Mongolia. The percentages of infection in the cattle and ticks ranged from 8.8 to 66.6 and from 3.7 to 73.3, respectively, on a per district basis. The genetic diversity of T. orientalis isolates was also studied, based on the protozoan gene encoding a major piroplasm surface protein (MPSP). At least five genotypes (types 1, 3, 5, 7, and N-3) of T. orientalis were found to be circulating among the Mongolian cattle and tick populations. In particular, types 3 and N-3 were common in most of the districts examined, while a strong geographical relationship among the genotypes was not detected in the present study. This is the first epidemiological report describing the presence of T. orientalis infection in Mongolian cattle. 相似文献
1