Phosphorus–microbes interaction on growth,yield and phosphorus-use efficiency of irrigated cotton

The phosphorus-use efficiency of crops in high pH soil is low. A randomized complete block design in a 3 × 2 split-plot experiment was conducted on a high pH silt loam (Typic Ustochrepts) to evaluate whether P-solubilizing microbial (PSM) inocula were able to improve the P fertilization effects on irrigated cotton (Gossypium hirsutum L., cultivar CIM-482). Cotton was planted after seed treatment with PSM inoculation at 0, 22 and 44 kg P ha^?1. Results showed that soil microbial populations were significantly higher throughout the cotton-growing season in response to P fertilization and PSM inoculation. Both P fertilization and PSM inocula exerted a significant effect on cotton biomass and Puptake without an interaction. Economic analyses suggest that PSM inocula alone significantly increased P-use efficiency (8%), reduced cost and improved net income (by $36 ha^?1) of irrigated cotton production. Moreover, the relationship between relative yield and P fertilization with PSM inocula showed that 95% of the maximum yield of cotton was produced at 22 kg P ha^?1, whereas in the absence of PSM inocula, 95% relative yield was obtained at 36 kg P ha^?1, asaving of ～39% applied P with PSM inoculation.     

基于倾向值匹配方法的土地督察制度的耕地保护效应研究

[目的]评估土地督察对耕地保护的效果以及解决样本选择带来的内生性问题,进一步完善土地督察制度提供理论支持。[方法]收集1999—2008年的省级面板数据,基于倾向值匹配分析估计土地督察的耕地保护效果。[结果](1)通过匹配变量的平衡性检验,最终采用了内核匹配方法。运用内核匹配法进行匹配估算,专项督察每年减少建设占用耕地面积8 037.489hm~2,例行督察每年减少建设占用耕地面积62 741.880hm~2。(2)专项督查地区的选择并非随机产生的,由此产生了样本选择偏误,即由于样本选择产生的内生性问题,采用倾向值匹配方法能够更为准确地估算专项督查的耕地保护效果。(3)例行督察对地区的选择相对专项督查而言,随机性更强,督察也更为全面,因此样本选择偏误也较小。以被督察地区面积比重表达政策变量方式估计得到的例行督查耕地保护效果要比倾向值匹配方法估计得到的结果更为可靠。[结论]例行督察的耕地保护效果较好。在土地政策评估中,需要考虑政策及其对象的相互关系的不同,以此考虑政策效果评估方法的选择。     

农户林权抵押贷款的收入效应及其差异性研究

林权抵押贷款能够有效缓解农户信贷约束，对实现林业可持续经营具有重要意义。以南方集体林区为例，利用福建、湖南和江西3省农户调研数据，采用倾向得分匹配法（PSM），分析集体林区农户林权抵押贷款的收入效应，探讨不同结构视角下的收入效应差异性。结果表明，样本农户中，获得林权抵押贷款农户占比较低，仅为11.81%；且获得林权抵押贷款农户与未获得林权抵押贷款农户在收入水平、农户基本特征和林地资源禀赋等方面存在显著差异。在未考虑农户差异的情况下，林权抵押贷款可以显著增加农户收入水平，且获得林权抵押贷款农户总收入均值明显增加1.74万元。林权抵押贷款具有正向收入效应，但不同收入结构和农户结构下林权抵押贷款的增收效应存在差异。从收入结构来看，林权抵押贷款仅增加农户总收入和林业收入，而对非林收入不显著；从农户结构来看，林权抵押贷款仅对劳动力资源配置占比25%~50%、中高收入水平和大规模经营农户显著。因此，建议进一步创新金融服务方式，探索林权抵押贷款多元运行机制，建立基于农户结构差异化的信贷产品设计。     

无机解磷菌的分离鉴定及解磷条件优化

解磷菌对于提高土壤磷元素的有效利用具有促进作用,而且对于土壤面源污染的防治也具有重要意义.通过对包头地区草坪土壤微生物的筛选,获得3株具有稳定解磷能力的解磷菌P1、P2和P3,其中P1的解磷效果最佳;复合菌群组合试验结果表明,不同组合的解磷能力依次为P1:P3＜P1:P2＜P1:P2:P3＜P2:P3,证实P1具有高效的解磷能力;分子鉴定结果表明,P1是伯克霍尔德氏菌(Burkholderia sp.),说明该菌具有较大的应用价值.     

植物根际解磷菌的研究进展

从植物根际分离具有固氮、溶磷、产生植物激素及分泌抗生素等功能的溶磷菌株研究成为微生物学研究及生物-生态肥料开发的一个重要领域和热点。介绍了溶磷菌的数量、特征、主要种类、溶磷机理、测定方法以及溶磷菌在农牧业中的应用现状,同时对其研究及应用中存在的问题和发展前景作了简评。     

劳动力流动、农地流转对农户收入的影响

在乡村振兴战略的背景下,鼓励农民从事非农就业,促使农民积极参与到农地流转市场中,对于提高农民收入,实现全面建成小康社会的目标具有重要意义。利用中国家庭收入调查数据库,运用分位数回归法和倾向得分匹配(PSM)模型,分析劳动力流动和农地流转的动态关系,探讨劳动力流动与农地流转动态关系对农户收入的影响。结果表明,样本农户中,相较于74.15%未进行农地流转的农户,25.85%进行农地流转农户的家庭可支配收入提高0.46万元;农地转出户的劳动力流动时间高出农地未流转户1.3倍,使其家庭可支配收入比农地未流转户提高0.70万元。另外,增加劳动力流动时间更有利于提升低收入农户的家庭可支配收入;进行农地流转也有利于提高农户家庭可支配收入,并且农地转出户比农地转入户的提高幅度更大。劳动力流动与农地流转动态关系程度越高,相较于西部地区更有利于提升东部和中部地区农户的家庭可支配收入。因此,建议不断加强对农民的投资和培训,完善农地流转市场的运行机制,实行有区域差别的农业政策,以保证有针对性地提高农民收入。     

利用PSM和G-5标记鉴定水稻对稻瘿蚊的抗性

利用广东省农科院等筛选的与Gm6基因连锁的PSM和G-5两个标记,以抗蚊青占、桂99、抗15-1、抗15-2、抗15-3、抗15-4、抗8、抗14、淦恢3号-169、淦恢3号和淦恢G398为试验材料,对Gm6基因进行检测。结果表明:抗15-1、抗15-2、抗15-3、抗15-4、抗8、抗14和淦恢3号-169、淦恢3号均含有Gm6基因,桂99和淦恢G398则不含Gm6基因。     

农地流转对劳动力资源利用效率的影响研究——基于阿瓦提县的调研分析

运用PSM模型,以实地调研数据研究农地流转对劳动力资源利用效率的影响。转入农地农户比未流转农地农户的农业劳动力资源利用效率和总劳动力资源利用效率分别高2 930.879元/人和2 547.636元/人,但转入农地农户的非农业劳动力资源利用效率比未流转农地农户的低6 701.481元/人;转出农地农户比未流转农地农户的非农业劳动力资源利用效率和总劳动力资源利用效率分别高2 982.759元/人和1 867.057元/人,但转出农地农户的农业劳动力资源利用效率比未流转农地农户的低1 431.492元/人。创新承包地流转政策的宣传方式,加大对承包地流转政策的宣传;拓宽非农就业渠道,提高非农就业收入;加大对农机补贴的力度。     

Phosphate solubilizing microorganisms isolated from rhizosphere of maize cultivated in an oxisol of the Brazilian Cerrado Biome

Many soil microorganisms are able to transform insoluble forms of phosphorus to an accessible soluble form, contributing to plant nutrition as plant growth-promoting microorganisms (PGPM). The objective of this work was to isolate, screen and evaluate the phosphate solubilization activity of microorganisms in maize rhizosphere soil to manage soil microbial communities and to select potential microbial inoculants. Forty-five of the best isolates from 371 colonies were isolated from rhizosphere soil of maize grown in an oxisol of the Cerrado Biome with P deficiency. These microorganisms were selected based on the solubilization efficiency of inorganic and organic phosphate sources in a modified Pikovskaya's liquid medium culture containing sodium phytate (phytic acid), soybean lecithin, aluminum phosphate (AlPO₄), and tricalcium phosphate (Ca₃(PO₄)₂). The isolates were identified based on nucleotide sequence data from the 16S ribosomal DNA (rDNA) for bacteria and actinobacteria and internal transcribed spacer (ITS) rDNA for fungi. Bacteria produced the greatest solubilization in medium containing tricalcium phosphate. Strains B17 and B5, identified as Bacillus sp. and Burkholderia sp., respectively, were the most effective, mobilizing 67% and 58.5% of the total P (Ca₃(PO₄)₂) after 10 days, and were isolated from the rhizosphere of the P efficient L3 maize genotype, under P stress. The fungal population was the most effective in solubilizing P sources of aluminum, phytate, and lecithin. A greater diversity of P-solubilizing microorganisms was observed in the rhizosphere of the P efficient maize genotypes suggesting that the P efficiency in these cultivars may be related to the potential to enhance microbial interactions of P-solubilizing microorganisms.     

瑞利衰落信道下认知无线电脉冲波形调制技术研究

提出一种用于瑞利衰落信道的认知无线电脉冲波形调制(PSM)方案。该方案采用多小波包滤波器组来构造正交脉冲,允许时域和频域的重叠,具有较高的灵活性和频带利用率,并可利用频率分集来提高抗衰落性能。仿真结果表明,基于多小波包的PSM方案不仅符合FCC模板的要求,而且具有比单小波方案更高的抗衰落性能。