玉米花生间作和磷肥对间作花生光合特性及产量的影响

揭示玉米(Zea mays)和花生(Arachis hypogaea)间作提高花生对弱光利用能力的光合特点及磷(P)肥效应, 对阐明间作花生适应弱光的光合机理和提高间作花生的产量具有重要意义。该试验于2011-2012年在河南科技大学试验农场分析了间作花生功能叶的叶绿素含量与构成、光响应曲线和CO₂响应曲线特点和荧光参数。结果表明: 与单作花生相比, 施P与不施P条件下玉米和花生间作显著(p < 0.01)提高了花生功能叶的叶绿素b含量, 降低了叶绿素a/b, 显著提高了光系统II最大光化学效率(F_v/F_m)、实际光化学效率(Φ_PSII)、光化学猝灭系数(q_P)、表观量子效率(AQY)和弱光时的光合速率, 显著降低了气孔导度、二磷酸核酮糖羧化酶羧化速率(V_cmax)、电子传递速率(J_max)和磷酸丙糖利用速率(TPU); 与不施P相比, 施P有利于提高间作花生功能叶的叶绿素含量, 显著提高了Φ_PSII、q_P、V_cmax、J_max和TPU, 说明间作花生通过提高功能叶的叶绿素b含量, 改变叶绿素构成, 提高了光系统II的F_v/F_m、Φ_PSII和q_P, 增强了对光能的捕获和转化能力, 提高了对弱光的利用能力, 而并非提高了对CO₂的羧化固定能力; 施P有利于提高间作花生对弱光的利用能力和产量, 土地当量比提高了6.2%-9.3%。     

磷肥对花生根系形态、生理特性及产量的影响

采用池栽, 测定不同施磷量对花生(Arachis hypogaea)根系性状、生理特性及产量的影响。结果表明: (1)结荚中期, 根系总长度、体积、表面积及根尖数量均随施磷量的增加而增加, 在施磷30-90 kg·hm^-2范围内, 施磷比不施磷4项指标分别增加3.5%-20.7%、9.3%-21.9%、9.7%-20.3%和12.6%-21.4%。特别是当施磷量超过60 kg·hm^-2时, 上述4项指标均显著高于不施磷处理; 施磷可使根系中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT) 3种酶活性分别提高12.7%-20.6%、14.8%-36.8%和17.0%-41.8%, 丙二醛(MDA)含量降低8.4%-19.5%, 根系活力和可溶性蛋白含量分别提高10.4%-25.0%、29.2%-53.5%; 同时, 施磷可使单株根瘤数量和鲜重分别增加10.7%-21.7%和22.6%-35.6%。(2)收获期, 除MDA含量随施磷量的增加而增加, SOD、POD和CAT活性, 根系活力和可溶性蛋白含量均随施磷量增加而呈降低趋势, 但多数指标施磷与不施磷及不同施磷量之间差异不显著。造成这一现象的原因与施磷后花生荚果库容增大, 对光合产物需求量增加, 导致植株和根系营养不良, 加速衰老有关。(3)花生单株结果数、生物产量、经济系数、出米率及产量均随施磷量的增加而增加, 其中产量的增加主要是通过生物产量和经济系数协同提高来实现的。     

Nonlinear response of nitric oxide fluxes to fertilizer inputs and the impacts of agricultural intensification on tropospheric ozone pollution in Kenya

Crop yields in sub‐Saharan Africa remain stagnant at 1 ton ha^?1, and 260 million people lack access to adequate food resources. Order‐of‐magnitude increases in fertilizer use are seen as a critical step in attaining food security. This increase represents an unprecedented input of nitrogen (N) to African ecosystems and will likely be accompanied by increased soil emissions of nitric oxide (NO). NO is a precursor to tropospheric ozone, an air pollutant and greenhouse gas. Emissions of NO from soils occur primarily during denitrification and nitrification, and N input rates are a key determinant of emission rates. We established experimental maize plots in western Kenya to allow us to quantify the response function relating NO flux to N input rate during the main 2011 and 2012 growing seasons. NO emissions followed a sigmoid response to fertilizer inputs and have emission factors under 1% for the roughly two‐month measurement period in each year, although linear and step relationships could not be excluded in 2011. At fertilization rates above 100 kg N ha^?1, NO emissions increased without a concomitant increase in yields. We used the geos‐chem chemical transport model to evaluate local impacts of increased NO emissions on tropospheric ozone concentrations. Mean 4‐hour afternoon tropospheric ozone concentrations in Western Kenya increased by up to roughly 2.63 ppbv under fertilization rates of 150 kg N ha^?1 or higher. Using AOT40, a metric for assessing crop damage from ozone, we find that the increased ozone concentrations result in an increase in AOT40 exposure of approximately 110 ppbh for inputs of 150 kg N ha^?1 during the March–April–May crop growing season, compared with unfertilized simulations, with negligible impacts on crop productivity. Our results suggest that it may be possible to manage Kenyan agricultural systems for high yields while avoiding substantial impacts on air quality.     

Oxysterol‐binding protein recruitment and activity at the endoplasmic reticulum‐Golgi interface are independent of Sac1

Oxysterol‐binding protein (OSBP) localizes to endoplasmic reticulum (ER)‐Golgi contact sites where it transports cholesterol and phosphatidylinositol 4‐phosphate (PI‐4P), and activates lipid transport and biosynthetic activities. The PI‐4P phosphatase Sac1 cycles between the ER and Golgi apparatus where it potentially regulates OSBP activity. Here we examined whether the ER‐Golgi distribution of endogenous or ectopically expressed Sac1 influences OSBP activity. OSBP and Sac1 co‐localized at apparent ER‐Golgi contact sites in response to 25‐hydroxycholesterol (25OH), cholesterol depletion and p38 MAPK inhibitors. A Sac1 mutant that is unable to exit the ER did not localize with OSBP, suggesting that sterol perturbations cause Sac1 transport to the Golgi apparatus. Ectopic expression of Sac1 in the ER or Golgi apparatus, or Sac1 silencing, did not affect OSBP localization to ER‐Golgi contact sites, OSBP‐dependent activation of sphingomyelin synthesis, or cholesterol esterification in the ER. p38 MAPK inhibition and retention of Sac1 in the Golgi apparatus also caused OSBP phosphorylation and OSBP‐dependent activation of sphingomyelin synthesis at ER‐Golgi contacts. These results demonstrate that Sac1 expression in either the ER or Golgi apparatus has a minimal impact on the PI‐4P that regulates OSBP activity or recruitment to contact sites.      

Orange light‐emitting Ca3Mg3(PO4)4:Sm3+ phosphors

This work reports the photoluminescence properties of Ca₃Mg₃(PO₄)₄:Sm³⁺ phosphors that were synthesized by the combustion method. The phase formation and morphology of the prepared phosphors were analysed by X‐ray diffraction studies and scanning electron microscopy. Ca₃Mg₃(PO₄)₄:Sm³⁺ phosphors give orange light emission when excited by near‐ultraviolet (NUV) and blue light. The photoluminescence characteristics of the as‐prepared phosphors were investigated and their emission spectra showed three peaks due to ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 transitions. The mechanism responsible for the concentration quenching of luminescence was found to be an electric dipole–dipole interaction. The CIE chromaticity coordinates suggested that the prepared phosphors are potential candidates for orange light‐emitting diodes (LEDs).     

The Detoxification of Heavy Metals in the Phosphate Tailing-contaminated Soil through Sequential Microbial Pretreatment and Electrokinetic Remediation

In this paper, the heavy metals (HMs) in the phosphate tailing-contaminated soil were detoxified using the microbial pretreatment in combination with electrokinetic remediation (EKR).. This study provides compelling evidence that the sequential usage of the bioleaching and electrokinetics is superior to the individual method for the detoxification of Pb, Cu, Zn, Cd, and As from the contaminated soil. In the sequential system, the detoxification efficiency of Zn was the highest and that of As was the lowest. Except the element As, the detoxification efficiencies of HMs in the sequential system were generally higher than that using the single biological treatment and EKR technique. Bioleaching, generation of the passivation, and migration direction of the ions are concluded as the factors attributable to the final results; and, the initial increase in the inoculation doping of Thiobacillus ferrooxidans considered has no obvious impact on improving the final detoxification efficiency rates.     

水稻土模拟土柱中肥料氮素的迁移转化特征

为了明确肥料氮素在模拟土柱中的迁移转化特征,通过布置室内模拟土柱试验,研究了3倍常规施肥水平下（360 mg·kg^-1）水稻土中矿质氮的变化.结果表明： 不同处理、不同土层间NH₄⁺-N和NO₃^--N含量差异显著.不施肥对照在整个培养期间养分含量变化不大,不同土层间亦没有显著性差异.施用尿素和硫铵后,土壤NH₄⁺-N和NO₃^--N含量显著提高,尤其是0～50 mm土层内,分别达到186.0～2882.1 mg·kg^-1和268.7～351.5 mg·kg^-1,分别相当于对照的4.8～242倍和5.7～316倍,50 mm以下各土层与对照处理相似,表明肥料氮素的迁移转化主要发生在0～50 mm土层内,并且在培养的前14 d变化最大.整个培养期间不同土层内,硫铵处理不同矿质态氮含量是尿素处理的0.7～2.0倍,硝化率是尿素处理的0.9～1.4倍,表明硫铵在水稻土中的转化效率略高于尿素.     

施氮水平和收获时期对夏玉米产量和籽粒品质的影响

为明确黄淮海夏玉米适宜的施肥量和最佳收获时期,设计了5个氮肥水平（不施肥、113、181、249和375 kg N·hm^-2）和2个收获时期（S₁：9月23日,农民习惯收获时间;S₂：9月29日,推迟6 d收获）,研究施氮量和收获时期对夏玉米产量和品质的影响.结果表明：随施肥量增加,夏玉米穗粒数、千粒重和产量均增加,但差异不显著,其中施肥量在113～181 kg N·hm^-2的玉米产量、氮素利用效率均相对较高;随施肥量增加,夏玉米蛋白质和赖氨酸含量增加,淀粉含量降低.与9月23日蜡熟期收获相比,9月29日完熟期收获的夏玉米籽粒千粒重、产量、淀粉和赖氨酸含量均增加,籽粒蛋白质和脂肪含量降低.依据产量水平,黄淮海高产夏玉米区适宜的施肥量在113～180 kg N·hm^-2,最佳收获时期应推迟至9月29日-10月5日.