喷施山梨醇螯合钙对花生生长及钾、钙、镁吸收的影响

为探究不同山梨醇螯合钙喷施浓度对花生生长及养分吸收的影响,采用大田试验,以花育22号为试材,在施基肥基础上设置5个钙素喷施浓度处理(以Ca²⁺计,单位g/L):0 (CK)、1.4 (T1)、1.6 (T2)、1.8 (T3)与2.0 (T4),测定了各处理对花生光合作用、收获期产量、品质、各器官干物质积累量及钾、钙、镁含量的影响。结果表明：(1)与CK处理相比,喷施山梨醇螯合钙提高了叶片SPAD值,促进了花生光合作用,尤其在结荚期;(2)喷施山梨醇螯合钙能提高花生产量及粗脂肪、粗蛋白含量,其中T2处理较CK处理分别提高11.48%、5.74%、7.82%;(3)喷施山梨醇螯合钙能够显著增加籽仁干物质积累量,有效提高花生生殖器官干物质占比,降低营养器官干物质分配比例,以T3处理改善效果较为突出,其次是T2处理;(4)喷施山梨醇螯合钙对花生各器官钾、钙、镁含量的影响不同,但总体上促进了花生对养分的吸收。主成分分析结果表明,喷施山梨醇螯合钙显著影响了花生生长发育。综合来看,喷施Ca²⁺浓度为1.6～1.8 g/L的山梨醇螯合钙对花生增产提质效果更...     

坡度对降雨径流挟沙能力影响的模拟试验

高陡边坡降雨径流侵蚀输移能力是一个重要的科学问题。通过室内模拟降雨试验研究相同雨强不同坡度和坡长条件下的降雨径流侵蚀输移规律。结果表明：(1)试验条件下,水深与水力坡度的1/3次方呈负相关,与坡长的3/5次方呈正相关,流速与水力坡度和水深呈幂函数增加;(2)相同雨强裸坡条件下,径流含沙量与水力坡度的1/2次方呈正相关,与坡长的4/5次方呈正相关。水流挟沙能力约与水力坡度的1/2次方呈正相关。(3)降雨径流的水流紊动扩散作用与重力作用的比值较明渠水流偏大,表明雨滴打击的紊动作用较明显,给出挟沙能力公式。与常用的河流泥沙挟沙能力公式比较,系数偏大,指数偏小。研究成果对深入分析降雨径流侵蚀输移的机制具有重要意义。     

Considering sink strength to model crop production under elevated atmospheric CO2

Climatic changes and elevated atmospheric CO₂ concentrations will affect crop growth and production in the near future. Rising CO₂ concentration is a novel environmental aspect that should be considered when projections for future agricultural productivity are made. In addition to a reducing effect on stomatal conductance and crop transpiration, elevated CO₂ concentration can stimulate crop production. The magnitude of this stimulatory effect (‘CO₂ fertilization’) is subject of discussion. In this study, different calculation procedures of the generic crop model AquaCrop based on a foregoing theoretical framework and a meta-analysis of field responses, respectively, were evaluated against experimental data of free air CO₂ enrichment (FACE) environments. A flexible response of the water productivity parameter of the model to CO₂ concentration was introduced as the best option to consider crop sink strength and responsiveness to CO₂. By varying the response factor, differences in crop sink capacity and trends in breeding and management, which alter crop responsiveness, can be addressed. Projections of maize (Zea mays L.) and potato (Solanum tuberosum L.) production reflecting the differences in responsiveness were simulated for future time horizons when elevated CO₂ concentrations and climatic changes are expected. Variation in future yield potential associated with sink strength could be as high as 27% of the total production. Thus, taking into account crop sink strength and variation in responsiveness is equally relevant to considering climatic changes and elevated CO₂ concentration when assessing future crop production. Indicative values representing the crop responsiveness to elevated CO₂ concentration were proposed for all crops currently available in the database of AquaCrop as a first step in reducing part of the uncertainty involved in modeling future agricultural production.     

硒的价态与浓度水平对6种植物种子发芽和根际生长的影响

本文研究了硒的价态（Se6＋和Se4＋）和浓度水平（0～100mgSe·L-1）对6种植物（大麦、小麦、花椰菜、萝卜、苜蓿和欧芹）种子萌发和根际生长特性的影响。结果表明,低浓度硒（〈1mgSe·L-1）对种子发芽促进作用不明显,而高浓度硒（〉4mgSe·L-1）则有显著抑制作用,不同种子对硒的抗性表现不同。根长和芽长的测定结果表明,低浓度对花椰菜和小麦种子生长具有显著促进作用,对欧芹种子表现出抑制作用。较高浓度（1～4mg·L-1）即对花椰菜、苜蓿和欧芹的根生长表现出抑制作用,高浓度对小麦、大麦和萝卜根生长有抑制作用,且使芽生长受到抑制的硒浓度高于根生长。比较价态,低硒时六价对花椰菜生长的促进作用显著高于四价,高硒时小麦和苜蓿对硒的抗性表现为六价硒强于四价硒,其余科属差异不显著。不同科属对硒的抗性为禾本科小麦和大麦最强,十字花科花椰菜和萝卜次之,豆科苜蓿较差,伞形科欧芹最差。     

Nitrogen Uptake and Use Efficiency in Upland Rice under Two Nitrogen Sources

Upland rice is an important crop in South America, including Brazil. Nitrogen (N) is one of the most yield-limiting nutrients in upland rice production in Brazil. A greenhouse experiment was conducted to evaluate N uptake and use efficiency as influenced by N sources. The soil used in the experiment was an Oxisol. The N sources were ammonium sulfate and urea, and N rates were 0, 50, 100, 150, 300, and 400 mg kg^?1 of soil. Nitrogen concentrations in the root, shoot, and grain were significantly influenced by N sources. The N rate and N source significantly influenced the N uptake in root, shoot, and grain. Similarly, nitrogen rate by N source interaction was also significant for N uptake in the root, shoot, and grain, indicating N source has a significant influence on uptake of N. Overall, concentration (content per unit dry weight) of N was greater in the grain, followed by root and shoot. Agronomical efficiency, apparent recovery efficiency, and utilization efficiency of N were significantly influenced by N rate and varied with N sources. However, physiological and agrophysiological efficiencies were only influenced significantly by N sources. Overall, N recovery efficiency was 33% for ammonium sulfate and 37% for urea. Hence, the large amount of N lost from soil–plant system may be by denitrification or voltilization.     

Influence of total soluble salt concentration on growth and elemental concentration of winged bean seedlings,Psophocarpus tetragonolobus (L.) DC.

Abstract

Winged bean (Psophocarpus tetragonolobus) (L.) DC) seedlings of the accession TPT‐1, were grown in a greenhouse with graded, balanced total soluble salt (TSS) concentrations. After 4.5 days, plant height increased quadratically, with a maximum (149 cm) at 3000 ppm TSS. Seedlings were shortest at 1000 and 10,000 ppm TSS, 44.0 and 79.0 cm, respectively. Fresh weight of shoots increased quadratically with greatest weight, 29.03 g, at 5000 ppm TSS. Percent dry matter increased linearly with increasing TSS. Concentration of N, K and P increased quadratically with an increase in the TSS concentration in the growth medium. Concentration of Ca decreased quadratically with increasing TSS. Among the micronutrients, Fe and Mo concentration was quadratic, both elements were highest in the seedlings at 1000 and 10,000 ppm TSS rates. Concentrations of Mn and Zn increased linearly with increasing TSS. Winged bean seedlings at the 1000 to 3000 ppm TSS rates had spindly stems and a sparse, yellow foliage, typical for winged bean seedlings observed in the field during the first 4 to 5 weeks of growth. Seedlings at the 4000 and 5000 ppm TSS rates had sturdy stems and an abundant green foliage. At higher TSS concentrations, 5000 to 10,000 ppm TSS, seedlings had short intermodes and dark green foliage.     

水稻拔节期根系呼吸对臭氧污染和厌氧—有氧环境变化的响应

依托O3FACE(Free-Air O3 Enrichment)研究平台,研究了大气臭氧(O3)浓度增加对拔节期水稻根系呼吸和生物量积累分配的影响,利用特制集气装置分析了厌氧—有氧条件对根系呼吸的影响。结果表明,O3浓度升高水稻冠层和总生物量略有降低,而根干物重和根/冠比分别显著降低14.7%和10.4%。9∶1和9.5∶0.5的纯N2∶O2配比利于根系呼吸,纯N2或空气、CO2饱和蒸馏水条件不同程度降低了根系呼吸速率;高臭氧处理、对照处理的水稻根系呼吸速率分别在CO2饱和蒸馏水、纯N2条件下最小,表明尽管不同根系测定条件影响根系呼吸速率,但影响程度也受植物生长的大气环境制约。臭氧污染处理水稻根系的呼吸速率在气态测定条件下显著高于正常大气处理23.6%～52.7%,在CO2饱和蒸馏水测定条件下未达到显著水平,臭氧污染效应明显降低。两个环境生长的水稻根系呼吸均随测定根系气态环境供氧量的增加呈凸二次函数变化,5%～10%比例的氧气供应促进了根系呼吸,较强的厌氧环境(纯N2)和有氧环境(Air)均不利于水稻根系呼吸。     

CO2浓度升高对毛竹和四季竹叶片主要养分化学计量特征的影响

运用开顶式气室(OTCs)模拟大气CO2浓度升高(500、700 μmol/mol),以目前环境背景大气为对照,研究CO2浓度升高对毛竹和四季竹叶片碳(C)、氮(N)、磷(P)和钾(K)化学计量特征的影响.结果表明,毛竹和四季竹叶片C、N、P和K含量在不同的CO2浓度(对照、500、700 μmol/mol)条件下,变化范围分别为512.13～543.30、19.23～22.97、1.26～0.96和8.40～5.88 mg/g,492.13～498.02、17.97～15.37、1.05 ～0.81和4.25～5.62mg/g.相同的CO2浓度条件下,毛竹叶片C、N、P和K含量均高于四季竹,且受CO2浓度升高的影响较四季竹强烈.毛竹和四季竹叶片C/N、C/P、C/K、N/P、N/K和K/P变化范围分别依次为26.64～23.65、406.58～565.93、60.98～92.40、15.26～23.93、2.29～3.91和7.00～6.22,27.39～32.40、468.70～614.84、115.80～88.61、17.07～18.98、4.24～2.73和4.04～6.94.与环境背景大气比较,CO2浓度升高到500 μmol/mol,对毛竹和四季竹叶片C、N、P和K含量及其化学计量比并不会产生明显影响,这反映了毛竹和四季竹对高CO2浓度环境均表现出较强的适应能力.但CO2浓度升高到700 μ mol/mol,除四季竹叶片C含量无明显变化外,毛竹和四季竹叶片主要养分元素含量及其化学计量比会发生明显的适应性变化,且毛竹较四季竹变化剧烈.综上,CO2浓度升高改变了毛竹和四季竹叶片C、N、P、K含量及其化学计量比格局,尤其是CO2浓度升高到700 μmol/mol时极为明显;在养分供应上,对四季竹生长的N、P、K限制性作用和毛竹生长的N、K限制性作用没有明显影响,但明显增强了毛竹生长的P素限制性作用.     

背角无齿蚌组织中的元素分布研究

利用Agilent7500ce型电感耦合等离子质谱仪研究了18种元素（Na、Mg、K、Ca、Zn、Mn、Fe、Al、Cu、Cr、Co、Ni、As、Se、Mo、Ag、Tl、Pb）在背角无齿蚌5种组织（外套膜、闭壳肌、足、鳃和内脏团）中的分布特征。结果表明,总体上鳃中元素的浓度最高,内脏团和外套膜次之,足和闭壳肌中较低。Ca、Mn、Mg、Zn、Al、Cu、Ni、As和Se9种元素浓度均在鳃中最高,Na在外套膜中浓度最高,K在足中浓度最高,Fe和Pb在内脏团中浓度最高。元素负荷量的绝大部分存在于重量较大的鳃和内脏团中,但近50%的Na却积累于外套膜、闭壳肌和足中。背角无齿蚌不同组织或器官对元素的积累具有明显的选择性。     

半透膜微萃取方法的建立及其在测定土壤间隙水中憎水性有机污染物的应用

提出了一种新型的基于半透膜被动采样技术的微萃取方法（semi-permeable membrane based micro-extraction, SPM-ME）,并以菲为模型污染物,测试了SPM-ME用于测定土壤间隙水中自由溶解态憎水性有机污染物的可行性。结果表明,菲在该SPE-ME装置与水相间的平衡可在6 h内达到,并且随着装置中三油酸甘油酯含量的增加,单元SPE-ME对于菲的富集系数也相应增加。该装置对土壤间隙水中菲的富集在10 d内能达到平衡,整个过程主要受菲从土壤向间隙水的传质控制。该装置测得间隙水中菲的浓度与实际测得间隙水浓度十分吻合,而由传统的相平衡分配法计算所得间隙水浓度则高出实测值4-5倍。同时,该装置对体系中污染物的耗竭小于体系中污染物总量的1%。因此,SPE-ME是一种准确、有效、非耗竭式的微萃取技术。