施用生物黑炭对新疆灰漠土肥力与玉米生长的影响

通过田间小区对比试验,研究生物黑炭作为改良剂与堆肥等其他生物质改良剂相比对新疆低产土壤——灰漠土的改良和玉米增产的效果。结果表明,施入20t·hm^-2和40t·hm^-2的生物黑炭,能显著提高土壤有机质含量,与基础土壤相比,提高了22．77％和49．80％,明显高于秸秆还田、羊粪和腐植酸有机肥等对土壤有机质的提升效果。施用生物黑炭提高了玉米单穗重、千粒重、产量以及生物量,降低了玉米的根冠比,促进玉米根系生长,而追施氮肥对玉米产量的影响差异不显著。因此,施用生物黑炭能够大幅度提高土壤有机质含量,对灰漠土土壤质量和作物产量以及农艺性状的提高具有重要作用。     

施氮水平对甘蔗氮素吸收与利用的影响

以新台糖22号(ROC22)为试材,设15N标记尿素2.5、5.0和7.5g/盆(相当于225、450和675kg/hm2)3个处理,采用网室盆栽试验方式,研究施氮水平对甘蔗氮素吸收与利用的影响。结果表明:甘蔗吸收的氮素17.27%～27.28%来自施用的氮肥,72.72%～82.73%来自土壤和种茎;甘蔗氮肥利用率为34.21%～42.46%。随施氮水平提高,甘蔗干物质积累、氮素积累及来源于肥料氮素的比率显著增加,同时蔗叶对氮素的吸收利用呈上升趋势,但蔗茎对氮素的吸收利用呈下降趋势,氮肥利用率也显著下降。土壤碱解氮和硝态氮在各土层中的含量随施氮水平的提高而增加,且两者在0～20cm土层的积累明显大于20～40cm土层。本试验条件下,甘蔗氮肥施用为尿素5.0g/盆(相当于450kg/hm2)及土层深度为20cm较为适宜。     

REDUCING NITRATE CONTENT IN LETTUCE BY PRE-HARVEST CONTINUOUS LIGHT DELIVERED BY RED AND BLUE LIGHT-EMITTING DIODES

Effect of pre-harvest continuous light with different red/blue ratio on photon flux density (R/B ratio) on reducing nitrate accumulation was studied by growing lettuce (Lactuca sativa L.) under continuous illumination delivered by light-emitting diodes (LEDs). Results show that nitrate concentration decreased by 1648.0–2061.1 mg kg^?1 in leaf blade and 962.9–2090.3 mg kg^?1 in petiole, accompanied by a dramatic increase in soluble sugar content. Compared with monochromatic red light treatment, the decrease in nitrate concentration and increase in soluble sugar content in lettuce under mixed red and blue light were more pronounced. The lowest nitrate concentration was observed in the treatment with R/B ratio of 4. It's concluded that pre-harvest exposure to 48?h continuous LED light could effectively reduce nitrate accumulation in lettuce and this process is strongly affected by R/B ratio of light. This study may provide new perspective for pre-harvest quality management of vegetable, especially in commercial leaf vegetable production under artificial lighting.     

Effect of phosphorus fertilizer application on the performance of maize/soybean intercrop in the southern Guinea savanna of Nigeria

Field experiments were conducted at the Teaching and Research Farm, Ladoke Akintola University of Technology, Ogbomoso, Nigeria in 2007 and 2008 to determine the effects of phosphorus fertilizer application on performance of intercropped maize and soybean. The experiments, arranged as a split plot in a randomized complete block design, replicated four times. A cropping system with sole maize, sole soybean and maize/soybean intercrop formed the main plot treatments while P rates with 0, 15 and 30 kg P₂O₅ ha^?1 were the subplot treatments. For both years, neither P fertilizer application nor cropping systems had a significant effect on maize grain yield. However, soybean grain yield was significantly higher (92.3% in 2007 and 44.5% in 2008) under sole cropping than under maize/soybean intercropping. On average, N fixed by soybean increased with the increase in P rate (from 51.8% without P to 60.5% with 30 P), but there was no significant difference in N fixed by sole soybean and soybean/maize intercrop. However, the interaction effect on N fixed between cropping systems and P rates was significant (P ≤ 0.05). N, P and K contents in maize grain were significantly higher (>100%) in intercropped maize than in sole maize. The cropping systems had no significant effect on post-harvest soil chemical characteristics. The land equivalent ratio was 1.52 in 2007 and 1.78 in 2008. The result shows that in utilizing legumes for N enrichment, the alleviation of P deficiency can enhance N₂-fixation by legumes. Furthermore, P replenishment in a maize/soybean intercrop may improve maize grain quality even though yield is not increased.     

玉米生长后期的根系分布研究

为了研究玉米生长后期根系的生长发育规律,利用中国气象局固城农业气象试验站大型根剖面系统,采用微根管观测系统及方形整段标本法和地下根系室玻璃窗,对‘屯玉46号’玉米根系的生长状况进行了试验研究。结果表明:垂直方向上,方形整段标本法和微根管法测得的根长密度占整层总根长密度比例的变化趋势一致,相关系数分别为0.987和0.717,且两种方法在0~20 cm土层的根长密度比例均为最大。0~60 cm土层为玉米根系生长活跃区,方形整段标本法测得根长密度生长量为其余层的4倍。两种方法测得的根长密度无显著差异,相关系数为0.830,均匀性水平较好。玉米成熟期根系的水平幅度较乳熟期窄,下层根系仍处于生长中,垂直深度增加。玻璃窗与方形整段标本法观测的根深测定结果存在差异,这可能与观测环境条件不一致有关。     

Influence of Rooting Media on Chrysopogon Zizanioides (L.) Roberty

The present study was carried out to find the influence of some organic materials on the optimum biomass production of Chrysopogon zizanioides (L.) Roberty (Vetiver) using soil (S), vermicompost (VC), cow dung (CD) and coir pith (CP) at different ratios. The final day results showed that the ideal combination for the growth of the Vetiver is 1:1:1:1 v/v ratio of VC/CD/CP/S. The pH, electrical conductivity (EC), nitrogen (N)- phosphorus (P)- potassium (K), organic carbon (OC), and carbon (C)/N ratio showed in 1:1:1:1 v/v ratio of (VC/CD/CP/S), on 120th day were 7.3, 0.38 dS m^?1, 1.36%, 0.11%, 8.7%, 20.5% and C/N ratio is 15:1. The root and shoot length, fresh weight, dry weight, number of culms, and total chlorophyll content of Chrysopogon zizanioides were 65cm, 197 cm, 312 g, 104.4 g, 36 culms/plant and 40.57 mg/g at 1:1:1:1 v/v ratio of (VC/CD/CP/S) treatment and compared to control sets, the increasing ratio were 6:1, 3:1, 12:1, 12:1, 3:1, 2:1 respectively.     

基于膨胀比的自由活塞发动机理想热力循环分析

为提高传统发动机的热效率,降低燃料消耗成本,减少尾气排放,该文建立了基于增压中冷和Atkinson循环的四冲程自由活塞发动机理想热力循环模型,着重分析了膨胀比对自由活塞发动机热力过程的影响,提出了膨胀极限的概念,通过数值模拟方法对膨胀比与发动机热效率关系进行了仿真研究和试验验证,结果表明,通过增大膨胀比可使发动机的热效率提高10%;膨胀终了温度降低500K以上。研究结果可为自由活塞发动机在混合动力车辆上的应用提供参考。     

CO2浓度升高和施氮对冬小麦光合面积及粒叶比的影响

利用开顶式气室和盆栽方法, 以冬小麦品种"小偃6号"和"小偃22"为供试材料, 在2种CO₂浓度(375 μL·L^-1和750 μL·L^-1)和3个施氮水平[0、0.15 g(N)·kg^-1(土)和0.30 g(N)·kg ^-1(土)]下分析了小麦抽穗期绿色叶片、非叶光合器官(茎鞘、穗、芒)的形态和光合面积以及粒叶比对CO₂浓度升高和施氮的反应。结果表明, 施氮有助于小麦叶和非叶光合器官伸长和增宽(粗), 增加其光合面积、穗粒数、穗粒重、粒数叶比和粒重叶比。与背景CO₂浓度(375 μL·L^-1)相比, CO₂浓度升高对叶片和茎节长度、茎叶和芒光合面积具有明显的正向效应(P<0.05), 但对叶宽、茎节直径、穗面积影响不明显(P>0.05), 使"小偃6号"和"小偃22"单茎光合面积分别增加8.1%~15.1%和2.8%~13.2%, 且均以0.30 g(N)·kg^-1(土)施氮水平下增幅最大。CO₂浓度升高后, 穗粒数和粒数叶比在3个施氮水平下均不同程度增加, 其中2个品种粒数叶比分别在0.30 g(N)·kg^-1(土)和0.15 g(N)·kg^-1(土)施氮水平下增加最明显, 增幅分别为44.2%和41.4%; 穗粒重和粒重叶比在不施氮时下降, 在施氮时显著增加, 其中2个品种粒重叶比平均增幅分别为43.6%和20.7%。由于芒面积远小于其他源器官面积, 在单茎光合面积中所占比例较小(3%左右), 因此认为CO₂浓度升高主要通过促进小麦茎叶伸长生长来增加光合面积, 同时提高单位叶面积库承载力和物质调运能力, 改善源库关系, 增加氮素供应有利于小麦源库生长对CO₂浓度升高的反应。     

中子仪测定砂性土壤水分的标定与测试参数的界定分析

以科尔沁沙地6个砂性土壤试验点为研究对象,实施中子水分仪测试土壤水分的标定试验,采用点聚图筛选和三点平滑处理土壤体积含水率数据,选用线性标定和非线性标定2种形式,系统分析中子仪计数时间、中子管安装稳定时间以及降雨、灌水等提高土壤含水率的方法对标定结果的影响,以界定中子仪的测试参数,经模拟与验证,确定砂性土壤的中子仪标定方程。结果表明：砂性土壤0-30cm表土采用二项式标定效果相对较好;砂土土质对中子仪读数影响较小,两种不同含水率的土壤可以统一标定;中子管安装稳定时间至少需7d,尤以经历一、两场较大降雨后进行标定其试验误差较小;标定和测量实施过程中,中子仪计数时间宜选用64s,再适当加大计数时间也能得到较好结果;在较大降雨和干旱两种状态下,选用64s中子仪计数时间进行测量,可得到砂性土壤测量水分范围为1.01%～29.92%且精度较高的标定方程。验证结果表明,中子仪测量结果能反映实际土壤含水量的分布状况,标定方程精度可满足实际测试要求。     

黄土高原肥水坑施技术下苹果树根系及土壤水分布

为了解黄土丘陵区雨养条件下山地老果园布设肥水坑(water-wertilizer pit,WFP)技术对红富士老果树(Malus pumila Mill)根系及土壤水分空间分布特征的影响,以无肥水坑处理为对照(CK),利用管式TDR系统监测0~300 cm土层土壤含水率,利用根钻法获得21a生旱地果园0~300 cm土层的根系干质量密度。结果表明:WFP能够显著增加果园含水率低值区间(≥40~80 cm土层)土壤含水率,WFP60(60 cm坑深)处理土壤平均含水率增量(145.4%)最显著。WFP40(40 cm坑深)根际土壤湿润区主要集中在≥40~100cm土层,WFP60在≥20~140 cm土层,WFP80(80 cm坑深)主要集中在深层土壤≥140 cm土层。在0~200cm试验土层,WFP60处理土壤多次平均含水率值都最高,为11.02%,依次为WFP40(10.67%)和WFP80(9.80%)。总根系质量密度WFP60处理最大(594.76 g/m3),WFP40(579.08 g/m3)和WFP80(491.82 g/m3)次之,CK最小(372.12 g/m3)。根系在0~100、≥100~200和≥200~300 cm土层中的分配比例为:CK(69.88%、13.74%和16.38)、WFP40(66.04%、14.26%和19.70%)、WFP60(70.35%、24.08%和5.58%)和WFP80(46.54%、15.04%和38.42%),其根系分布与水分分布正相关。该研究表明WFP能够显著改变土壤水分在不同土层深度的分布,坑深越大向下湿润的土体范围也越深;从而显著促进果树根系的生长和根系在不同湿润土层的分配比例关系。总体而言,WFP60处理效果显著好于WFP40和WFP80处理。研究结果将对黄土高原旱地果园集雨和灌溉制度的制定和肥水坑技术的推广提供参考。