洪家渡水库溶解二氧化碳分压的时空分布特征及其扩散通量

为了了解水库温室气体的释放特征,于2006年4月、7月、10月和2007年1月对中国西南喀斯特地区新建的洪家渡水库入库水体、出库水体和水库坝前水体的CO2分压(pCO2)特征进行了分析.结果表明:入库河流pCO2为春季<夏季<秋季<冬季,其中,六冲河全年平均值为488μatm,凹水河全年平均值为624 μatm;水库库区表层水体pCO2冬季最高,春季最低,分别为925和279 μatm,全年平均值为598 μatm;在水体垂直剖面上,pCO2随水深的增加而增加;出库水体pCO2夏季最高,达8 417 μatm,春季最低,为382 μatm,全年平均值为3 260 μatm.就全年平均而言,入库水体、水库库区表层水体以及出库水体PCO2均高于大气CO2分压(380 μatm),其向大气中释放的CO2通量分别为3.93～6.29、4.87～7.79和64.29～102.86 mmol·m-2·d-1.该水库总体上是大气CO2的源,天然河流水体经水库作用后CO2释放强度增加,导致水库泄水pCO2为天然河流的16倍、水库库区表层水体的13倍,其向大气中释放CO2量也相应增加.因此,水库泄水的CO2释放问题值得关注.     

阜平山区草莓错季栽培的生物表现及适宜区域

通过田间试验和平行观测气象资料,利用地理信息技术和气候要素计算模型,研究了阜平山区种植草莓的生物表现及适宜种植区域.结果表明:在阜平山区种植草莓能够安全越冬、开花、结果,草莓发育期滞后于河北平原,从而达到错季生产的目的;其草莓品质优良,果实中可溶性固形物和维生素C含量均高于河北平原对应的草莓品种;阜平山区错季草莓的适宜发展区域为海拔900～1 200 m的地区.     

半干旱区不同垄沟集雨种植马铃薯模式对土壤蒸发的影响

通过垄沟集雨种植马铃薯试验,研究了不同垄沟集雨种植模式对土壤蒸发的影响.结果表明,在马铃薯全生育期,垄上覆盖塑料薄膜(CR)处理土壤蒸发量为122.9～165 mm,垄上原土夯实不覆膜(UR)处理土壤蒸发量为90.9～101.2 mm,无垄带状种植(CK) 土壤蒸发量为80.7 mm.其中,覆膜垄处理CR₆₀在马铃薯成熟期土壤蒸发强度最大,达2.6 mm·d^-1,平均为1.46 mm·d^-1,而对照的土壤蒸发强度为0.65 mm·d^-1;不覆膜土垄处理(UR₃₀)土壤蒸发强度苗期最小,只有0.2 mm·d^-1,平均为0.39 mm·d^-1,而对照的土壤蒸发强度为0.58 mm·d^-1.在马铃薯生长的现蕾期和开花期,水面蒸发量最大,日平均水面蒸发量分别为8.3和9.0 mm,与土壤蒸发不同步.马铃薯成熟期,各处理棵间土壤蒸发量都达到最大值.覆膜垄蒸发量最大,集雨效果显著,所以应采取抑制土壤蒸发措施,以便进一步提高水分利用效率.     

Disease development of Pythium root rot in bulbous Iris and Crocus

Iris bulbs and Crocus corms were planted at two planting dates in sandy soil infested with Pythium spp. At monthly intervals during the growing season root rot infection was assessed over 3 consecutive years and disease development curves were predicted for both crops. The disease development was remarkably different for Iris and Crocus and the curve shape was determined by the crop rather than by the Pythium species. Planting date had a significant effect on disease development in both crops. No correlation was found between disease development and soil temperature.     

Effects of mixtures of citrus viroids as transmissible small nuclear RNA on tree dwarfing and commercial scion performance on Carrizo citrange rootstock

The term ‘transmissible small nuclear ribonucleic acids' (TsnRNAs) describes well characterised viroid RNA species that do not induce any disease syndromes in specific citrus hosts but rather act as regulatory genetic elements modifying tree performance. Twelve-year-old navel orange and 10-year-old Clementine mandarin trees on Carrizo citrange (Citrus sinensis×Poncirus trifoliata) rootstock treated with a mixture of three TsnRNAs (−Ia, syn. Citrus bent leaf viroid, +IIa, syn. Hop stunt viroid and +IIIb, syn. Citrus dwarfing viroid) were reduced in size by 33% and 43%, respectively. Clementine trees treated with a mixture of TsnRNA−Ia+IIa or −Ia+IIIb also had reduced canopy volume (CV) (∼38 and 31%, respectively), whereas trees treated with TsnRNA−IIa+IIIb showed little effect. The effects of the double TsnRNA treatments −Ia+IIa and −Ia+IIIb on Clementine canopy size and commercial performance were comparable and in some cases superior to that of the triple TsnRNA mixture. The TsnRNA−Ia+IIa treatment had the most attractive commercial traits with increased production of Clementine fruit per CV (23.6%), more fruit with high commercial value (31.7%), and more fruit optimally distributed in the canopy (68% of fruit between 0.5 and 2.5 m). None of the TsnRNA treatments affected the growth of Carrizo rootstock seedlings after 8 years in the field. Navel orange and Clementine scions treated with the same triple TsnRNA mixture expressed different trunk and fruit production patterns although effects on CV were similar.     

透光抚育强度对小兴安岭“栽针保阔”红松林凋落物水文效应的影响

为了揭示“栽针保阔”及透光抚育在恢复东北温带地带性顶极植被阔叶红松林过程中对凋落物层水文效应的影响规律,采用样地调查法和室内浸泡法,同步测定小兴安岭山杨-红松林、白桦-红松林和蒙古栎-红松林(冠下栽植红松25～35年)在不同透光抚育强度(对照,轻、中、强度透光抚育)下的凋落物量、凋落物持水过程、最大持水量、最大拦蓄量和有效拦蓄量。结果表明: 透光抚育对3种林型凋落物蓄积量(7.32～15.58 t·hm^-2)影响不同,使蒙古栎-红松林(各强度)、山杨-红松林(轻、中度)及白桦-红松林(强度)分别显著提高24.3%～34.6%、15.3%～19.3%和27.1%。凋落物未分解、半分解层的持水量(W)、吸水速率(V)随浸泡时间(t)变化符合W=alnt+b(R²＞0.908)、V=ktⁿ(R²≥0.999)函数关系。各透光抚育(除强度透光抚育山杨-红松林外)使3种林型凋落物层最大持水量(17.86～45.12 t·hm^-2)、最大拦蓄量(16.10～34.19 t·hm^-2)和有效拦蓄量(13.42～27.42 t·hm^-2)分别显著提高30.1%～74.8%、27.4%～83.6%和26.7%～86.0%,且改变了各林型间凋落物层有效拦蓄量的差异。透光抚育显著增强了中期“栽针保阔”红松林凋落物层的水文生态功能,蒙古栎-红松林、山杨-红松林和白桦-红松林依次采取轻、中和强度透光抚育的效果最佳。     

基于富营养化水体修复的凤眼莲放养及采收条件研究

为实现富营养化水体的修复,对影响凤眼莲〔Eichhornia crassipes(Mart.)Sloms〕高产高效的放养及采收条件(包括初始放养日期、采收标准和采收比例)进行了研究,并对凤眼莲的生长曲线以及N、P和K的积累量进行了分析。实验结果表明:在总氮、总磷和钾含量分别为3.41~7.18、0.05~0.27和2.24~5.18 mg.L-1的水体中,在生长前期由于产生分蘖和植株个体生长,凤眼莲生物量快速增加;当植株生长至一定高度,生物量增幅减小;通过这一生长过程,凤眼莲的最高生物量可达28.28 kg.m-2。初始放养日期对凤眼莲的生长曲线和生物量均有明显影响,随初始放养日期的推迟生物量逐渐增大,在4月10日、4月17日、4月24日、5月1日和5月8日放养的凤眼莲经过63 d的放养,生物量均明显增加,其中,5月8日放养的凤眼莲总生物量最高,达到24.36 kg.m-2。采收标准和采收比例对凤眼莲的采收频率和累计采收量以及N、P和K积累量具有显著影响。按照10~15、15~20、20~25、25 kg.m-2以上及最高生物量的采收标准以及1/2和2/3的采收比例进行采收,凤眼莲的累计采收量均高于一次性采收(对照),且与其生物量呈抛物线型关系,但采收频率则与生物量成反比;采取不同的采收标准及采收比例,凤眼莲的干物质含量及N、P和K含量及总量均有一定的差异,但除干物质含量外,N、P和K含量及总量均明显高于一次性采收;总体上,采用20~25 kg.m-2的采收标准及2/3采收比例,凤眼莲的累计采收量最高、采收频率较少,对N、P和K的积累量最大。综合比较结果显示:在南京地区凤眼莲可于4月初开始放养,4月至5月分蘖,6月以后正常生长,并可按照20~25 kg.m-2的采收标准和2/3的采收比例进行采收。     

Sunn Hemp Cover Cropping and Organic Fertilizer Effects on the Nematode Community Under Temperate Growing Conditions

Field experiments were conducted in Maryland to investigate the influence of sunn hemp cover cropping in conjunction with organic and synthetic fertilizers on the nematode community in a zucchini cropping system. Two field treatments, zucchini planted into a sunn hemp living and surface mulch (SH) and zucchini planted into bare-ground (BG) were established during three field seasons from 2009 to 2011. In 2009, although SH slightly increased nematode richness compared with BG by the first harvest (P < 0.10), it reduced nematode diversity and enrichment indices (P < 0.01 and P < 0.10, respectively) and increased the channel index (P < 0.01) compared to BG at the final harvest. This suggests a negative impact of SH on nematode community structure. The experiment was modified in 2010 and 2011 where the SH and BG main plots were further split into two subplots to investigate the added influence of an organic vs. synthetic fertilizer. In 2010, when used as a living and surface mulch in a no-till system, SH increased bacterivorous, fungivorous, and total nematodes (P < 0.05) by the final zucchini harvest, but fertilizer type did not influence nematode community structure. In 2011, when incorporated into the soil before zucchini planting, SH increased the abundance of bacterivorous and fungivorous nematodes early in the cropping season. SH increased species richness also at the end of the season (P < 0.05). Fertilizer application did not appear to influence nematodes early in the season. However, in late season, organic fertilizers increased enrichment and structure indices and decreased channel index by the end of the zucchini cropping cycle.     

连栽杉木人工林参与土壤碳氮转化过程酶活性及其与土壤理化因子的相关性

选取福建三明不同连栽代数杉木人工林(一代、二代、三代)及格氏栲天然林为研究对象,运用冗余分析法研究不同林地土壤理化性质、养分含量与参与碳,氮转化过程酶活性之间的相互关系,以探究中亚热带连栽杉木人工林土壤酶的季节变化及其影响因素,为揭示杉木人工林养分循环特点和林地土壤质量评价提供依据。结果表明:连栽杉木人工林地土壤pH显著低于天然林,但一、二、三代杉木林间无显著差异。12月份土壤全碳、全氮含量在不同连栽代数杉木林中无显著差异,并且二代和三代林土壤全碳、全氮含量均显著高于天然林(P<0.05);6月份杉木三代林土壤全碳含量显著高于一代林(P<0.05),但与二代林和天然林无显著差异。12月份土壤铵态氮和硝态氮含量在一、二、三代杉木林间无显著差异。6月份杉木一代林土壤硝态氮含量显著高于二代林和天然林(P<0.05),但与三代林无显著差异。12月份天然林土壤脲酶活性显著高于连栽杉木人工林(P<0.05),而一、二、三代杉木林土壤脲酶活性无显著差异;杉木一代、二代林和天然林土壤天冬酰胺酶活性无显著差异,均显著高于三代林(P<0.05)。冗余分析表明,土壤含水量、NO...     

Effects of spacing interval of wide bed planting on canopy characteristics and yield in winter wheat

2010-2012连续两年在大田试验条件下以多穗型品种‘百农矮抗58’为供试材料, 研究了宽幅播种(播幅8 cm)种植方式下不同带间距7 cm (KF7)、12 cm (KF12)和17 cm (KF17)对冬小麦(Triticum aestivum)冠层特征及产量的影响。结果表明: 与常规条播比较, 宽幅播种群体叶面积指数、平均叶倾角、光截获量、相对湿度、成穗数、生物量和产量较高, 而冠层开度和温度较低; 2010-2011年和2011-2012年宽幅播种成穗数和产量显著高于常规条播, 成穗数分别增加4.8%-16.4%和8.9%-21.0%, 产量分别提高2.96%-15.94%和4.09%-14.23%。宽幅播种下随带间距增大, 叶面积指数、平均叶倾角、光截获量、湿度及成穗数降低, 而冠层开度和温度升高; 穗粒数、千粒重、产量、生物量和收获指数以KF12最高, KF7最低。综合分析, 宽幅播种下12 cm带间距处理的小麦冠层结构合理, 微环境适宜, 产量最高, 可作为该种植方式的适宜带间距。