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1.
为探讨磁化水灌溉处理在促进植物生长、提高植株重金属耐受性方面的作用机制,本研究采用随机区组试验设计,研究了镉胁迫（0 μmol·L-1、50 μmol·L-1、100 μmol·L-1）下磁化水灌溉处理对1 a生欧美杨''I-107''光合特性、叶绿素荧光动力学参数及生长特性的影响。结果表明：1）镉胁迫会显著降低植株高生长和根茎叶干物质量;低浓度（50 μmol·L-1）镉处理促进根系直径及体积增大（P<0.05）,高浓度（100 μmol·L-1）则会抑制根系各形态参数;镉胁迫下欧美杨叶绿素b和类胡萝卜素含量分别降低12.50%、43.24%和19.27%、46.37%（P<0.05）,净光合速率（Pn）、蒸腾速率（Tr）、胞间二氧化碳（Ci）分别降低13.68%和33.68%、8.07%和27.81%、5.00%和14.99%（P<0.05）,同时,PSⅡ潜在活性（Fv/Fm）、最大光化学速率（Fv/Fo）、光合性能指数（PIabs）和量子产额（φEo）均有不同程度降低。2）磁化水灌溉提高镉胁迫植株高生长及根茎叶干物质量,增加植株根系长度及表面积;同时,叶绿素a、叶绿素b和类胡萝卜素含量在0 μmol·L-1和100 μmol·L-1镉胁迫下分别提高16.99%、40.20%,8.67%、39.10%和17.32%、50.52%（P<0.05）;Gs、Ci及WUE显著升高,Tr则降低24.20%、23.33%、12.06%（P<0.05）;另外,Fv/Fm、Fv/Fo、PIabs显著升高（P<0.05）。综上所述,磁化水灌溉处理有助于提高镉胁迫下欧美杨幼苗光合色素含量,维持光合机构功能,增强光合碳同化速率,减轻镉胁迫对植株生长发育的抑制。 相似文献
2.
以甘肃白银某污灌区重金属污染农田土壤为研究对象，对影响高精度便携式X荧光光谱（HDXRF）法总镉（CdT）测定精度的主要因素进行了筛选，分别研究了土壤水分、有机质类型与含量、土壤类型对HDXRF法CdT测定的影响，并采用相对误差（RE）、相对标准偏差（RSD）和决定系数（R2）对测定结果的准确度和精密度进行了评价。结果表明：HDXRF法CdT测定的RE≤10%、RSD≤10%、R2>0.99，符合农田土壤环境质量监测技术规范和美国环境保护署标准的准确度和精密度规定。HDXRF法CdT测定结果随着土壤水分含量的增加呈指数衰减趋势，衰减方程为y=0.803e–1.3284x，衰减系数（μω）为–1.328 4，R2为0.984 5。HDXRF法CdT测定结果与有机质含量呈显著的负相关关系（r=–0.955），且腐殖酸（HA）比泥炭（Peat）对测定结果的影响更大，HA与测定结果的校正方程为y=–1.555x +0.780，R2为0.934 4。土壤类型对HDXRF法CdT测定结果存在一定的影响，相对于红壤和水稻土，灰钙土的测定结果与传统实验室分析方法测定结果更接近。总之，虽然HDXRF法CdT测定结果受多种因素影响，但通过校正模型校正，其校正结果的可靠性能够满足Cd污染农田土壤精准调查需求。 相似文献
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[目的] 探究菊芋在滨海盐土改良过程中的作用机制,分析菊芋和碱蓬根系分泌物的组分差异,明确土壤微生态环境的变化规律,进一步为盐土改良提供理论依据。[方法] 以种植菊芋和自然碱蓬植被为样地,对菊芋和碱蓬的根系分泌物进行对比分析,研究在根系分泌物作用下土壤微生物数量,微生物量碳氮,微生物群落结构以及土壤酶活性的变化,从而系统地阐明根系分泌物介导下盐土改良的微生物机制。[结果] 菊芋根际土壤中含有果糖（2.343×10-3 g/kg）、葡萄糖（4.235×10-3 g/kg）、蔗糖（2.670×10-3 g/kg）,分别是碱蓬根际土壤的9.28,1.52和2.43倍。而菊芋根际与非根际中的果糖含量存在显著性差异（p<0.05）,其根际中含量为非根际的12.02倍。菊芋土壤还含有低聚果糖（蔗果三糖、蔗果四糖和蔗果五糖）,而碱蓬土壤中未检测出低聚果糖。除糖类外,菊芋根系分泌物还含有烷烃、酚、醛、酯、有机酸、醇、酮、酰胺,其组分较碱蓬土壤更为复杂且某些组分为菊芋特有〔1-氯—十八烷、正十六烷酸、2-甲基-Z-4-十四碳烯、十二酮、（Z）-9-十八碳酰胺、苯丙酸十六烷基酯等〕。功能性根系分泌物（如低聚果糖、果糖、十六烷、十八烷酸等）为根际微生物提供碳源、氮源和营养元素的同时,使菊芋根际土壤中微生物数量显著增加（p<0.05）,土壤微生物量碳、氮显著高于碱蓬土壤（p<0.05）,其值分别是碱蓬土壤的1.95和1.6倍,且菊芋根际的微生物量碳、氮约为非根际的1.69和1.50倍,优势菌群（变形菌门、放线菌门、绿弯菌门、酸杆菌门）所占比重达到90%,土壤有益菌群（Actinobacteria和Acidobacteria）的相对丰度显著增加（p<0.05）,土壤生物活性提升。此外,菊芋根际特有的分泌物（十六烷、烯醛等）,抑制了病原菌的生长,优化了微生物群落结构。除过氧化氢酶外,土壤脲酶、蔗糖酶和碱性磷酸活性显著提高（p<0.05）,其活性分别是碱蓬土壤的1.83,1.88和3.30倍。[结论] 种植菊芋后,通过根际分泌物介导,改善土壤微生物群落结构与功能,增加土壤酶活性,使土壤生物活力得以整体提升,与原生植被碱蓬相比,降低了土壤含盐量,起到了改良盐土的作用。 相似文献
4.
探讨外源镉（Cd）和温度变化对水稻抽穗期光合特性的影响,为水稻生长过程中应对稻田土壤重金属污染和气候变暖的复合作用提供理论依据。通过添加外源Cd （0和2 mg/kg土）和模拟温度（白天/夜晚分别为30℃/25℃（CK）、33℃/28℃（T1）、36℃/31℃（T2））,研究外源Cd和温度变化对不同品种水稻（武运粳30号和新两优6号）抽穗期光合参数、荧光参数及其生物量的影响。结果表明,单一Cd处理显著降低了新两优6号的SPAD值,而单一增温处理则显著降低了武运粳30号的SPAD值（P<0.05）。虽然外源Cd和温度的复合作用未显著影响武运粳30号和新两优6号的净光合速率（Pn）,但Cd处理显著降低了两品种的Pn,而增温处理则显著影响了新两优6号的Pn;大部分Cd和温度处理下,新两优6号的SPAD值和Pn大于武运粳30号。Cd处理和增温处理均影响了水稻叶绿素诱导动力学曲线的形状,O、K、J和I点的荧光因处理的不同而具有一定差异。Cd处理和增温处理对水稻Fv/Fm和比活度参数的影响与水稻品种有关,Cd处理未显著影响运粳30号和新两优6号的Fv/Fm值,而增温处理则显著减少了武运粳30号的Fv/Fm值;新两优6号的比活度参数ABS/RC、DIo/RC、TRo/RC、ET0/RC在Cd处理下显著降低,而武运粳30号的比活度参数在增温处理下则显著增加（P<0.05）。Cd处理显著降低了新两优6号的茎叶生物量,而增温处理则显著降低了武运粳30号茎叶生物量,然而两者的复合作用对水稻茎叶和根生物量的影响因品种不用而具有差异,新两优6号的茎叶和根干物质量在大部分处理下大于武运粳30号。综上可知,Cd和增温处理通过影响水稻的光合参数和荧光参数,从而影响水稻的生物量,但影响程度因品种不同而具有差异,其中,武运粳30号对Cd具有较强的抗性而新两优6号对增温有较强的抗性。因此,在实际的田间管理中,应选择合适的水稻品种,以应对土壤Cd污染和温度升高对水稻生长的影响。 相似文献
5.
氮肥对镉在土壤-芥菜系统中迁移转化的影响 总被引：6，自引：0，他引：6
以芥菜为研究对象, 采用盆栽试验, 探讨了不同用量的5种氮肥对污染农田土壤中镉(Cd)在土壤–根系–地上部迁移累积的影响。结果表明: 5种氮肥均促进了芥菜根系对Cd的吸收, 且根系Cd含量随施氮量的增加而增加; 但根系吸收转运Cd的能力随氮肥施用量的增加呈先降后增的变化趋势。在≤200 mg(N)·kg-1(土)的施氮水平下, CO(NH2)2和Ca(NO3)2处理能显著降低芥菜地上部Cd含量, 降低幅度分别为13%~29%和24%~30%。在施氮量相同的条件下, NH4Cl和(NH4)2SO4显著降低了土壤pH, 增加了土壤DTPA-Cd含量, 促进了芥菜对Cd的吸收。本试验条件下, 200 mg(N)·kg-1(土)的CO(NH2)2在增加芥菜产量和降低芥菜地上部Cd含量等方面优于其他氮肥处理。 相似文献
6.
为精确测定、准确模拟阿克苏地区滴灌枣树腾发过程,基于大型称重式蒸渗仪测定枣树全生育期逐时及逐日腾发强度（ET）,利用水量平衡方程、PM公式及经典统计原理,分析不同时间尺度下叶面积指数（LAI）、气象因素[温度（I）、风速（V）、净辐射（Rn）]、表层土壤含水率（W）与枣树腾发强度的相关关系并建立预测模型。结果表明：枣树日内腾发强度呈单峰型变化趋势,夜间变化幅度较小且腾发贡献率低。枣树全生育期逐日腾发强度变化呈先增大后减小的趋势,花期的腾发强度最大,为4.42 mm·d-1;全生育期腾发总量为640.83 mm,其中花期和果实生长发育期耗水量占比较大,分别为38.61%和32.72%。在小时和日时间尺度上,影响腾发强度的主要因素不完全相同,且影响程度有所差异。综合考虑各影响因素,以萌芽期、花期、果实发育期为基础,分别建立以小时、日尺度下估算腾发强度的经验模型ET1（h）=0.153+0.004T+0.012V+0.176Rn+0.002W+0.067LAI、ET2（d）=-3.325+0.081T+0.163Rn+0.069W+2.089LAI,拟合度R2均在0.7以上,以果实发育期与成熟期数据对模型进行检验,纳什效率系数分别达0.63、0.80。经偏相关检验,冠层净辐射（Rn）对两种尺度的腾发强度均影响最显著,因此以枣树全生育期数据量为基础,仅建立冠层净辐射（Rn）与腾发强度的回归模型ET1（h）=-0.063 3Rn2+0.361 2Rn—0.003 7、ET2（d）=-0.018 3Rn2+0.684 7Rn–1.642 1,R2分别为0.704 7与0.743 6,可满足缺少数据支撑情况下的腾发过程估算。这些模型明确了阿克苏地区滴灌枣树腾发机制及影响程度,可为水分管理精准化提供计算基础。 相似文献
7.
通过人工控制水分,形成单株幼龄侧柏的不同土壤水分梯度环境。在自然环境下对侧柏叶片定时、定位进行蒸腾速率及林冠层的光照、空气温度、空气湿度、叶水势和土壤水分等因子的同步观测。蒸腾速率与各个因子的相关分析表明:黄土半干旱地区侧柏蒸腾速率ηt/(μg·cm-2·s-1)与光照强度E/(μmol·m-2·s-1)、空气饱和差pv/kPa、叶水势Ψ/kPa、气温t/℃的关系可以分别表示为:ηt=>αEb,ηt=αpvb,ηt=αψb,ηt=αt2+bt+c;侧柏的蒸腾速率ηt与气孔阻力Rs/(s·cm-1)和土壤含水量W/％有密切关系,可以分别表示为:ηt=α+bW+cW2+dW3,Rs=α+bW+cW2+dW3。用气温、空气饱和差、叶水势3个因素建立了半干旱黄土地区幼龄单株侧柏蒸腾速率的非线性指数预测模型:ηt=0.6950exp（0.03158t-14.2492/pv+0.7606/Ψ）,经检验获得了满意的数值模拟结果。 相似文献
8.
不同规格生态沟渠对排水中污染物的处理能力之比较研究 总被引：1，自引：0，他引：1
利用三种不同深度规格的生态沟渠（E0.80、E1.05和E1.30）,通过控制相同的表面水力负荷,比较研究了动态进水（TN 0.86~6.13 mg?L-1、TP 0.11~0.28 mg?L-1）条件下生态沟渠对农业面源主要污染物的去除效果,同时考察其耐冲击负荷能力和适宜建造长度。结果表明：整个试验期间,三种不同深度规格的生态沟渠对铵态氮（NH4+-N）、总氮（TN）、总磷（TP）和悬浮物（SS）的去除率均达到50%以上,其中E1.30对污染物的去除效率较高,NH4+-N、TN、TP和SS的总平均去除率分别为64.8%、63.1%、71.8%和60.8%。同时,E1.30的污染物出水浓度较为稳定,耐冲击负荷能力相对较强。进水浓度较高情况下,E1.30在TN、TP出水浓度为2 mg?L-1和0.2 mg?L-1时所需长度分别为27.4 m和4.9 m,为三种规格生态沟渠中最短。表明生态沟渠是有效去除农业面源污染物的技术,在实际应用中可因地制宜地建设E1.30规格的生态沟渠,并可辅以高效吸附氮磷材料等其他措施,进一步提高生态沟渠对农业面源污染物的去除能力。 相似文献
9.
为探究作物冠层受阳光直射或阴影遮挡对无人机热红外遥感诊断作物水分胁迫、监测土壤含水率的影响，该研究以不同灌溉处理的夏玉米为研究对象，将热红外图像划分为光照冠层、阴影冠层、光照土壤、阴影土壤4个部分，分别提取光照温度与阴影温度后计算了11:00、13:00、15:00的冠气温差（冠层温度与大气温度之差，ΔT）、作物水分胁迫指数（crop water stress index，CWSI）、蒸发比（潜热通量与有效能量的比值，evaporative fraction，EF），并对比了3种指数在不同时刻使用光照温度（ΔTL、CWSIL、EFL）与阴影温度（ΔTS、CWSIS、EFS）后对土壤含水率的监测效果变化情况。结果表明：1）3种指数的监测效果会随时间发生变化，11:00与15:00时EF监测效果较好，13:00时CWSI监测效果较好，ΔT的监测效果较差但随时间波动最小；2）拔节期在区分光照温度与阴影温度后监测效果在11:00时提升幅度最大，EF、EFS、EFL的R2分别为0.54、0.65、0.78，CWSI、CWSIS、CWSIL的R2分别为0.47、0.64、0.70，抽雄期与灌浆期使用光照温度对监测效果提升不大，但使用阴影温度的指数监测效果有明显降低，在13:00时CWSIS较CWSI有最大降幅，R2降幅分别为0.11、0.06；3）在拔节期与抽雄期使用11:00的EFL，在灌浆期使用13:00的CWSI能取得最好的土壤含水率监测效果，预测土壤含水率的R2分别为0.75、0.75、0.89。该研究可以为无人机热红外监测土壤含水率提供参考。 相似文献
10.
[目的] 分析南昌市浅水湖泊象湖表层沉积物的释放特征及有机质对氮、磷释放的影响,为城市内浅水湖泊治理中富营养化控制提供理论依据。[方法] 通过释放动力学试验以及释放潜能试验研究了城市浅水湖泊氨氮（NH4+-N）和溶解性活性磷（SRP）的释放特征,以及与通过H2O2去除有机质后的释放特征进行了对比。[结果] 去除前后的氮磷的释放速率都是先由一个较快的过程逐渐变慢最后趋于稳定达到最大释放量（Qmax）。去除有机质后NH4+-N的释放平衡时间缩短,SRP则几乎不变。去除有机质后,NH4+-N的最大释放量（Qmax）与有机质含量呈显著正相关,而SRP与有机质无显著相关性。[结论] 影响沉积物氮磷释放的因素多样,其中高等水生植物丰富的区域对磷的释放有明显的抑制作用。沉积物有机质的含量越高沉积物氮的最大释放量（Qmax）也越高,磷的的最大释放量（Qmax）则受有机质含量、活性、组成成分、吸附与结合的铁铝磷含量等因素共同影响。 相似文献
11.
In order to identify key adaptive traits which affect productivity in Mediterranean grain and forage legumes and simultaneously determine the agricultural potential of a wide range of Vicia species, germplasm collected from the wild throughout the eastern Mediterranean was grown under semi-arid conditions in Tel Hadya, Syria (313 mm growing season rainfall). These included species currently in use in Mediterranean agriculture, such as V. sativa L., as well as those more widely used in the past-such as V. ervilia L., but also a broad selection from Section Narbonensis (B. Fedtsch. ex Radzhi) Maxted, including V. narbonensis L, V. johannis Tamamsch., V. hyaeniscyamus Mout., V. serratifolia Jacq., and V. kalakhensis Khattab et al. V. faba, a near relative of the taxa in Section Narbonensis, was included as a domesticated control. Where applicable, a representative range of subspecies was used. Accessions were chosen from a wide range of habitats in terms of latitude (31.02–40.72 decimalo), longitude (27.1–43.17 decimalo), altitude (20–1510 m), rainfall (180–1700 mm/yr) and soil depth (5–50 cm) in order to maximise diversity within species. Agricultural potential was determined by measuring seed, hay and biological yield, as well as agronomic traits such as harvest index, standing crop height, and seed size. The comparative influence of phenology and key agronomic traits such as plant habit and seed size on productivity varied tremendously between species, depending on their reproductive strategies. In V. sativa and V. ervilia, the smaller seed species which rely on long vegetative phases and growing seasons to accumulate sufficient biomass to set seed, and in which there was comparatively little agronomic variation, phenology had a large impact on yield. In early emerging taxa such as V. ervilia and V. s. subsp. sativa, with built-in long vegetative phases and growing seasons, seed yield was negatively correlated with flower ing (r = –0.86 to –0.88), whereas the opposite was the case for later emerging taxa such as V. s. subsp. nigra (L.) Ehrh. (r = 0.95). Within V. narbonensis and relatives, the larger seeded Vicia species which rely on more conservative reproductive strategies where high seedling vigour associated with large seeds enables the species to enter reproductive phases relatively early, phenology had a much smaller impact on yield than did variation of key traits such as seed weight, plant habit and pod shattering. Among the undomesticated germplasm harvest indices ranged from 0.09–0.31, hay yields from 0.1–3.4 t/ha, seed yield from 0–2.0 t/ha, and dry matter at maturity from 1.6–6.5 t/ha. Sub-specific taxonomy was crucial in determining agronomic potential. V. narbonensis var. aegyptiaca Kornhuber ex Asch. et Schweinf. showed the most potential, combining an upright habit, large seeds (212 mg) and tendency to retain intact pods after maturity, with the highest yield, harvest index and crop height of all the wild Vicia species. V. sativa subsp. sativa, V. ervilia and V. narbonensis var. narbonensis were less productive, but still showed agricultural potential. The smaller seeded V. narbonensis, var. affinis, var. jordanica H. Schäf. and var. salmonea (Mout.) H. Schäf., and their close relatives V. johannis, V. hyaeniscyamus, V. serratifolia and V. kalakhensis have little to offer Mediterranean agriculture on the basis of poor agronomy. 相似文献
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13.
The effects of five agroforestry woody species (Dactyladenia barteri, Gliricidia sepium, Leucaena leucocephala, Senna siamea andTreculia africana) on the surface aasting activity ofHyperiodrilus africanus were studied in an Alfisol (Oxic Paleustalf) in southwestern Nigeria. Casting activity under the woody species decreased in the following order:Dactyladenia sp. (26.4 Mg ha-1 year-1)>Gliricidia sp. (24.4 Mg ha-1 year-1)>Treculia sp. (22.9 Mg ha-1 year-1)>Leucaena sp. (18.6 Mg ha-1 year-1)>Senna sp. (18.3 Mg ha-1 year-1). These differences in casting activity were partly explained by microclimatic effects. Irrespective of the woody species, the worm casts were higher in clay and silt contents, bulk density, water-stable aggregates, pH, organic C, exchangeable cations, effective cation exchange capacity, and extractable P levels than the corresponding surface soils. The woody species did affect the physicochemical properties and P sorption of the worm casts. The content of water-stable aggregates of worm casts decreased in the following order:Dactyladenia sp.>Treculia sp.>Senna sp.>Leucaena sp.>Gliricidia sp. Large differences in extractable P levels were observed.Senna sp. was associated with the highest extractable P level (11.5 mg kg-1) andTreculia sp. the lowest (4.9 mg kg-1). P sorption was highest on worm casts underDactyladenia sp. and lowest on those underTreculia sp. Without fertilizer application, there were no significant differences in the dry weight of maize grown in the different worm casts. With NPK applications, the dry weight of maize grown in worm casts associated withTreculia sp. was significantly lower than that of maize grown in the other worm casts, mainly due to the low extractable P level. Despite a high organic C and exchangeable K status, maize grown in the worm casts still responded significantly to N and K applications. The N uptake by maize grown in worm casts associated withTreculia sp. was lower than that in the other treatments. 相似文献
14.
The phylogenetic relationships within the genus Actinidia and among 3 allied genera Clematoclethra, Saurauia, and Sladenia have been very controversial. In order to understand the systematic implication of foliar trichomes in those genera, the micromorphological characteristics of foliar trichomes from 34 taxa were examined by means of light microscopy and scanning electron microscopy (SEM). The observed micromorphological characteristics were classified into eight main types. A phylogenetic analysis of Actinidia and related genera based on 15 micromorphological characters of foliar trichomes was conducted using Wagner parsimony method and Sladenia celastrifolia, Rhododendron hybridum and R. simsii as a complex outgroup. In the resulting phylogenetic tree, Actinidia is shown to be a monophyletic group, and Clematoclethra and Saurauia form another monophyletic group. This study also presents the phylogenetic relationships among 4 sections within the genus Actinidia: the monophyly of sect. Leiocarpae and of sect. Strigosae, and polyphyly of sect. Maculatae and of sect. Stellatae. 相似文献
15.
Effects of mixing radiata pine needles and understory litters on decomposition and nutrients release 总被引：1，自引：0，他引：1
Girisha K. Ganjegunte Leo M. Condron Peter W. Clinton Murray R. Davis 《Biology and Fertility of Soils》2005,41(5):310-319
A microcosm experiment was conducted to understand the impacts of mixing radiata pine (Pinus radiata D. Don) needle litter and understory (gorse—Ulex europaeus L., broom—Cytisus scoparius L., bracken—Pteridium aquilinum L., and lotus—Lotus pedunculatus L.) litter materials on decomposition and nutrient release dynamics. Mixing of pine needle litter with understory litter material had significant impacts on both the rate of decomposition and nutrient release patterns of pine litter as well as that of the understory species. Incubation in microcosms over 10 months resulted in significantly lower mass loss of radiata pine needle litter mixed with broom and lotus litters (35.8±8.4 and 41.3±0.8%, respectively) than pure pine needle litter (63.5±2.3%). Mixing with pine needle litter significantly increased the mass loss of broom (53.1±6.1%) compared to that of pure broom (30.2±1.0%). Significant transfers of nutrients, especially of magnesium and potassium, were observed in litter mixture treatments. Concentration of K in litter materials was found to be the most limiting factor for the decomposing microorganisms in the present study. The findings of this study suggest that management of understory litter composition via weed control could be used to manipulate carbon turnover and nutrient release in the forest floor. Also, initial selection of understory species will be important and could be managed. 相似文献
16.
Massimo Romani Efisio Piano Luciano Pecetti 《Genetic Resources and Crop Evolution》2002,49(4):341-349
Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium. 相似文献
17.
Garnett Erin Jonsson Lena M. Dighton John Murnen Katherine 《Biology and Fertility of Soils》2004,40(6):421-426
We investigated the influence of three concentrations of water extracts of three leaf litter species (pitch pine, huckleberry and white oak) and a mixture of all litters on the germination of pitch pine seeds and initial seedling growth in a microcosm experiment. All three plant species are important components of the pine barrens ecosystems in New Jersey, where it has been seen that pine seedling recruitment occurs only after stand replacing fire or in disturbed sites, where surface organic soil horizons and leaf litter have been removed. Leaf litter extracts did not influence seed germination, but significantly reduced seedling growth at high concentrations. There was little difference between the leaf litter species in growth suppression. As charcoal is a natural residue on the forest floor following fire, its influence on growth suppression was examined; it has been shown to immobilize polyphenols. Charcoal removed the inhibitory effect of leaf litter extracts and allowed the fertilizer effect of nutrients leached from the leaves to enhance seedling growth, particularly at the higher concentration of litter extract used. Responses to litter extracts were compared to four pure phenolic compounds, catchecol, p-coumaric acid, p-hydroxybenzoic acid and tannic acid. None of these compounds suppressed pine seedling growth, suggesting that these phenolics are not allelopathic to pine seedlings. The results are discussed in the context of fire as a driving factor in these oligotrophic and seasonally dry ecosystems and the interactions between nutrient supply and allelopathic chemistry of different leaf litters. 相似文献
18.
Gérard Branlard Mireille Dardevet Nardjis Amiour Gilberto Igrejas 《Genetic Resources and Crop Evolution》2003,50(7):669-679
Wheat endosperm storage proteins, namely gliadins and glutenins, are the major components of gluten. They play an important role in dough properties and in bread making quality in various wheat varieties. In the present study, the different alleles encoded at the 6 glutenin loci and at 3 -gliadin loci were identified from a set of 200 hexaploid wheat cultivars grown primarily in France using SDS PAGE. At Glu-A1, Glu-B1 and Glu-D1, encoding high molecular weight glutenin subunits (HMW-GS), 3, 8 and 5 alleles were observed respectively. Low molecular weight glutenin subunits (LMW-GS) displayed similar polymorphism, as 5 and 11 alleles were identified at loci Glu-A3 and Glu-B3 respectively. Four alleles were observed at Glu-D3 loci. Omega-gliadin diversity was also very high, as 7, 13 and 9 alleles were found at Gli-A1, Gli-B1 and Gli-D1, respectively. A total of 147 (or 149) patterns resulted from the genetic combination of the alleles encoding at the six glutenin loci (or Glu-1 and Gli-1 loci). Although Glu-1 and Glu-3 loci were located on different chromosome arms and were theoretically independent, some associations were revealed due to pedigree relatedness between some French wheat cultivars. The usefulness of allelic identification of LMW-GS together with HMW-GS and gliadins for future genetic and technological wheat improvement is discussed. 相似文献
19.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization
and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition
with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the
decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots
with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass,
soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration,
N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially
(<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation
in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils,
indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but
the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation
for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community
performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea. 相似文献