采收期对猕猴桃果实品质及其耐贮性的影响

选用海沃德猕猴桃为试验材料,对8个不同采收期(盛花后151、155、159、163、167、171、175和179 d,采收Ⅰ~Ⅷ期)猕猴桃果实在(0±1)℃冷藏过程中的生理生化变化进行比较.结果显示:(1)采收Ⅰ、Ⅱ期果实采收时具有较高的硬度、淀粉含量和可滴定酸含量,可溶性固形物含量则低于6%,贮藏期间出现的呼吸高峰和乙烯释放高峰均比其它采收期高;采收Ⅶ、Ⅷ期果实采收时硬度明显低于前面的采收期,淀粉含量和可滴定酸含量降低,可溶性固形物含量达到8%以上,贮藏期间乙烯释放速率高峰比其它采收期提前10 d,果实衰老过程明显提前;(2)入贮150 d后,采收Ⅰ、Ⅱ、Ⅶ和Ⅷ期果实的失重率差异不显著,采收Ⅰ期与采收Ⅷ期果实的腐烂率差异不显著,但均与其它采收期存在显著差异.研究发现,盛花后第159~171天采收猕猴桃,果实采收时的可溶性固形物含量在6.5%以上,贮藏120 d后与其它采收期相比仍保持相对较高的硬度、淀粉含量、Vc含量和可滴定酸含量,而且贮藏150 d后失重率和腐烂率都比较低,表明该期间为海沃德"猕猴桃的适宜采收期.     

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。     

施肥对水曲柳生长及开花结实的影响

为了研究施肥对水曲柳生长及开花结实的影响,以2年生水曲柳嫁接苗、13年生水曲柳幼树、29年生已开花水曲柳大树为材料,采用氮、磷、钾3因素3水平正交试验设计,连续三年进行施肥处理。通过测量嫁接苗的树高、地径;幼树的树高、胸径;已开花大树的开花率、结实率等生长发育指标研究不同配方施肥对水曲柳生长发育状态的影响,得出促进水曲柳生长发育的施肥最优组合。结果显示:施肥处理对水曲柳的生长发育具有促进作用。3种肥料对2年生水曲柳嫁接苗生长的影响顺序为氮肥磷肥钾肥,施肥最优组合为氮肥每株0.006 kg、磷肥每株0.012 kg、钾肥每株0.008 kg;对13年生水曲柳幼树生长的影响顺序为氮肥磷肥钾肥,施肥最优组合为氮肥每株0.15 kg、磷肥每株0.3 kg、钾肥每株0.2 kg;对已开花水曲柳大树开花率及结实率的影响顺序为氮肥钾肥磷肥,施肥最优组合为氮肥每株0.3 kg、磷肥每株0.6 kg、钾肥每株0.4 kg。结果表明合理施肥可以促进水曲柳的生长和开花结实,本试验结果也为水曲柳合理施肥提供了技术依据。     

不同施磷水平对香蕉产量与品质影响初报

在定量施用氮、钾肥条件下,采用单因素田间试验方法研究不同施磷水平对香蕉产量与品质影响。结果表明,在土壤速效磷含量适宜的香蕉园,株施尿素0.87 kg、氯化钾1.335 kg、有机肥2.0 kg、硫酸镁125.0 g、0.2%硼砂溶液喷1次,以施过磷酸钙1.165 kg/株,N∶P2O5∶K2O=1∶0.35∶2,田间蕉株生长较快、假茎较粗,采收时功能叶片数较多、采收期较早且较短,产量较高;同时,果实外观和内质较好,果指较长较粗、淀粉和总糖含量、可食率略高、可滴定酸居中;经济效益最佳,净利润达2 637.6元/667m2,投入产出比为1∶1.83。     

葛仙米室内规模化培养、群体显微结构及营养成分分析

以葛仙米为材料开展室内规模化培养,在15个月的培养期间,每月可产鲜藻38.3~293.7 kg,每立方米的培养体积葛仙米每月产量波动在9.58~77.45 kg,高温明显降低月产量。在葛仙米的表层和内部的显微结构明显不同,藻丝的长短、排列存在明显的差异。同时以人工培养的葛仙米为材料,测定了其生化组成;结果表明:人工培养的葛仙米含16种氨基酸,蛋白质含量为29.69%;脂肪的含量为0.78%,远低于野生葛仙米中脂肪的含量;维生素的含量较低;砷、铅、汞、镉4种重金属元素含量较低,其含量符合国家食品卫生标准。     

AAS测定五指山苦丁茶中重金属含量

采用火焰原子吸收光谱法对海南五指山苦丁茶不同级别新鲜茶叶中的锌、锰、铜、铅、镉五种元素进行了含量测定,详细地研究了消解酸的种类、HNO3、HCIO4和H2O2的比例、消解酸的体积及消解时间对测定结果的影响。用HNO3-HClO4-H2O2处理样品,测定结果表明不同等级的海南五指山苦丁茶重金属含量不一样,其含量排序为Mn>Cu>Zn,各样品平均含量分别是:Mn:10.22×10-3mg/kg;Cu:8.368×10-3mg/kg;Zn:5.667×10-3mg/kg。所有样品中Cu含量均低于药典规定的20mg/kg,重金属Cu和Zn、Mn的含量之和也小于20mg/kg,符合标准;各样品中的Pb、Cd的含量因其含量较低未能检测出,这种结果得益于海南省五指山市得天独厚的生态环境。采用此方法回收率为101.02%—103.63%之间,相对标准偏差(RSD)在0.20%—1.57%之间,小于10%。其方法简便、精密度和灵敏度高,结果令人满意。     

鱼腥草游离氨基酸组成及含量的HPLC分析

研究不同鱼腥草材料间及其两个不同采收时期游离氨基酸组成及含量差异 ,筛选游离氨基酸种类较多 ,含量较高的新品系 ,并确定适宜的采收时期。对 1 9份鱼腥草材料阴干地上部分游离氨基酸成分进行了高效液相色谱分析。 6月和 1 0月采收的鱼腥草中分别含有 1 5种和 1 4种氨基酸 ,都不含Cysteine -ss -Cysteine和Lysine,1 0月采收的还不含有Tyrosine。氨基酸中Proline含量最高 ,Glycine含量最低。此外 ,1 0月采收的鱼腥草的游离氨基酸总量高于 6月采收的鱼腥草。供试材料中 6月采收的W0 1 - 86和 1 0月采收的W0 1 - 5多数游离氨基酸含量均为同一采收时期的最高值。分别为 5 894 .76mg/kg和 6 1 6 6 .1 3mg/kg。此外 ,蕺菜与峨眉蕺菜间游离氨基酸成分间无显著差别。因此鱼腥草不同材料间及不同采收时期游离氨基酸含量不尽相同 ,游离氨基酸含量与染色体数目间相关不显著     

湖南烟区烤烟(Nicotiana tabacum L.)硼含量与土壤有效硼含量的关系

分析湖南烟区烤烟硼含量与土壤有效硼含量的关系,结果表明：（1）湖南烟叶硼含量偏低,平均为（21.72±12.98）mg/kg,变幅为9.22-89.04mg/kg,有88.89%的烟叶样本硼含量落在10.00-40.00mg/kg范围内;（2）湖南植烟土壤有效硼含量较低,平均为（0.25±0.23）mg/kg,变幅较大（0.07-1.28mg/kg）;有93.40%的土壤样本在不同程度上缺硼（≤0.40mg/kg）,另有4.51%的土样有效硼含量充足（〉1.0mg/kg）,满足优质烟叶生长发育正常的土样仅占2.09%;（3）烟叶硼含量与土壤有效硼含量呈极显著正相关（相关系数为0.745）,288个样品的烟叶硼含量（y^）与土壤有效硼含量（x）建立的回归方程为y^=11.47＋41.71x;（4）在土壤有效硼含量分组后,采用方差分析方法研究了烟叶化学成分的组间差异,表明烟碱、氮/碱、糖/碱的组间差异均达到1%的极显著水平,而总氮、总糖含量的组间差异不显著。     

营养液供应量对番茄产量、品质和挥发性物质的影响

为探讨基质栽培条件下不同供应量的营养液对番茄果实产量、品质和挥发性物质的影响,以"HL2109"番茄为试验材料,设置4个处理.对照:每株全生育期只浇清水,共计117 L;T1:每株全生育期共浇营养液39.0 L;T_2:每株全生育期共浇营养液58.5 L;T_3:每株全生育期共浇营养液117 L,利用化学方法及固相微萃取-气相色谱-质谱联用(SPME-GC-MS)技术测定番茄果实品质和挥发性物质.结果表明:随着营养液供应量的增加,番茄单株产量和产量呈先升后降的变化趋势,以T_2处理最大,达到每株2.53 kg;T_1、T_2、T_3处理的番茄产量分别比对照增加了29.3%、72.6%、47.0%;T_1处理的灌溉水分利用效率最大,T_2次之,两者差异不显著.T_2处理番茄果实的可溶性固形物含量、糖酸比最高,果实的风味品质显著提升.随着营养液供应量的增加,果实的可溶性蛋白、抗坏血酸含量逐渐增加,可溶性总糖、还原糖含量呈现先增加后减少的趋势,均以T_2处理最高.利用GC-MS共检测出挥发性物质69种,T_1、T_2、T_3的果实挥发性物质总含量高于对照,表现为T_2>T_1>T_3>对照.其中T_2、T_1和T_3处理果实挥发性物质总含量分别为6971、6095和4070μg·kg^-1,比对照分别增加了1.97、1.56和0.73倍;随着营养液供应量的增加,1-戊烯-3-酮、6-甲基-5-庚烯-2-酮、己醛、己酸、苯乙醛、顺-3-己烯醛等均以T_2处理的含量最高,并且T_2处理果实的特征挥发性物质含量、挥发性物质数量和总含量都最高.在本试验条件下,采用每株全生育期浇营养液58.5 L处理能够提高果实品质和挥发性物质含量,效果最佳.     

叶面喷施微肥对川白芷主要有效成分含量的影响

在川白芷生长旺盛期叶面喷施锌、硼、钼,研究微量元素锌、硼、钼配合喷施对川白芷主要有效成分含量的影响以及最适宜的喷施量.结果表明: 叶面喷施锌、硼、钼有利于川白芷欧前胡素和总香豆素含量的提高,对异欧前胡素含量的影响不显著;硼对欧前胡素和总香豆素含量的积累影响最大,锌次之,钼最小;硼和钼互作对欧前胡素含量有拮抗效应,锌和硼互作对总香豆素含量有协同效应;施锌0.15～0.24 kg·hm^-2、硼2.02～2.36 kg·hm^-2、钼0.08～0.13 kg·hm^-2时,川白芷总香豆素含量≥0.7%;施锌0.15～0.20 kg·hm^-2、硼1.37～1.47 kg·hm^-2、钼0.09～0.13 kg·hm^-2时,欧前胡素含量≥0.2%.叶面喷施锌、硼、钼有利于川白芷中香豆素类成分的积累和品质的提高.     

岩黄连引种栽培研究

岩黄连 ( Corydalis saxicola Bunting)为石山特有的多年生草本药用植物 ,局限分布裸露石山 ,生于石缝、石穴 ,资源稀少且濒于枯竭。通过近四年的引种栽培研究 ,表明其对丘陵区酸性土壤亦有较强的适应性 ,能正常生长发育 ,种子发芽率可达 4 0 %～ 50 % ,药材产量 (干品 ) 90 0～ 12 0 0 kg/hm2 。报道了其生物学特性和主要的栽培技术。     

Comparative analysis of the chemical profile of wild and cultivated populations of Corydalis saxicola by high-performance liquid chromatography

Studies on the simultaneous determination and chemical fingerprinting of alkaloids in Corydalis saxicola Bunting. (Yanhuanglian) were performed for authentication purposes. Ninety samples prepared from different parts of C. saxicola, including whole plants, roots, stems, leaves and flowers, from wild and cultivated populations, were submitted to quantitative determination and fingerprint analysis. Five major alkaloids, namely, tetradehydroscoulerine, dehydroapocavidine, dehydroisoapocavidine, coptisine and dehydrocavidine, were quantitatively analysed by reversed-phase HPLC with acceptable recoveries (>98.2%). Chemical fingerprinting of C. saxicola was established and involved 11 markers. The results indicated that there were no obvious differences between the chemical profiles of wild and of cultivated C. saxicola populations, and that the mean alkaloid contents of the five marker compounds in cultivated populations were significantly higher than those of the wild plants. The highest content of total alkaloids (up to 28.8 mg/g) was found in roots of C. saxicola. The total alkaloids of the leaves were approximately 50% of those of roots, suggesting that the leaves may be employed as an alternative source of alkaloids. Chemical fingerprints and quantitative HPLC analysis will have a positive impact on the conservation and cultivation of this medicinal plant.     

Seed production of cut-leaved teasel (<Emphasis Type="Italic">Dipsacus laciniatus</Emphasis>) in central Missouri

Cut-leaved teasel is an invasive weed in Missouri that reduces the diversification of native species along roadsides and impairs traffic visibility. Teasel is a biennial and grows as a rosette in the first year and flowers the second year. Reproduction is only by seed. Field studies were conducted in 2004 and 2005 at two locations to assess the seed production of cut-leaved teasel. From a natural stand, fifteen plants were tagged at the onset of flowering. Selected plants included those considered growing in a group and those growing alone; a plant was considered alone when no other plant was adjacent for at least 60 cm. Whenever a seedhead completed flowering, it was covered with a cellophane bag and harvested one month later. Linear regression was used to correlate the weight of seeds from a single seedhead and number of seeds to estimate the total seed production per seedhead. The number of seedheads per plant varied from 3 to 56. On average, plants growing alone had 64% more seedheads per plant than plants occurring in a group. Seed numbers in the primary seedhead ranged from 511 to 1,487. Total seed production per plant ranged from 1,309 to 33,527. Seed production was 61% greater for plants growing alone versus those growing in a group and was more prolific in 2005 than in 2004. In addition, seed production per plant varied between locations for plants growing alone, but seed yield per plant was similar for plants growing in groups. Colonization of teasel in new areas is facilitated by higher seedhead numbers per plant and total seed production compared to reproduction of plants in areas of intraspecific competition.     

氮磷肥配施对苦荞根系生理生态及产量的影响

以苦荞品种‘迪庆’为材料,在盆栽试验条件下,研究了氮(纯氮用量分别为0g/kg、0.1g/kg、0.2g/kg)、磷(P2O5用量分别为0.1g/kg和0.2g/kg)配施对苦荞根系生长、生理指标及其产量的影响,旨在为黄土高原苦荞高产优质栽培提供理论依据。结果表明:(1)在相同施磷量条件下,苦荞幼苗的株高、茎粗、茎叶干重、主根长、根表面积、根系体积、根系直径、根系干重以及壮苗指数等均随施氮量的增加而呈先升后降的趋势,但根冠比随施氮量的增加而呈先降后升的趋势;叶片叶绿素含量以及根系活力、酸性磷酸酶(Apase)活性、可溶性蛋白含量和植株氮积累量随施氮量的增加呈抛物线变化趋势,根系硝酸还原酶(NR)活性和植株氮含量随施氮量的增加而增加;而根系可溶性糖含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、丙二醛(MDA)含量和游离脯氨酸含量等指标均随施氮量的增加而呈先降后升的趋势,0.1g/kg施氮处理各指标均显著低于其他处理;成熟期单株粒重、百粒重随施氮量的增加呈先升后降的趋势,0.1g/kg施氮处理各指标均显著高于其他处理。(2)在相同施氮量条件下,随着施磷量的增加,苦荞根系酸性磷酸酶(Apase)活性、SOD活性、POD活性、MDA含量、可溶性糖含量、可溶性蛋白以及游离脯氨酸含量等指标均降低,其余各指标则呈增加趋势。(3)无论施磷量条件如何,0.1g/kg的施氮处理下苦荞产量最高,与其他施氮处理相比,在低磷和高磷处理下的增产幅度分别为7.04%~37.40%和14.73%~68.26%;在施氮量一定的情况下,高磷处理比低磷处理增产15.96%~42.00%。(4)在该试验条件下,适当的氮磷肥配施表现出了明显的正加和效应,但过量施肥也有可能导致增产幅度下降,中氮高磷(施纯N量0.1g/kg,施P2O5量0.2g/kg)配施效果最优。     

Impact of planting density and soaking seeds in melatonin solution on yield,secondary products content and antimicrobial activity of lovage plant

Many studies worldwide have been done on the effect of medicinal uses of lovage plant but, very little works have been done on its production. In this study the effect of different planting density and soaking seeds in different concentration of melatonin solution as well as their combination treatments on yield, secondary products content and antimicrobial activity of lovage plant were studied. It was observed that using planting space of 15 cm gave the maximum mean values of total phenolic and antioxidant content and essential oil percentage. Using 30 cm planting space gave the maximum mean values of plant height, yield of herb fresh and dry weight per hectare, yield of roots dry weight and essential oil per hectare. While the plant space of 45 cm recorded the maximum mean values of fresh and dry weight of herb and roots fresh weight per plant and chlorophyll content. For melatonin levels, using 100 µM melatonin solution had the minimum mean values of number of days to emergence. While, soaking seeds in 75 µM melatonin solution recorded the best results of all studied parameters. Regarding the combination treatments, measurements comprising of herb fresh and dry weight as well as essential oil yield per hectare showed that the combination treatment of 30 cm between plants in row plus soaking seeds in 75 µM melatonin solution was able to achieve the maximum values of these parameters. While the combination treatment of 15 cm between plants in row plus soaking solution of 75 µM melatonin is recommended for getting the maximum yield of root fresh and dry weight per hectare and the maximum total phenolic and antioxidant contents per herb in both cuts of both studied season. The first major compound of lovage essential oil of herb is α-terpinyle acetate followed by β-Phellandrene. The percentages of these compounds were affected by the applied treatments. The volatile oil of lovage plant exhibits high antibacterial and antifungal properties in the concentrations range of 75–100 µg mL^?1.     

Simultaneous determination of eight bioactive alkaloids in Corydalis saxicola by high-performance liquid chromatography coupled with diode array detection

Corydalis saxicola Bunting (Papaveraceae), a traditional folk medicine, has been used to treat hepatic diseases for a long time. Owing to its signicant clinical effectiveness against hepatitis, cirrhosis and hepatoma, C. saxicola and its preparation are widely applied. In this study, eight alkaloids, namely isocorydine, scoulerine, dehydrocheilanthifoline, dehydrodiscretamine, dehydroisoapocavidine, dehydrocavidine, palmatine and berberine, which have been previously proven to possess potential antitumour activity, were selected as the chemical markers of C. saxicola. To evaluate the quality of C. saxicola, a simple, accurate and reliable HPLC-DAD method was developed for the simultaneous determination of the above eight compounds. Separation was achieved on a Gemini C(18) column (5 microm, 250 x 4.6 mm i.d., Phenomenex Inc., CA, USA) with a gradient solvent system of 20 mM aqueous ammonium acetate-acetonitrile, at a flow-rate of 1.0 mL/min and detected at 270 and 280 nm. All eight calibration curves showed good linearity (R(2) > 0.9992). The method was reproducible with intra- and inter-day variations of less than 5%. The recovery was in the range of 96.09-102.80%. This assay was successfully utilised to quantify the eight alkaloids in C. saxicola from different locations. The results demonstrated that this method is simple, reliable and suitable for the quality control of this medicinal herb.     

The effect of a rosette-crown fly, Botanophila turcica, on growth,biomass allocation and reproduction of the thistle Carthamus lanatus

Plant growth and reproductive output of the winter annual invasive thistle, Carthamus lanatus was characterised in relation to plant size in three native populations in southern France. The effects of the rosette-crown feeding fly Botanophila turcica on these plant characteristics were assessed by comparing unattacked with naturally attacked plants at each site and by a field experiment. Indirect effects of B. turcica on plant seed production were also compared with direct seed loss caused by a guild of capitulum-feeding insects that incidentally attacked the marked plants at these sites. C. lanatus showed no size or weight requirement for flowering, but larger flowering plants produced less total receptacle surface and less seed production (female reproductive potential) in proportion to plant weight than smaller flowering plants. B. turcica did not select hosts on the basis of size or density. B. turcica reduced plant relative growth rate (RGR) in all situations, but attacked plants compensated fully at two of three sites as attack failed to halt rosette growth. Attacked plants suffered 12 % mortality, and 71 % lower seed production than unattacked plants at the site with the lowest RGR. This corresponded to 9 % lower seed production for the whole thistle population compared to 8.6–19.5 % direct seed loss to capitulum insects across all sites.     

High-frequency embryogenesis and regeneration of plants with high content of gentiopicroside from the Chinese medicinal plant Gentiana straminea Maxim.

Gentiana straminea Maxim. (MahuaQinjiao) is an important Chinese medicinal herb that is rich in secoiridoids. To increase the production of this plant, we have developed an efficient tissue culture system for high-frequency plant regeneration. We have also obtained plants with high secoiridoid monomer production through tissue culture and somatic embryogenesis. We have found that the MB medium is better than the B5 medium for callus induction. Calluses induced from immature seeds are superior to those from hypocotyls or young leaves in regeneration via somatic embryogenesis. We have also demonstrated that 2,4-dichlorophenoxyacetic acid is efficient for both callus induction and embryogenesis, indole-3-acetic acid is suitable for embryogenic callus proliferation, and N ⁶-(benzyl)-adenine promotes both embryo development and the accumulation of gentiopicroside in the cultures. Regenerated plants have been selected for high gentiopicroside content. One plant contains 5.82% of gentiopicroside, which is higher than the control plants (1.20–3.73%). The regenerated plants are genetically more stable than the calluses based on both cytological and random amplified polymorphic DNA analyses.     

The potential of Thlaspi caerulescens for phytoremediation of contaminated soils

Uptake of Cd, Zn, Pb and Mn by the hyperaccumulator Thlaspi caerulescens was studied by pot trials in plant growth units and in populations of wild plants growing over Pb/Zn base-metal mine wastes at Les Malines in the south of France. The pot trials utilised metal-contaminated soils from Auby in the Lille area. Zinc and Cd concentrations in wild plants averaged 1.16% and 0.16% (dry weight) respectively. The unfertilised biomass of the plants was 2.6 t/ha. A single fertilised crop with the above metal content could remove 60 kg of Zn and 8.4 kg Cd per hectare. Experiments with pot-grown and wild plants showed that metal concentrations (dry weight basis) were up to 1% Zn (4% Zn in the soil) and just over 0.1% Cd (0.02% Cd in the soil). The metal content of the plants was correlated strongly with the plant-available fraction in the soils as measured by extraction with ammonium acetate and was inversely correlated with pH. Bioaccumulation coefficients (plant/soil metal concentration quotients) were in general higher for Cd than for Zn except at low metal concentrations in the soil. There was a tendency for these coefficients to increase with decreasing metal concentrations in the soil. It is proposed that phytoremediation using Thlaspi caerulescens would be entirely feasible for low levels of Cd where only a single crop would be needed to halve a Cd content of 10 g/g in the soil. It will never be possible to remediate elevated Zn concentrations within an economic time frame (<10 yr) because of the lower bioaccumulation coefficient for this element coupled with the much higher Zn content of the soils.     

Does endophyte influence resource acquisition and allocation in defoliated tall fescue as a function of microsite conditions?

Tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] often benefits in terms of productivity and persistence when infected with Neotyphodium coenophialum ([Morgan-Jones and Gams], Glenn, Bacon, and Hanlin) endophyte, but the influence of novel non-ergogenic endophytes is unclear. We conducted a field experiment using container-grown tall fescue plants to determine how plants allocated resources when clipped repeatedly in microsites differing in the amount of available light associated with open (full sun), and partially shaded (about 20 or 40% of full sun) conditions. Plants of the same tall fescue cultivar (Jesup) were host to either a native or novel non-ergogenic fungal endophyte (MaxQ™), or were devoid of endophyte. Seedlings of plants infected with the novel endophyte had slower germination, germinated later, and allocated more photosynthate to shoots than roots, when compared to J− or J+ plants. Herbage production of undisturbed canopies was not influenced by host–endophyte association within a microsite, with more herbage produced at the open than at the heavily shaded site. Clipping plants to a 5- or a 10-cm residue height tended to accentuate differences, with diminished productivity and greater variability occurring when plants were maintained at 5 cm. This trend was supported by allometric resource allocation patterns, and in terms of vegetative propagule mass relative to the number of propagules. Tall fescue, irrespective of host–endophyte association, grown as forage in silvopastoral situations should be managed to maintain no less than a 10-cm residual plant height. Trends in photosynthate allocation and plant size might influence persistence and should be investigated for more than two growing seasons.