钾肥减量分期施用对莴笋产量和品质的效应研究

通过大田试验研究了紫色菜园土壤钾肥减量分期施用对莴笋产量和品质的影响。结果表明：两个试验点钾肥减量10%~30%分期施用对莴笋产量有提高作用，各处理以K2（钾肥减量10%分期等量追施）效应最好，增产最大（4.2%和4.5%）、施肥利润最高（84923元/hm²和72075元/hm²）。两个试验点莴笋叶维生素C含量均呈下降趋势，K2处理较常规施肥(CK)处理均显著降低莴笋叶维生素C含量（8.0%和8.7%）；而莴笋茎维生素C含量变化规律不一致。钾肥减量分期施用降低两个试验点莴笋叶和茎硝酸盐含量，以K4处理（钾肥减量30%分期等量追施）降低作用最大；从莴笋叶和茎糖组分的均衡性看，以K3处理最好。钾肥减量分期施用对两个试验点莴笋叶必需氨基酸含量有显著增加作用，改善叶氨基酸品质性状，但降低莴笋茎必需氨基酸含量和品质性状；莴笋氨基酸品质性状以K4处理为最优，其次是K2处理。综合考虑莴笋产量和品质，紫色菜园土壤以K2处理（钾肥减量10%分期等量追施）最优。     

莴苣花叶病毒北京分离物基因组3′末端序列分析

笔者通过RT-PCR方法对LMV北京分离物（LMV-BJ）基因组3＇端1620nt的核苷酸片段进行了克隆和序列分析（GenBank登录号为EF423619）。所获片段含有NIb基因3＇端的574nt,编码NIb C-端190个氨基酸;完整的CP基因,全长为834nt,编码一个由277个氨基酸组成的分子量约为30kDa的结构蛋白;3＇非编码区含有209nt。通过序列分析软件将LMV-BJ与已经报道的法国分离物O（X97704）、法国分离物E（X97705）,美国分离物（X65652）,巴西分离物（AJ278854）和余杭分离物（AJ306288）基因组3＇末端和CP基因的核苷酸序列与氨基酸序列分别进行了比较。     

Novel pathotypes of lettuce mosaic virus — breakdown of a durable resistance?

Summary Resistance to lettuce mosaic virus (LMV) is derived either from cv. Gallega (g gene) or the wild accession PI251245 (mo gene). Previous studies indicated that these two genes were identical. Breeders in Europe produced numerous resistant cultivars utilisingg while in the USAmo was used. The resistance has been effective for over 20 years. However, recently there have been reports of LMV isolates causing unusually severe and sometimes necrotic symptoms on cultivars with these resistance genes. Investigations of these severe isolates have distinguished three new pathotypes in addition to the common pathotype (II) and identified a novel dominant gene for resistance. Themo/g genes confer resistance to pathotypes I and II but pathotype III possesses virulence for cultivars withg but not for those withmo. These two genes are therefore not identical but are probably either closely linked genes or alleles. Pathotype IV possesses virulence for all lettuce lines so far tested. Some isolates of this pathotype are seed transmitted in cultivars possessingmo org and have caused severe crop losses in southern France. The durability of the resistance conditioned by these two genes is discussed.     

生菜叶片光谱红边参数对氮营养的响应特征分析

以不同氮素供应水平下的水培生菜为研究对象,采用光谱仪和叶绿素仪分别获得生菜叶片的漫反射光谱信息和叶绿素含量,通过提取生菜叶片光谱的红边参数,分析不同氮素供应水平下红边参数的变化规律,以及各个红边参数与生菜叶片叶绿素含量间的关系.结果表明,随氮营养供应水平的提高,生菜叶片各红边参数呈现不同的响应趋势.红边位置、最小振幅、红边面积以及红边振幅和最小振幅比值与生菜叶片SPAD值间均具有极显著的相关关系,其中以红边位置的相关程度最高,其相关系数为0.9420,均方根误差为1.803.可见,红边位置可以作为生菜叶片氮素营养诊断的一种有效指标.     

叶用莴苣抗氧化物及其生物活性研究进展

叶用莴苣(Lactuca sativa L.)又名生菜,富含多酚化合物、抗坏血酸、类胡萝卜素、VE等高活性抗氧化物质。本文从生菜抗氧化活性物质的组分及含量、抗氧化活性评价及抗氧化机理、外界因素对生菜抗氧化物的影响等方面综述了生菜抗氧化研究领域近年来的研究成果,并对未来研究方向进行了展望。     

不同土壤和氮钾肥配比对莴笋的营养效应研究

通过田间小区试验研究了不同N、K肥料配比对酸性和碱性土壤上两个莴笋品种(科兴 3 号和双尖莴笋)产量及品质的影响.结果表明,不同土壤上施用不同N、K配比肥料对双尖莴笋和科兴 3 号的产量影响不同.在酸性土壤上,对照(N15K10)是适宜两种莴笋高产的最佳N、K肥配比处理.在碱性土壤上种植双尖莴笋时,可以考虑在对照基础上适当地降低N肥用量.在碱性土壤上两种莴笋的产量均高于酸性土壤.减N和增K处理有利于降低莴笋的硝酸盐含量.在酸性土壤上莴笋中的硝酸盐含量高于碱性土壤.莴笋采收后期茎的硝酸盐含量高于叶片.不同施肥处理对两种土壤上科兴3号和双尖莴笋营养品质的作用不一致.在酸性土壤上增施K肥或提高N肥的用量对莴笋营养品质的改善更有效果.莴笋的Vc含量以叶片＞茎,且酸性土壤＞碱性土壤.除双尖莴笋在增K处理(N15K15、N20K15)中茎的可溶性糖含量表现为酸性土＜碱性土以外,其他处理莴笋茎叶中的可溶性糖均为酸性土＞碱性土.不同处理莴笋的氨基酸含量均表现为茎＞叶.     

Potential of Trichoderma spp. as consistent plant growth stimulators

In a series of repeated trials, six Trichoderma spp. strains, applied as a dried powder from a liquid fermentation in molasses/yeast medium, proved to be consistent at promoting the growth of lettuce (Latuca sativa L.) seedlings grown in a peat-sand potting compost in the glasshouse. Strains WT, 92, 20, and 75 at 0.75% or 1% w:w concentrations increased shoot dry weight by up to 26%, although WT did inhibit germination. For example, after 4 days only 13% of seeds sown in WT 1% w:w treated compost had germinated, whereas in other treatments germination was consistently greater than 32%. WT increased shoot fresh and dry weights by 14.3 g and 0.6 g per pot, respectively, without affecting the root dry weights, to give concomitant increases in shoot: root ratios of fresh and dry weight. The potential use of these Trichoderma spp. strains for plant growth promotion is discussed.     

生物复混肥施用量对土壤养分及作物生长的影响

通过盆栽试验,以等养分量的有机无机肥做对照,研究了生物复混肥施用量对土壤有效N、P、K含量及玉米和油麦菜生长的影响.结果表明:生物复混肥的施用可以显著提高土壤有效N、P、K含量;施 N 量为 0.1 g/kg土的生物复混肥处理可以显著提高玉米和油麦菜的 N、P、K 吸收量及玉米的生物量.     

连续光照及光质对水培生菜生长及营养品质的影响

以罗马生菜为材料,研究在不同LED光质下采前连续光照24、48、72 h对生物量和营养品质的影响。结果表明,连续光照24 h后,生菜叶片中硝酸盐含量大幅下降,随着连续光照时间的增加,硝酸盐含量趋于稳定。地上鲜重、可溶性糖、VC含量在连续光照48 h后增幅最大,之后趋于稳定。可溶性蛋白含量随连续光照时间的增长而轻微下降。R/B=4、连续光照48 h对生菜生物量及营养品质的提高效果最好。     

不同浓度钾素对莴苣产量与品质的影响

试验以莴苣为试验材料,采用通用随机排列设计,利用基质培方法,研究不同供应水平的钾素营养对莴苣产量和品质的影响。结果表明：在供试条件下,硝酸盐含量随着钾素浓度的增大而降低,产量及各项品质指标随着钾素浓度的增大而增加。