Effects of inoculum density,leaf wetness duration and nitrate concentration on the occurrence of lettuce leaf spot     

Masahiro Nao 《Journal of General Plant Pathology》2008,74(3):208-212

In Ehime Prefecture, Japan, lettuce leaf spot (Septoria lactucae) caused huge losses in marketable lettuce yields. To explore potential measures to control disease outbreaks, the effects of inoculum density, leaf wetness duration and nitrate concentration on the development of leaf spot on lettuce (Lactuca sativa) were evaluated. Conidia were collected from diseased plants in an infested field by single-spore isolation and were used to inoculate potted lettuce plants with different conidial concentrations. Lesions developed on inoculated lettuce plants at inoculum concentrations from 10⁰ to 10⁶ conidia/ml. The disease was more severe when the inoculum exceeded 10² conidia/ml, and severity increased with increasing concentrations. Assessment of the relationship between disease development and the duration of postinoculation leaf wetness revealed that symptoms appeared when the inoculated plants remained wet for 12 h or longer. The number of lesions and total nitrogen content in the lettuce leaves both increased when nitrate was applied.  相似文献   

Accumulation and Primary Metabolism of Nitrate in Lettuce (Lactuca Sativa L. Var. Youmaicai) Grown Under Three Different Light Sources     

Hui Liu  Yuming Fu  Juan Yu 《Communications in Soil Science and Plant Analysis》2016,47(17):1994-2002

Light-emitting diodes (LEDs) hold great potential as electric light source for leafy vegetable production in controlled environment. However, most of LED lights in vegetable cultivation were only combined with red and blue LEDs, and the spectral composition was oversample. Previous studies reported that light spectral composition could influence nutritional quality of vegetables, e.g., nitrate content. In order to better understand the influence of spectral composition on nitrate accumulation of leafy vegetables grown in closed-type system. The nitrate content, nitrate primary metabolism of 35-day-old lettuce (Lactuca sativa L. Var. youmaicai) in vivo and its biomass were investigated. The results showed that cool white fluorescent light (T5) and high-pressure sodium light (HPS) with wide spectrum significantly reduced nitrate content in lettuce than red and blue combination LED light (RB-LED) treatment. Our findings demonstrated that a proper optimizing procedure of light spectrum with supplemental other wavebands in RB-LEDs is necessary for reducing nitrate accumulation of lettuce.  相似文献   

叶用莴苣富硒效果影响的研究   总被引：1，自引：1，他引：0       下载免费PDF全文

许晓宁韩莹琰  范双喜郝敬虹郭婉香  韩亚文 《农学学报》2014,4(5):70-73

对‘射手101’、‘大像生一号’、‘美国大速生’3种叶用莴苣的富硒效果进行比较。分别采用叶面喷施浓度梯度为7.5、15.0、22.5 g/hm2的硒酸钠与亚硒酸钠溶液,进行1次或2次叶面喷施,利用原子荧光光谱仪标准曲线法测量硒含量。结果显示：不同浓度的2种硒源均可以提高3种叶用莴苣含硒量。其中,浓度为22.5 g/hm2的亚硒酸钠富硒效果最好。喷施1次,‘射手101’效果最佳,含硒量为(11.33±1.52753) μg/100 g。喷施2次,‘大像生一号’效果最佳,含硒量为(14.33±0.5774) μg/100 g,约为喷施1次时含硒量(4.87±0.3215) μg/100 g的3倍。  相似文献   

外源水杨酸对镉毒害下莴苣种子萌发的缓解效应   总被引：6，自引：0，他引：6  

任艳芳  何俊瑜  黄天兴  罗辛灵 《华北农学报》2009,24(Z2)

重金属Cd作为毒性较高的环境毒物,不仅危害植物的生长和发育,也对人类健康带来严重威胁.水杨酸(Salicylic acid,SA)作为一类新型植物生长调节物质,在诱导植物抗性方面起重要调节作用.以莴苣笋王一号为试验材料,研究了不同浓度SA处理对cd胁迫下莴苣种子萌发的效应及其生理机制.结果表明,Cd胁迫条件下,莴苣种子萌发受到影响,表现为发芽势、发芽指数、活力指数和根长明显降低.Cd胁迫还可引起氧化胁迫产生,并造成膜脂过氧化伤害.不同浓度SA对Cd胁迫下莴苣种子萌发和幼苗生长的缓解作用不同,表现为低促高抑效应;以0.1mmol/L的SA效果最好.SA处理能缓解Cd对种子萌发和幼苗生长的伤害与植株体内CAT、APX、SOD和GPX等抗氧化酶活性变化有关.  相似文献   

The overexpression of asparagine synthetase A from E. coli affects the nitrogen status in leaves of lettuce (Lactuca sativa L.) and enhances vegetative growth     

Donato Giannino  Chiara Nicolodi  Giulio Testone  Giovanna Frugis  Emanuela Pace  Pietro Santamaria  Mauro Guardasole  Domenico Mariotti 《Euphytica》2008,162(1):11-22

  相似文献   

Ultralow oxygen treatment for postharvest control of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), on iceberg lettuce: II. Effects of pre-treatment storage on lettuce quality     

Yong-Biao Liu   《Postharvest Biology and Technology》2008,49(1):135-139

Iceberg lettuce stored under normal atmosphere and controlled atmosphere (CA) with about 3% oxygen at low temperature for 1 week was compared with fresh lettuce for their response to 2 d ultralow oxygen (ULO) treatment with 0.003% oxygen at 10 °C for control of western flower thrips. Lettuce which had been stored for 1 week under normal or CA tolerated ULO treatment while over 30% of fresh lettuce sustained minor injury to heartleaves. Therefore, pre-treatment storage at low temperature enhanced tolerance of lettuce to the subsequent insecticidal ULO treatment. A sequential combination of CA storage and ULO treatment was demonstrated to be effective against western flower thrips and lettuce aphid and safe to all seven lettuce cultivars tested. The study indicated that ULO treatment can be made safer to lettuce through pre-treatment storage to increase lettuce tolerance.  相似文献   

Effect of synthetic nano-hydroxyapatite as an alternative phosphorus source on growth and phosphorus nutrition of lettuce (Lactuca sativa L.) plant     

Mehmet Burak Taşkın  Özge Şahin  Havva Taskin  Orhan Atakol  Ali Inal 《Journal of plant nutrition》2018,41(9):1148-1154

Phosphorus (P) is one of the least available mineral nutrients to the plants in calcareous and alkaline soils. In this study, we investigated the synthesis, characterization and use of synthetic nano-hydroxyapatite (NHA), P uptake by plants as well as its residual effects. Soluble P source (H₃PO₄) was also included as treatment for comparison. NHA prepared by wet chemical techniques, characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and elemental dispersive X-ray (EDX) analysis. NHA and H₃PO₄ were applied at a rate of 200 mg kg^?1 to find out their effects on phosphorus nutrition and growth of lettuce on the low and high calcareous soil. In addition to this, residual effects of NHA and H₃PO₄ were also determined for lettuce plants grown after first lettuce plants in the both soil. Dry weights of the first and second lettuce plants grown in low and high calcareous soil were significantly increased by applied phosphorus regardless of the source. NHA seems to be more effective than that of ordinary phosphorus source (H₃PO₄-P) on growth and P concentration of the lettuce plants. The promising results of this study needs to be supported with long term field studies regarding the uptake, translocation and interactions of nano-P with the other elements.  相似文献   

生菜种植温度控制系统的设计     

方婷  叶明  周平 《安徽农业科学》2017,45(32):216-220

为实现冬季寒冷条件下生菜的正常生长,以STM32F103嵌入式单片机为核心控制器,结合DS18B20温度传感器、4×4矩阵按键、TFT液晶显示屏以及光警报器等外围器件,设计了一个温度智能控制系统。  相似文献   

浒苔制作有机肥研究   总被引：3，自引：1，他引：2  

黄连光  石艳玲  徐中平 《安徽农业科学》2010,38(23):12888-12890

[目的]摸索以浒苔为原料制作有机肥的技术条件,观测其施用效果。[方法]以浒苔为主料,用不同比例的秸秆、鸡粪、污泥调整含水量、有机质和碳氮比进行堆肥发酵,观测、比较堆肥温度变化、有机质和N、P、K含量及卫生学等指标。在作物栽培试验中,观测浒苔有机肥对种子发芽、盆栽和田间生菜生长的影响。[结果]单独用浒苔为原料制作有机肥,总养分含量偏低,而用麦草、鸡粪、污泥和浒苔混合堆肥时,总养分含量提高,且产品中有害元素含量符合国家标准。浒苔含量不超过50%,经调配使有机质、含水量、碳氮比分别控制在35%、55%和30左右,该条件下的堆肥产物对种子发芽无明显毒性,并可显著促进生菜生长。[结论]以浒苔为主料制作的有机肥促进作物生长效果显著。  相似文献   

不同昼夜温度对水培生菜生长和品质的影响   总被引：2，自引：0，他引：2  

严妍  雷波  汪力威  别之龙 《长江蔬菜》2010,(24):39-42

利用人工气候箱研究了3种不同昼温（20℃/15℃,25℃/15℃和30℃/15℃）和夜温（30℃/25℃,30℃/20℃和30℃/15℃）对生菜生长和品质的影响。结果表明,随着昼温的升高,生菜的叶片数、地上部干鲜质量、根干鲜质量、叶面积等均显著增加。30℃条件下,茎长/茎粗的值显著增大,但并未造成抽薹现象,不影响生菜的商品性。综合昼温对水培生菜产量和品质的影响,昼温保持在25~30℃较为适宜。相对昼温,夜温对生菜生长影响较小。夜温从20℃降低到15℃,生菜地上部干鲜质量、根干鲜质量、叶片数和叶面积均无显著性变化,较低的夜温有助于抑制抽薹的发生,有利于提高生菜品质。  相似文献