小麦、蚕豆和油菜对向日葵列当种子萌发的影响

通过盆栽试验和水培试验的方法在不同地区分别种植小麦、蚕豆和油菜3种作物,研究这3种作物的甲醇浸提液以及根系分泌物对向日葵列当种子萌发的影响。结果显示,小麦和蚕豆植株的根部甲醇浸提液以及根系分泌物对向日葵列当种子的萌发有较强的刺激作用,其中小麦甲醇浸提液处理的向日葵列当种子萌发率最高(41.5%)。蚕豆植株的甲醇浸提液和根系分泌物也对向日葵列当种子萌发有较强的影响,其中蚕豆根系分泌物处理向日葵列当种子的萌发率高达41.1%。综合得出,小麦和蚕豆的根部可能含有刺激向日葵列当发芽的物质,具有作为向日葵列当诱捕作物的可能性。     

多功能列当生防镰刀菌的筛选及种类鉴定

从河北省张家口地区种植的烟草上采集的感病弯管列当植株,从中分离得到20株镰刀菌,采用孢子悬浮液浸根和灌根法对小麦、玉米、棉花、向日葵、番茄、烟草、辣椒、茄子、西瓜、甜瓜等作物和蔬菜进行了安全性检测,筛选出对主栽作物和蔬菜安全且具有促生作用的4个菌株。其中菌株Br-2对烟草、辣椒、西瓜有显著促生作用,且对弯管列当的防治效果最好：施用菌株Br-2后烟草、辣椒、西瓜增高分别为123.53%、62.16%、28.95%;其发酵上清液对弯管列当种子萌芽抑制率为71.79%;小区试验中对弯管列当的寄生率防效为50%,寄生度防效为79.38%;田间试验中对弯管列当的寄生率防效为58.27%,寄生度防效为75.70%。形态学和分子生物学鉴定结果表明菌株Br-2为尖孢镰刀菌。     

Direct infection of potato tubers by the root parasite Orobanche aegyptiaca

Parasitic plants of the Orobanchaceae are known as obligate root parasites that develop haustoria that connect to roots of various host plants. This article describes, for the first time, a case where the root parasite successfully connected to potato tubers, i.e. to the swollen portion of an underground stem rather than to a root. The rhizosphere of Orobanche aegyptiaca and of its host Solanum tuberosum (potato) was carefully examined. In anatomical studies, the adventitious roots were directly connected to potato tubers. Numerous secondary haustoria, which developed along the adventitious roots in close vicinity to the potato tuber, penetrated the tuber epidermis and the perimedullary tuber parenchyma and developed xylem strands that are presumably connected to the minor xylem strands within the tuber cortex. These findings indicate that parasites of the Orobanchaceae that normally attack host roots may also parasitise underground stem tubers.     

Seed viability determination in parasitic broomrapes (Orobanche and Phelipanche) using fluorescein diacetate staining

Fluorescein diacetate (FDA) was investigated as a potential viability stain for seeds of holoparasitic broomrapes Orobanche and Phelipanche (Orobanchaceae), using four weedy and two non-weedy taxa. FDA viabilities were compared with the currently used 2,3,5-triphenyl tetrazolium chloride (TTC) test, and in vitro germination induced by the strigolactone analogue GR-24. Viable FDA-stained seeds were characterised by bright yellow–green fluorescence under 450–490 nm blue light. These viable seeds could be discriminated from non-viable seeds, in which low levels of fluorescence, similar to non-stained control seeds were observed. FDA viabilities were not significantly different from those obtained using the TTC stain; however, viability values for both stains were consistently higher than levels of artificially induced germination. Positive TTC-staining showed continuous variation that was difficult to interpret. Nevertheless, the TTC test does not involve grinding seeds, and therefore probably remains a practical alternative to FDA for screening soil samples contaminated with Orobanche and Phelipanche seeds, which indicates different applications for the two viability tests. Interestingly, the strigolactone analogue GR-24 only induced germination in O. crenata , P. ramosa and O. minor , suggesting a high specificity towards this germination inducer among the species investigated. We suggest that FDA-staining provides a potential alternative to the currently used TTC test for seed viability assays for Orobanche and Phelipanche , and other parasitic weeds which are an obstacle to crop cultivation.     

Selection in Faba Bean for Tolerance to Broomrape, Orobanche crenata Forsk.

Six populations of faba bean (Vicia faba L.) were developed through various selection schemes to examine the influence of selection In improving tolerance to Orobanche crenata (Forsk.) in local faba bean stocks. All populations trace their origin to 209 farmers’ seed lots that were collected from Egypt. The entries of each population were grown during the 1982/1983 season in the Orobanche nursery located at Giza in Egypt. Comparison among means of the selected, populations showed that more progress in improving Orobanche tolerance could be achieved from combined selection between and within lots. Between-lots selection was less efficient than single-plant selection. Results, of this study show that considerable progress could be achieved from selection for Orobanche tolerance in local faba bean germplasm. There was sufficient residual genetic variation in the selected populations to expect substantial progress from further selection for most tolerance traits.     

Tolerance of parsley varieties to Orobanche

Parasitic plants infest numerous plants throughout the world depleting them of nutrients, minerals and water. Orobanche species are chlorophyll-lacking root holoparasites that cause severe damage to broad-leaved crops. Orobanche aegyptiaca and Orobanche crenata parasitize field, vegetable, fodder, flower and herb crops in the Mediterranean region. Curled parsley (Petroselinum crispum), a major crop in the dry herb industry in Israel, is highly susceptible to O. aegyptiaca and O. crenata and in infested fields suffers severe yield and quality damage. An in vitro study in polyethylene bags, greenhouse experiments in soil-filled pots and trials in a naturally Orobanche-infested field were performed in order to screen and test for differential susceptibility of parsley varieties to O. aegyptiaca and O. crenata. Results revealed that the parsley varieties Garland and Garbo were tolerant to Orobanche compared to the susceptible varieties Darki, Extra Triple and Kaderava.     

R-41, a sunflower restorer inbred line, carrying two genes for resistance against a highly virulent Spanish population of Orobanche cernua

The inheritance of resistance to a highly virulent population of sunflower broomrape (Orobanche cernua) has been studied in R-41, a Spanish sunflower restorer inbred line. Using the cytoplasmic male-sterile inbred line HA-89 (cms; very susceptible to this population of broomrape) as a female parent, progenies of the cross with R-41, i.e. Fl, F2 and BC1 to both parents, as well as the parental lines, were analysed for their reaction to the broomrape population EC-94. The goodness of fit of the observed vs expected segregation ratios indicated that the inheritance of resistance to broomrape in line R-41 is conferred by two independent dominant genes.     

Effects of Broomrape Parasitism on Sunflower Plants: Growth,Development, and Mineral Nutrition

Sunflower broomrape (Orobanche cumana Wallr.) is a parasitic plant that infects sunflower (Helianthus annuus L.) plants. In this work, sunflower plants were grown under greenhouse conditions in pots with the substrate infested or non-infested with broomrape seeds. At different numbers of days after sowing, plant height, internode lengths, number of leaves, head diameter, mineral composition of leaves, and potassium (K) concentration in stem were measured. The negative effects of broomrape parasitism were assessed from 57 d after sowing, when broomrape started to emerge. Parasitized plants exhibited lower shoot dry weight, height, and head diameter than control plants. The reduction in internode lengths was associated with a decrease in the gradient of K concentration from basal to apical stem. The mineral composition of leaves was also affected in parasitized plants. The concentrations of calcium (Ca), magnesium (Mg), manganese (Mn), and zinc (Zn) in leaves of parasitized plants were lower than those of the control plants, while there were few differences for K, phosphorus (P), iron (Fe), and copper (Cu). The effects of parasitism are discussed in relation to their competition for resources and to perturbations of the host physiology such as hormonal and water balance.     

列当杂草及其防除措施展望

根寄生杂草列当Orobanche spp.每株可产生大量细小的种子,易于传播,且在出苗前已经对寄主作物造成危害,使列当的防除成为一个世界性难题。本文详述了列当的生活史、为害现状以及防除措施,并突出了生物防除的生态效益与经济效益。基于＂诱捕＂作物及＂捕获＂作物诱导列当种子＂自杀发芽＂理论的防除机制,本文提出了新型可持续生态防除思想,为列当科杂草防除提供参考。     

Three<Emphasis Type="Italic">Orobanche</Emphasis> species newly found on crops in israel

Orobanche amethystea Thuill.,O. loricata Reichenb. andO. pubescens D’Urv. were found to parasitize the roots of cultivated plants in Israel.Orobanche pubescens is known from the local flora, and was now found to cause damage in parsley fields and toTropaeolum majus L. (nasturtium) in ornamental gardens.Orobanche amethystea andO. loricata are known as occasional weeds in Europe and were recently found for the first time in Israel.Orobanche amethystea densely populated vetch fields in Israel, andO. loricata was found in ornamental gardens. A key for the identification ofOrobanche species in cultivated areas in Israel is given, based on morphological features. http://www.phytoparasitica.org posting Jan. 13, 2002.