Occurrence, purification and properties of narcissus tip necrosis virus

Narcissus tip necrosis virus (NTNV), a previously undescribed virus, was detected in the Netherlands and the United Kingdom in plants of twenty-one cultivars of trumpet, large-cupped, small-cupped, double, tazetta and poeticus narcissus. In some cultivars distinct leaf symptoms were sometimes associated with infection but in others infected plants remained symptomless and detection was dependent on serological tests. The virus was readily transmitted by manual inoculation to narcissus, but it failed to infect any of forty-six other plant species from fourteen families. Up to 50 mg of virus/kg of tissue were obtained by differential centrifugation of narcissus leaf extracts previously clarified with either diethyl ether, n-butanol or a mixture of n-butanol and chloroform. The virus particles are isometric, c. 30 nm in diameter, have a sedimentation coefficient (^s°₂₀ w) Of 123 S a buoyant density of 1·356 g/cm³, migrate as a single component in polyacrylamide gel electrophoresis, and contain a single RNA species of mol. wt 1·6×10⁶ and two major polypeptides of mol. wt 42000 and 39000. Although NTNV resembles tombusviruses it showed no serological relationship to the type member or six putative members of this group or to thirty-four other viruses with isometric particles. Its present cryptogram is R/*:1.6/(18):S/S:S/*.     

Control of smoulder (Botrytis narcissicold) in narcissus with fungicides

Smoulder, caused by Botrytis narcissicola, is the most widespread foliar disease of narcissus (Narcissus cultivars) in the UK and causes significant losses in bulb and flower yield. A range of current and novel fungicide treatments was examined to determine if control of the disease could be improved and to measure the effect of treatments on bulb yield. In assays on pot-grown plants, carbendazim+flusilazole, epoxiconazole, iprodione + thiophanate-methyl, tebuconazole and vinclozolin reduced lesion size by more than 90%, compared with untreated plants, when applied 1 day before inoculation with the fungus; vinclozolin and tebuconazole were also effective when applied 2 days after inoculation. In field experiments in Cambridgeshire and Lincolnshire, significant reductions were observed in secondary smoulder symptoms (leaf lesions and stem rot) following fungicide sprays. Spray programmes of the novel fungicides azoxystrobin, cyprodinil, kresoxim-methyl, tebuconazole and pyrimethanil were as effective, or more so, than the standard treatments (chlorothalonil, vinclozolin) used by growers. Mixtures of carbendazim + tebuconazole and azoxystrobin + tebuconazole also gave effective control of smoulder. Programmes of four to six sprays, using two or three fungicides with different modes of action, applied alternately, reduced smoulder by 35–69% and increased bulb yields by 7–59%. Although treatment around and after flowering resulted in the greatest control of secondary smoulder, treatment before flowering was required for the highest bulb yields. The choice of fungicides for use in spray programmes to provide effective and reliable control of smoulder, and the possibility of control using fewer sprays, are discussed.     

Some hosts and properties of narcissus latent virus, a carlavirus commonly infecting narcissus and bulbous iris

Narcissus latent virus (NLV) is common in many cultivars of narcissus and bulbous iris, but was detected in only one of nineteen cultivars of nerine. It induced symptoms in some narcissus cultivars, but inconspicuous infection in bulbous iris and nerine. NLV was not seed-borne in narcissus or Nicotiana clevelandii but was transmitted readily by aphids (Acyrthosiphon pisum, Aphis gossypii and Myzus persicae) in the non-persistent manner and by sap-inoculation to twelve of fifty-three species from three of sixteen families. Sap from N. clevelandii was infective after dilution to io^-3 but not io*, after 10 min at 65 but not 70 ^oC or after 3–4 days at 20 ^oC or 16–32 days at 2 ^oC. Purified virus preparations were obtained from infected N. clevelandii by clarification of buffered leaf extracts with diethyl ether and carbon tetrachloride, followed by one or two cycles of differential centrifugation and molecular permeation chromatography. NLV has filamentous particles c. i3times65onm which sediment as a single component (i^o_{20, w}= 156S). They contain c. 5% nucleic acid and a single polypeptide of mol. wt 32·6 × 10³. The biological and physical properties of NLV place it in the carlavirus group; it is serologically related to lily symptomless virus, but not to fourteen other authentic carlaviruses. NLV has the cryptogram */*:*/(5):E/E:S/Ve/Ap.     

Vectoring of Pepino mosaic virus by bumble‐bees in tomato greenhouses

Pepino mosaic virus (PepMV) has become an important viral disease of greenhouse tomatoes worldwide. The ability of bumble‐bees (Bombus impatiens), used for pollination, to acquire and transmit PepMV was investigated, and the prevalence of PepMV in plants and bumble‐bees in commercial tomato greenhouses was determined. PepMV infection in plants was determined using enzyme‐linked immunosorbent assay, while in bumble‐bees direct real‐time PCR was used. In the first experiment, the bumble‐bees were exposed for 14 days to PepMV‐infected plants. After 14 days, almost all bumble‐bees were PepMV positive both in the hive (78.5 ± 17.5%) and in the flowers (96.3 ± 3.6%). In the second experiment, bumble‐bees were released into a greenhouse with both PepMV‐infected source plants and healthy non‐infected target plants for 14 days. At the end of the experiment, 61.0 ± 19.5% of the bees collected from the hive and 83.3 ± 16.7% of the bees sampled from the flowers were PepMV positive. Bumble‐bees transmitted PepMV from the infected to the healthy non‐infected tomato plants. Two weeks after bumble‐bee release, the virus was detected in leaf, fruit and flower samples of formerly healthy plants. After 6 weeks, the percentage of PepMV positive samples from the target plants increased to 52.8 ± 2.8% of the leaves and 80.6 ± 8.4% of the fruits. In the control greenhouse without bumble‐bees, the target plants did not become infected. Based on the infection levels in flowers, fruits and leaves, the PepMV infection occurred possibly first in the pollinated flowers, and then spread from the fruit that developed from the flowers to other parts of the plant. In commercial greenhouses where PepMV was present, 92–100% of the plants and 88–100% of the bumble‐bees were PepMV positive. No infected plant samples were found in the control commercial greenhouse, but a small number of bumble‐bees (10%) tested PepMV positive.     

Interrelations of Flowering and Vegetative Growth in Callistephus chinensis (var. Queen of the Market)

In a study of the effect of photoperiod upon the growth andflowering of Calistephus chinensis (var. Queen of the Market)it has been shown that a one-hour night break of low intensityred light given to plants growing in eight hours daylight canhave a number of morphogenetic effects. In the young plant, such a treatment increased the total areaof the leaf surface and the area per unit weight of leaf material,i.e. the specific leaf area. This effect enabled the treatedplants to make greater use of the incident light, for afternine weeks they were at least 25 per cent heavier than comparableplants which had not had the benefit of the night-break treatment.This treatment also caused flower induction and concomitantstem extension, but transfer back into eight-hour days afteran inductive period accelerated further flower development andrestricted stem extension of both the main axis and the laterals.If flower development was delayed by continuing night breaksor by delaying the onset of induction then more flowers wereeventually formed, but in the very prolific treatments flowersize was reduced. The experiment also indicated that the partition of availabledry weight between leaves, stems, and roots followed a definitepattern dependent only upon total plant dry weight. The diversionof dry weight into flowers was strongly accelerated by transferinto eight-hour days after induction but the remaining dry matterstill appeared to be distributed between the vegetative partsalong the general pattern determined by total vegetative weight. Finally the experiment showed that a wide range of plant formsbearing varying amounts of flowers could be obtained by appropriatetransfers between treatments.     

Temporal patterns of seed set and decelerating fitness returns on female allocation in Zigadenus paniculatus (Liliaceae), an andromonoecious lily

I describe temporal patterns of seed production in the andromonoecious lily Zigadenus particulatus. Fruit set per flower and seed set per fruit declined through time within plants. Hand pollination experiments showed that this was not due to increasing pollen limitation. Nutrient supplementation had little effect on seed output, but leaf clipping reduced seed production, especially in late-blooming flowers, and removal of early-blooming flowers increased seed set by later flowers. Thus, the temporal pattern of seed output was due to declining availability of photosynthates. Plants with larger bulbs produced larger inflorescences, a greater proportion of hermaphrodite flowers, more fruits per hermaphrodite flower, and more seeds per fruit, but lost a greater fraction of their initial bulb mass as a consequence of fruiting. After controlling for the effects of bulb mass, plants with larger inflorescences produced a greater proportion of male flowers, and plants with more hermaphrodite flowers produced fewer fruits per hermaphrodite flower and fewer seeds per fruit. Thus, the female fitness gain curve was decelerating. The temporal decline in seed output provides a partial explanation for the parallel decline in allocation to pistils. However, a complete explanation for the pattern of gamete packaging requires an understanding of factors controlling male, as well as female, fitness.     

Narcissus late season yellows potyvirus: symptoms, properties and serological detection

Narcissus late season yellows virus (NLSYV) was obtained, apparently unmixed with other viruses, in selected naturally infected narcissus plants. The virus was not transmitted by manual inoculation to any of the 12 herbaceous species tested but was transmitted by Myzus persicae to virus-tested narcissus plants, which then developed symptoms characteristic of late season yellows. Typically, symptoms develop late in the growing season but their expression is unreliable. NLSYV particles, which measured c. 750 ± 12 nm, were purified from fresh leaf extracts of narcissus in 0·3 m sodium citrate containing 10 mm sodium EDTA and 10 mm sodium DIECA by differential centrifugation followed by clarification with diethyl ether, gel filtration and isopycnic banding in caesium sulphate. Using antibodies from antisera prepared to virus particles, NLSYV was detected by ELISA in 14 of the 18 cultivars examined and nine seemed totally infected. Detection of the virus by immunosorbent electron microscopy was as sensitive as by ELISA but neither test detected all infections. The virus was detected by ELISA only in samples collected after flowering and capsid antigen concentration was greatest in the distal region of leaves. The reliability of detection depended on the cultivar. Immuno-electron microscopy tests confirmed the occurrence of a distinct potyvirus, presumably narcissus degeneration, in narcissus cv. Grand Soleil d'Or, failed to detect any virus other than NLSYV in narcissus plants affected by white streak disease, and showed that NLSYV is related to three of five other potyviruses tested.     

Composition of Carotenoids and Flavonoids in Narcissus Cultivars and their Relationship with Flower Color

Narcissus is widely used for cut flowers and potted plants, and is one of the most important commercial bulbous flowers in the floricultural industry. In this study, ten carotenoid and eighteen flavonoid compounds from the perianths and coronas of fifteen narcissus cultivars were measured by HPLC–APCI-MS/MS and UPLC-Q-TOF-MS/MS. Among these, six carotenoids, a total of seventeen flavonols and chlorogenic acid were identified in narcissus for the first time. A multivariate analysis was used to explore the relationship between flower color and pigment composition. We found that all-trans-violaxanthin and total carotenoid content were the main factors that affected flower color. These investigations could provide a global view of flower color formation and a theoretical basis for hybridization breeding in narcissus.     

Carotenoids in floral parts of a narcissus, a daffodil and a tulip

1. The qualitative and quantitative distribution of carotenoids of the floral parts of three monocotyledons, the narcissus Scarlet Elegance, the daffodil King Alfred and the tulip Golden Harvest, were studied. β-Carotene, lutein or epoxy-β-carotenes were usually the main pigments, depending on the floral part and on the flower. When β-carotene was the major pigment there were only small amounts of, or sometimes no, epoxycarotenes. 2. Anthers, stigmas and styles of the three flowers did not possess any specific carotenoids but in some cases contained appreciable amounts of epoxycarotenoids. The possibility that these take part in reproduction is discussed. 3. The generalization that yellow flowers contained large amounts of xanthophylls and only traces of carotenes, whereas deep-orange flowers seemed to be characterized by the presence of large amounts of one carotene, was not always the correct one. It is suggested that the floral parts are yellow or orange depending on what carotenoids are present, which is the major one and the amount of total carotenoids, and also on the presence of other non-carotenoid pigments. 4. Two new probable isomers of 5,6:5′,6′-diepoxy-β-carotene were isolated and found together in various floral parts of the tulip Golden Harvest.     

红光与远红光比值对温室切花菊形态指标、叶面积及干物质分配的影响

以切花菊品种‘神马’(Chrysanthemum morifolium Ramat ‘Jinba’)为试材,于2010-2011年设计不同红光(R: (660 ±10) nm)与远红光(FR: (730±10)nm)比值(R/FR分别为0.5、2.5、4.5、6.5)的LED灯照射处理,研究不同R/FR值对温室切花菊形态指标、叶面积形成及干物质分配的影响。结果显示R/FR=2.5处理的植株叶片数、株高、茎粗、花径、叶面积及总干重均为各个处理中最高,R/FR=0.5处理的节间最长。所有R/FR处理的单株地上干物质重量与光质处理天数呈指数-线性模型。随处理天数的增加不同R/FR值处理菊花植株地上部分及地下部分干物质分配指数差异均不显著,叶片和花的干物质分配指数随处理天数的增加分别呈降低和升高的趋势,茎干物质分配指数则呈现先升高后降低的趋势,R/FR=2.5处理下,菊花叶片干物质分配指数和花干物质分配指数最高,而茎干物质分配指数却为最低;R/FR=6.5处理茎干物质分配指数最高,叶片干物质分配指数最低;0.5处理花朵干物质分配指数最低,说明远红光比例增加能够促进干物质向茎中分配,R/FR=2.5处理利于干物质向花朵中分配。     

丛枝菌根真菌对郁金香生长及其切花生理的影响

为认识丛枝菌根真菌（arbuscular mycorrhizal fungi,AMF）对郁金香Tulipa gesneriana生长、光合特性以及切后瓶插期生理的影响,通过温室盆栽接种试验,以摩西斗管囊霉Funneliformis mosseae和幼套近明球囊霉Claroideoglomus etunicatum分别单独接种和共同接种,进行温室盆栽实验。结果表明,共同接种F. mosseae和C. etunicatum的郁金香叶片叶绿素a含量、叶绿素b含量和总叶绿素含量均显著高于不接种对照,分别增加了32%、18%和28%。与不接种对照相比,接种AMF处理的郁金香叶片的净光合速率、气孔导度、胞间CO₂浓度和蒸腾速率均显著提高,共同接种F. mosseae和C. etunicatum的郁金香在正午12点达到光合参数最大值。接种AMF处理的郁金香花葶长、地上干物质质量、地上鲜物质质量和叶面积均高于不接种对照,开花期早于不接种对照。切花瓶插期间,接种AMF处理的郁金香切花花瓣可溶性糖含量、可溶性蛋白质含量、超氧化物歧化酶（SOD）和过氧化物酶（POD）等抗氧化酶活性比不接种对照显著提高;且降低了膜脂过氧化产物丙二醛（MDA）含量和相对电导率。接种处理有效地改善切花花枝的水分平衡,并延长郁金香切花的瓶插寿命、最佳观赏期和花期。     

Acclimation to High CO(2) in Monoecious Cucumbers : I. Vegetative and Reproductive Growth

CO₂ concentrations of 1000 compared to 350 microliters per liter in controlled environment chambers did not increase total fruit weight or number in a monoecious cucumber (Cucumis sativus L. cv Chipper) nor did it increase biomass, leaf area, or relative growth rates beyond the first 16 days after seeding. Average fruit weight was slightly, but not significantly greater in the 1000 microliters per liter CO₂ treatment because fruit numbers were changed more than total weight. Plants grown at 1000 and 350 microliters per liter CO₂ were similar in distribution of dry matter and leaf area between mainstem, axillary, and subaxillary branches. Early flower production was greater in 1000 microliters per liter plants. Subsequent flower numbers were either lower in enriched plants or similar in the two treatments, except for the harvest at fruiting when enriched plants produced many more male flowers than the 350 microliters per liter treatments.     

辣椒拟种群对模拟昆虫捕食行为的反应

基于拟种群理论,动用方差分析法、主分量分析法及植物生长分析法,研究７月高温期辣椒拟种群不同程度的剪叶对模拟短期虫害的反应。结果表明,辣椒具有较强的补偿能力;老叶的数量、干重和叶面积随剪叶程度的增加而下降,新叶则相反,但总叶数量相近;总叶面积和干重受老叶影响大,差异显著;枝的数量、干重、长度差异不显著;果、花、花蕾的数量差异也不显著,但干重差异显著;用数量指标代替干重、叶面积和长度等指标来进行植物的     

The control of narcissus leaf diseases; Sclerotinia polyblastis Greg. on Narcissus tazetta var. Soleil d'Or

In the extreme south-west of England Narcissus tazetta grown for the outdoor flower crop is regularly attacked by narcissus fire ( Sclerotinia polyblastis ). A randomized strip experiment on the variety Soleil d'Or laid down in 1937, in which half the plots were sprayed each season, gave data on the effect of controlling this disease on the number and quality of flowers produced in 1939, 1940 and 1941, and on the weight and grade of bulbs lifted in 1941.
There was an average increase of 26 % in the number of flowers produced on sprayed plots, and a 35% increase in weight of bulbs. There was no evidence of a cumulative improvement because most of the gain in one year appears to have been immediately expended in increased flowers in the following season, but the sprayed plots maintained a higher general level throughout. The quality was improved by spraying, mainly by the addition to the inflorescence of an average of one extra 'bell'. Although not cumulative, there was a residual effect shown by the increased yield of bulbs in 1041 after a season in which only one post-flowering spray had been applied.
The effect of treatment on the date of flowering (anthesis) was negligible and its direction depended on the season. In this respect Soleil d'Or differs from Golden Spur, in which spraying induced the marked retardation of flowering noted in 1938 and 1939.     

The Distribution of Garlic Viruses in Leaves and Bulbs during the First Year of Infection

Garlic plants are naturally infected with a mixture of viruses. Virus‐free garlic plants, obtained by meristem culture, rapidly become reinfected when planted in the field. With the aim of understanding virus movement and fluctuations in virus concentration in leaves and cloves of garlic plants in the first year after infection, Onion yellow dwarf virus, Leek yellow stripe virus, and other viruses were analyzed by double‐antibody sandwich enzyme‐linked immunosorbent assay. Significant differences were detected in virus concentration in different leaves, but the distribution of the viruses was variable. Therefore, no one type or position of leaf is preferable for detecting virus presence. Instead, sampling any leaf at the end of the crop cycle, about 200 days after planting, is advisable because virus concentration is several times higher in older plants. The analysis of virus distribution in bulbs revealed that virus concentration was higher in early‐inoculated than in late‐inoculated plants. In 81% of the bulbs, cloves were either all positive or all negative in serological tests. Only in 6% of the cases were positive and negative cloves found in the same bulb, and in 13% of the bulbs, negative results coexisted with an uncertain status. The tests of virus concentration in relation to the layers of each bulb revealed important differences. Only the innermost layer showed differences with other layers, but this was poorly represented as it had fewer cloves.     

Changes in growth and photosynthetic characteristics of Ocimum sanctum under growth regulator treatments

A field experiment was conducted to investigate the effect of growth regulators on growth characteristics such as root length, shoot length, total leaf area, number of inflorescence per plant, number of flower per inflorescence, whole plant fresh weight and whole plant dry weight. Photosynthetic characteristics were also analyzed based on the same experiment. For this, various photosynthetic pigment contents such as chlorophyll, carotenoid, anthocyanin and xanthophyll content were calculated. The conventional growth regulator abscisic acid (ABA) and non-conventional growth regulator triazole compound paclobutrazol (PBZ) were used. Root length increased due to growth regulator treatment, but shoot length decreased. Leaf area was decreased due to growth regulator treatment. The number of inflorescence increased in ABA treated plants, but it was decreased in PBZ treated plants. In ABA treated plants, the number of flowers per inflorescence was increased. In PBZ treated plants the number of inflorescence was reduced. The whole plant fresh weight (FW) and dry weight (DW) were increased in ABA and PBZ treated plants. There was an increase in chlorophyll content in growth regulator treated plants compared to control, and it was more in PBZ treated plants. The carotenoid content was also increased in ABA and PBZ treated plants.     

Inhibition of flowering of cucumber grafted on rooted squash stock

For the elucidation of the mechanisms of floral transition in indifferent plants, cucumber seedlings ( Cucumis sativus cv. Rennsei or cv. Shimoshirazu-jibai) were grafted onto squash seedlings ( Cucurbita maxima Duchesne X C. moschata Duchesne cv. Shintosa-ichigou) of which the meristems had been removed, and the effect on flower induction on the cucumber scion was examined. In both cultivars, the grafted cucumber bore no flowers, whereas control plants developed flowers above the second to fourth nodes. The inhibition of flower formation on the grafted cucumber scion occurred even when the root of cucumber was left with the squash root on the grafted plant, and flower formation occurred after removal of the squash stock. The inhibitory effect of the squash stock in the presence of the cucumber root was abolished by removal of the squash root. Neither the dry weight of stem plus leaf nor the chlorophyll content of the leaf, as indicators of vegetative growth, were correlated with flower formation on cucumber plants that had been grafted in the presence of cucumber roots on whole, cotyledon-free or root-free squash stock. These results indicate that flower formation in cucumber was inhibited by a factor produced by squash roots, an inhibition probably not involved in the modulation of vegetative growth. The root may control floral transition by the production of inhibitory factors in some day-neutral Cucurbitaceae plants.     

Host/parasite relations up to the time of tuber initiation in potato plants infected with Verticillium spp

The growth pattern of potato plants, infected with V. albo-atrum and V. dahliae, was studied, using growth-analysis techniques, during the initial stages of development up to tuber initiation. During the first 5–6 weeks of growth the morphology of the infected plants was not affected, but the distribution of dry weight materials between various plant organs and the growth rates of the whole plants were affected much sooner. In contrast to healthy plants, those infected exhibited lower specific leaf areas, higher leaf weight ratios and higher leaf area ratios, and, under dry conditions, lower relative growth rates and lower unit leaf rates. Thus during the incubation phase of the disease, although effects of infection are not immediately apparent, Verticillium pathogens have a considerable influence upon the development of the host.     

ANDROMONOECY IN ZIGADENUS PANICULATUS (LILIACEAE): SPATIAL AND TEMPORAL PATTERNS OF SEX ALLOCATION

I describe patterns of sex allocation and gamete packaging in the andromonoecious lily Zigadenus paniculatus. In this species, pistil length was continuously, but bimodally, distributed within plants, and smaller pistils contained fewer mature ovules. In hermaphrodite flowers, ovule number per flower increased with blooming rank in small plants but decreased with blooming rank in large plants. Flowers with pistils less than three-fourths stamen length almost never produced fruits and were classified as males. The pedicel, tepals, stamens, and pistil of hermaphrodite flowers were all heavier than those of males. Hermaphrodite flowers were concentrated on the terminal raceme, males on the lower racemes. In combination with acropetal blooming, this spatial separation of flower types resulted in a seasonal decline in the proportion of open flowers that were hermaphrodite. However, individual flowers were protandrous, so that the population sex ratio, initially strongly male-biased, declined as the season progressed. Hand pollinations showed that plants were self-incompatible. Inflorescence size was positively correlated with bulb size, and plants with large inflorescences had a higher proportion of male flowers. Nutrient supplementation had no effect on inflorescence size, but increased the proportion of hermaphrodite flowers. Nutrient-supplemented plants also began blooming earlier than controls. I discuss these patterns in relation to the adaptive significance of andromonoecious breeding systems.     

Effects of turnip mosaic virus and turnip yellow mosaic virus on the survival, growth and reproduction of wild cabbage (Brassica oleracea)

Wild plants of Brassica oleracea (wild cabbage) are commonly infected with turnip mosaic poty virus (TuMV), turnip yellow mosaic tymovirus (TYMV) and several other viruses. A field experiment in which plants were inoculated either with TuMV or TYMV showed that virus infection significantly reduced survival, growth and reproduction. Relative to water inoculated-controls, plants infected with TYMV had greater mortality, were shorter, had a smaller leaf area and number, showed a greater amount of damage from herbivory and chlorosis, were less likely to flower and produced fewer pods and lower total seed output. Plants infected with TuMV did not appear to be adversely affected at first; however, mortality after 18 months was higher than control plants. Although TuMV infection had no effect on the number of plants flowering, the infected plants did produce fewer pods and a lower total seed output. We conclude that both viruses can significantly affect vegetative and reproductive performance of wild cabbage and hence that introgression of virus resistance (particularly when conferred by a major gene or a transgene) from a crop might increase plant fitness in natural populations of this species. Ecological risk assessments of virus resistance transgenes must do more than survey adult plants in natural populations for the presence of the target virus. Failure to detect the virus could be due to high mortality on infection with the virus.