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1.
In experiments to develop a method for assessing the field susceptibility of potato cultivars to blackleg (Erwinia carotovora subsp. atroseptica) seed tubers were stab-inoculated near the stolon (attachment end), with a suspension of the bacterium, or with water, before planting. Disease symptoms were recorded in three years (1980–1982) and plant growth and yield in 1982. Estima and Maris Bard were the most susceptible cultivars with many plants failing to emerge and most of those that did showing disease symptoms. Pentland Crown was the most resistant: few plants failed to emerge and few showed blackleg. Nevertheless compared with water-inoculated plants bacterial inoculation of the seed tubers of this cultivar caused loss of yield and differences in tuber size distribution. Cara, Wilja and King Edward showed intermediate reactions.  相似文献   

2.
Abstract

Three antagonists: Pseudomonas fluorescens (Pf1), Bacillus subtilis and Trichoderma viride, were tested alone and in combination for suppression of onion leaf blight (Alternaria palandui) disease under glasshouse and field conditions. The average mean of disease reduction was 24.81% for single strains and 42.44% for mixtures. In addition to disease suppression, treatment with a mixture of antagonists promoted plant growth in terms of increased plant height and ultimately bulb yield. Though seed treatment of either single strain or strain mixtures alone could reduce the disease, subsequent application to root, leaves or soil further reduced the disease and enhanced the plant growth. The mixture consisting of Pseudomonas fluorescens Pf1 plus Bacillus subtilis plus Trichoderma viride was the most effective in reducing the disease and in promoting plant growth and bulb yield in greenhouse and field tests.  相似文献   

3.
Two field experiments, planted in a split plot design, were conducted during 2002 in the forest zone of Cameroon, to investigate the effect of border rows with Pennisetum purpureum (Poaceae) or with Panicum maximum (Poaceae) on soil water, plant nitrogen (N), phosphorus (P) and potassium (K), borer infestations, parasitism and maize yield. The grassy boundaries were the main plots and fertilizer treatment the sub plots. Soil humidity was significantly higher under the grass borders than in maize plots. Nitrogen uptake by maize tended to be highest in plots surrounded by P. purpureum but the differences were significant during the second season only. Busseola fusca (Fuller) (Lepidoptera: Noctuidae) was the predominant borer species followed by Eldana saccharina (Walker) (Lepidoptera: Pyralidae). The predominant parasitoid species was the scelionid egg parasitoid Telenomus busseolae Gahan (Hymenoptera: Scelionidae). During both seasons, plant nitrogen, B. fusca infestation, plant damage and yield were significantly higher in maize sub-plots that received fertilizer The interaction between the grassy margin effect and the fertilization was significant only for B. fusca infestations, during the second season with maize + P. purpureum having a significantly lower number of borers in the fertilized than the unfertilized sub-plots. The grassy borders had no effect on B. fusca egg parasitism variables except in the first season, when maize with P. purpureum had a significantly higher percentage of egg batches parasitized. During both seasons, there were some significant differences in yield variables between main plots but the trends were not clear. Multiple regression showed that B. fusca infestation, plant damage, egg parasitism, plant N, P and K affected yield, with plant nutrients explaining most of the variability. The implication of the findings for the feasibilty of this habitat management technology to farmers in southern Cameroon is discussed.  相似文献   

4.
The predatory mite Neoseiulus cucumeris (Oudemans) (Acarina: Phytoseiidae) successfully controlled the broad mite Polyphagotarsonemus latus (Banks) (Acarina: Tarsonemidae) on two varieties of greenhouse-grown sweet peppers (Capsicum annuum L.). A survey of pre-plant seedlings showed that nurseries were a source of infestation for the broad mite. The predatory mites were released twice (on day 1 and 5, or 15 days later) on each plant, every second plant or every fourth plant. Broad mite populations were evaluated by sampling young leaves from the top of the plant. The effect of the broad mite on plant height, dry mass and yield was evaluated. Additionally, since N. cucumeris is known to control thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), blue sticky traps and flower sampling were used to evaluate changes in thrips populations. All three release rates of N. cucumeris significantly (P<0.05) controlled broad mite populations, but when the predatory mites were released only on every fourth plant, the overall height and yield of the plants were adversely affected by broad mites. Releasing N. cucumeris on each or every second plant was as efficacious in controlling broad mites as sulfur treatments in terms of plant height, dry mass and yield. Plants treated with sulfur, however, had significantly higher thrips populations and fruit damage.  相似文献   

5.
More than 40 monogenic dwarfing mutants have been described in maize; however, the majority of these lead to great reductions in grain yield and, consequently, they have not been used to enhance crop yield in germplasm that is sensible to lodging. An exception in terms of commercial value is the maize mutant brachytic 2 (br2). Br2 gene was cloned in 2003, and it encodes for a protein most probably involved in auxin polar transport. We have isolated a new brachytic mutation that is allelic to the br2 locus and denoted this novel mutant as br2–23. Characterization of this mutant revealed that the br2 mutation modified not only the length of the internodes, as previously reported, but the structure of the leaves as well. Br2–23/br2–23 heterozygotes have a useful intermediate phenotype in terms of plant height, ear height and leaf angle, suggesting a possible utilization of this effect in developing new hybrids. This mutant also appears to be an useful tool by which to study the switch points of the complex developmental program determining maize plant height and architecture.  相似文献   

6.
Although much research on the density effect in nonself-thinning populations has been conducted, there has been very little research on density effects in self-thinning populations. Furthermore, the density effect of plant organs in self-thinning populations is little reported. The present study analyzed the yield–density (Y–D) effects on organs, such as stem, branch and leaf, together with that on stands of self-thinning Pinus densiflora Sieb. et Zucc.. The stand yield- and organ Y–D effects were well described by reciprocal and parabolic equations, respectively, throughout the experiment. The value of coefficient B in the reciprocal equation decreased monotonically with increasing stand age and became significantly closer to zero at the end of experiment (33-year-old stand), indicating that the constant final stand yield was established regardless of the density realized. The value of the relative growth coefficient h in the allometric equation between mean organ weight and mean aboveground weight was significantly smaller than 1.0 for stem, indicating that stem yield increases monotonically with increasing realized density. The h-value was significantly larger than 1.0 for branch throughout the experiment, and for leaf except at 33 years old, indicating that optimum densities exist. The h-value for leaf was not significantly different from 1.0 at 33 years old, indicating that the leaf yield reached a constant level regardless of realized density. The constant final leaf yield was established at almost the same growth stage as the establishment of constant final stand yield.  相似文献   

7.
The objective of this work was to study the influence of three Glomus species—Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, Glomus intraradices (Schenck and Smith) and Glomus deserticola (Trappe, Bloss, and Menge)—on the development of Verticillium-induced wilt in Capsicum annuum cv. Piquillo. Results showed that the effectiveness of arbuscular mycorrhizal fungi (AMF) as biocontrol agents varied among different Glomus species. In pepper colonized by G. intraradices the severity of the disease was even higher than that observed in non-mycorrhizal plants in terms of plant growth and pepper yield. On the other hand, the high effectiveness exhibited by G. mosseae in improving plant growth and the early beginning of the reproductive stage in these plants was not associated with great plant protection and high pepper yield in diseased plants. Only plants associated with G. deserticola had greater yield than non-mycorrhizal ones despite the lower P fertilization applied to the mycorrhizal treatment and this fact was observed in both healthy and diseased plants. It is suggested that the higher specific phosphorus uptake in Verticillium-inoculated plants associated with G. deserticola could contribute to diminish the deleterious effect of pathogen on yield. On the other hand, the possible influence of endogenous phenolics in roots on the tolerance or resistance of pepper against wilt induced by Verticillium dahliae remains unclear.  相似文献   

8.
Cell nuclei have been released from various plant tissues (barley leaves, roots and embryos, tobacco leaves and tissue cultures,Vicia faba roots,Arabidopsis thaliana leaves) by several homogenization methods and the optimal method was established for each tissue. The effect of the composition of isolation medium on the yield and appearance of isolated nuclei was also studied. Longer incubation withn-octanol increases the yield considerably in most cases. Low concentrations of osmoticum increase the yield and their adverse effect on the integrity of nuclei is of little significance. Gum arabic has a favourable effect on nuclei isolation from roots only.  相似文献   

9.
Triacontanol (TRIA) has been realized as a potent plant growth promoting substance for a number of agricultural and horticultural crops. Out of a large number of essential oil bearing plants, mint (Mentha arvensis L.) constitutes the most important source of therapeutic agents used in the alternative systems of medicine. The mint plant has marvelous medicinal properties. In view of enhancing growth, yield and quality of this medicinally important plant, a pot experiment was conducted according to simple randomized block design. The experiment was aimed at studying the effect of four concentrations of TRIA (10−0, 10−7, 10−6 and 10−5 M) on the performance of mint with regard to growth and other physiological attributes, crop yield and quality attributes and the yield and contents of active constituents of the plant. The growth and other physiological parameters as well as yield and quality attributes were studied at 100 and 120 DAP. The foliar application of TRIA at 10−6 M concentration significantly enhanced most of the growth and other physiological attributes, crop herbage yield and the yield and content of active constituents (menthol, l-methone, isomenthone and menthyl acetate) of mint at both the stages. However, the next higher concentration of TRIA (10−5 M) exhibited slightly negative effect and did not further increase the values of the attributes studied, but it proved significantly better than the control. Application of TRIA significantly enhanced the yield and content of all the active constituents determined by GLC technique.  相似文献   

10.
Irradiated carrageenan (IC) could elicit plant growth promoting activities in plants. The effect of foliar spray of five concentrations of IC (20, 40, 60, 80 and 100 mg L−1) was studied on Mentha arvensis L. in terms of plant growth, physiological attributes, herbage yield and the content and yield of essential oil and its components. Un-irradiated carrageenan and deionized water had no effect on the attributes studied. GPC study revealed formation of low molecular weight fractions in irradiated samples containing less than 20,000 molecular weight oligomers which are responsible for plant growth promotion in this study. 80 mg L−1 of IC was the most effective concentration which resulted in the highest values of growth attributes, herbage yield and the content and yield of essential oil and menthol content of the oil. It also improved the leaf-nutrient contents, photosynthetic rate and other physiological parameters. 100 mg L−1 of IC did not further improve the attributes studied, but it was always better than the control.  相似文献   

11.
Field experiments were conducted with sesame (Sesamum indicum L. cv. Rama) for two years (1997 and 1998) to study the effect of three level of irrigation (F+C, B+C, B+F+C) and two growth regulators (CCC, 200 ppm CCC; 100 ppm and BX-112, 100 ppm; BX-112, 50 ppm) on growth (root and shoot length, average number of primary branches/plant), morpho-physiological growth parameters(LAI, LAD, CGR and NAR), yield attributing parameters(average number of capsule/plant, average number of seeds/capsule) and seed yield. Irrigation at B+F+C stage showed significant effect on these parameters. Among the growth regulators, CCC, 200 ppm showed remarkable results on these parameters and seed yield. Seed yield in CCC, 200 ppm treatment was more than 53% in comparison to water soaked seeds. The interaction between irrigation and PGR showed better seed yield and it was concluded that the growth regulator CCC might be utilized for enhancement of seed yield of summer sesame under field condition.  相似文献   

12.
以蒙古黄芪为试验材料,设置大田随机区组试验,研究苗期、开花期和根茎伸长期叶面喷施不同浓度硅(500、1000、2000和4000 mg/L)对蒙古黄芪生长发育、抗氧化酶活性、药材产量和品质的影响,并检测施硅对黄芪白粉病、根腐病的防治效果,以揭示硅对增强黄芪抗病性、提升品质和产量的影响机理,为生产中蒙古黄芪的高效栽培提供理论依据。结果表明:(1)在不同生育时期,喷施不同浓度硅能增加蒙古黄芪株高、茎粗、株幅和叶绿素含量,促进蒙古黄芪生长,并以2000 mg/L硅处理效果较佳。(2)不同生育时期喷施硅能提高蒙古黄芪叶片SOD、CAT、POD和APX等抗氧化酶活性,降低MDA含量,以开花期、根茎伸长期2000 mg/L硅处理较佳。(3)施硅能有效降低蒙古黄芪白粉病、根腐病的病情指数,当施硅浓度为2000 mg/L时防效均达到最高,并分别达到47.05%和39.08%。(4)施硅处理能有效提高蒙古黄芪单株干、鲜生物量、产量以及可溶性浸出物和黄芪甲苷含量等品质指标,并在2000 mg/L硅浓度处理下均达到最佳水平,此时可溶性浸出物和黄芪甲苷含量分别比对照显著提高了16.48%和31.96%。研究发现,叶面喷施适宜浓度硅可显著增强蒙古黄芪对白粉病、根腐病的抗性,促进植株生长,进而显著提高药材产量,改善药材品质,并以硅浓度为2000 mg/L时效果最佳。  相似文献   

13.
To determine the plant variable for coupling a disease model to a soybean growth model, effects of soybean rust (caused by Phakopsora pachyrhizi) on soybean were quantified at four levels: vegetative parts, yield components, plant yield, and plot yield. Path analysis was conducted to determine the most correlated components to disease in each level. The responses of vegetative parts, such as shoot weight and branches/plant, to disease effects were inconsistent among cultivars. Yield components responded consistently to disease effects among the cultivars, indicated by the high values of correlation coefficients between disease and the components. Path coefficients indicated that reduction of 100-seed weight was the most important cause of yield loss in this level. No significant within-plant compensation was detected using path coefficient analysis except for that between pod length to pod width. The most consistent response to disease effect was at population level. Correlation of disease to plant yield was as significant as these to plot yield. Correlations between disease and these plant levels were in the order of plot yield, plant yield, yield components, and vegetative parts. Regression between plot yield and green leaf area duration (GLAD) from flowering to seed full size was highly significant (P < 0,001). This study suggests that green leaf area at population level was the best variable for coupling disease model to crop model.  相似文献   

14.
Growth of broad beans infected by Uromyces viciae-fabae   总被引:2,自引:0,他引:2  
The effect of artificially regulating the level of a rust infection with Uromyces viciae-fabae (Pers.) Schroet. on the growth and yield of two cultivars of Viciafaba L. (broad beans) was examined in 1973/74. Disease decreased leaf area ratio without increasing net assimilation rate particularly during the stage of ‘pod filling’. Consequently, assimilate supply to developing beans was diminished and the weight of beans per pod and yield of beans per plant decreased. This is unlike the effect of Botrytis fabae Sard, on broad beans which reduces yield by decreasing the number of pods per plant. This suggests that the two leaf spotting pathogens decrease yield in different ways and so may require different approaches to minimise yield losses.  相似文献   

15.
Effects of inoculating four Arachis hypogaea ssp. fastigiata cultivars with 17 Bradyrhizobium spp. strains were studied in a glasshouse experiment using a sandy soil devoid of an indigenous Bradyrhizobium population. Firstly, a wide range of parameters, indicative of symbiotic performance, were assessed for their influence on seed yield, by correlation and statistical analyses. It was found that nodule dry weight and leaf area were relevant parameters concerning seed yield. Secondly, the effects of host and strain genotype on those parameters were described.Variations in nodule dry weight did not have an effect on seed yield, except for cultivar Natal Common at lower nodule dry weight values. Therefore, it was concluded that the quantity of nitrogen fixing tissue met the demand for combined nitrogen and did not limit seed yield. This conclusion was further supported by the observation that at low nodule numbers per plant the nodule size increased to generate sufficient nitrogen fixing tissue.Leaf area, which comprises components for both photosynthetic capacity and plant development, was found to correlate well with seed yield. An increase in leaf area resulted in significant seed yield increases for all three spanish-type cultivars, but not for the valencia-type cultivar. Leaf area, thus, appeared as a factor limiting seed yield of spanish-type groundnuts.Cultivar performance concerning seed yield was significantly better for Natal Common compared to the other three cultivars, while Natal Common had a significantly lower plant (biomass excluding seed) dry weight value.Inoculation with different strains of Bradyrhizobium resulted in significantly different nodule dry weight values, but hardly led to significant differences in seed yield. This agreed with the finding that the amount of nitrogen fixing tissue appeared not to limit the availability of combined nitrogen.A large quantity of nitrogen was partitioned to the groundnut seeds: 62% to 76% of total accumulated nitrogen was located in the seeds.This study showed that testing for symbiotic effectiveness in the groundnut Bradyrhizobium symbiosis should include assessment of final (seed and biomass) yield, because parameters measured at stages prior to maturity, like nodulation parameters, may lead to flawed effectiveness ratings.  相似文献   

16.
The effect of the arbuscular mycorrhizal symbiosis (AM) varies in plant cultivars. In the present study, we tested whether wild-type, old and modern tomato cultivars differ in the parameters of the AM interaction. Moreover, the bioprotective effect of AM against the soilborne tomato pathogen Fusarium oxysporum f. sp. lycopersici (Fol) was tested in the different cultivars. Ten tomato cultivars were inoculated with the arbuscular mycorrhizal fungus (AMF) Glomus mosseae alone or in combination with Fol. At the end of the experiment, AM root colonization, Fusarium infection, and the plant fresh weight was determined. The tomato cultivars differed in their susceptibility to AMF and Fol, but these differences were not cultivar age dependent. In all the cultivars affected by Fol, mycorrhization showed a bioprotective effect. Independent of the cultivar age, tomato cultivars differ in their susceptibility to AMF and Fol and the bioprotective effect of mycorrhization, indicating that the cultivar age does not affect the AM parameters tested in this study.  相似文献   

17.
【目的】本研究分析三株固氮菌PGPR性状特征及其对中国青菜产量和土壤酶活的影响。【方法】氮(N)-修复(固氮)细菌被认为是一种能够促进植物生长和增产的施氮方式。在本研究中,我们用无氮培养基分离出了30株根际固氮细菌:11株来自小麦根际,16株来自中国青菜根际和3株来自莲花根际。基于16S r DNA序列分析,对小麦、中国青菜和莲花等植物根际中属于类芽孢杆菌属的主要固氮细菌进行研究。【结果】本研究从这30株固氮菌中筛选出三株属于类芽孢杆菌属(Paenibacillus)的细菌,分别命名为P-4、W-7和L-3,它们的固氮酶活性不但高于对照组(圆褐固氮菌),而且可以有效抑制两种或三种植物病原菌的生长,即核盘菌(Sclerotinia sclerotiorum)、玉蜀黍赤霉(Gibberella zeae)和棉花黄萎病菌(Verticillium dahliae)。菌株W-7还具有溶解难溶磷的能力,中国青菜在接种菌株W-7和L-3后,其鲜重显著增加,同时改变了田间土壤蔗糖酶、磷酸酶和过氧化氢酶的活性;而接种了菌株P-4对植物的生长和酶活性没有显著的影响。【结论】土壤蔗糖酶、磷酸酶和过氧化氢酶活性与中国青菜的生物量呈正相关。同时,菌株W-7和L-3具有促进植物产量和提高土壤质量的良好潜力。  相似文献   

18.
We tested whether differences in the herbivory tolerance of plant species is related to their abundance in grassland communities and how herbivory and nutrient availability affect competitive balances among plant species through changes in their tolerance. The experimental approach involved a simulated grazing treatment (clipping) of two competitive grass species (Arrhenatherum elatius and Holcus lanatus) and two subordinate forb species (Prunella vulgaris and Lotus corniculatus) along a gradient of nutrient availability and under conditions of competition. Total standing, aboveground, root, and regrowth biomass were evaluated at the end of the experiment as an estimate of the capacity to compensate for twice removing aboveground biomass at different nutrient levels (NPK). Although clipping had a more pronounced negative effect on dominant plant species (Arrhenatherum and Holcus) than on subordinate species, the negative effects on dominant species were offset by the application of fertilizer. The combined effect of fertilizer and competition had more negative effects on the performance of Lotus and Prunella than on the dominant species. In terms of competition, the regrowth ability of Arrhenatherum and Holcus increased with the application of fertilizer, while the opposite pattern was observed for Lotus and Prunella. The addition of fertilizer has a positive effect on both grass species in terms of growth in clipped pots and competition, while subordinate species did not respond to the addition of fertilizer to the clipped pots and were negatively affected by competition with both grass species. The results suggest (1) that species replacement towards subordinate species as a function of herbivory is partially dependent on the herbivory tolerance of that species, (2) competitive relations between competitive grass species and subordinate forb species change under different environmental conditions, and (3) although grazing disturbance significantly influences competitive relations in favor of less competitive species, increasing nutrient levels counteract the negative effect of grazing on dominant competitive plant species.  相似文献   

19.
Effects on seed yield of mechanical defoliation and inoculation with Botrytis fabae were compared using pot-grown plants of Vicia faba (cv. Maris Beagle). Treatments, which were made at the end of flowering, were applied singly and in all combinations to leaves (a) below, (b) at, and (c) above the flowering nodes (i.e. 23 factorial). Yield was unaffected by treatments applied to leaves below the flowering nodes. Removal of leaves at flowering nodes did not reduce the number of pods but yield was reduced because there were fewer and smaller seeds. Inoculation of this zone also reduced yield; pods were lost at some nodes but it could also be shown that, irrespective of pod loss, yield at individual nodes was reduced in proportion to the severity of infection on leaves at the same nodes. Removal of leaves above flowering nodes reduced yield almost to the same extent as removal of leaves at flowering nodes but inoculation resulted in only a small amount of infection and yield was not reduced significantly. These results, taken in conjunction with recent studies on the physiology of the host plant, show that beans are exceptionally vulnerable to attack by B. fabae at the stage of flowering and early pod development. At later stages of development infection is unlikely to have a substantial effect on yield.  相似文献   

20.
Relative effectiveness of seven different application methods of five native bacterial and fungal biocontrol agents (BCAs) and one fungicide (azoxystrobin) was evaluated against Rhizoctonia solani, under pot and field conditions on rice cultivar Pusa Sugandha-5. Plants grown in pots infected with Rsolani suffered a 30%–49% decrease in plant growth and yield of grain. However, treatment with BCAs reduced the adverse effect of the pathogen but significantly varied with the treatment schemes. Amongst the treatments, soil application (SA) at 20 + 40 days after planting (DAP) followed by foliar application (FA) at 60 DAP was recorded as most efficacious, and reduced the severity of disease by 42–68%, resulting in a 21–36% plant growth promotion and yield enhancement. Treatment comprising SA 20 + FA 40 DAP was next in effectiveness but statistically equal to seed priming (SP) + SA 40 DAP of treatment. Amongst the BCAs, Pseudomonas putida was shown to be the most efficient, trailed by Trichoderma harzianum, P. fluorescens, T. viride and Bacillus subtilis. Field trials under naturally infested fields have also validated the effectiveness of Pputida. The SA 20 + 40 + FA 60 DAP with Pputida and Tharzianum were found quite effective and decreased the disease severity and incidence (40–81%), and improved the grain yield (42–72%). Relatively lower ShB control was recorded with SA 20 + FA 60 DAP, however, it was statistically at par with SA 20 DAP treatment and equal to SA 20 + FA 40 DAP.  相似文献   

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