Effects of sowing seed with different levels of infection, plant density and the growth stage at which plants first develop symptoms on cucumber mosaic-virus infection of narrow-leafed lupins (Lupinus angustifolius)

1994 ◽  
Vol 45 (7) ◽  
pp. 1395 ◽  
Author(s):  
AM Bwye ◽  
RAC Jones ◽  
W Proudlove
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Field Experiments ◽  
Plant Density ◽  
Lupinus Angustifolius ◽  
Virus Spread ◽  
Current Season ◽  
Infected Seed ◽  
High Plant Density ◽  
Sowing Seed

During 1990-92, narrow-leafed lupins (Lupinus angustifolius) cv. Gungurru, were grown in six field experiments in which plots were sown with healthy seed or seed that carried 0.5-5% infection with cucumber mosaic virus (CMV). Seed-infected plants were the primary source for subsequent virus spread by aphids. The rate of CMV spread and the extent of infection in plots depended on the level of infection in the seed sown, the proportion of infected seeds that successfully developed into established plants and the time of arrival and number of aphid vectors. In general, higher seed infection levels, better establishment of seed-infected plants and early aphid arrival favoured greater virus spread, yield loss and infection in the harvested seed. In 1991, in two experiments, late arrival of aphids resulted in minimal CMV spread, no effect on yield and much less infection in the harvested seed than in the seed sown. In the other four experiments, significant yield losses (25-42%) always resulted when seed with 5% or 3% infection was sown. Sowing 1% infected seed resulted in significantly decreased yields in two experiments, while 0.75% and 0.5% infected seed caused significant losses in one experiment (16-19% losses). Yield decreases were due to both fewer seeds being formed and decreased seed size. Levels of infection in harvested seed did not exceed 15%. In a further field experiment in 1991, individual plants that developed CMV symptoms before initiation of flowering or during flowering had significantly smaller yields than those that developed symptoms after flowering had finished. In four field experiments during 1990-91, 10-15% CMV-infected lupin seed was sown at rates of 20-150 kg ha-1 to generate a range of plant densities. The numbers of seed-infected plants were recorded at different times. The extent of loss of seed-infected plants due to shading by neighbouring healthy plants depended on plant density and the time when canopy closure developed. Where no canopy formed there was little or no loss of seed-infected plants, while early canopy formation at high plant density was most effective in removing them. Current-season spread was also decreased by early canopy formation and high plant density, but this effect was smaller when aphids arrived early. This work supports recommendations for management of CMV infection in lupins by sowing seed with low infection (<0.5%) to minimize infection sources, and sowing early at high seeding rates to remove seed-infected plants through improved canopy formation.

Effects of different cultural practices on spread of cucumber mosaic virus in narrow-leafed lupins (Lupinus angustifolius)

1999 ◽  
Vol 50 (6) ◽  
pp. 985 ◽  
Author(s):  
A. M. Bwye ◽  
R. A. C. Jones ◽  
W. Proudlove
Keyword(s):  
Grain Yield ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Field Experiments ◽  
Cultural Practices ◽  
Lupinus Angustifolius ◽  
Row Spacing ◽  
Virus Spread ◽  
Current Season ◽  
Wide Row Spacing

Lupinus angustifolius (narrow-leafed lupin) was sown in 7 field experiments to examine the effects of cultural practices on incidence of cucumber mosaic virus (CMV). The factors investigated were row spacing, banding fertiliser below seed, straw groundover, and tillage. The seed sown carried 5–15% CMV infection. Seed-infected plants were the primary source for subsequent virus spread by aphids. Incidence of seed-infected plants and the extent of virus spread were gauged by counting numbers of lupin plants showing typical seed-borne and current-season CMV symptoms. Due to greater competition with other plants within wide than narrow rows, wide row spacing diminished the survival of seed-infected plants by 46%. Increased plant growth from banding superphosphate below seed did not significantly decrease numbers of seed-infected plants surviving. Straw spread on the soil surface suppressed final CMV incidence by 25–40% and, when applied at different rates, diminished recorded CMV incidence more at 4 than 2 t/ha and least at 1 t/ha. Where there was no straw, CMV incidence increased faster with narrow spacing than wide spacing. Soil disturbance from sowing seed with double discs instead of tynes significantly increased incidences of both seed-borne and current-season infection and diminished grain yield. Neither straw nor row spacing treatments significantly affected grain yield, but the decrease in CMV spread due to straw ground cover significantly increased individual seed weight once and overall yields were greater with straw. Myzus persicae was the main colonising aphid species but Aphis craccivora and Acyrthosiphon kondoi also colonised the lupins. There were significantly fewer colonising M. persicae in plots with 4 t/ha of straw than in those with none. This work suggests that stubble retention, minimum tillage, and wide row spacing should be included as components of an integrated disease management strategy for CMVin L. angustifolius crops.

Effects of applying insecticides to control aphid vectors and cucumber mosaic virus in narrow-leafed lupins Lupinus angustifolius)

1997 ◽  
Vol 37 (1) ◽  
pp. 93 ◽  
Author(s):  
A. M. Bwye ◽  
W. Proudlove ◽  
F. A. Berlandier ◽  
R. A. C. Jones
Keyword(s):  
Grain Yield ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Field Experiments ◽  
Virus Transmission ◽  
Primary Source ◽  
Lupinus Angustifolius ◽  
Current Season ◽  
Infected Seed ◽  
Carbamate Insecticides

Summary. Narrow-leafed lupins (Lupinus angustifolius) were sown in 4 field experiments to investigate the effects of applying organophosphorus and carbamate insecticides on the spread of cucumber mosaic virus (CMV), which is transmitted non-persistently by aphids. The seed sown carried 0 or 5% CMV infection and seed-infected plants were the primary source for subsequent virus transmission by aphids. Virus incidence was gauged by calculating the percentage of plants per plot showing typical current-season CMV symptoms. At final assessment in plots sown with 5% infected seed, recorded CMV incidence was always significantly smaller (up to 3-fold less) when they received sprays of pirimicarb and/or methamidophos every 2 weeks than when they received no insecticide. When single or double strategic sprays of methamidophos or a mixture of pirimicarb/thiometon were applied in late August or early September, they either decreased recorded CMV incidence (up to 2-fold less infection) or had no significant effect on it. Recorded CMV incidence was not significantly diminished by dressing seed with disulfoton or by single- or double-foliar applications of pirimicarb used alone. However, pirimicarb sprays applied every 2 weeks improved grain yield (24% increase), as also did single or double applications of pirimicarb (14%). In one experiment, applications of methamidophos every 2 weeks to plots originally sown with 5% infected seed resulted in increased grain yield (35%) and yields were increased in plots sown with healthy seed whether sprayed every 2 weeks with methamidophos or left unsprayed (42–61%). Pirimicarb suppressed numbers of colonising Acyrthosiphon kondoi and Aphis craccivora to a greater extent than those of Myzus persicae, especially when sprayed every 2 weeks. Single-, double- and sprays of methamidophos every 2 weeks also decreased numbers of Acyrthosiphon kondoi, but had less effect on M. persicae. When different insecticides were tested for their abilities to kill colonising, insecticide-resistant M. persicae, methamidophos was the most effective. This work suggests that single or double strategic foliar sprays of organophosphorus or carbamate insecticides cannot be relied on to control CMV adequately to be recommended for use in increasing grain yields in CMV-infected lupin grain crops.

scholarly journals Marginal superiority of maize: an indicator for density tolerance under high plant density

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Guangzhou Liu ◽  
Wanmao Liu ◽  
Yunshan Yang ◽  
Xiaoxia Guo ◽  
Guoqiang Zhang ◽  
...  
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Plant Density ◽  
Significant Negative Correlation ◽  
Growth Conditions ◽  
High Density ◽  
Leaf Angle ◽  
Individual Plant ◽  
High Plant Density ◽  
Tolerance Field

Abstract Marginal superiority is a common phenomenon in crops, and is caused by the competitiveness of individual plant for resources and crop adaptability to crowded growth conditions. In this study, in order to clarify the response of marginal superiority to maize morphology and plant-density tolerance, field experiments without water and nutrition stress were conducted at Qitai Farm in Xinjiang, China, in 2013–2014 and 2016–2019. The results showed that no more than three border rows of all the cultivars had marginal superiority under high density, about 90% of all the cultivars had no more than two border row that had marginal superiority and a significant negative correlation was observed between marginal superiority and population grain yield (first border row: y = − 2.193x + 213.9, p < 0.05; second border row: y = − 2.076x + 159.2, p < 0.01). Additionally, marginal superiority was found to have a significant positive relationship with plant density (first border row: y = 6.049x + 73.76, p < 0.01; second border row: y = 1.88x + 95.41, p < 0.05) and the average leaf angle above the ear (first border row: y = 2.306x + 103.1, p < 0.01). These results indicated that the smaller the leaf angle above the ear, the weaker the marginal superiority and the higher the grain yield. It suggests that the magnitude of marginal superiority in the border rows can be an indicator for plant-density tolerance under high density. What’s more, cultivars with small leaf angle above the ear can be selected to weaken the marginal superiority and improve grain yield under high plant density. Conversely, cultivars with a large leaf angle above the ear can be selected to achieve higher individual yield in intercropping systems with no more than four rows alternated with other crops.

Grading monogerm sugar-beet seed and its influence on performance

1974 ◽  
Vol 83 (1) ◽  
pp. 125-133 ◽  
Author(s):  
P. C. Longden ◽  
R. K. Scott ◽  
D. W. Wood
Keyword(s):  
Sugar Beet ◽  
Seed Weight ◽  
Field Experiments ◽  
Plant Density ◽  
Seedling Emergence ◽  
Growth And Yield ◽  
Viable Seed ◽  
True Seed ◽  
High Plant Density ◽  
Fruit Diameter

SUMMARYFrom monogerm sugar-beet seed as harvested non-viable fruits have to be eliminated, multigerm ones rejected and the size made sufficiently uniform for use in precision drills. Seed which had been gently rubbed to remove some of the cortex was graded for diameter, thickness and by aspiration, either singly or in combination. Effects of grading were determined by laboratory germination tests, radiography and field sowings in which seedling emergence and crop growth and yield were recorded.Grading by thickness was effective in removing multigerm fruits. Grading by aspiration and diameter rejected non-viable seed and reduced the variation in size. By combining all three grading methods, samples of seed of 80% germination and 90% monogermity were produced, provided the seed lot as threshed gave at least 50% germination. True seed weight increased with fruit diameter but only the first aspiration was effective in removing light true seeds. Radiography showed that both aspiration and, to a less extent, grading by diameter were effective in removing most empty fruits but neither eliminated those with shrivelled seed. The field experiments confirmed that increase in fruit diameter or aspiration gave more seedlings. Even at uniform, high plant density, sugar yields were less from the smallest (less than 3 mm diameter) than from the other grades of seed. The initial aspiration also improved sugar yield but further aspiration decreased yield.

Inoculation with root nodulating bacteria reduces the susceptibility of Medicago truncatula and Lupinus angustifolius to cucumber mosaic virus (CMV) and addition of nitrate partially reverses the effect

1993 ◽  
Vol 44 (8) ◽  
pp. 1917 ◽  
Author(s):  
WS Wahyuni ◽  
JW Randles
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Medicago Truncatula ◽  
Growth Conditions ◽  
Lupinus Angustifolius ◽  
Acetylene Reduction Activity ◽  
High Concentration ◽  
Virus Particles ◽  
Barrel Medic ◽  
Virus Content

The susceptibility of Medicago truncatula ssp. truncatula (barrel medic) cv. Jemalong and Lupinus angustifolius (lupin) cv. Illyarrie and Gungurru to cucumber mosaic virus (CMV) was reduced by prior inoculation of seedlings with commercial strains of root nodulating bacteria (Rhizobium or Bradyrhizobium, respectively). This effect was observed both with strains of CMV originating from legumes and with strains originating from non-legumes. The virus content of the nodulated plants which were successfully inoculated was not markedly affected by nodulation, indicating that nodulation affected susceptibility to inoculation, and not the ability of CMV to replicate. In lupins, the reduction in susceptibility followed mechanical and graft inoculation of plants with virus. The effect was first noted at about the time that acetylene reduction activity (ARA) was first detected and just before nodules appeared. Virus-infected lupins showed a delay in the development of nodules and a reduced ARA, compared with uninfected plants, indicating that there was a two-way interaction between the virus and Bradyrhizobium. Different growth conditions did not affect the ARA values, the severity of symptoms or the susceptibility of lupin to CMV. A minimum level of nitrate was required for medic growth both with and without the root nodulating bacteria. The addition of higher levels of nitrate to the nutrient solution partially reversed the effect of the nodulating bacteria, in that it increased the susceptibility of the plants. Medics not inoculated with Rhizobium and supplied with a high concentration of nitrate were the most susceptible to CMV. In a test to compare competent with incompetent bacteria, Rhizobium strain 1021 (which fixes N2) and its mutant, Rm 1491 (which does not fix N2), did not differ in their effect on susceptibility. Aggregates of virus particles and crystals of virus were found in nodule cells of medic plants, but virus particles and bacteroids were not found in the same cell. Individual and aggregated virus particles were commonly located along the cell wall of cells free of bacteroids. It is concluded that infection by root nodulating bacteria and external nitrogen supplementation have opposite effects on the susceptibility of barrel medic and lupin to CMV, and that CMV, in turn, reduces the effectiveness of the symbiosis between these bacteria and their host. Nodulation has little effect on virus replication, and both virus and bacteroids occur in the same nodule tissue.

Unraveling the impact of plant-density genetic architecture on agronomic traits in canola

2021 ◽  
Author(s):  
Yesica C Menendez ◽  
Diego H Sanchez ◽  
Rod J Snowdon ◽  
Deborah P Rondanini ◽  
Javier F Botto
Keyword(s):  
Complex Traits ◽  
Field Experiments ◽  
Plant Density ◽  
Agronomic Traits ◽  
Crop Productivity ◽  
Growth And Yield ◽  
Yield Traits ◽  
Density Dependent ◽  
High Plant Density ◽  
The Impact

Abstract Plant density defines vegetative architecture and competition for light between individuals. Brassica napus (canola), as a model system of indeterminate growth, presents a radically different plant architecture compared to traditional crops commonly cultivated at high density. Using a panel of 152 spring-type canola accessions and a double haploid (DH) population of 99 lines from a cross between Lynx and Monty, we performed Genome-Wide-Analysis-Studies (GWAS) and Quantitative Trait Locus (QTL) mapping for 12 growth and yield traits at two contrasting plant densities (15 and 60 plants m -2). We revealed mostly novel associations by GWAS (19) and QTLs (11) for growth and yield traits being the most significant for flowering, biomass, rosette height, silique and seed number, and grain yield; often representing density-independent signals although we also uncovered some density-dependent associations typically mapping at low density. Further RNA-seq transcriptomics revealed distinctive latent gene regulatory responses to simulated shade between Lynx and Monty. Given the phylogenetic relatedness, we additionally used Arabidopsis thaliana aiming at testing genes to validate density effects of homologous counterparts mapping into relevant rapeseed QTLs. Our results suggest that TCP1 may promote the growth independently of plant neighbors, while HY5 could increase biomass and seed yield specifically at high plant density. For flowering time, the observations in tested mutants suggested that the corresponding genes may plausibly contribute to promote flowering in plant-density dependent (i.e., PIN) and independent (i.e., FT, HY5 and TCP1) manner. This work underscores the advantages of using agronomic field experiments together with genetic and transcriptomic approaches to decipher quantitative complex traits that potentially mediate superior crop productivity.

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