Silicon is an inducible and effective herbivore defence against Helicoverpa punctigera (Lepidoptera: Noctuidae) in soybean

2019 ◽  
Vol 110 (3) ◽  
pp. 417-422 ◽  
Author(s):  
Scott N. Johnson ◽  
Rhiannon C. Rowe ◽  
Casey R. Hall
Keyword(s):  
Leaf Biomass ◽  
Insect Herbivores ◽  
Strong Negative Correlation ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Soybean Pest ◽  
Hyper Accumulators ◽  
Lepidoptera Noctuidae ◽  
Herbivore Defence

AbstractThe role of silicon (Si) in alleviating the effects of biotic and abiotic stresses, including defence against insect herbivores, in plants is widely reported. Si defence against insect herbivores is overwhelmingly studied in grasses (especially the cereals), many of which are hyper-accumulators of Si. Despite being neglected, legumes such as soybean (Glycine max) have the capacity to control Si accumulation and benefit from increased Si supply. We tested how Si supplementation via potassium, sodium or calcium silicate affected a soybean pest, the native budworm Helicoverpa punctigera Wallengren (Lepidoptera: Noctuidae). Herbivory reduced leaf biomass similarly in Si-supplemented (+Si) and non-supplemented (–Si) plants (c. 29 and 23%, respectively) relative to herbivore-free plants. Both Si supplementation and herbivory increased leaf Si concentrations. In relative terms, herbivores induced Si uptake by c. 19% in both +Si and –Si plants. All Si treatments reduced H. punctigera relative growth rates (RGR) to a similar extent for potassium (−41%), sodium (−49%) and calcium (−48%) silicate. Moreover, there was a strong negative correlation between Si accumulation in leaves and herbivore RGR. To our knowledge, this is only the second report of Si-based herbivore defence in soybean; the rapid increase in leaf Si following herbivory being indicative of an induced defence. Taken together with the other benefits of Si supplementation of legumes, Si could prove an effective herbivore defence in legumes as well as grasses.

Establishment and growth of shoots following low and high cutting of lucerne in relation to the pattern of nutrient uptake

1973 ◽  
Vol 24 (4) ◽  
pp. 497 ◽  
Author(s):  
KC Hodgkinson
Keyword(s):  
Phosphorus Content ◽  
Lateral Roots ◽  
Nitrogen And Phosphorus ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Tap Root ◽  
Cutting Frequency ◽  
Net Uptake ◽  
High Level

Lucerne plants (Medicogo sativa cv. Hunter River) were either frequently or infrequently cut down and subsequent differences in shoot regrowth were compared in two experiments. The first experiment demonstrated that differences in final shoot weights arose from differences developed during the first 7 days of regrowth. High level cutting (15 cm) increased the shoot yield of frequently but not of infrequently cut plants. Net uptake of both nitrogen and phosphorus was related to the growth rate of shoots until commencement of flowering, when uptake ceased for c. 15 days even though both roots and shoots continued to gain weight. Towards the end of flowering uptake of nitrogen and phosphorus recommenced and accumulation of both nutrients occurred in the tap-root and lateral roots. The relative nitrogen and phosphorus content of leaves on crown shoots was highest on day 7 and the same for frequently and infrequently cut plants. Leaves on crown and stubble shoots 7 days after high level cutting had a significantly lower relative nitrogen and phosphorus content than leaves on plants cut low. Thereafter the relative nitrogen and phosphorus content of a11 leaves declined with the greatest decline occurring after the commencement of flowering. In the second experiment early morphogenesis of the shoot population was investigated. Establishment of shoots was completed between 3 and 5 days after cutting. Higher shoot weights on infrequently cut plants were accounted for by a larger number of small shoots at the time of cutting. Relative growth rates of shoots did not appear to be influenced by prior cutting frequency. The relative nitrogen content of buds and shoot apices was low at cutting but doubled within 2 or 3 days and then declined after day 7. These results are discussed in relation to the role of 'plant factors' in shoot regrowth of lucerne.

scholarly journals Comportamento vegetativo do tomateiro-cereja (Lycopersicon pimpinellifolium) irrigado com águas salinas

2019 ◽  
Vol 1 (44) ◽  
pp. 132
Author(s):  
Lidiane Maria dos Santos Guimarães Barros ◽  
Jose Lucínio de Oliveira Freire ◽  
Andreza Agda Dantas Silva
Keyword(s):  
Growth Rate ◽  
Biomass Allocation ◽  
Growth Rates ◽  
Root Biomass ◽  
Water Levels ◽  
Stem Diameter ◽  
Leaf Biomass ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
The Absolute

Saltwater in irrigation is an alternative to agriculture in the semi-arid region of the Northeast of Brazil. Due to the lack of research on this theme, this work aimed at the effects of water salinity on the vegetative behavior of cherry tomatoes. The experiment was carried out in a completely randomized design with 50% shade, using six water levels (0.5, 2.0, 3.5, 5.0, 6.5 and 8.0 dS m-1) and eight replicates. Absolute and relative growth rates in height, stem diameter, fresh epigene phytomass, dry leaf phytomass, days for initial, stem, root and total flowering, leaf biomass, root and root biomass were analyzed. The salinity reduced absolute and relative growth rates in height; the absolute growth rate of the fresh epigene phytomass and the dry foliar, caulinar, root and total phytomass; the allocation of the biomass; and the flowering days of the crop. The absolute and relative growth rates of the stem diameter, the relative growth rate of the fresh epigene phytomass and the root biomass allocation were not influenced by the increase in the electrical conductivity of the water. The leaf biomass allocation was the indicator that best represented the effect of saline stress and obtained linear growth

A Measure of Economic Growth in East and in West Pakistan

1961 ◽  
Vol 1 (2) ◽  
pp. 49-54
Author(s):  
S. U. Khan
Keyword(s):  
Regional Planning ◽  
National Income ◽  
Future Planning ◽  
Correct Evaluation ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
National Planning ◽  
Income Data ◽  
Regional Basis ◽  
The Difference

It is sometimes said that "national planning will simply have no meaning if it completely ignores the economic disparities between the two wings and fails to evolve a sensible pattern of regional planning"2. The lack of much essential data on a regional basis, however, renders any precise estimate of the relative growth rates almost impossible. Data either are not available or are inadequate on such important variables as production, income, consumption and trade, so that even a correct evaluation of past development efforts is not possible. The implications of such a situation for future planning are not difficult to understand. In this article an attempt is made to estimate the absorption of specified commodities in East and West Pakistan separately3. This will indicate the pattern of consumption and also give a rough idea about the growth rate of the two wings. With this purpose in view, quantity indices of absorption are prepared for each wing separately, taking data on availability of goods and prices from the Institute's monograph on Inflation. The quantity indi¬ces, however, are not of course strictly comparable with national income estimates because of the difference in coverage of the two series. National income data include government, services, trade, etc., while the quantity indices cover only specified goods available for each region.

CHANGES IN ENZYMES AND PROTEINS IN SALT-SHOCKED VS. GRADIENT INCREASES IN NACL IN `POINSETT' CUCUMBER ROOTS

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1091G-1091
Author(s):  
Anne K. Hurley ◽  
B. Greg Cobb
Keyword(s):  
Invertase Activity ◽  
Shock Treatment ◽  
Cucumis Sativus L ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Salt Shock ◽  
Gradient Solution ◽  
Cucumber Roots ◽  
Average Plant ◽  
Plastochron Index

Cucumis sativus, L., `Poinsett' seedlings were grown under artificial light in 40% modified Hoagland's solution until an average plant plastochron index of 4.73 was reached. Plants were then placed in solutions of (1) 0 mM NaCl, (2) 80 mM NaCl (salt-shock), or (3) placed in a dropwise gradient solution of NaCl and Hoagland's until the final concentration of 80 mM NaCl was reached at 41 hours. Leaves of the 80 mM shock treatment wilted immediately, but recovered turgor within 6 hours. Leaves of 80 mM gradient did not wilt at anytime. The control and gradient treatments had relative growth rates which were similar to each other, but RGR decreased in the shock treatment. Invertase activity was measured in the roots at 24, 41, and 48 hours after initial treatment. Invertase activity of shock treatment increased significantly over the controls at 24 hours. The 80mM gradient was not significantly different than either treatment. Four isozymes of α– galactosidase were detected. The relative intensities of the bands varied with time and treatment. One invertase band was resolved in roots on 8% native acrylamide gels. SDS gels indicated increases in proteins in the gradient treatment compared to the control and the 80 mM shock treatment.

Rates of growth of the food fungus of the leaf-cutting ant Atta cephalotes (L.) (Hymenoptera: Formicidae) on different substrates gathered by the ants

1979 ◽  
Vol 69 (1) ◽  
pp. 141-148 ◽  
Author(s):  
A. Mudd ◽  
G. L. Bateman
Keyword(s):  
Nutrient Availability ◽  
Plant Material ◽  
Growth Inhibitors ◽  
Atta Cephalotes ◽  
Leaf Extracts ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Foraging Preferences ◽  
Leaf Cutting ◽  
Rates Of Growth

AbstractGrowth of the food fungus of the leaf-cutting ant Atta cephalotes (L.) on extracts of plants selected by the ants was shown to be affected by the plant species, the pH of the extract, the concentration of the sap or plant extract and pretreatment of the substrate by the ants. It was not possible to establish an unambiguous relationship between the rate of growth of the fungus on leaf extracts and the foraging preferences of the ants for the leaves. There were indications, however, that the fungus grows most rapidly on extracts of plant material preferred by A. cephalotes. Relative growth rates of the fungus on different substrates may be related to the presence of growth inhibitors rather than to nutrient availability.

scholarly journals Pathogenicity of Metarhizium rileyi (Farlow) Kepler, S.A. Rehner and Humber isolates against Spodoptera litura (Fabricius) and their extracellular enzymatic activities

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Gurmehar Kaur Grewal ◽  
Neelam Joshi ◽  
Yadhu Suneja
Keyword(s):  
Spodoptera Litura ◽  
Larval Mortality ◽  
Screening Methods ◽  
Metarhizium Rileyi ◽  
Percent Mortality ◽  
Commercially Important ◽  
Extracellular Enzymatic Activities ◽  
Chemical Pesticides ◽  
Lepidoptera Noctuidae

Abstract Background Spodoptera litura (Fab.) (Lepidoptera: Noctuidae) is a serious agricultural pest that infests many commercially important crops of Southeast Asian countries. Indiscriminate use of chemical pesticides has led to various health hazards as well as insecticide resistance. Entomopathogenic fungi (EPF) provide an important alternative as biological control agents. Metarhizium rileyi is an EPF with a specific host range for lepidopteran pests. The present study aimed to identify virulent M. rileyi isolate against S. litura larvae and analyse their extracellular cuticle-degrading enzyme activities. Results Three M. rileyi isolates viz M. rileyi NIPHM, M. rileyi MTCC 4254 and M. rileyi MTCC 10395 formulations were evaluated at different concentrations against 2nd instar larvae of S. litura. A maximum percent mortality of 63.33% was recorded in M. rileyi NIPHM (12 g/l), followed by M. rileyi MTCC 4254 (58.33%) at the same concentration, 10 days post-treatment. Maximum means of chitinase, protease and lipase activities (0.44, 1.58 and 2.95 U/ml, respectively) were recorded in the case of M. rileyi NIPHM. Correlation analysis was positive between enzyme activity and larval mortality. Conclusions Metarhizium rileyi NIPHM recorded the highest enzymatic activity and exhibited the maximum mortality rate against 2nd instar larvae of S. litura, suggesting the possible role of these enzymes in the pathogenicity of the fungus. Further knowledge in this regard may help in the development of enzyme-based screening methods for selecting virulent fungal isolates for the eco-friendly management of crop pests.

Selection for biomass production based on respiration parameters in eucalypts: effects of origin and growth climates on growth rates

1996 ◽  
Vol 26 (9) ◽  
pp. 1556-1568 ◽  
Author(s):  
Thimmappa S. Anekonda ◽  
Richard S. Criddle ◽  
Lee D. Hansen ◽  
Mike Bacca
Keyword(s):  
Temperature Dependence ◽  
Growth Rates ◽  
Heat Rate ◽  
Eucalyptus Species ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Metabolic Heat ◽  
Respiratory Parameters ◽  
Metabolic Heat Rate ◽  
Different Climates

Seventeen Eucalyptus species and 30 rapid-growing Eucalyptuscamaldulensis trees (referred to as plus trees), growing in a plantation were studied to examine relationships among measured plant growth and respiratory parameters, geographical origins, and growth climate. The respiratory parameters measured at two different temperatures by isothermal calorimetry were metabolic heat rate, rate of CO2 production, and the ratio of heat rate to CO2 rate. Metabolic heat rate was also measured as a continuous function of temperature by differential scanning calorimetry in the range of 10 to 40 °C. Tree growth was measured as rates of height and stem volume growth. The values of respiratory and growth variables of Eucalyptus species are significantly correlated with latitude and altitude of origin of their seed sources. The maximum metabolic heat rate, the temperature of the maximum heat rate, the temperature coefficients of metabolic rate, and the temperatures at which the slopes of Arrhenius plots change are all genetically determined parameters that vary both within and among species. Measurement of growth rate–respiration rate–temperature relationships guide understanding of why relative growth rates of Eucalyptus species and individual genotypes differ with climate, making it possible to identify genotypes best suited for rapid growth in different climates. The temperature dependence of respiration rates is an important factor determining relative growth rates of eucalypts in different climates. To achieve optimum biomass production the temperature dependence of individual plants must be matched to growth climate.

Studies on the sowing dates of cotton in the Sudan Gezira: I. The influence of date of sowing on plant growth and development

1967 ◽  
Vol 69 (3) ◽  
pp. 305-315 ◽  
Author(s):  
J. E. Jackson
Keyword(s):  
Growth Rates ◽  
Slow Growth ◽  
Seasonal Pattern ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Research Division ◽  
Sowing Dates ◽  
Net Assimilation ◽  
State Growth ◽  
Sudan Gezira

Growth analysis of cotton crops sown in the Sudan Gezira at monthly intervals between August and May revealed a marked seasonal pattern of growth. Irrespective of plant age and fruiting state growth of non-senescent plants was slowest during the cool winter months. Relative growth rates of young plants were highest in August, September and early October due to the high specific leaf areas and fairly high net assimilation rates found then. They were lowest when minimum temperatures were lowest. Net assimilation rates were also lowest in the coolest months, probably as a result of restricted growth. High temperatures in the spring reduced fruiting. It is concluded that low minimum temperatures and high evaporation rates are both associated with slow growth, and play a large part in determining the characteristic decline of growth rates of cotton sown at the usual date in August.I wish to thank the Chief of the Research Division, Ministry of Agriculture, Sudan, for permission to publish this paper and to record my gratitude to the team of field and laboratory assistants, especially Salih Saad and Hassan Osman, who helped in the work.

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