Glyphosate-induced hormesis: impact on seedling growth and reproductive potential of common sowthistle (Sonchus oleraceus)

Weed Science ◽  
2020 ◽  
Vol 68 (6) ◽  
pp. 605-611
Author(s):  
Ahmadreza Mobli ◽  
Amar Matloob ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Production ◽  
Reproductive Potential ◽  
Low Doses ◽  
Sonchus Oleraceus ◽  
Pot Trials ◽  
Plant Maturity ◽  
Number Of Leaves ◽  
Sublethal Doses ◽  
The University ◽  
Herbicide Drift

AbstractIn Australia, glyphosate is widely used in glyphosate-tolerant crops and fallows to control weeds such as common sowthistle (Sonchus oleraceus L.). It has been hypothesized that glyphosate at sublethal doses, as a consequence of herbicide drift, may have a stimulatory effect on S. oleraceus growth. In 2017, pot trials were conducted to evaluate the effect of low doses of glyphosate on growth and seed production of this weed at the Weed Science Screenhouse Facility at the University of Queensland, Australia. At the 4- to 5-leaf stage (3-wk-old rosette), plants were treated with low doses of glyphosate (0 [control], 5, 10, 20, 40, 80, and 800 g ae ha−1), and their responses were recorded until plant maturity. The study was repeated after completion of the first experimental run. An additional glyphosate dose (2.5 g ha−1) was added in the second run. The low doses of glyphosate (<40 g ha−1) caused a significant increase in S. oleraceus plant height and number of leaves compared with the no-glyphosate treatment. The highest stimulatory effect was observed at 5 g ha−1. At 5 g ha−1 glyphosate, S. oleraceus seed production increased by 154% and 101% in the first and second experimental runs, respectively, compared with the no-glyphosate treatment. The results of this study suggest that the sublethal doses of glyphosate produced hormetic effects on growth and seed production of S. oleraceus that changed the dynamics of weed–crop competition.

Effect of Spraying Foliar with Humus and Izomen Biostimulants on Some Vegetative and Flowering Parameters of Freesia hybrida L.

2019 ◽  
Vol 9 (2) ◽  
pp. 240-246
Author(s):  
Neveen Anwer Abdalla
Keyword(s):  
Plant Height ◽  
Landscape Design ◽  
Vase Life ◽  
College Of Agriculture ◽  
Flowering Date ◽  
Freesia Hybrida ◽  
Loam Soil ◽  
Number Of Leaves ◽  
The University

The experiment has been conducted in the nursery of the Department of Horticulture and Landscape Design, College of Agriculture, the University of Basrah to study the effect of Spraying foliar of the biostimulants Izomen and Humus on the growth and flowering of Freesia plants. The corms in similar size were planted in pots with a diameter and height of 25 cm, which filled with 2.5 kg of sterilized loam soil. After 50 days of planting, the plants sprayed with Humus at 0, 1.5, 2.5 ml L-1 and after five days sprayed with Izomen at 0, 1.5, 2.5 ml L-1 The different concentrations of biostimulants are sprayed three times, the period between one spray and another 15 is days. The results showed that the spraying of Humus at 2.5 ml L-1 significantly increased the plant height, the number of leaves and the leaf content of chlorophyll recorded (29.56 cm, 8.33 and 58.43%) respectively. Moreover, it is recorded early the flowering date (130 days), and the highest flowering mean is (2.12 inflorescence/plant) and the highest period of the remained flowers on the plant and the vase life (10 and 8 days) respectively. The effects of both Humus and Izomen were similar. In addition to the highest mean of their interaction at 2.5 ml L -1for all the studied traits.

Phenology and seed production in Chenopodium rubrum, Rumex maritimus, and Rumex palustris as related to photoperiod in river forelands

1992 ◽  
Vol 70 (2) ◽  
pp. 392-400 ◽  
Author(s):  
A. J. M. Van der Sman ◽  
C. W. P. M. Blom ◽  
H. M. Van de Steeg
Keyword(s):  
Life Cycle ◽  
Seed Production ◽  
Population Level ◽  
Flowering Phenology ◽  
Chenopodium Rubrum ◽  
Axillary Shoots ◽  
Critical Photoperiod ◽  
Number Of Leaves ◽  
Rumex Maritimus ◽  
Flooded Areas

Reproductive development in three species from irregularly flooded areas of river forelands was studied in relation to time of emergence. In Chenopodium rubrum, flowering was induced earlier in plants germinated in April–May than in later cohorts. However, the period of vegetative growth diminished and the life cycle was completed in a shorter time in later germinated plants. Seed number was reduced, but seed size as well as reproductive effort per plant increased in later cohorts. Plants of both Rumex species flowered after a certain number of leaves had developed and before a critical photoperiod had passed. In earlier cohorts, the main shoot and several axillary shoots elongated and flowered. Fewer axillary shoots flowered closer to the critical photoperiod, and this resulted in a reduced seed output in later cohorts. The critical photoperiod as well as the time needed for completion of the life cycle was longer in Rumex palustris than in Rumex maritimus. It is argued that in the riparian habitat, plants of both Rumex species are only occasionally able to complete their life cycle in one growing season. Survival of these species on the population level will rely more upon adaptations towards flooding during the established phase than is the case for C. rubrum. Key words: flowering phenology, photoperiod, seed production, Chenopodium rubrum, Rumex maritimus, Rumex palustris.

scholarly journals The Response of Fordhook Giant / Swisschard (Beta vulgaris var Cicla) and Mustard (Brassica Juncea) Spinach Vegetables to Irrigation with Saline Water

2020 ◽  
pp. 20-26
Author(s):  
M. V. Dlamini ◽  
M. T. Masarirambi
Keyword(s):  
Plant Height ◽  
Irrigation Water ◽  
Saline Water ◽  
Block Design ◽  
Water Source ◽  
Saline Irrigation ◽  
Randomized Block Design ◽  
Salinity Levels ◽  
Number Of Leaves ◽  
The University

Saline irrigation water is becoming an important water source as fresh water is fast becoming a scarce resource in many areas of the world, including Eswatini, especially in arid and semi-arid regions.  A study to test the response of two varieties of spinach (fordhook giant and mustard) to salinity was conducted in a field pot experiment at the Faculty of Agriculture at the Luyengo Campus of the University of Eswatini.  The treatments were laid in a randomized block design (RCBD).  The experiment consisted of four treatments, each replicated twelve times.  Treatments were salinity levels of 0.0 dS/m, 1.5 dS/m, 2.0 dS/m and 3.5 dS/m.  All the treatments were subjected to similar agronomic practices. Spinach was grown and observed for a period of five weeks.  Plant height was measured and the number of leaves counted weekly throughout the experiment. Significant differences (P < 0.05) between salinity treatments were obtained for plant height beginning in week 2 but were more pronounced in week 3, 4 and week 5.  No significant differences were obtained for the number of leaves.  There were however, clear significant differences between spinach irrigated with none saline irrigation water compared to saline irrigation water.   It was concluded that irrigating spinach with saline water of more than 2.0 dS/m drastically reduce plant growth but not the number of leaves under the conditions of the experiment.

scholarly journals Influence of Detasseling Methods on Seed Yield of Some Parent Inbred Lines of Turda Maize Hybrids

Agronomy ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 729
Author(s):  
Alexandru Bogdan Ghețe ◽  
Voichița Haș ◽  
Roxana Vidican ◽  
Ana Copândean ◽  
Ovidiu Ranta ◽  
...  
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Weather Conditions ◽  
Inbred Lines ◽  
Plant Performance ◽  
Yield Response ◽  
Genetic Purity ◽  
Short Period ◽  
Number Of Leaves ◽  
Hybrid Maize

During the process of maize seed production, in order to ensure the genetic purity of parental forms of hybrid maize, an important work performed is the removal of male inflorescences from plants on mother rows. Hand detasseling has high precision but is labor-intensive. Mechanical detasseling offers the possibility to cover large acreages in a short period of time, but the number of leaves removed has a varying influence on plant performance and seed yield. The aim of this study was to simulate three types of damages on plants similar to those induced through mechanical detasseling and to assess the effects for five inbred lines during the course of three years. Results show that when tassels alone were removed, the average seed yield decreased an average of 4–21%. When two leaves were removed with the tassel, yield decreased an average of 22–31%, while when plants were cut above the main ear, seed yield decreased an average of 31–66%. Environmental conditions influenced seed yield, especially high temperatures during flowering. Yield response to tassel and leaves removal varied between the inbred lines. Genotype controls maize ear and kernel characters, while environmental factors exercise a strong influence on seed yield, due to the succession of years with contrasting weather conditions in a key phenophase. Within the trend of full mechanization in agriculture, identification of inbred lines that cope better with plant damage can assist in optimizing seed production.

Seed production in forests of Chamaecyparislawsoniana

1979 ◽  
Vol 9 (3) ◽  
pp. 327-335
Author(s):  
Donald B. Zobel
Keyword(s):  
Seed Production ◽  
Reproductive Potential ◽  
Basal Area ◽  
Annual Production ◽  
Forest Community ◽  
Regional Pattern ◽  
Crop Size ◽  
Seed Collection ◽  
Open Forest ◽  
Seed Crops

In 3 years of seed collection throughout the range of Chamaecyparislawsoniana (A. Murr.) Parl., 30 seed crops varied from 20 000 to 4 600 000 seeds per hectare. The overall mean was 829 000 seeds per hectare per year. Annual production per square metre of basal area (BA) varied from 600 to 185 000. Only 6 of 30 seed crops exceeded 50 000 seeds/m2 BA per year but these were produced by the youngest (65 year old) and oldest (450 + year old) stands and throughout the environmental range of the species. Of other seed crops, 11 had 10 000–50 000 seeds/m2 BA per year and 13 had fewer than 10 000 seeds/m2 BA per year. Year-to-year variation had a local, not regional, pattern. An open-forest community produced more seed per square metre of basal area than a denser one at two mixed evergreen zone sites. Seedfall peaked from October to November, with a smaller spring peak, but some seeds fell throughout the year. Most sites differed little in the timing of peaks. Germination of trapped seed from seven sites in 1 year was 11–44% and showed no correlation with crop size. Other species in this genus produce many more seeds per hectare than C. lawsoniana but there is no evidence that seed production limits reproductive potential of this species. In mixed forests, C. lawsoniana and especially Tsugaheterophylla (Raf.) Sarg. were over represented in the seedfall (compared with their basal area), whereas Pseudotsugamenziesli (Mirb.) Franco and Abiesconcolor (Gordon and Glend.) Lindl. ex Hildebr. produced less than their share.

Pre-dispersal seed predation by the weevils Trichapion rostrum and Tychius sordidus limits reproductive output of Baptisia alba (Fabaceae)

Botany ◽  
2017 ◽  
Vol 95 (8) ◽  
pp. 809-817 ◽  
Author(s):  
Ashley M. Hembrough ◽  
Victoria A. Borowicz
Keyword(s):  
Seed Production ◽  
Seed Predation ◽  
Reproductive Output ◽  
Pollen Limitation ◽  
Reproductive Potential ◽  
Prairie Restoration ◽  
Seed Number ◽  
Nutrient Supplementation ◽  
Perennial Legume ◽  
Herbaceous Perennial

Baptisia alba (L.) Vent., an herbaceous, perennial legume, produces more flowers than will mature into pods. Single-year experiments on two reconstructed prairies tested the hypothesis that reproductive potential of B. alba depends on nutrients, but pollen limitation and pre-dispersal seed predation by weevils reduce final production. Ramets were assigned one of four treatments that were combinations of fertilizer (none/70 g fertilizer twice) and insect barrier (none/application of Tanglefoot). Within inflorescences, flowers were naturally pollinated or supplemented with pollen. Fertilizer produced no effects, suggesting that B. alba are unresponsive within a season to nutrient supplementation. Pollen supplementation increased pod initiation at the two sites by 6.7% and 2.3%, respectively, but did not affect the proportion of initiated pods that matured or seed number within pods. Where Tychius sordidus occurred, only 67 pods matured on 19 ramets and only four seeds survived. Where only Trichapion rostrum was present, insect barrier increased pod maturation almost three-fold, but did not affect seed number within pods. Barrier treatment increased the reproductive output of entire ramets by increasing seed production, from 3.6 seeds·ramet−1 to 60.5 seeds·ramet−1. Prairie restoration frequently uses fruit collected from other populations. Managers should be careful to avoid the unintended introduction of voracious seed predators.

Theses on Sub-Saharan Africa Accepted by the University of California at Berkeley

1969 ◽  
Vol 12 (02) ◽  
pp. 157-166 ◽  
Author(s):  
R. Philip Hoehn ◽  
Jean Judson
Keyword(s):  
Social Science ◽  
Central Africa ◽  
Sub Saharan Africa ◽  
University Of California ◽  
General Reference ◽  
Interlibrary Loan ◽  
Reference Service ◽  
Number Of Leaves ◽  
Sub Saharan ◽  
The University

This bibliography attempts to list all known theses on sub-Saharan Africa accepted by the University of California at Berkeley, and catalogued by the University Library through January, 1969. The earliest item is dated 1914. The list was compiled from a card file of theses arranged by academic department which is maintained by the Library's General Reference Service. The availability of theses on interlibrary loan is indicated by symbols following the number of leaves (L) in the thesis. An asterisk indicates that the Library has catalogued more than one copy of a title, and that the second copy may be borrowed on interlibrary loan. The symbol # indicates that the Library's Graduate Social Science branch has an uncatalogued copy of the thesis which may be borrowed. Absence of these symbols indicates that the title is not available on interlibrary loan. Photocopies of all M.A. and those Ph.D. these completed before September, 1962 may be purchased from the Library's Photographic Service; those Ph.D. theses from September, 1962 on, from University Microfilms, Inc. The bibliography is in two parts. The first part contains those items which cover more than one country, and is divided into General, Central Africa, East Africa, and West Africa; the second part, arranged by country (present name), lists those titles dealing with only one political unit.

Sunflower (Helianthus annuus L) tolerance to sublethal doses of imazethapyr

1996 ◽  
Vol 76 (4) ◽  
pp. 937-940 ◽  
Author(s):  
David A. Wall
Keyword(s):  
Oil Content ◽  
Seed Oil ◽  
Field Experiments ◽  
Yield Losses ◽  
Seed Oil Content ◽  
Pyridinecarboxylic Acid ◽  
Percentage Points ◽  
Untreated Check ◽  
Sublethal Doses ◽  
Herbicide Drift

Field experiments were conducted from 1992 to 1995 at Morden, Manitoba to investigate the tolerance of sunflower to sublethal doses of imazethapyr {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid). Imazethapyr was applied at 0, 0.375, 0.75, 1.5, 3, and 6 g a.i. ha−1 plus a nonionic surfactant at 0.25% vol/vol when sunflowers were in the six-leaf stage. Dosages higher than 1.5 g ha−1 severely injured sunflowers in some years. Injury symptoms consisted of chlorosis, stunting and seed head deformities. At the dosages tested, imazethapyr reduced sunflower yields in only 1 of 4 yr. In 1994, dosages greater than 1.5 g ha−1 reduced achene yields by 19–38%. Seed oil content was reduced in 2 of 4 yr. At 6 g ha−1 of imazethapyr seed oil content was reduced by as much as 3.2 percentage points compared with the untreated check. While low dosages of imazethapyr may not reduce yields in most years, the potential for severe yield losses and reduced oil contents exist and caution should be used when applying imazethapyr in fields next to sunflowers. Key words: Crop injury, herbicide drift, yield, oil content

scholarly journals LOW DOSES OF FENOXAPROP-P-ETHYL CAUSE HORMESIS IN LITTLESEED CANARYGRASS AND WILD OAT

2016 ◽  
Vol 34 (3) ◽  
pp. 527-533 ◽  
Author(s):  
T. ABBAS ◽  
M.A. NADEEM ◽  
A. TANVEER ◽  
A. ZOHAIB
Keyword(s):  
Seed Production ◽  
Growth Stimulation ◽  
Research Area ◽  
Initial Increase ◽  
Low Doses ◽  
Wild Oat ◽  
Crop Species ◽  
Pot Experiments ◽  
Promotive Effect ◽  
Number Of Seeds

ABSTRACT Hormetic effects of herbicides at ultra-low doses have been proved against range of crop species, although available data of herbicides hormesis about the weeds growth is very limited. This study investigates the promotive effect of low doses of fenoxaprop-Pethyl on growth and seed production of littleseed canarygrass and wild oat. Pot experiments were conducted twice in Wire House at Agronomic Research Area, University of Agriculture, Faisalabad, during 2014-15. Seven different concentrations of fenoxaprop-P-ethyl [0, 1, 3, 6, 9, 12 and 15 g a.i. ha-1] were applied as post emergence herbicide at 3-4 leaves stage of the weeds. Results revealed that increase in growth occurred within first two weeks after spraying at fenoxaprop-P-ethyl doses 1, 3 and 6 g a.i. ha-1. More growth stimulation as compared to all other treatments was observed at fenoxaprop-P-ethyl dose 6 g a.i. ha-1. This initial increase in growth sustains with time up to the maturity of both weeds and positively influences seeds production ability. Up to 28% and 17% increase in number of seeds per plants were occurred in littleseed canarygrass and wild oat, respectively. Doses above 6 g a.i. ha-1 negatively affect the weeds growth and seed production ability.

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