scholarly journals Differing Vernalization Responses of Laurentia axillaris and Veronica spicata `Red Fox': Evidence for Two Thermometers?

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 878D-878
Author(s):  
Beth A. Fausey ◽  
Arthur C. Cameron*

Many herbaceous perennials require vernalization although effective temperatures (ET) and durations for specific species are largely unknown. To investigate vernalization of Laurentia axillaris (Lindl.) E. Wimm. and Veronica spicata L. `Red Fox', vegetative plugs were stored at -2.5, 0.0, 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 17.5, and 20.0 °C for 0 to 15 weeks (Laurentia) or 0 to 8 weeks (Veronica). Following storage, plugs were grown in a 20 °C glass greenhouse with a 16-h photoperiod. Laurentia plugs did not survive storage at -2.5 or 0 °C. Survival varied for plants stored at 2.5 °C, and some plants flowered. ET and the minimum duration for 100% flowering of Laurentia were: 5 weeks at 5 to 10 °C and 10 weeks at 12.5 °C. Time to first visible bud and node number below first visible bud decreased with increasing duration at ET. Veronica plugs survived storage at all temperatures. 100% flowering occurred when plants were vernalized at -2.5 and 0 °C for 4 or more weeks, at 2.5 and 5.0 °C for 6 or more weeks, and at 7.5 °C for 8 weeks. Incomplete vernalization (19 to 93%) occurred at temperatures of 2.5 °C for 4 weeks, 5 °C for 4 or 6 weeks, 7.5 °C for 6 weeks and at 10 °C for 6 or 8 weeks. Vernalization did not occur above 10 °C or following 2 weeks storage at any temperature. The percentage of reproductive lateral shoots increased while node number below the inflorescence remained constant or decreased with increasing storage at ET. The results indicate distinct vernalization optima for the two species; Laurentia 5 to 10 °C, and Veronica -2.5 to 0 °C. These differences provide evidence that separate “thermometers” may be involved in vernalization perception.

2007 ◽  
Vol 132 (6) ◽  
pp. 751-757 ◽  
Author(s):  
Beth A. Fausey ◽  
Arthur C. Cameron

Many polycarpic herbaceous perennials are known to have a cold-requirement for flowering. To determine the range and relative effectiveness of vernalization temperatures for flower induction, clonally propagated plants of veronica (Veronica spicata L.) ‘Red Fox’ and laurentia [Laurentia axillaris (Lindl.) E. Wimm.] were exposed to temperatures from −2.5 to 20 °C at 2.5 °C increments for 0, 2, 4, 6, or 8 weeks (veronica ‘Red Fox’) and 0, 2.5, 5, 7.5, 10, 12.5, or 15 weeks (laurentia). After treatments, growth and flowering were monitored in a glass greenhouse set at 20 °C with an average daily light integral of ≈5 mol·m−2·d−1. Both veronica ‘Red Fox’ and laurentia exhibited obligate vernalization requirements for flowering, but the temperature–response curves were distinctly different. A minimum of 4 weeks at −2.5 and 0 °C, 6 weeks at 2.5 °C, and 8 weeks at 5 and 7.5 °C was required for complete (100%) flowering of veronica ‘Red Fox’, while a minimum of 5 weeks at 5 to 10 °C, 7.5 weeks at 12.5 °C, and 10 weeks at 2.5 °C were required for complete flowering of laurentia. For veronica ‘Red Fox’, node number under each flower and flower timing were relatively fixed following up to 8 weeks at each temperature, although these values generally decreased at each temperature with extended exposure for laurentia. Based on percent flowering and percentage of lateral nodes flowering, vernalization of veronica ‘Red Fox’ was most effective at 0 and −2.5 °C, while based on percent flowering and flower number, vernalization of laurentia was most effective at 5 to 10 °C.


HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 510A-510
Author(s):  
James E. Faust ◽  
Elizabeth Will ◽  
Xian Duan ◽  
Effin T. Graham

Poinsettia stem breakage reduces plant quality and marketability. The cultivar `Freedom' is susceptible to stem breakage; however, the severity of stem breakage varies with crop and year. The following four experiments were conducted to determine the factors that influence stem breakage of `Freedom' poinsettias: 1) Cutting Stem Diameter. Cuttings were graded by stem diameter into small (5.0–5.4 mm), medium (6.0–6.7 mm), and large (7.3–8.3 mm) cuttings. 2) Premature Lateral Shoot Development.Small (1- to 3-cm-long) leaves near the shoot tip of the rooted cuttings were excised to remove the lateral shoots from apical dominance prior to pinching, thus causing the lateral shoots to develop prematurely. 3) Container Spacing. The control group was spaced to 35.6 × 35.6 cm at the time of pinching. The plants in one treatment were spaced to 23.1 × 23.1 cm 25 days after pinching, and then spaced to 35.6 × 35.6 cm 11 days later. The plants in a second treatment were grown pot-to-pot for 36 days after pinch, at which time they were spaced to 35.6 × 35.6 cm. 4) Node Number. Plants were pinched to eight nodes, while the control group was pinched to 5 nodes. Tissue development in the stem crotch; i.e., the area of lateral stem attachment to the main stem, was observed by microscopic examination of paraffin-embedded samples from each experiment every 2 weeks until anthesis. Lateral shoot strength was quantified by hanging a plastic beaker from the lateral stem and gradually adding water until stem crotch failure occurred. We observed that stem strength increased as cutting stem diameter increased. Plants pinched to eight nodes produced weaker lateral shoots than those pinched to five nodes. Premature lateral shoot development and container spacing did not affect stem strength.


2016 ◽  
Author(s):  
Ines Pedro Perpetuo ◽  
Alessandro Felder ◽  
Andrew Pitsillides ◽  
Michael Doube ◽  
Isabel Orriss

2019 ◽  
Vol 53 (1) ◽  
pp. 107-142 ◽  
Author(s):  
D. E. Himelbrant ◽  
I. S. Stepanchikova ◽  
T. Ahti ◽  
V. Yu. Neshataeva

The first lichenological inventory in Koryakia has resulted in the list of 315 species reported from Parapolsky Dale, within and in vicinities of the Koryak State Reserve. Altogether 46 species are published from the Kamchatka Territory for the first time, including Lecanographa grumulosa new to Russia, East Asia and Beringia; Cercidospora trypetheliza, Lecania dubitans, Pertusaria borealis, Piccolia ochrophora, Protoparmelia cupreobadia, Rimularia badioatra and Strangospora moriformis new to Russian Far East; Abrothallus bertianus, Cladonia strepsilis, Physciella melanchra, Rimularia badioatra, Sclerococcum parasiticum, Sphinctrina leucopoda and Strangospora moriformis new to Beringia. The lichen diversity of the study area is relatively poor due to natural reasons. Comparison with neighboring regions (Kamchatka Peninsula, Chukotka, Magadan Region, Yakutia and Alaska) shows that the lichen flora of Parapolsky Dale contains almost no specific species. The majority of the species recorded here are also known from neighboring regions, especially Alaska and Kamchatka Peninsula.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 540a-540
Author(s):  
K.J. Prevete ◽  
R.T. Fernandez

Three species of herbaceous perennials were tested on their ability to withstand and recover from drought stress periods of 2, 4, and 6 days. Eupatorium rugosum and Boltonia asteroides `Snowbank' were chosen because of their reported drought intolerance, while Rudbeckia triloba was chosen based on its reported drought tolerance. Drought stress began on 19 Sept. 1997. Plants were transplanted into the field the day following the end of each stress period. The effects of drought on transpiration rate, stomatal conductance, and net photosynthetic rate were measured during the stress and throughout recovery using an infrared gas analysis system. Leaf gas exchange measurements were taken through recovery until there were no differences between the stressed plants and the control plants. Transpiration, stomatal conductance, and photosynthesis of Rudbeckia and Boltonia were not affected until 4 days after the start of stress. Transpiration of Eupatorium decreased after 3 days of stress. After rewatering, leaf gas exchange of Boltonia and Rudbeckia returned to non-stressed levels quicker than Eupatorium. Growth measurements were taken every other day during stress, and then weekly following transplanting. Measurements were taken until a killing frost that occurred on 3 Nov. There were no differences in the growth between the stressed and non-stressed plants in any of the species. Plants will be monitored throughout the winter, spring, and summer to determine the effects of drought on overwintering capability and regrowth.


Author(s):  
Kusum Lata ◽  
G. Das ◽  
Nitesh Kumbhakar ◽  
Rupanjali Saiyam

The present study was conducted to investigate the prevalence of gastrointestinal (GI) parasites of goats in and around Jabalpur. During 9 months of study period, out of 1675 faecal sample of goats examined, 1224 (73.07%) were found positive for different gastrointestinal parasites. The maximum prevalence recorded was of Strongyles (61.43%) followed by Coccidia (25.97%), Amphistomes (9.73%), Monieziaexpansa (8.66%), Trichuris spp. (2.03%), Strongyloides spp. (1.79%) and Fasciolagigantica (0.66%). When prevalence was compared in goats maintained at field and farm conditions, significantly higher infection (P>0.01) was observed at farm (85.90%) as compared to field (67.22%) conditions. The prevalence of gastrointestinal parasitism was found higher in adults (73.83%) in comparison to young goats (69.71%). Overall specific species prevalence showed strongyles infection was significantly higher (P>0.01) in adult (64.25%) as compared to young (48.86%) whereas Coccidia and Monieziaexpansa infection was observed significantly high in kids than adult goats. The seasonal prevalence of gastrointestinal parasites was found significantly higher (P>0.01) in Monsoon (81.20%) and post-monsoon (76.66%) as compared to spring and winter seasons.


1998 ◽  
Vol 116 (2) ◽  
pp. 981-986 ◽  
Author(s):  
H. M. Dyck ◽  
G. T. van Belle ◽  
R. R. Thompson

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 241
Author(s):  
Joon Moh Park ◽  
Jachoon Koo ◽  
Se Won Kang ◽  
Sung Hee Jo ◽  
Jeong Mee Park

Rhodococcus fascians is an important pathogen that infects various herbaceous perennials and reduces their economic value. In this study, we examined R. fascians isolates carrying a virulence gene from symptomatic lily plants grown in South Korea. Phylogenetic analysis using the nucleotide sequences of 16S rRNA, vicA, and fasD led to the classification of the isolates into four different strains of R. fascians. Inoculation of Nicotiana benthamiana with these isolates slowed root growth and resulted in symptoms of leafy gall. These findings elucidate the diversification of domestic pathogenic R. fascians and may lead to an accurate causal diagnosis to help reduce economic losses in the bulb market.


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