scholarly journals Regeneration responses to water and temperature stress drive recruitment success in hemiepiphytic fig species

2020 ◽  
Author(s):  
Huayang Chen ◽  
Nalaka Geekiyanage ◽  
Bin Wen ◽  
Kun-Fang Cao ◽  
Uromi Manage Goodale
Keyword(s):  
Water Stress ◽  
Relative Humidity ◽  
Temperature Stress ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Effect Of Temperature ◽  
Ambient Conditions ◽  
Forest Canopies ◽  
Seedling Emergence And Survival ◽  
Substrate Moisture

Abstract Mechanisms for surviving water and temperature stress in epiphytes are essential adaptations for successful regeneration in forest canopies. Hemiepiphytes start their life cycle as epiphytes, eventually establishing areal root connections to the ground. This strategy allows for greater light capture, while benefitting from minimized risk of fire, flooding, and damage by terrestrial herbivores, but exposes the vulnerable seedling stage to heat and drought stress. However, the response to temperature and water stress during early regeneration in hemiepiphytes is not known. In this study, we tested the effect of temperature (15/5°C, 25/15°C, 35/25°C; day/night diurnal variation) and water availability, as substrate moisture (0.00 MPa, −0.20 MPa, −0.35 MPa) and water vapor (18.5% to 99.5% relative humidity), on seed germination, seedling emergence, and survival in six hemiepiphytic and nine non-hemiepiphytic Ficus species. Under high temperature conditions (35/25°C), hemiepiphytes had higher gemination and seedling survival, achieved peak germination slower and extended germination. Greater water stress (−0.35 MPa) in the growth substrate resulted in higher germination of non-hemiepiphytes; hemiepiphytes, in contrast, took a shorter time to complete germination, but had higher seedling emergence and survival. Hemiepiphytes germinated at 99.5% relative humidity more readily compared to non-hemiepiphytes. These findings provide the first comprehensive evidence that hemiepiphytic Ficus species are better adapted to drier and warmer conditions during the critical transition from seed to seedling. Through greater flexibility in achieving peak germination and duration of regeneration activity, hemiepiphytes modulate their recruitment process to be more resilient under abiotic stressors. This may allow them to be more successful in regenerating in forest canopies under ambient conditions that are transient. These results support previous work showing greater drought tolerance of hemiepiphytic Ficus species in larger size classes, and extend this finding to show that physiological adaptations for drought and heat tolerance start from the early seedling emergence stage.

Seed-bank and seedling dynamics in Hyparrhenia hirta are influenced by herbicide application and mowing management

2012 ◽  
Vol 34 (2) ◽  
pp. 199 ◽  
Author(s):  
V. K. Chejara ◽  
P. Kristiansen ◽  
B. M. Sindel ◽  
R. D. B. Whalley ◽  
C. Nadolny
Keyword(s):  
Seed Bank ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Climatic Conditions ◽  
Control Treatment ◽  
Native Flora ◽  
Seedling Dynamics ◽  
Herbicide Treatments ◽  
Seedling Emergence And Survival

Hyparrhenia hirta (L.) Stapf (Coolatai grass) is a summer-active, C4 perennial tussock grass, native to southern Africa and the Mediterranean region, which has invaded areas of native flora in Australia in recent decades. Understanding its seed and seedling dynamics and how various management treatments (e.g. mowing, herbicide and no management) affect these may assist in identifying the conditions and management strategies required to limit its invasion. The population dynamics of H. hirta have not been comprehensively studied previously. A 2-year field experiment (December 2005–December 2007) was conducted to determine the seed-bank size, pattern of seedling emergence and survival of H. hirta seedlings at three sites in northern New South Wales, Australia, under three treatments: unmanaged (control), mowing and herbicide treatments. The density of H. hirta seeds in the soil at each experimental site under different treatments was measured in December 2005 at the start of the experiment, in December 2006 before the application of the second round of treatments and again at the end of the experiment in December 2007. Hyparrhenia hirta seedlings were assessed at monthly intervals in permanent quadrats (0.5 × 0.5 m) to determine seedling emergence and survival. Seedling emergence occurred on many occasions during the 2-year period of the experiment in each treatment and at all sites but the main seedling flushes were observed from mid summer to early autumn. In 2007, at all sites, seedling emergence declined by more than 90% on the mowing and herbicide treatments compared with the control treatment. Seedling survival was greater in the mowing and herbicide treatments than in the control treatment. The seedling cohorts emerging in winter had a lower survival. This study showed that H. hirta infestations have a large viable seed-bank (~3000 m–2), dependent on the level of infestation and climatic conditions, but that the seed-bank declines rapidly when seed addition is prevented. Some form of direct control of established H. hirta plants in combination with providing appropriate grazing management to encourage competition between grasses will assist in the control of H. hirta.

Seedling emergence and survival of Warea carteri (Brassicaceae), an endangered annual herb of the Florida Scrub

2007 ◽  
Vol 85 (7) ◽  
pp. 621-628 ◽  
Author(s):  
Carl W. Weekley ◽  
Eric S. Menges ◽  
Pedro F. Quintana-Ascencio
Keyword(s):  
Seedling Survival ◽  
Seedling Emergence ◽  
Annual Plants ◽  
Seedling Density ◽  
Florida Scrub ◽  
Seedling Emergence And Survival ◽  
History Of ◽  
Annual Herb ◽  
Winter Annual ◽  
Persistent Seed Bank

Seedling emergence and survival to flowering are critical processes in the life history of annual plants. We evaluated the importance of year and habitat on seedling emergence and the effects of year, habitat, timing of seedling emergence, and seedling density on survival of Warea carteri Small, an annual mustard endemic to Florida scrub. We tagged 1329 seedlings in 78 permanent 0.25 m2 quadrats in two habitats (scrub and disturbed) between 1999 and 2002 and followed seedlings monthly. Most (>80%) seedling emergence occurred between September and December. Emergence peaked 2 months earlier and was more variable in disturbed sites than in scrub. Seedling survival among years ranged from 3.5% to 12.0%. Seedling density varied from 1 to 75 per 0.25 m2 quadrat, with an overall median of 6.0. Survival was not density dependent. Median age at flowering ranged from 11.7 to 15.2 months, with late season recruits most likely to survive to flowering. Warea carteri recruits like a winter annual but flowers like a summer annual. Its delayed germination and a 12–15 month life span contribute to population cycling. Complete reproductive failure in unfavorable years, high seed production in favorable years, low rates of seed germination, and a persistent seed bank are consistent with predictions for an annual species in a variable habitat.

scholarly journals Regeneration and Endogenous Phytohormone Responses to High-Temperature Stress Drive Recruitment Success in Hemiepiphytic Fig Species

2021 ◽  
Vol 12 ◽  
Author(s):  
Chuangwei Fang ◽  
Huayang Chen ◽  
Diana Castillo-Díaz ◽  
Bin Wen ◽  
Kun-Fang Cao ◽  
...  
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Temperature Stress ◽  
Growth And Development ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Functional Trait ◽  
High Temperature Stress ◽  
Growth Forms ◽  
Early Regeneration

Exposure to high-temperature stress (HTS) during early regeneration in plants can profoundly shape seed germination, seedling growth, and development, thereby providing stress resilience. In this study, we assessed how the timing of HTS, which was implemented as 8 h in 40°C, could affect the early regeneration stages and phytohormone concentration of four hemiepiphytic (Hs) and four non-hemiepiphytic (NHs) Ficus species. Their seed germination, seedling emergence, and seedling survival probabilities and the concentrations of three endogenous phytohormones, abscisic acid (ABA), indole-3-acetic acid (IAA), and salicylic acid (SA) were assessed after HTS imposed during imbibition, germination, and emergence. In both groups, seeds were more sensitive to HTS in the early regeneration process; stress experienced during imbibition affected emergence and survival, and stress experienced during germination affected subsequent emergence. There was no effect from HTS when received after emergence. Survival was highest in hemiepiphytes regardless of the HTS treatment. The phytohormones showed growth form- and regeneration stage-specific responses to HTS. Due to the HTS treatment, both SA and ABA levels decreased in non-hemiepiphytes during imbibition and germination; during germination, IAA increased in hemiepiphytes but was reduced in non-hemiepiphytes. Due to the HTS treatment experienced during emergence ABA and IAA concentrations were greater for hemiepiphytes but an opposite effect was seen in the two growth forms for the SA concentration. Our study showed that the two growth forms have different strategies for regulating their growth and development in the early regeneration stages in order to respond to HTS. The ability to respond to HTS is an ecologically important functional trait that allows plant species to appropriately time their seed germination and seedling development. Flexibility in modulating species regeneration in response to HTS in these subtropical and tropical Ficus species could provide greater community resilience under climate change.

scholarly journals Giant buttercup (Ranunculus acris L) seedling emergence and survival in Golden Bay dairy pastures

2009 ◽  
Vol 62 ◽  
pp. 222-227 ◽  
Author(s):  
C.S. Lusk ◽  
S.L. Lamoureaux ◽  
G.W. Bourd?t
Keyword(s):  
New Zealand ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Dairy Farms ◽  
Permanent Plots ◽  
Pasture Management ◽  
Seedling Emergence And Survival ◽  
Ranunculus Acris ◽  
Milk Solids ◽  
Autumn And Winter

Giant buttercup (Ranunculus acris L) is an unpalatable weed in New Zealand dairy pastures and is estimated to cost the dairy industry over 150 million annually in lost milk solids revenue In this study the survival of giant buttercup seedlings was determined by following their fates in permanent plots on eight randomly selected dairy farms in the Takaka Valley from November 2004 to August 2008 Seedling emergence occurred yearround but tended to be higher in winter and spring than in summer and autumn Seedling survival was very low with less than 5 of seedlings surviving beyond 12 months Seedlings that germinated in autumn had significantly higher survival at 6 and 12 months (22 and 12 respectively) than seedlings germinating in spring summer and winter (37 and 23 respectively) Good pasture management that prevents overgrazing and pugging in autumn and winter should reduce the autumn flush of seedlings and minimise their survival

Germination of Piptochaetium Napostaense (Speg.) Hackel and Stipa Tenuis Phil. And Seedling Survival Under Field Conditions.

1992 ◽  
Vol 14 (1) ◽  
pp. 49 ◽  
Author(s):  
RA Distel ◽  
DV Pelae ◽  
OA Fernandez
Keyword(s):  
High Temperatures ◽  
Seedling Establishment ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Canopy Cover ◽  
Grass Species ◽  
Plant Canopy ◽  
Seedling Emergence And Survival ◽  
Neighbouring Plant ◽  
High Level

The objectives of this work were to investigate the germination of Piptochaetium napostaense and Stipa tenuis under laboratory conditions and to evaluate the effects of different plant canopy cover on seedling emergence and survival of the two species in the field. Fresh seeds of both species present a high level of dormancy associated with the lemma and palea, preventing seedling emergence immediately after the seeds fall in NovemberPecember. Seventy per cent of the seedlings of both species emerged in autumn. The germination behavior of these grass species may be an ecological adaptation serving to avoid seedling loss through exposure to the high temperatures and drought occurring during summer in the Calden District. Seedling survival was greater in the grazed, low plant canopy cover site, indicating that a certain degree of disturbance to reduce neighbouring plant interference favours seedling establishment in both species.

Effects of overstory tree density, site preparation and ground vegetation on natural Scots pine seedling emergence and survival in northern boreal pine forests

2021 ◽  
Author(s):  
Mikko Johannes Kyrö ◽  
Ville Hallikainen ◽  
Sauli Valkonen ◽  
Mikko Hyppönen ◽  
Pasi Puttonen ◽  
...  
Keyword(s):  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Site Preparation ◽  
Ground Vegetation ◽  
Seedling Mortality ◽  
Bottom Part ◽  
High Coverage ◽  
Efficient Treatment ◽  
Seedling Emergence And Survival

Natural regeneration is commonly used forest regeneration method in Northern Finland. It is not known however, what would be the optimal overstory density and ground vegetation composition for seedling emergence and survival, and if site preparation is needed to accompany overstory density manipulation. We studied the effects of overstory density (unthinned control and thinning to 50, 150 and 250 trees ha-1) and ground vegetation removal (mechanical site preparation with disc trenching) on the number of naturally germinated pine seedlings and survival of individual seedlings during 8-11 years. Bare mineral soil was a superior seedbed compared to intact vegetation cover, even though also mortality rate was high on mineral soil. Greater cover of lingonberry, crowberry and slash had a negative effect on seedling number. Seedling mortality was initially high (60% died during the first two years) but decreased throughout the first five years. The mineral soil in the elevated part of disc trencher track showed twice the survival rate in the bottom part of the track. High coverage of small haired mosses was associated with poorer seedling survival. An overstory density of 50-150 trees ha-1 with site preparation seems to be an efficient treatment to promote regeneration under these circumstances.

scholarly journals Batch drying of sliced tomatoes at specific ambient conditions

2018 ◽  
Vol 11 (2) ◽  
pp. 134-140 ◽  
Author(s):  
Mohammad Jafar Royen ◽  
Abdul Wasim Noori ◽  
Juma Haydary
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Flow Rate ◽  
Ambient Pressure ◽  
Air Flow ◽  
Force Sensor ◽  
Effect Of Temperature ◽  
Air Flow Rate ◽  
Ambient Conditions ◽  
Drying Time

Abstract In this work, drying of tomato slices was studied in a laboratory scale batch dryer working at conditions specific for geographical locations with low ambient pressure and low relative humidity of air. Tomato is a perishable farm product with high moisture content. Despite their high value, tomatoes are subjected to wastage and spoilage during their seasonal period; to last longer after harvested, they need to be treated by drying. Drying is one of the most widely used methods of tomato preserving for a longer period of time. This study involves experimental work on tomatoes drying in a tray laboratory batch dryer with the dimensions of (490 × 330 × 310) mm, a load cell-force sensor (range: 0–5 kg), fan (speed: 0–2500 rpm), air flow sensor (0–150 l/min) and a temperature and humidity monitoring system. This study was aimed at the development of a suitable drying method for the production of dehydrated agricultural products under specific air properties and climate conditions such as low ambient pressure and low relative humidity. During the experiment, the average ambient pressure was 82 kPa, and the average relative humidity of air was 20 %. Drying characteristics of tomato slices were determined at three temperature levels, namely: 50 °C, 60 °C and 70 °C,and three air flow rates: 30 l/s, 40 l/s and 50 l/s, for each temperature level. In this study, the effect of temperature, air flow rate, and ambient conditions on the drying rate of tomato slices were studied. The results indicate that during the experiments, tomatoes were dried to the final moisture content of 32.2 % from 92 %. Drying time at 50 °C, 60 °C and 70°C, and air flow of 30 l/s was 17.80 h, 15.80 h, and 14.08 h, respectively. For the air flow rate of 40 l/s, the drying time was 15.0 h, 12.9 h and 11.7 h and for the air flow rate of 50 l/s, the drying time of tomato slices was 14.0 h, 11.6 h and 10.2 h, respectively.

Seed-germination responses of Calotropis procera (Asclepiadaceae) to temperature and water stress in northern Australia

2016 ◽  
Vol 64 (5) ◽  
pp. 441 ◽  
Author(s):  
E. O. Menge ◽  
S. M. Bellairs ◽  
M. J. Lawes
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Seed Mass ◽  
Calotropis Procera ◽  
Northern Australia ◽  
Germination Time ◽  
Seed Biology ◽  
Mean Germination Time

Understanding the seed biology of the introduced weed rubber bush (Calotropis procera (Aiton, W.T.Aiton)) is critical to its management in northern Australia. We examined the numbers of seeds produced and the effects of environmental temperature and water stress on germination performance (germinability G; mean germination time MGT) of rubber bush seeds from across northern Australia. Germination trials were conducted using seeds from wild populations monitored for 3 years. Seed numbers per fruit did not vary significantly among the six populations studied (mean ± s.e. = 433.2 ± 19.0), but seed mass did (range from 8.32 ± 0.24 to 5.24 ± 0.06 mg), with no negative correlation between the measures. Maximum seed germination (68–100%) occurred at 30°C, associated with a mean germination time of 2.58 days. Under water stress, the proportion of germinated seeds declined significantly with increasing temperature from 92.5 ± 1.1% at 20°C and 0 MPa to 2.8 ± 1.7% at 40°C and –0.4 MPa respectively. Seeds were unable to germinate at ambient temperatures ≥40°C, but remained quiescent and hence viable. Planting depth influenced seedling emergence, with minimal germination of seeds on the surface (5.8%) but 88.5% germination at 3-cm depth. The effect of water stress was dependent on temperature, with water stress inducing a reduction in optimum germination temperature from 30°C to 20°C. Phenotypic plasticity in G and MGT did not show clear patterns among populations or years. Short MGTs increase seedling survival by rapid transition from endosperm resources to photosynthesis, whereas seed quiescence (cf. dormancy) optimises germination opportunities in a semiarid environment. Thus, the germination traits reported in the present study are likely to promote seedling survival and potential spread of rubber bush in semiarid Australia.

scholarly journals Effects of High Soil Surface Temperature on Seedling Survival in Pearl Millet

1993 ◽  
Vol 29 (2) ◽  
pp. 215-225 ◽  
Author(s):  
J. M. Peacock ◽  
P. Soman ◽  
R. Jayachandran ◽  
A. U. Rani ◽  
C. J. Howarth ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Pearl Millet ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Soil Moisture Deficit ◽  
High Soil ◽  
Moisture Deficit ◽  
Seedling Emergence And Survival ◽  
Soil Surface Temperature

SummaryA field technique to screen pearl millet genotypes for their emergence and survival at high soil surface temperatures is described. Genetic variation in seedling emergence and survival is shown and it is argued that this variation is largely due to tolerance of high temperatures rather than tolerance of soil moisture deficit, although some interaction occurred. An index for ‘thermotolerance’ is defined and genotypes are ranked accordingly for this trait, which is shown to be highly heritable. The technique is repeatable and allows a large number of genotypes to be screened at the same time.

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