scholarly journals Comparison of desiccation tolerance among mosses from different habitats

2005 ◽  
Vol 57 (3) ◽  
pp. 189-192 ◽  
Author(s):  
Jasmina Sinzar-Sekulic ◽  
Marko Sabovljevic ◽  
Branka Stevanovic

Three moss species from the karst region were compared to establish their respective patterns of desiccation tolerance. Different life forms of bryophytes were chosen to obtain evidence of their life strategies during drought conditions. Comparative analyses of electrolyte leakage were performed to screen for tolerance of the membrane to water stress and for signs of damage to the fine structure of the protoplasm. The experiments were carried out by exposing the plants to water stress caused by PEG 600. The results show that the most desiccation tolerant species is Thamnobryum alopecurum, less but fairly tolerant is Anomodon viticulosus, while the aquatic Rhynchostegium riparioides is intolerant of desiccation.

2018 ◽  
Vol 26 (4) ◽  
pp. 339-353
Author(s):  
I. V. Rabyk ◽  
O. V. Lobachevska ◽  
N. Y. Kyyak ◽  
O. I. Shcherbachenko

Bryophytes possess a wide ecological diapason allowing them to populate substrates of technogenic origins which are scarcely suitable or completely unsuitable for viability of vascular plants. 49 bryophyte species, which belong to 2 divisions, 3 classes, 8 orders, 17 families, and 33 genera have been found on the dump territory of sulphur extraction of the mining-chemical enterprise “Sirka” (Yavoriv district, Lviv region). Seven transects, three on the north slope (base, slope, top), three on the south slope and one on the plateau were laid for sample selections. 20 investigated 0.5 × 0.5 m plots located 2 m apart were analyzed within each 10 × 10 m transect. Specific composition, life forms, projective cover, biomass of bryophytes, numbers of male, female and sterile plants, moisture content in the turfs, pH and physiological investigation of mosses were determined on each plot. The quantitative analysis of the biomorphological structure allowed us to establish the dependence of the spread of life forms on exposition and slope height; essential variability of the projective cover and moss biomass. Bryophyte cover plays an essential part in optimization of the moisture regime and surface layer temperature of technogenic substrates, improving the conditions of growth localities. We established that on the dump the dominant moss species are dioecious with a high level of reproductive effort (sexual and sexless), with short ontogenesis and age of first reproduction, which provides the chance to produce the maximum number of progeny in the minimum period and to form a complete moss cover. The analysis of seasonal moss photosynthesis dynamics has demonstrated the adaptability of moss photosynthetic apparatus to contrasting climatic conditions and the ability to support the intensity of photosynthetic processes on a rather stable level during the vegetative period. Our research showed that bryophytes play an important role in productivity of plant cover on the post-technogenic territories of sulphur extraction. It was found that bryophytes play a role in accumulation of organic carbon and biogenic elements in the substrate of the sulphur extraction dump . Carrying out research of specific composition dynamics and species activity is the precondition for revealing the essence of the dynamic processes taking place in the structure of the bryophyte communities on devastated territories and the influence of these processes on the formation of vegetation on dump complexes.


2017 ◽  
Vol 39 (4) ◽  
Author(s):  
SAULO DAVID REZENDE DA SILVA ◽  
DALMO LOPES DE SIQUEIRA ◽  
LUIS CARLOS CHAMHUM SALOMÃO ◽  
PAULO ROBERTO CECON ◽  
ACELINO COUTO ALFENAS

ABSTRACT The occurrence of water stress in mango trees grown in orchards located in semi-arid climates in Brazil is frequent. Water stress caused to plants may predispose them to the incidence of fungal diseases. The aim of this study was to evaluate the effect of water deficit on the incidence and severity of Ceratocystis wilt in mango trees considered resistant. Seedlings of ‘Ubá’ and ‘Dura’ were kept in pots and submitted to different water stress levels and inoculated with Ceratocystis fimbriata isolate (CEBS15). Mortality was low in ‘Ubá’ plants and high in ‘Dura’ plants. ‘Ubá’ plants showed lower severity and lesion length. In ‘Ubá’ plants, water deficit influenced the increase in lesion length. ‘Dura’ plants showed greater severity and lesion length, which were not affected by increasing water stress. It was concluded that ‘Ubá’ variety is resistant to fungus Ceratocystis fimbriata, even in severe drought conditions, while ‘Dura’ variety was not resistant to CEBS15 isolate, even under optimum irrigation conditions.


2003 ◽  
Vol 19 (2) ◽  
pp. 197-208 ◽  
Author(s):  
Karsten Wesche

The paper presents climatic and plant ecological data for unusually severe dry-season conditions on Mt. Elgon (Uganda/Kenya) and the Bale Mountains (Ethiopia). There is clear evidence that plants are exposed to desiccation stress during high-altitude droughts, which occur on average every 7-10 y in the study sites. Although high vapour-pressure deficits and consequently high potential evapotranspiration led to conspicuous wilting of several plant species, no lethal damage was observed and plant communities maintained increased flowering activity under drought conditions. Moreover, highest outposts of ericaceous vegetation were regularly found on thin soil covering rocky outcrops, where water stress apparently is high. Probably more important than direct water stress are the extensive fires occurring under drought conditions, which cause large-scale replacement of woody vegetation by grasslands. Additional consequences of drought include adverse conditions for seedling stablishment.


1973 ◽  
Vol 105 (3) ◽  
pp. 449-458 ◽  
Author(s):  
W. H. Foott ◽  
P. R. Timmins

AbstractThe effects of various levels of infestation of the corn leaf aphid, Rhopalosiphum maidis (Fitch), on yield of field corn were examined from 1965 to 1970 inclusive when all plants whose yield might have been influenced by factors other than aphid feeding were excluded from the data. A possible relationship between moisture stress in plants and degree of aphid injury was also investigated.A light infestation (maximum of 400 aphids on the tassel) caused average yield reductions up to 8.3% when plants were under moisture stress, but nil to negligible losses when moisture was adequate. Moderate infestations (many hundreds of aphids on part of the tassel) produced average losses up to 34.8% under drought conditions and up to 11.8% when moisture was abundant. Severe infestations (many hundreds of aphids on most of the tassel) caused average yield reductions ranging from 43.2 to 91.8% when plants were under water stress and up to 58.9% even with abundant moisture. Very severely infested plants (many hundreds on all of the tassel and whorl leaves) were usually barren or had ears with just a few kernels regardless of moisture conditions.Most injury from aphid feeding appeared to occur before and during pollination. No particular combination of temperature and rainfall favored aphid buildup.


1993 ◽  
Vol 73 (2) ◽  
pp. 525-529 ◽  
Author(s):  
Allen G. Good ◽  
James L. Maclagan

The physiological responses of different species of Brassica to induced drought stress were studied by analysing the relationships between relative water content, leaf water potential and leaf osmotic potential during the onset of drought stress. These data indicate that while there was a decrease in leaf osmotic potential with the onset of drought stress, this did not result from a net increase in solutes. Therefore, these genotypes of Brassica do not appear able to osmoregulate under these drought conditions. Key words: Brassica, drought, osmoregulation, water stress


1972 ◽  
Vol 50 (1) ◽  
pp. 105-108 ◽  
Author(s):  
M. S. Carceller ◽  
A. Soriano

The effect of pretreatments given to wheat grains which are supposed to increase drought resistance was studied in young plants under controlled conditions of water stress. In one of the two cultivars used, root growth was found to be significantly greater in plants from pretreated seeds, during and after a period of water stress.Under conditions of ample water availability, root growth was not influenced by the pretreatments.


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