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382. Water relations and gas exchange in Coespeletia moritziana (Sch. Bip) Cuatrec., a giant rosette species of the high tropical Andes

Creator:
Rada, F., Azócar, A., and Rojas-Altuve, A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, net photosynthetic rate, osmotic adjustment, plant growth stages, stomatal conductance, tropical mountains, 2, and 58
Language:
Multiple languages
Description:
Giant rosettes are ones of the most striking features of the vegetation in the high tropical Andes, with Coespeletia moritziana reaching the highest altitudes up to 4,600 m a.s.l. Different from other giant rosettes, this species grows on rock outcrops with poorly developed soils and where water availability may be limited. Two questions are addressed in this study: How does this species respond in terms of water relations to maintain favorable gas-exchange conditions? Considering that adult plants rely on a water-reserving central pith, how do early stages respond to this environment’s extreme conditions? Water relations and gas-exchange studies were carried out on juveniles, intermediate and adult C. moritziana plants during wet and dry seasons in Páramo de Piedras Blancas at 4,200 m a.s.l. Adult plants maintained higher leaf water potentials (ΨL) during the wet season, however, no differences between stages were found for the dry season. Minimum dry season ΨL were never near the turgor loss point in any of the stages. Juveniles show a more strict stomatal control during the dry season to maintain a favorable water status. Net photosynthesis significantly decreased in intermediate and juvenile stages from wet to dry seasons. Our results suggest that C. moritziana resists more extreme conditions compared to other Andean giant rosettes., F. Rada, A. Azócar, A. Rojas-Altuve., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

383. Water-stress and N-nutrition effects on photosynthesis and growth of Brassica carinata

Creator:
Pan, X., Lada, R. R., Caldwell, C. D., and Falk, K. C.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, Brassica carinata, instantaneous water-use efficiency, instantaneous N-use efficiency, nitrogen supply, soil water potential, and water stress
Language:
Multiple languages
Description:
Effects of water and nitrogen (N) supply on growth and photosynthetic response of B. carinata were examined in this study. Plant growth and related characteristics varied significantly in response to the availability of water and nitrogen. B. carinata maximized the utilization efficiency of the most limiting resources by developing physiological adaptations, such as changes in root and leaf development. The utilization of water and N was tightly linked with the availability of each resource. Instantaneous water-use efficiency (WUE) was always greater in plants with high-N nutrition [50, 100, and 150 kg(N) ha-1] than in the low-N-treated plants [0 kg(N) ha-1] in all watering treatments. Instantaneous N-use efficiency (PNUE) decreased significantly with increasing water stress in all N treatments. Seed yield is significantly related to PNUE (p>0.05) but not WUE (p<0.05). The positive relationship between leaf net photosynthetic rate (PN) and seed yield suggests that PN can be used as an important tool for selection of new strains with high seed yield. and X. Pan ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

384. Water-use efficiency in Flaveria species under drought-stress conditions

Creator:
Dias, M. C. and Brüggemann, W.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, drought stress, Flaveria, intermediate species, and water-use efficiency
Language:
Multiple languages
Description:
Environmental conditions that promote photorespiration are considered to be a major driving force for the evolution of C4 species from C3 ancestors. The genus Flaveria contains C3 and C4 species as well as a variety of intermediate species. In this study, we compare the water-use efficiency of intermediate Flaveria species to that of C3 and C4 species. The results indicate that under both well-watered and a drought-stress condition, C3-C4 and C4-like intermediacy in Flaveria species improve water-use efficiency as compared to C3 species. and M. C. Dias, W. Brüggemann.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

385. Why is it better to produce coffee seedlings in full sunlight than in the shade? A morphophysiological approach

Creator:
Moraes, G. A. B. K., Chaves, A. R. M., Martins, S. C. V., Barros, R. S., and DaMatta, F. M.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, biomass allocation, Coffea, growth, oxidative stress, photoinhibition, photosynthesis, and xanthophylls
Language:
Multiple languages
Description:
The coffee plant is native to shaded environments and its seedlings are often produced in shaded nurseries. However, some nursery managers, in an effort to improve the acclimation of seedlings to field conditions after transplantation, produce seedlings in full sun exposure. In this study, the morphological and physiological parameters of arabica coffee (Coffea arabica) seedlings produced in full sun (T1) and in shade (T2) were examined. The biomass accumulation and relative growth rate of T1 and T2 seedlings were similar. The T1 seedlings had less biomass allocation to shoots, a lower leaf mass ratio and a lower leaf area ratio; however, they had a greater net assimilation rate (rate of increase in plant mass per unit leaf area), which was associated with a greater net photosynthetic rate. There were no alterations in the concentrations of total chlorophylls or in the chlorophyll a/b ratio when comparing T1 and T2 seedlings. No indications of photoinhibition or photooxidative damage were observed in the T1 plants, which were shown to have a more robust antioxidant system than the T2 plants. Seedlings transferred from shade to full sun (T3) were not capable of utilising the incident extra light to fix CO2. These seedlings showed a remarkable nocturnal retention of zeaxanthin and a significantly increased deepoxidation state of the xanthophyll cycle, even at predawn, but the activity of antioxidant enzymes was lower than in the T1 and T2 plants. Despite the acclimation capacity of T3 seedlings to the new light environment, they exhibited chronic photoinhibition and considerable photooxidative damage throughout the seven days following the transfer to full sun exposure. We further discuss the practical implications of producing coffee seedlings in full sunlight and under shade. and G. A. B. K. Moraes ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

388. Za botanikou na Korejský poloostrov

Creator:
Jiří Kolbek
Format:
print
Type:
article, články, model:article, and TEXT
Subject:
Věda. Všeobecnosti. Základy vědy a kultury. Vědecká práce, Botanický ústav (Akademie věd ČR), botanika, botany, Korejská lidově demokratická republika, Korea (North), 12, and 00
Language:
Czech
Description:
The history of Czech-Korean botany co-operation has been covering nearly 20 years. Czech scientists helped to form multi-national team that brought together two distinctive publications: Forest Vegetation of Northeast Asia and Distribution and Phytoceonology of Selected Woody Species of North Korea. The official partner of the Academy of Sciences in Korea is KOSEF (Korea Science and Engineering Foundation) that has already supported unique range of 2042 research projects. and Jiří Kolbek.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

389. Za jarní květenou na Maltu

Creator:
Jan Čeřovský
Format:
print
Type:
article, články, journal articles, model:article, and TEXT
Subject:
Botanika, botanika, jarní rostliny, vstavačovité, botany, spring flowers, orchids, Malta, Gozo (Malta), 2, and 58
Language:
Czech
Description:
Během několika uplynulých tisíciletí byla Malta – středozemní souostroví se dvěma velkými a osídlenými ostrovy Malta a Gozo – zcela zbavena lesních porostů s převládajícími borovicí halebskou (Pinus halepensis) a dubem cesmínovitým (Quercus ilex). Současná planě rostoucí vegetace, tvořená převážně degradovanou macchií a formacemi garrigue a frygana, je nyní soustavně potlačována šířícími se sídlišti. Nicméně stojí za to navštívit Maltu a seznámit se s její květenou vyšších rostlin, čítající kolem jednoho tisíce druhů (včetně 36 zajímavých orchidejí), a to zejména v časně jarním období., Malta, a Mediterranean archipelago with two large, inhabited islands, has over the past millennia been totally deprived of forests with dominating Allepo Pine (Pinus halepensis) and Holm Oak (Quercus ilex). The contemporary wild vegetation – mainly of degraded macchia, garrigue and phrygana is being continuously suppressed by urban explosion. Nevertheless, the Maltese wild flora numbering around 1,000 vascular plant species (including 36 interesting orchids) makes a visit to Malta worthwhile, particularly in the early springtime., and Jan Čeřovský.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public