Agrolesnické systémy v tropických oblastech nabízejí možnost, jak zajistit trvale udržitelnou produkci na obdělávaných pozemcích, a často představují jediný zalesněný ekosystém v okolní odlesněné krajině. Tento článek se věnuje problematice agrolesnictví v tropech se zaměřením na kávové plantáže pěstované v Peru., Agroforestry systems present a way to keep sustainable production in cultivated areas, especially in the tropical zone. At the same time it is often the only forested ecosystem in otherwise deforested landscape. This article is about agroforestry in tropical areas, with the focus on coffee (Coffea) plantations in Peru., and Lenka Ehrenbergerová.
Ground-dwelling sciurids, including prairie dogs (Cynomys), marmots (Marmota) and several genera of ground squirrels (e.g. Ammospermophilus, Spermophilus, Notocitellus, Ictidomys, Urocitellus), emit alarm calls in the presence of predators to warn their kin. These calls show high intra- and inter-species variation. The alarm calls of many species have potential to encode information about caller identity, and possibly enable the ground squirrels to recognize unreliable callers or to estimate the degree of risk. The alarm calls can be used to determine species or subspecies, and can also help resolve some taxonomic complexities. and Irena Schneiderová.
The article summarises results of our research on inter- and intra-species variability in alarm calls (emitted in the presence of predator) of the European Ground Squirrel (Spermophilus citellus) and closely related species (Taurus Ground Squirrel - S. taurensis, Anatolian Ground Squirrel - S. xanthoprymnus). Alarm calls of all three species mostly consist of two different elements; individuals producing alarm calls with only one of them were, however, also recorded. Although their alarm calls share the same basic structure, the three species can be clearly distinguished. Significant inter-individual differences allow identification of particular callers in a colony. and Irena Schneiderová, Richard Policht.
Alkali stress is an important agricultural problem that affects plant metabolism, specifically root physiology. In this study, using two rice cultivars differing in alkali resistance, we investigated the physiological and molecular responses of rice plants to alkali stress. Compared to the alkali-sensitive cultivar (SC), the alkali-tolerant cultivar (TC) maintained higher photosynthesis and root system activity under alkali stress. Correspondingly, the Na+ content in its shoots was much lower, and the contents of mineral ions (e.g., K+, NO3-, and H2PO4-) in its roots was higher than those of the SC. These data showed that the metabolic regulation of roots might play a central role in rice alkali tolerance. Gene expression differences between the cultivars were much greater in roots than in shoots. In roots, 46.5% (20 of 43) of selected genes indicated over fivefold expression differences between cultivars under alkali stress. The TC had higher root system activity that might protect shoots from Na+ injury and maintain normal metabolic processes. During adaptation of TC to alkali stress, OsSOS1 (salt overly sensitive protein 1) may mediate Na+ exclusion from shoots or roots. Under alkali stress, SC could accumulate Na+ up to toxic concentrations due to relatively low expression of OsSOS1 in shoots. It possibly harmed chloroplasts and influenced photorespiration processes, thus reducing NH4+ production from photorespiration. Under alkali stress, TC was able to maintain normal nitrogen metabolism, which might be important for resisting alkali stress., H. Wang, X. Lin, S. Cao, Z. Wu., and Obsahuje bibliografii