فهرست مطالب seyed reza mehrjuyan

This study is the first attempt to investigate some diatom species in the western rivers of Lake Urmia. The study presents the details of Encyaonema, Craticula, and Cymatopleura at the lowest taxonomic level to provide information in terms of species taxonomy, morphology and ecology. In order to determine the morphological similarities in species level of the aforementioned genera, 14 sites were repeatedly sampled along the rivers from September 2021 to August 2022. The results showed a high diversity of diatoms including Encyonema caespitosum. Encyonema silesiacum, Encyonema prostratum, Craticula cuspidata, Craticula ambigua, Cymatopleura solea, Cymatopleura apiculata, Cymatopleura hibernica and Cymatopleura elliptica. The taxonomic and ecological study of the observed species from the western rivers of Lake Urmia indicates diatom assemblage closely integrated with the limnology and ecological status of the rivers. Indeed, the results infer that the rivers undergo a transition from freshwater to brackish, particularly where the rivers terminate at Lake Urmia.

The study of plant death is completed by defining plant cell senescence. Senescence is an inseparable part of plant growth. Like many other plant processes, this is a genetic control program that is regulated by a set of environmental and genetic factors. These factors and their mechanisms respond to the relationship between sources and sinks in which glucose signals and hormonal regulation and cellular genetics play a major role. During senescence, nutrients such as nitrogen, phosphorus, and glucose are released from the breakdown of macromolecules in leaf cells, to be assigned to growing organs or storage tissues. Symptoms of leaf senescence include chlorophyll loss, dehydration, and eventually plant death. Recognition of senescence is very necessary because with sufficient knowledge, senescence can be manipulated in the desired direction. For example, current molecular genetic approaches are used for postpone senescence, like blocking ethylene production or increasing cytokinin production. They are based on plant hormone mechanisms. Plant storage products increase their life span. In order to understand leaf senescence, many genetic SAGs, especially transcription factors and encoding components of transmission pathways, various gene functional methods are described.