Ecoterra, 2020, 17(1):1-6
Ion Mărunțelu
Transilvania University of Brașov, Brașov, Romania
Soil works are technological processes of general character in agriculture that are made in order to create the right environment for the development of plants by soil loosening, enrichment in water, air, heat and nutrients, regenerating their production capacity. The amount of water existing in the soil, in the layer in which the root system of plants is developed, can ensure higher or lower harvests depending on several factors and first of all by the applied crop technology. Ground water ensures that all biological, physical and chemical processes are carried out. The accumulation, conservation and storage of water in the soil is the most important task of the users of agricultural land. The correct management of the water resources of the soil is a problem that needs to be solved with the following consideration: of the concrete climatic situation of one or another agricultural territory; of the hydro- physical properties of the soils used in agriculture; the water requirements of sown agricultural crops; of the real possibility of partially regulating the water regime in the soil through agro-technical measures and irrigation etc. Soil moisture is also related to its physical, physical-mechanical, chemical and biological properties. The soil supplies the plants with nutrients, but for the plants to be able to use the nutrition from the soil, it must necessarily be dissolved in water. An eastern proverb says that “where there is water, there is life”. The loss of moisture from the soil occurs due to the increase of evaporation under the influence of the passage of agricultural equipment during soil work. This loss of soil moisture is unfavorable for plants and therefore for agricultural production.
Ecoterra, 2020, 17(1):7-12
Mazaher Zamani-Faradonbe, Yazdan Keivany, Farhad Kermani
Department of Natural Resources (Fisheries Division), Isfahan University of Technology, Isfahan 8415683111, Iran
This study was carried out to examine morphological changes and allometric growth patterns in Nile tilapia (Oreochromis niloticus (L., 1758)), as a valuable aquaculture species, during early developmental stages (from hatching up to 40 days after hatching) under rearing conditions. For extracting morphological data, a total of 160 larval specimens were collected in different days, then the left side of the specimens was photographed, and eight morphometric characters including body height, caudal peduncle height, eye diameter, head length, postorbital length, standard length, snout length and total length were measured. The larvae are born with developed feeding system and vision (jaws and eyes) that able them to see and take the food items immediately after hatching. These morphological changes in head (snout and eye) and caudal regions may be related to changes in feeding and swimming (to avoid predators) habits of this species.
