جستجوی مقالات مرتبط با کلیدواژه « رشد » در نشریات گروه « محیط زیست »

The aim of this study was to investigate the effect of replacing fish meal with plant protein sources on growth performance, digestive enzymes activity and also introducing a diet suitable for cultured Asian sea bass species in terms of biological efficiency. A total of 600 juveniles with an average weight of 54±2.5 gr were distributed in 15 tanks (500 liters) with a density of 40 pieces in each tank and were fed with prepared diets for 60 days. The composition of plant proteins (soybean meal, wheat gluten and corn gluten) was used at two levels of 35 and 70% to replace fish meal and the growth performance and activity of digestive enzymes were examined.The results showed that T1 (fish meal) and T2 (35% replacement) had the best performance in specific growth factor, weight gain percentage, relative growth rate, weight gain. Also, replacement of 70% fish meal with plant protein sources led to a significant reduction in specific growth rate, daily weight gain and relative growth rate compared to T1 (P<0.05).The results of gastrointestinal enzymes activity showed that the T4 (commercial 1) in alkaline phosphatase, lipase, α-amylase and the T2 in trypsin activity had a significant difference compared to other treatments (P<0.05). It can be inferred that Asian sea bass can easily have good growth performance by replacing 35% fish meal with plant protein sources.

Water quality management in culture ponds is the most important factor in the proper growth of shrimp and achieving proper production, which can help to improve the quality of the conditions of the pool floor and achieve the desired production. Poor quality water causes stress and illness. Today, ozone technology can be used in areas with viruses, bacteria, and fungi. Due to the high oxidation potential, ozone oxidizes the cellular components of the bacterial cell wall to reduce the number of inactive microorganisms. In this study, chronic ozone concentrations (0.02, 0.04, 0.06 mg/l) were applied serially to western white-leg shrimp for 60 days two hours after each diet. During the experiment, quality factors were measured, and at the end, growth factors and Body composition were performed. The results showed that salinity and temperature were in the optimal range of western white-leg shrimp and there was no significant difference between treatments (p>0.05). With increasing ozone concentration between treatments, dissolved oxygen, pH and nitrate increased and total ammonia, suspended solids, and nitrite decreased. Also, according to Body composition, there was a significant difference between the treatments in protein and ash levels with a decreasing trend and fat and moisture with an increasing trend concerning ozone concentration. The results of growth factors showed a significant difference between ozone levels, indicating the optimal level of growth factors in concentrations of 0.02 and 0.04, respectively.

Heavy metals are especially important because of the toxic effects of the environment, the accumulation of biodiversity in various aquatic species and the creation of biological magnification in food chains. The present study was conducted to compare the toxicity of heavy metals of cadmium and lead in different concentrations (500, 250, 100, 50, 5 μg/L) on microorganism growth of Isochrysis galbana during 15 days in F2 culture media. The results showed that the effect of two metals on growth of I. galbana was dependent on two factors of time and concentration. Observations showed that concentrations of 500 micrograms per liter of cadmium on day 4 significantly inhibited the growth of I. galbana. The highest growth rate was obtained at a concentration of 5 μg/L for both tested metals. In this experiment, the highest content of chlorophyll a for cadmium and lead was 5 g/L and the lowest content of chlorophyll was in two concentrations of 250 and 500 μg/L. Also, by studying the effect of cadmium and lead on the amount of alfalfa protein, low concentrations increased protein levels and high concentrations reduced the amount of microalgae protein.

Recently, the use of Acidifier (a group of organic acids) has been increased in aquaculture. The purpose of this study is to evaluate the effects of Acidifier (sodium diformate and Formic acid) on the growth performance, nutrition indices, and Digestive enzymes activity of the juvenile Huso huso. A total of 420 juvenile Huso huso (30.55 ± 1.72 g) was randomly divided into seven experimental treatments (Three replicates each). All groups were fed with the experimental diet for 60 days. The Bioassay conducted on the first day and after 30 and 60 days and then growth parameters were investigated. The experimental diets contain 0.05, 0.1 and 0.15 % sodium diformate (NDF) and 0.05, 0.1 and 0.15 % Formic acid (Formi). diet control was without any acidifier. Results show that all growth and Intestinal enzymes (trypsin, chymotrypsin and alkaline phosphatase) are affected by acidifier and in these two parameters  groups that fed 0.1 % supplemented food by NDF and citric acid compared to the control group. The best FCR and SGR observed in the groups fed with 0.1 % supplemented food by NDF)0.5±00), (0.5±0.005) (p < 0.05) at day 30 respectively. Although the best FCR and SGR observed in the groups fed with 0.1 % supplemented food by Formic acid (0.81±0.001), (2.7±0.005) (p < 0.05) at day 60 respectively. Intestinal enzymes (trypsin, chymotrypsin and alkaline phosphatase) are affected by acidifier. The highest activity of trypsin and chymotrypsin was significant in groups 0.1 % supplemented food by NDF (P˂0.05) in  the first 30 days. Alkaline phosphatase activity increased with increasing acidifier diets in groups, but this increase was not significant compared to the control (p>0.05). It can be concluded that the addition of  0.1% of NDF to beluga diets improves growth parameters and decreases FCR, increases digestive enzyme activity. Moreover, these results indicated that 0.1 % of NDF and citric acid in the diet could be a useful food supplement preferably at 30 days and can be used to improve the growth parameters in juvenile Huso huso.

This study was carried out to investigate population dynamic of Caspian roach (R. caspicus) on the south east Caspian Sea in 2018 (In the 6 months of the catch season). A total of 215 samples were collected using beach siene (Total length with 0.01 accuracy and total weight with accuracy of 0.001 were measured). The length of samples range from 16.74 to 30.03 cm and weighing from 52 to 346 gr. The age of the specimens was ranges from 3+ to 7+. Length-weight relationship was W=0.009L3.09, indicating positive allometric growth for population. After fitting the regression using least square method, the relationship was W=0.009L3.42. The Von Bertalanfy growth equation as, Lt=37.1033(1-EXP (-0.19(t+0.40)) . Natural mortality using Pauly's experimental equation calculated as 0.445. The highest condition factor and growth rate was 0.42 and 0.44 respectively, for population in the south east Caspian Sea. Overall, the Caspian roach stocks in the southeastern part of the Caspian Sea appear to be in serious danger and require effective management strategies to maintain their reserves.

Dust is an atmospheric pollutant that is considered as one of the major environmental problems all over the world. This phenomenon is problematic, especially in agriculture, health, and transportation sections. Dust causes considerable environmental problems for agriculture and human health in Iran every year and so attention must be paid to the negative consequences of this phenomenon. Therefore, this study was conducted to quantify the effects of dust on growth and yield of red bean, weeds growth, and the competitive balance between weeds and the crop.

A greenhouse experiment was conducted in a replacement series based on a complete randomized design with three replicates in Ilam University, Ilam, from late October 2017 to early March 2018. The treatments consisted of soil dust (with and without), two weed species (Echinochloa crus-galli and Chenopodium album), and mixtures of 100% crop, 75% crop+25% weed, 50% crop+50% weed, 25% crop+75%weed, and 100% weed. The speed of photosynthesis, amount of chlorophyll α, chlorophyll b, total chlorophyll and carotenoids content of leaves, number of pod per plant, one thousand seed weight, and crop seed yield, crop and weed biomass were measured.

The results showed that the speed of photosynthesis amount of chlorophyll α, chlorophyll b, total chlorophyll content of leaves, carotenoids, number of pod per plant, one thousand seed weight, biomass, and seed yield of the red bean as well as biomass of weeds were significantly affected by dust. In addition, the effect of weeds on crops was increased by an increase in the weed proportion in the mixtures, which was worsening by the dust. The dust caused a 39.7% reduction in the yield and 52.8% in biomass of bean on average. The bean yield (gr/plant) in the 50% mixture in competition with C. album with and without dust effect were 7.5 and 4.7 gr/plant, respectively, while the corresponding values for E. crus-galli were 16.9 and 8.4 gr/plant , respectively. On the other hand, E. crus-galli as a narrow leave species was less affected by dust than C. album as a broad leave species and thus biomass reduction due to dust in C. album and E. crus-galli were 10.6% and 7.1% in comparison with the control , respectively. Moreover, the red bean was affected by dust more than weeds.

The growth and yield of red bean were significantly affected by competition with weeds and also the competitive effect of C. album was more than E. crus-galli. In addition, the dust had significant effects on the growth of red bean and weeds (C. album more than E. crus-galli). This might be due to the morphological characteristics of each species, because the broader leaves of the red bean and C. album may have caused more absorption of dust particles. In general, the dust phenomenon caused a reduction in crop growth and yield and also affected the competitive balance between weeds and crops.

One of the most fundamental problems that may affect growth and development of plants and animals are environmental pollution by some heavy metals. Cadmium is a contaminant metal which has harmful effects on the physiological activity of the plant. The aim of this study was to investigate the possibility of using the Nasturtium officinal plants for clarifying of contaminated water and evaluation of this plant ability for phytoremediation.

In this study the effect of different concentrations of Cadmium (including 10, 50, 100, 300 and 500 µM CdCl2) was investigated on physiological parameters and Cadmium absorption of Nasturtium officinal plant. The experiment was carried out in completely randomized design with three replications.

The obtained result showed that the effects of Cd was significant on growth, physiological characters and the amount of Cadmium in plants, so that fresh and dry weight of shoot and root, height of shoot and root and the photosynthetic pigments increased as levels of Cadmium increased in nutrient solution. By increasing Cadmium concentration in medium culture, the amount of Cadmium was enhanced in roots and shoots. The highest Cadmium content in both root and shoot organs was observed in 500µM cadmium treatment.

The current results revealed that Nasturtium officinal plants have certain ability for Cd phytoremediation.

Iran has various habitats in lakes and wetlands for microalgae Dunaliella. There are limited researches on the physiological behavior of Iranian Dunaliella in different environments including light intensity and salt concentration.

The experiment was done based on completely randomized design with three replications and three factorials including two light levels (25 and 500 µmol photon m-2s-1), three salinity levels (2, 3 and 4 M NaCl) and three isolates (SH1, M1, G28) and CCAP19/18 strain.The isolates SH1, M1 and G28 were selected from Urmia Lake, Maharloo Lake and Gavkhoni wetlands, respectively. A non-native and standard strain, CCAP19/18, was used to compare the behavior of the native isolates.

The results showed that microalgae physiological behavior affected not only by environmental factors but also by genetic characteristics and the metabolic potential of microalgae. Under 25 µmol photon m-2s-1 and 3 M NaCl condition, Urmia isolate (SH1) had high cell number and chlorophyll content. However, Maharloo isolate (M1) was showed high carotenoids contents under above mentioned condition.

 The results are showing that: a) isolate with Urmia lake origin (SH1) has good potential for high growth and reproduction and it is the proper candidate for high biomass production.With measuring traits such as growth and cell number, content and photosynthetic pigment ratios may suggest that b) isolates with Urmia (SH1) and Maharloo (M1) lakes origin are suitable for the extraction of chlorophyll and carotenoids and c) it seems reasonable to expect that the Maharloo isolate (M1) is proper for photosynthetic studies.