نشریه تحقیقات منابع طبیعی تجدید شونده
سال نهم شماره 2 (پیاپی 30، پاییز و زمستان 1397)

Considering the chemical behavior of the pulping process under variable conditions, especially in nonwoods species, is important as it can help us to develop the pulping models to reach the pulps with desired properties. In the present research, the soda pulping under different conditions was investigated to produce whole stalk kenaf pulp as the most common pulping processes for non-woody species. The cooking conditions were included temperatures (160 and 165 °C), active alkali levels (18, 23, and 28 %) and cooking duration (90, 105, 120, 135, 150, 165, and 180 min). Results indicated that pulp yield was in the range of 47 to 69 % and the kappa number was in the range of 29 to 67. The statistical analysis showed that cooking durations, alkali levels, and cooking temperatures had significantly independent effects on pulp yield and kappa number, although their interactions on pulp yield and kappa number were not significant. Based on the present results, the fastest and the slowest changing rates of kappa number and pulp yield were related to the pulping condition of 23% active alkali in 160 C and 18% active alkali in 165 C, respectively.

The ecological characteristics of Festuca sulcata Beck were studied in this research to examine its potential application in rangeland improvement. Five sites were selected for sampling using vegetation map, field visit based on the species distribution. In each sampling site, three 100-m transects and 10 plots (1m×1m) along the transects were selected using systematic-randomized method. The factors related to canopy cover, bush height, species frequency forage, and seed production were measured on the transects in the plots. Also some qualitative characteristics such as root system, phenology, seed quality, regeneration, preference value, and chemical composition of the plant were studied. The results showed that Festuca sulcata is distributed from 2200 to 3800 m from the sea level on acidic and alkaline clay-loam textured soils in the study area. The growth time was begun from May to the end of June and the time of ripened and seed dissemination was started from July to mid-August. In early flowering stage, the palatability was in grade I and the best grazing time was in seed ripened stage. In the post-seeding stage, the plant became woody and livestock grazing preference was reduced. Forage production yield was 528.58 kg dry matter ha-1, while seed production was 95.33 kg ha-1. Due to the resistance to cold and frost conditions, this species is suitable for restoration and improvement of rangelands with more than 350 mm rainfall.

The aim of this study was to compare the antioxidant activities of ascorbic acid and butylated hydroxyanisole on biochemical deterioration and tasting indexes of painted sweetlips, Diagramma pictum, fillet under frozen condition (-18 C) for a period of 4 months. The fish fillet was treated with 1.5 % ascorbic acid, 1.5% butylated hydroxyanisole and a combined treatment with their 0.5% concentrations. The fat deterioration indices including peroxide value, free fatty acids, thiobarbituric acid, volatile nitrogenous bases, and by the intuitive evaluation were monthly measured after freezing. The results indicated that the peroxide value in the treatment of 1.5% butylated hydroxyanisole and 1.5 % ascorbic acid were higher than that in the combined treatment. However, peroxide value in all treatments didn’t cross the limited level of 10 meq O2 kg-1. Minimum average of thiobarbituric acid index was found in the combined treatment (0.593 mg MDA kg-1) indicating the effectiveness of this treatment in controlling the deterioration index (p<0.05). Fatty acids index in 1.5% ascorbic acid treatment was significantly higher than other treatments (p<0.05). At the end of the experimental period, the combined treatment limited the amount of volatile nitrogenous bases to the lowest level compared with the other treatments (p<0.05). The maximum amount of volatile nitrogenous bases was recorded in 1.5% butylated hydroxyanisole treatment. However, the volatile nitrogenous bases in all treatments did not cross the limited value of 30-35 mg 100 g-1. Findings of the present study indicated that the combined treatment had more ability to inhibit the deterioration indexes of fat compared with the other treatments. In case of intuitive evaluation, the combined treatment (0.5% ascorbic acid +0.5% butylated hydroxyanisole) had the best results with significant differences in three factors of taste, tissue and color compared to the other treatments (p<0.05).

The effects of planting method and planting time on seed and forage production of Astragalus brachyodontus was investigated in the natural rangelands of Meshgin-Shahr from 2013 to 2016. The bioassay was conducted in a completely randomized split-plot design with three replications. The factor A was different planting times (autumn and spring), while the factor B was different planting methods (Seedling, row cropping and dry farming methods in the natural rangelands). Forage and seed yield were measured after growing and seedling establishment. All data were analyzed by SAS statistical software and means statistical comparison was done using duncan multiple range test. The results showed significant effect of planting time on seed and forage yield (p<0.01). Comparison of means showed that autumn planting was better than spring one. Planting method also had significant effect on seed yield (p<0.05). The highest amount of seed yield was related to row cultivation in the second year. Accordingly, planting of Astragalus brachyodontus in autumn at 1500-m height from the see level is recommended to achieve better results. In order to saving the seeds used in cultivation and creating a uniform distribution, row cultivation with a certain depth (2.5-3 cm) were recommended.

This experiment with the aim of optimizing the propagation of Tamarix androssowii was conducted in a completely randomized factorial design with cutting length (10-20, 20-30, 30-40 cm) as the first factor and cuttings diameter (0.5-1.0, 1-1.5, 1.5-2 cm) as the second fator in 15 replicates in February 2018. In order to investigate the role of IBA hormones on vegetative traits of T. androssowii, another experiment was conducted in a completely randomized factorial design with soaking time (one minute, five minutes) as the first factor and the concentration of solution (zero, 500, 1500, 3000 ppm) as the second factor in 10 replicates. The results showed that the maximum mean root length was 10.4 cm in the treatment of the cuttings length of 30-40 cm and the lowest was found in the treatment of the length of the cuttings 10-20 cm with an average of 6.7 cm. Also, the highest number of flowers with an average of 3.1 and the highest plant fresh weight with the amount of 42.3 g were recorded in the length of the cuttings 40-30 cm treatment. The analysis of variance showed that the highest number of roots, number of stems and the highest mean root length were related to the cuttings diameter of 0.5-1 cm treatment. By increasing the cutting diameter, the plant's fresh weight was also increased. The effect of soaking time in indole butyric acid solution was not significant on all traits except for the number of stems produced (p<0.05) . However, the indole butyric acid solution concentration had significant positive effect on the measured traits such as number of roots, number of stems, and ratio of number of stems to roots and fresh weight of the plant (p<0.05).

A bioassay was conducted to investigate the effect of static magnetic field on hatching function of kutum (Rutilus kutum) in Veis incubators. For this purpose, three experimental treatments were conducted in triplicate with magnetic flux densities of 5, 15 and 25 milli-tesla along with control treatment (fish without exposed to the magnetic field). The obtained eggs from 8 female broodstock were randomly transferred to the incubators with density of 49,000 eggs in each incubator. Changes in water physicochemical parameters including water temperature, pH, dissolved oxygen, total hardness, nitrogen derivatives (ammonia and nitrite) and phosphate levels were daily evaluated during the incubation period. At the end of the incubation period, hatched larvae from each treatment were transferred to 100-liter Zug incubators without any magnetic exposure for monitoring their growth. The results of this study showed significant differences in total hardness, ammonia and dissolved oxygen concentration of water among the treatments (p<0.05). By considering the physiological characteristics of kutum, the best effect of static magnetic field was obtained in the 25 milli-tesla treatment. Besides, the number of hatched larvae in 25 milli-tesla treatment was significantly higher than the control treatment. However, there was no significant difference in the survival rate of larvae before yolk sac absorption among the experimental treatments (p>0.05). The results of this study showed that static magnetic field could have positive effects on water quality and survival rate of kutum larvae.

Capoeta capoeta gracilis (Keyserling, 1891) as a commercial valuable species belongs to cyprinid fish is native to Iran. In this study, the possibility of inducing artificial reproduction of C. Capoeta gracilis was investigated using OvaprimTM hormone. For this purpose, four wild-caught females and one male were selected. Female fish were injected by OvaprimTM at doses of 0.1 and 0.4 mg/kg with 12 hours interval. At the time of the second injection, the male fish was injected at a dose of 0.2 mg/kg. Spawning occurred less than 48 h after the first injection. Maximum and minimum of working fecundity were 2473.17 and 23430.5 number. The male fish did not respond to hormone injection and all of the broodstock positively responded to the hormonal induction. These preliminary results revealed that OvaprimTM is a suitable synthetic hormone for reproductive induction in C. capoeta gracilis.