Journal of Agricultural Sciences and Natural Resources
Year:2000 | Volume:7 | Issue:2|Papers Count:9

Bromoperoxidase is isolated from the lichen xanthoria parietina. The enzyme contains vanadium, which is essential for enzymic activity. Under denaturing conditions the preparation shows a single protein band with a molecular weight of 65000. Thermal denaturation studies has showed that the bromoperoxidase could tolerate high temperatures. The affinity of the enzyme for its substrate (bromide) is hight and excess substrates (50 mmol) inhibited enzymic activity considerably.

To study the relationships between pollution emitted by fossil fuels and urban development, six cities of Golestan province have been selected. The density of emitted materials such as SO2, Nox, CO, HC and SPM (suspended particle material) have been estimated by using JICA (1997) scale and also the related factors such as climate, topography and city area were considered to realize the capacity of cities air. In the other hand the development factors such as population, city area and constructed area for urbanization in the same time period have been estimated. The data analysis resulted that the air pollutants were increasing with urban development. There was linear correlation between CO and SO2 content of air cities development indices.

One of the important factors on soil infiltration is the crop cover. Temporal variation of infiltration causes change in application efficiency. For evaluating temporal variation of infiltration two methods namely double rings and advance phase in border were used. The irrigation method was border and the crop type was Chickling Vetch . Infiltration equation used in this study was Kostiakov-Lewis. The double rings method was used in the bare land. The infiltration parameters were determined using the method of advance phase in border for 0 , 20 , 40 , 60 , 80 and 100 percent of crop cover. The results show that infiltration characteristics change with changing crop cover percentage. The cumulative infiltration for a target time decrease with increasing crop cover percentage. In this research the double rings and advance phase methods were compared. The results showed that the cumulative infiltration was greater than that for double rings method. In addition the infiltration parameters using the two methods were compared.

In order to control of seed and root rot of cotton (Sahel cultivar) antagonistis activity of Pseudomonas flourescens and fungi Trichoderma viridae, T. harzianum were studied on Rhizoctonia solani and Pythiwn ultimum. To study antagonistis activity, cotton seeds immersed into suspensaon of antagonistic agents and then was planted in plastic pots. The precen tage of soil infection in each pot were different and the linear regression analysis indicated that infection rate inoculated soils with antagonist agents were more than free soils. The suppression effect of antagonist bacterium was more than antagonist fungi on pathogenic agents. Also antagonists were paired (on opposite) with 4 isolates of each pathoges.Significant differences (P<0.05) were observed on inhibition zone between bacterium and pathogenic agents but not antagonist fungi.

One of the basic solution of correct management for rangelands is conservation of plant covering together with best exploitation of its potential capacity. This is possible only with nutritive value and animal output determination is fed by rangelands plants. Therefore this experiment was carried out to evaluation of two Aleuropus species of dominant gramineae family plant using eight castrated rams of Dalagh breed sheep. Statistical model of completely randomized design as a factorial with two factors, species and three factor of growth stages were used Alfalfa forage was used as a standard. At first experimental plants were collected and after air drying were cutted in 2 to 3 centimeters, after that were fed to sheep that placed in individual metabolic cages to determine the voluntary intake, nutrients digestibility and energy of experimental plants in three stage of growth including vegetation, flowering and seed maturity. Dry matter daily intake (kg), dry matter intake to live weight ratio (percentage) and dry matter intake to metabolic weight (g/day) for A.littoralis were 1.038, 2.42, 61.88 respectively and for A.lagopoides were 0.802, 2.06 and 51.43. There were significant differences between these two species of plant in mentioned traits (P<0.01). These traits in vegetation growth, were 1.088, 2.70 and 68.12 and in flowering stage were 1.041,2.39 and 61.48 and in seed maturation stage were 0.630, 1.61 and 40.36, respectively. There were significant differences between vegetative growth and flowering stage vs. seed maturity, but no significant differences between vegetative growth and flowering stage (p>0.05). crude protein digestibility of A.littoralis and A.lagopoides were 60.57, 36.62 and 56.55, 45.32 respectively that there was significant differences between two species (P<0.05). Crude fiber digestibility of two species were 45.02 and 34.76 respectively with significant difference between them (P<0.01). There was significant differences of crude protein, ether extraction, nitrogen free extraction and crude fiber digestibility between vegetative and two other stages of growth, but there was no differences between flowering and seed stages (P>0.05). TDN , crude energy digestibility and digestible energy of A.littoralis and A.lagopoides were 37.77, 49.19 , 1.88 and 38.54 , 40.93, 1.61, respectively. There was significant differences between two species in digestible crude energy and crude energy (P<0.01). Also mean of these three traits in vegetative, flowering and seed stages were 44.07, 46.42 & 1.88 ; 35.80, 42.88 & 1.67 and 34.50, 44.87 & 1.68, respectively. There was significant difference between vegetative and two other stages in TDN (P<0.01) and in digestible energy (0.05) . Totally the results of the experiments showed that voluntary intake, nutrients digestibility and energy productivity of A.littoralis was more than A.lagopaides and in both species nutritive value in vegetative stage was better than two others stages. There were in due attention to high nutritive value of two experimental plants. They are suggested to support by seed production and other techniques with preference of A.littoraliy species.

The allelopathic potential of Johns ongrass and bermuda grass on seed germination and seedling growth of wheat was investigated. Effect of aerial and subterranean part and mixed of them for each weed was studied separately. These experiments were carried out using Completely Randomised Design: From the first aqueous extract (10% W/V), using distilled water, solutions with 5, 10, 20 and 40 percent were obtained. Then the effects of these solutions on germination, coleoptile and radicle lengths of wheat were investigated in the laboratory. The two weed satistically reduced seed germination and seedling growth of wheat. Mixed of aerial and subterranean part bermuda grass had more allelopathic effect than each of them alone. Since Johnson grass reduced seed germination and radicle length in wheat with lower percentage of solution than bermud agrass, it seems that Johnson grass has more allelopathic effect on wheat.