Showing 4 results for Enzymes Activity
Jabraeil Razmjou, Mahdieh Jafary , Ehsan Borzoui,
Volume 8, Issue 2 (2-2019)
Abstract
The antibiosis, host preference in free-choice situation, and digestive enzyme activity of Brevicoryne brassicae L. (Hemiptera: Aphididae) were evaluated in the laboratory (25 ± 1 °C, 60 ± 5% R. H. with a 14-h day) on nine host plants: broccoli, canola (leaf, flower, and pod), cauliflower, kohlrabi, radish, red cabbage and white cabbage. The antibiosis test was based on life table parameters and the experiment started with 50 replicates for each host plant using clip cages. The immature survival varied from 34% on red cabbage to 78% on cauliflower. The viviparous aphids reared on rapeseed (flower) had the highest GRR and R0 values, and those on red cabbage had the lowest GRR and R0 values. Also, aphids reared on rapeseed (flower) had significantly higher rm value. The lowest rm value was obtained when individuals fed upon red cabbage. In host preference experiment, rapeseed (leaf) attracted the significantly higher number of adults as opposed to radish, which attracted the lower number of adults. Females who came from nymphs reared on rapeseed (flower) were heavier than other hosts. The growth index of nymphs varied from 0.035 to 0.103, with the minimum on red cabbage and the maximum on cauliflower. The amylolytic activity in adults was higher on rapeseed (flower) and the lowest on red cabbage. In addition, the highest and lowest proteolytic activity was on rapeseed (flower) and red cabbage, respectively. The results of this study indicated that red cabbage was an unsuitable host for feeding of B. brassicae.
Roohallah Saberi-Riseh, Fariba Fathi, Mojtaba Moradzadeh-Eskandari,
Volume 9, Issue 1 (12-2020)
Abstract
One critical environmental stress that limits plant production and development is salinity stress. Recently it has been shown that application of plant growth-promoting rhizobacteria (PGPR) can alleviate the deleterious effects of environmental stresses. Present study aimed to evaluate the effects of some bacterial strains on proline, sugar, total phenolic compounds (TPC), Phenylalanine ammonia lyase (PAL), photosynthetic pigments and antioxidant activities (guaiacol peroxidase, polyphenol oxidase and superoxide dismutase) of cucumber plants under salinity stress. A completely randomized design was applied with a factorial arrangement of two factors: salinity at three levels (0, 50 and 100 mM) and Pseudomonas fluorescens and Bacillus subtilis strains, with three replications. The results showed that cucumber plants that were inoculated with Pseudomonas and Bacillus strains possessed noticeable variations in proline, sugar, TPC, PAL and enzymes activity compared to un-inoculated control. These results suggest that use of these bacterial strains overcame harmful effect of salinity by accumulation of proline, TPC, sugar, PAL activity and enzymes activity that can be considered as a suitable method to manage salinity stress.
Volume 11, Issue 1 (2-2023)
Abstract
Aims: There are few studies on the effectiveness of this type of management on soil properties of Golestan province as the main agricultural pole in Iran. The purpose of this study is to investigate the effect of limited tillage on improving biological soil quality indicators.
Methods: Three types of operations which include No Tillage (NT), Minimum or Occasionally Tillage (OT or MT) and Conventional Tillage (CT) were selected. From each management, 30 samples were taken at depths of 0-30 cm. Microbial respiration, microbial biomass, urease, acid and alkaline phosphatase, dehydrogenase and cellulase activity were measured.
Findings: Conservation tillage (ST) which include both MT and NT increased acid and alkaline phosphatase by 1.6 to 2.5 times. The reverse trend was observed for cellulase, which showed a decrease from 37.5% in MT to 25% in NT. Urease and dehydrogenase increased by 14 and 18% in MT and decreased by 5.7 and 10% in NT. Microbial biomass and microbial respiration increased by 1.8 and 2.5 times in MT and in no tillage, operation decreased by 15 and 44%.
Conclusion: The emphasis is on the advice of ST, However, it seems that some points related to the promotion of this method in agricultural lands should be considered. It seems that MT has a better condition for enzyme activity than NT. Low enzyme activity in NT conditions may reduce the availability of nutrients and thus reduce the yield, then extension experts should be inform the Farmers.
Volume 25, Issue 3 (5-2023)
Abstract
Ethephon was widely used in rubber tree plantation to stimulate latex production. Numerous studies demonstrated that ethephon treatment prolongs the flow of the latex and promotes latex regeneration in the trunk of mature rubber tree seedlings. However, how rubber tree leaves responded to ethephon treatment on the trunk is still unknown. We used rubber tree seedlings to detect the physiological response of leaves after the trunk treatment with ethephon. The photosynthetic rate, the sugar and starch content, as well as the enzyme activities involved in sugar metabolism were measured after 0, 12, 24, 36 and 48 hours with 0.6% ethephon treatment. The result demonstrated that ethephon treatment increased latex production on the trunk, while the net photosynthetic rate, transpiration rate, and stomatal conductance in leaves were significantly reduced. At the same time, sucrose decreased significantly with concomitant slight increase in glucose and fructose. Also, the enzymatic activities of Sucrose Phosphate Synthase (SPS), Sucrose Synthase (SS) and Neutral/alkaline Invertase (NI) increased significantly after ethephon treatment. Ethephon treatment affected the starch content, but did not change the composition of starch in rubber tree seedlings leaves; the overall starch changing pattern was similar to that of sucrose in leaves. It can be concluded that ethylene-stimulated latex production in rubber tree seedlings is partly due to the alteration of sucrose metabolism in leaves, and ethylene has an adverse physiological effect on rubber trees.
