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91.
Substrate-dependent biosynthesis of ethylene by rhizosphere soil fungi and its influence on etiolated pea seedlings 总被引:1,自引:2,他引:1
Muhammad J. Akhtar Muhammad Arshad Azeem Khalid Muhammad H. Mahmood 《Pedobiologia》2005,49(3):211-219
Several fungi were isolated from rhizosphere soils of various crops through enrichment on l-methionine (l-MET) as a sole C and N source. These fungi were examined for their C2H4 production potential in vitro. GC-FID analysis indicated that 78%, 83%, 89% and 72% of fungi isolated from rhizosphere soil of wheat, maize, potato and tomato, respectively, produced C2H4 from substrate l-MET. Eight of the most efficient C2H4-producing fungal isolates (two from each crop) were further tested for their ability to produce C2H4 from 2-keto-4-methylthiobutyric acid (KMBA) and α-ketoglutaric acid (α-KGA). Interestingly, all eight fungi produced C2H4 from KMBA, but none used α-KGA as C2H4 precursor. This result implies that the MET→KMBA→C2H4 pathway was most likely operating in these fungi. The most efficient C2H4 producer fungus (isolated from maize rhizosphere soil) was identified as Aspergillus terreus; this isolate was further studied to determine the optimal conditions for C2H4 production from l-MET. It was observed that a substrate (l-MET) concentration of 10 mmol l−1, a glucose (C-source) concentration of 6.0 g L−1, no nitrogen, a pH of 6.0, an incubation temperature of 30 °C and an incubation time of 72 h were optimal conditions for l-MET-derived C2H4 biosynthesis by Aspergillus terreus. In addition, C2H4 released from precursor (l-MET) by Aspergillus terreus significantly affected the seedling length and stem diameter of etiolated pea seedlings in both sterilized and non-sterilized soils compared to a control. C2H4-producing microflora may be ubiquitous in soil, and the availability of a substrate like l-MET could enhance C2H4 synthesis in the rhizosphere of a plant, in turn evoking a physiological response. As far as we know, this study represents the first comprehensive screening of rhizosphere fungi for their ability to produce C2H4 from l-MET and KMBA. 相似文献
92.
Soil compaction affects plant growth by causing increased resistance to root penetration and a decreased uptake of water and ions. A pot experiment was conducted to study the effect of soil compaction in conjunction with the soil salinity and waterlogging on root growth and leaf ionic composition of two wheat genotypes (Aqaab and MH-97). Compaction was achieved at a 10% soil moisture content by dropping 5 kg weight, controlled by a tripod stand for 20 times from 0.6 m height on a wooden block placed inside the soil-filled pots. Soil bulk density of non-compact and compact treatments was measured as 1.21 and 1.65 Mg m−3, respectively. The desired salinity level (15 dS m−1) was developed by mixing required amount of NaCl in the soil before filling the pots. Waterlogging was developed by flooding the pots for 21 days both at tillering and booting stages. Compaction significantly reduced the root length density (RLD) of both the wheat genotypes while the combined effect of compaction×salinity was more drastic on root length density than compaction alone. Waterlogging however, did not decrease the root length density, rather it mitigated the effect of compaction. Compaction decreased the concentration of K+ and K+:Na+ ratio in leaves. Salinity also decreased the concentration of K+ and K+:Na+ ratio, but increased the concentrations of Na+ and Cl− in the crop leaves. Salinity and compaction interacted to cause a greater reduction in K+ concentration and the K+:Na+ ratio, while there was lesser increase in the concentrations of Na+ and Cl− compared with salinity alone. Waterlogging also decreased the concentration of K+ and K+:Na+ ratio in leaves. It intensified the effect of salinity but decreased the effect of compaction on leaf ionic composition. Therefore, the effect of compaction on root growth and ion uptake is more severe under salt-affected soil conditions than under normal soil conditions while occasional waterlogging of a compact soil for a few days makes the soil conditions favorable for root growth both under non-saline as well as saline soil conditions. Also, the performance of a genotype in stressed environment is related to maintenance of higher root length density, leaf K+ concentration and K+:Na+ ratio and lower leaf Na+ and Cl− concentrations. 相似文献
93.
Akhtar Muhammad Uzair Hifzulrahman Imran Muhammad Pasha Talat Naseer Khalique Anjum Saadullah Muhammad Tahir Muhammad Naeem Ikram-ul-Haq Muhammad Naveed-ul-Haque Muhammad 《Tropical animal health and production》2021,53(4):1-10
Tropical Animal Health and Production - The aim of the study was to assess the effect of feeding the same diet to different breeds of chickens and at different ages on fatty acid (FA) composition... 相似文献
94.
M. Abdul Hafeez Masood Akhtar M. Mazhar Ayaz 《Journal of veterinary science (Suw?n-si, Korea)》2006,7(1):59-61
Eimeria (E.) tenella (local isolate) sporozoites were adapted on the chorioallantoic membrane (CAM) of 10-12 days chicken embryos and completed its life cycle in 6~7 days at 39℃ and 70 per cent humidity. Only 23 embryos (4.6%) were found dead from 1~4 day post inoculation of sporozoites with mild lesions on CAM with no gametocytes but few sporozoites in chorioallantoic fluid (CAF). On 5~7 day post inoculation, 432 embryos (86.4%) were found dead with severe haemorrhages on CAM and CAF contained uncountable number of gametocytes. After seven days post inoculation, 45 embryos (9%) were found to be alive. Some oocysts were also detected in the CAF on 6~7 days post inoculation. In the histological sections of the CAM, there were abundant small dark colored rounded bodies of gametes; distributed extensively in tissues of CAM on 5~7 days post inoculation of sporozoites. In some cases, cluster of small mature and immature relatively large bodies were seen in increasing numbers on 5~6 days post inoculation. 相似文献
95.
Customary evaluations of irrigation performance based upon crop yield per unit area do not reflect an adequate assessment of performance in water scarce environments such as Pakistan. Yield per unit water is a complementary and sometimes more appropriate measure. This note illustrates the different evaluations based upon yields of irrigated wheat and rice in Pakistan. 相似文献
96.
Abdus Sattar Neelofar M. A. Akhtar 《Plant foods for human nutrition (Dordrecht, Netherlands)》1990,40(3):185-194
Influence of irradiation (0.05–0.20 kGy) and germination (24–120 hours) in distilled and tap water on phytate, protein and amino acids of soybean, was studied. Phytate values significantly decreased with increasing germination period and irradiation dose (P<0.01). Irradiation independently decreased the original phytate (212.0 mg/100 g) to a range value of 205.0–190.0 mg/100 g depending upon dose level. Germination of unirradiated seeds for 120 hours in distilled and tap water lowered the phytate to 55.0 and 94.9 mg/100 g (74.1 and 55.2% reduction) respectively. Maximum destruction of phytate to levels of 20.5 and 50.9 mg/100 g (90.3 and 76.0% reduction) occurred during germination of 0.20 kGy samples for 120 hours in distilled and tap water respectively. Total protein content significantly increased during germination (P<0.05) and the increase was more in tap than distilled water. Germination for 120 hours of untreated seeds in tap water increased the essential and decreased non-essential amino acids while in the 0.10 kGy sample, increases in both cases were observed. 相似文献
97.
Dietary L‐tryptophan modulates growth and immuno‐metabolic status of Labeo rohita juveniles exposed to nitrite 下载免费PDF全文
Alexander Ciji Narottam Prasad Sahu Asim Kumar Pal Mohammad Shahbaz Akhtar 《Aquaculture Research》2015,46(8):2013-2024
Effect of nitrite exposure on growth and immuno‐metabolic responses of Labeo rohita fed L‐tryptophan (TRP) was studied. Fish previously fed normal and elevated levels of tryptophan for 60 days were exposed to nitrite (2.0 mg L?1) for another 45 days with same feeding regime. There were four treatment groups, viz., TRP0‐N (control), TRP0+N, TRP0.75+N (0.75% supplemental tryptophan in the diet) and TRP1.5+N (1.5% supplemental tryptophan in the diet). Highest weight gain% and SGR were observed in control and lowest in TRP0+N. Dietary supplementation of elevated levels of tryptophan augmented weight gain% and SGR. Nitrite exposed groups recorded higher catalase, SOD, LDH, AST and ALT activities compared with control. However, activities reduced with additional levels of tryptophan supplementation. Nitrite exposure reduced WBC count, total protein, albumin, globulin and lysozyme activity compared with unexposed group but groups which were fed additional amounts of tryptophan restored total protein, albumin and globulin similar to TRP0‐N. In conclusion, nitrite exposure had adversely affected growth, increased activities of LDH, AST, ALT, catalase, but decreased WBC, serum protein, lysozyme and acetylcholine esterase activity of L. rohita. Normal requirement of tryptophan was unable to combat nitrite stress. However, dietary fortification with tryptophan (minimum 0.75% of diet + normal requirement) found effective in combating nitrite induced stress. 相似文献
98.
Shamim Naigaga Claude E. Boyd Philippe Gaillard Hisham A. Abdelrahman Joseph J. Molnar 《Journal of the World Aquaculture Society》2017,48(4):555-562
Water‐analysis kits are useful for practical aquaculture only if they provide equivalent decision‐making as compared to standard water‐analysis methods. This study used weighted Cohen's kappa (κ) statistics to compare management decisions made by farmers who used water‐analysis kits (e.g., Seneye slide kit, Tetra EasyStrips, API test strips, Seachem Ammonia Alert, Salifert Profi test kit, and Hach dissolved oxygen (DO) and alkalinity kit) and decisions made by those who used standard methods. The decisions made by farmers were similar for water‐analysis kits and standard methods, except for Tetra and API test strips, when measuring nitrate concentrations. The highest conformity between the two methods (κ‐value = 1.0, P < 0.0001) was obtained with the Hach and Salifert Profi test kits (for measuring DO) and the API test strip (for measuring total hardness). The rapid, simple measurements by the kits appear suitable for use by farmers if they are properly maintained and manufacturer's instructions are followed. 相似文献
99.
An experiment was conducted to study the effects of short-term exposure to sublethal levels of nitrite on electrolyte regulation, antioxidative enzymes and haematological parameters in Labeo rohita juveniles. The fishes were exposed to graded levels of nitrite (0-15?mg?l(-1)) for different duration (0, 12, 24, 48 and 96?h). The 96-h LC(50) value for L. rohita (avg. wt, 66.5?±?0.5?g) was found to be 11.28?mg?l(-1). Activities of antioxidative enzymes (catalase and superoxide dismutase), acetylcholine esterase (AChE) and methaemoglobin reductase, serum electrolytes (sodium, potassium and chloride), haematological parameters and blood glucose level significantly varied (P?0.05) in a dose-dependent manner. With increasing nitrite concentration and exposure period, a progressive reduction in the total erythrocyte count and haemoglobin were observed. With increase in nitrite concentration, a significant (P?0.05) increase in activities was evidenced in catalase and superoxide dismutase in liver as well as gill, methaemoglobin reductase in blood, while progressive decline in AChE activity in brain was recorded. The serum sodium and chloride content showed a progressive decline, while potassium showed an increasing trend upon increase in nitrite concentration. The serum K(+) and Cl(-) after 96-h exposure demonstrated a linear relationship (Y?=?0.221x?+?2.542, R (2)?=?0.938, P?0.01 and Y?=?-5.760x?+?129.5, R (2)?=?0.952, P?0.01, respectively) with nitrite concentrations. This study revealed that nitrite exposure causes alteration in all measured tissue enzymes, serum electrolytes and haematological parameters. 相似文献
100.