Samia Ageeb Akladious

APPLICATION OF TRICHODERMA HARZIANUM T22 AS A BIOFERTILIZER POTENTIAL IN MAIZE GROWTH

This study was conducted to investigate the effect of Trichoderma harzianum (T22) on the growth and development of maize (Zea mays) plants. T. harzianum was applied to the grains in two different treatments, either by inoculating the soil with air-dried mycelia of T. harzianum or by treating the seeds with different concentrations of the metabolic solution (as the culture supernatant of T. harzianum) before sowing. Comparisons were made between the two treatments to determine if any beneficial effects for improving the growth of maize plants occurred. Results revealed that application of the highest concentration of air-dried mycelia and all concentrations of the metabolic solution of T. harzianum caused increases in all measured parameters which include growth parameters, chlorophyll content, starch content, nucleic acids content, total protein content and phytohormone content of maize plants but the magnitude of these increases was much more pronounced in case of treating the seeds with the metabolic solution of T. harzianum.

Changes in antioxidants potential, secondary metabolites and plant hormones induced by different fungicides treatment in cotton plants

The use of fungicides for an effective control of plant diseases has become crucial in the last decades in the agriculture system. Seeds of cotton plants were treated with systemic and contact fungicides to study the efficiency of seed dressing fungicides in controlling damping off caused by Rhizoctonia solani under greenhouse conditions and its effect on plant growth and metabolism. The results showed that Mon-cut showed the highest efficiency (67.99%) while each of Tondro and Hemixet showed the lowest efficiency (31.99%) in controlling damping off. Rhizolex T, Mon-cut and Tondro fungicides caused significant decrease in plant height, dry weight of plant, phytohormones, photosynthetic pigments, soluble sugars, soluble proteins, total free amino acids but caused significant increases in total phenols, flavonoids, antioxidant enzymes, ascorbic acid, reduced glutathione, MDA and hydrogen peroxide as compared with untreated plants. On the other hand, the other fungicides (Maxim, Hemixet and Flosan) increased all the above recorded parameters as compared with untreated plants. Our results indicated that the fungicides application could be a potential tool to increase plant growth, the antioxidative defense mechanisms and decreased infection with plant diseases.

Physiological role of exogenous nitric oxide in improving performance, yield and some biochemical aspects of sunflower plant under zinc stress

The present study was undertaken to examine the possible roles of sodium nitroprusside in protection against oxidative damage due to zinc toxicity in sunflower plants. Physiochemical parameters in sunflower plants exposed to Zn2+ (100, 200 and 300 mg/kg soil) alone or combined with SNP were measured. The results showed that excess of Zn decreased plant growth, seed yield components and photosynthetic pigments content. On the other hand, Zn stress increased the level of non-enzymatic antioxidants (ascorbic acid and reduced glutathione) and enzymatic antioxidants (superoxide dismutase, ascrobate peroxidase and glutathione reductase), coupled with the appearance of novel protein bands. Furthermore, Zn stress increased Zn content in roots and shoots. The amounts of Zn in roots were higher than shoots. A marked increase in total saturated fatty acids accompanied by a decrease in total unsaturated fatty acids was observed. Exogenously application of SNP (20 μM) increased growth parameters, photosynthetic pigments content, ascorbic acid and glutathione contents, antioxidant enzyme activities and the quality of the oil in favour of the increase of unsaturated fatty acids. Moreover, SNP application increased Zn concentration in roots and inhibited Zn accumulation in shoots. Therefore, it is concluded that SNP treatment can help reduce Zn toxicity in sunflower plants.

Physiological and molecular studies on the effect of gamma radiation in fenugreek (Trigonella foenum-graecum L.) plants

This experiment assessed the biochemical changes in fenugreek plants exposed to gamma radiation. Two pot experiments were carried out during two growing seasons of 2015 and 2016. Seeds were subjected to five doses of gamma irradiation (25, 50, 100, 200 and 400 Gy) and were immediately planted into soil pots in a greenhouse. The experimental analysis was performed in M1 and M2 generations. Significant differences between irradiated and control plants were detected for most studied characters in M1 and M2 generations. It was demonstrated that low doses of gamma irradiation led to gradually increases in growth, yield characters, leaf soluble protein concomitantly with increases in the contents of phenolic and flavonoids compounds particularly at 100 Gy. These changes were accompanied by a substantial increase in ascorbic acid, α-tocopherol and retinol contents. Proline content was increased under all doses of gamma rays in M1 generation and the highest amount of proline was obtained at 200 Gy with visible decrease in M2 generation under the same dose. Meanwhile, the highest dose of gamma radiation (400 Gy) decreased all the studied parameters in both mutagenic generations as compared with control plants. In addition, gamma irradiation doses induced changes in DNA profile on using five primers and caused the appearance and disappearance of DNA polymorphic bands with variation in their intensity. These findings confirm the effectiveness of relatively low doses of gamma rays on improving the physiological and biochemical criteria of fenugreek plants.