الفهرس 
IMPACT OF NANOPARTICALES ON THE PERFORMANCE AND DROUGHT RESISTANCE OF MAIZE (Zea mays L.)Only 14 pages are availabe for public view
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Abstract
Water stress is probably the most significant abiotic factor limiting plant growth and development. Thus, drought has a significant negative impact on crop yield and morphological behavior of corn. The main objective of this study was to investigate the effectiveness of Nano-materials in mitigating the adverse effect of drought stress on corn seeds germination and development. The specific objectives of the study were to characterize the physical and chemical properties of nano scale water treatment residuals (nWTRs); to evaluate the impact of the nWTRs on physiological parameters and to investigate the anatomy change consequences through plant-nWTRs interaction using electron microscope. To achieve these objectives, series of experiments were conducted. The experiment of seed germination and seedling growth of maize plants under different concentration (250, 500, 1000 mg/l) of nWTRs and nPPs (nano pomegranate peels) was carried out. The results revealed the following:
1. Seed priming treatments have resulted in more healthy and vigorous seedlings than control treatments.
2. Increasing concentration of nanoparticles (nWTRs and nPPs) significantly increased growth parameters (radical length, plumule length, seedling volumes, roots and vigor index). Radicle and plumule lengths of seedlings primed with nWTRs were significantly longer (1.5 times) than control seedlings and those primed with nPPs at 1000 mg/l concentration.
3. Seedling volume and vigor index of nWTRs primed seedlings significantly improved by approximately 10 and 4 times respectively compared to control.
4. The application of nWTR at different concentrations significantly increased fresh weight of shoots by 420 %, dry weight of shoots by 680 % and dry weight of roots by 730 % relative to control (DW).
5. The germination percentage of corn seeds was significantly improved when seeds were primed with nWTRs or nPPs at different concentrations.
6. It is also worth noticing that the germination of corn seeds primed with pomegranate peels nanoparticles (nPPs) improved to a lesser extent than that of seeds primed with nWTRs.
7. Application nWTRs at a rate of 500 mg/l or higher is recommended to get the best germination percentage
Greenhouse Experiment
Maize seeds were sown in pots containing sandy soil mixed with biosolids. nWTRs at rates of 0, 1000, 3000 and 6000 mg/l were added to the biosolids amended soil. Four levels of drought were applied after 30 days of planting (100%, 75 %, 50%, and 25 % of available water, AW). After 30 days of drought treatment, the plants were harvested and the growth and biochemical attributes of all plants were measured. The results revealed the following:
1. Shoot fresh and dry weights as well as root fresh and dry weights of primed and unprimed seeds were negatively affected by drought stress. The adverse effect of drought stress was less pronounced in primed Zea mays .L plants than in unprimed one.
2. Root volume and length increased gradually with increasing nWTRs application rates. The highest increases in shoot length and root volumes were recorded at nWTR application rate of 6000 mg/l.
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3. Plants biomass increased with increasing nWTRs concentration and decreased with increasing drought level.
4. Water deficit significantly decreased chlorophyll content in both primed and unprimed plants. However, the reduction was more pronounced in unprimed Zea mays.L plants than primed ones under different levels of drought stress.
5. Chlorophyll content significantly increased with increasing nWTRs concentration applied.
6. The enzymes activity (catalase, peroxidase), proline and total soluble sugar increased in leaves with increasing water shortage and significantly decreased with increasing nWTRs concentrations.
7. Drought stress negatively and significantly affected N and K contents in unprimed and primed shoots and roots of maize plants. On the other hand application of different nWTR rates significantly increased NPK contents in shoots of Zea mays.L plants under drought stress levels. Soluble protein increased in shoots and roots by increasing in nWTRs concentration.
8. The anatomy of root cells was strongly influenced by water deficit stress where cell walls were damaged, and the root circular decreased during drought because of shrinkages and deformations due to dehydration and solute concentration. However, application of nWTRs at a rate of 6000 mg/l to maize plants under stress has protected root cells from dehydration and lowered the damage of root tissue. It is therefore concluded that the addition of nWTRs may alleviate drought stress in maize plant through increasing turgid pressure which may lead to reduce shrinkages of root cells.
9. Exposure of maize seeds to nWTR showed some stimulating effects on germination potential and rate. In response to drought stress, proline and soluble sugar contents in maize seedlings increased in our study, and their contents were further enhanced after application of nWTRs.
10. Application of WTR nanoparticles at a rate of 6000 mg/l demonstrates a protective mechanism against oxidative damage in maize plants under drought stress, as follows Figs. ( 56 and 57 )
1. Maintaining osmotic balance.
2. Improve chlorophyll and photosynthesis by increasing CO2 influx and gas exchange.
3. Detoxify ROS, up regulating the activities of antioxidant enzymes, such as, CAT, and POD.
As a result, application of nWTR and priming in nWTRs were successful in alleviating water stress in maize plants.