الفهرس 
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Abstract
Maize (Zea mays L.) is considered one of the most important cereal crops in the world. Stored ears and corn grains are found to attack by different fungi upon harvest i.e. Fusarium moniliforme, F. graminearum, F. oxysporum, Aspergillus flavus, A. niger, Penicillium spp., Nigrospora oryzae, Mucor sp. and Rhizopus spp.
The obtained results could be summarized as following:
1- Isolation trails from grain samples of five yellow corn hybrids collected from different Egyptian governorates verified association of large number of mold fungi to the harvested grains of these corn hybrids. The isolated fungi were identified as Aspergillus niger, A. flavus, A. clavatus, A. candidus, A. ochraceus, Aspergillus sp., A. versicolor, Fusarium moniliforme, Fusarium solani, Fusarium oxysporum, Humicola sp., Mucor sp., Penicillium digitatum and Penicillium sp., as well as some unknown fungi.
2- The occurrence of isolated mold fungi from the different selected Egyptian governorates was varied from governorate to another and from hybrid to another in each one of surveyed governorates. Among these surveyed governorates, the highest frequency of isolated mold fungi was recorded on El-Minia samples followed by Sharkiya governorate samples. Meanwhile, the least frequency of isolated mold fungi was recorded on surveyed yellow corn samples of Assuite and Qena governorates. On the other hand, the associated mold fungi were varied in their frequency on harvested grains of the five tested yellow corn hybrids i.e., SX-3062, SX-SHAMS, SX-3080, 3WC-352 and SX-30N11 from governorate to another where the occurrence of these mold fungi of the same hybrid was affected by the source of grain samples collection.
3- It is clear also that occurrence of Aspergillus group was prevalent in its dominance on tested yellow corn grains than the Fusarium group and other isolated fungi in all surveyed governorates. No one of Fusarium group was detected on collected yellow corn grain samples of Assuite governorate. Meanwhile, F. moniliforme did not detect in all tested grain samples of Qena governorate.
4- As for aflatoxins production in harvested grain samples, it clear that all collected grain samples of the five tested yellow corn hybrids from El-Minia governorate were found to be contaminated with considerable quantities of aflatoxins. The highest amount of aflatoxins was recorded in grain samples of 3WC-352 collected from El-Minia governorate followed by SX-SHAMS (El-Minia) and SX-3080 (Giza). On the other hand, the least amount of aflatoxins was recorded in grains of SX-3062 (Qena), SX-SHAMS (Dakahliya and Assuite), 3WC-352 (Dakahliya) and SX-30N11 (Giza and El-Minia).
5- All grain samples of SX-SHAMS in all governorates except Qena were found to be contaminated with aflatoxins. Also, the highest amount of aflatoxins was recorded in El-Minia samples. Meanwhile, the least amount of aflatoxins was recorded in Assuite samples.
6- As for hybrids, the highest amount of aflatoxins was recorded in grain samples of SX-SHAMS. Whereas, the least amount of aflatoxins was recorded in grain samples of SX-30N11. On the other hand, Aspergillus flavus was able to produce aflatoxins B1, B2, G1 and G2 in vitro where the quantities of aflatoxin B1 is higher than B2 meanwhile, G2 was higher than G1. Also, Aspergillus ochraceus was able to produce high amount of ochratoxin. On the other hand, Fusarium moniliforme produce high quantity of zearalenone mycotoxins.
7- As for the effect of grain moisture content on infection with the tested mold fungi i.e. Fusarium moniliforme, Fusarium oxysporum, Aspergillus flavus and Aspergillus ochraceus, data indicated that increasing the grain moisture content from 12-21% of the four tested corn hybrids increased gradually the infection with these tested mold fungi. Also, increasing the storage periods from 15 to 45 days affected positively on the grain mold infection with the tested fungi. Also, 12% moisture content of corn grains was not favorable for infection with F. moniliforme, Fusarium oxysporum, Aspergillus flavus and Aspergillus ochraceus.
8- It is clear that 21% moisture content was more favorable for infection of infested or un-infested corn grains with all tested grain mold fungi or natural infection. Also, increasing the storage period from 15 to 45 days at this moisture content increased gradually the recorded infections% to reach their maximum at 45 days of storage onto the four tested corn hybrids.
9- The least infection % with F. moniliforme was recorded onto grains of SX-30N11 hybrid at 15 days of storage while, the highest infection % with same mold fungus was recorded onto grains of SX-3062 hybrid. It is pronounced also that SX-30N11 was the least infective corn hybrid with the natural and F. moniliforme infections at 15 days of storage while, SX–Shams was least infective one with the natural and F. moniliforme infections at 21% grain moisture content and 45 days of storage.
10- At 21% grain moisture content, the maximum infections % with Fusarium oxysporum were recorded onto grains of 3WX- 352 and SX –Shams hybrids at 45 days of storage while the minimum infection % was recorded onto grains of 3WX-352 at 15 day of storage.
11- At 21% grain moisture content, grains of SX-3062 were the more tolerant to infection with A. flavus at all tested storage periods. The levels of 12% and 15% moisture content of corn grains were not favorable for infection with A. ochraceus. On the other hand, the highest recorded infection % with A. ochraceus was recorded onto infested grains of 3WX-352 hybrid when stored for 45 days at 21% moisture content.
12- Electrophretic protein patterns using SDS-PAGE technique cleared that the highest number of detected protein patterns was recorded with SX-30N11 hybrid which considers the most tolerant to infection with grain mold fungi among the other tested hybrids. Meanwhile, the least number of detected protein patterns was recorded with 3WX-352 which reveals more susceptibility to infection with the tested grain mold fungi whereas, SX-Shams and SX-3062 hybrids revealed moderate susceptibility
13- Two tested fungicides (Maxim and Vitavax) reduced the mycelial growth of tested fungi i.e., F. moniliforme, F. oxysporum, A. flavus and A. ochraceus comparing to control treatment. Also, increasing the concentration of the two tested fungicides from 500-2500 ppm increased gradually their effects in reducing the growth of the four tested mold grain fungi. Maxim fungicide was more effective than Vitavax in reducing the growth of the four tested molds fungi.
14- Maxim fungicide with 1000 and 2500 ppm could be able to inhibit the growth of Fusarium moniliforme completely. Also, Maxim fungicide was effective in reducing the mycelial growth of the other tested fungi comparing to control treatment. Results indicated also that Vitavax fungicide with the three tested concentrations was effective in reducing the growth of F. moniliforme and F. oxysporum more than A. flavus and A. ochraceus comparing to the control treatment.
15- Dressing the grains of the tested yellow corn hybrids with the two tested fungicides i.e., Maxim and Vitavax before or after 24 and 48 hrs of infestation with F. moniliforme or F. oxysporum and A. flavus or A. ochraceus was effective in controlling the grain mold infection caused by the inoculated fungi at the three tested storage periods. Also, all concentrations of the two tested fungicides were effective in controlling F. moniliforme or F. oxysporum and A. flavus or A. ochraceus infection on grains of the tested yellow corn hybrids without clear differences among them compared with the control treatment. Meanwhile, increasing the concentration of the tested fungicides decreased gradually the infection with F. moniliforme or F. oxysporum and A. flavus or A. ochraceus where the concentration of 2500 ppm was better in its effect than the two other concentrations respectively.
16- Maxim fungicide was more effective in controlling the infections with F. moniliforme or F. oxysporum and A. flavus or A. ochraceus than Vitavax. In this respect, Maxim fungicide inhibited completely the grain mold infection caused by F. moniliforme, F.oxysporum, A. flavus and A. ochraceus onto the grains of the four tested yellow corn hybrids at 2500 ppm when these grains were dressed before or after 24 and 48 hrs of infestation. Also, Vitavax at 2500 ppm was greatly effective in reducing the grain mold infection caused by F. moniliforme when the grains were dressed after 24 and 48 hrs of infestation. It is clear that the lowest grain mold infection caused by F. moniliforme on dressed grains of the four tested yellow corn hybrids with the tested fungicides before or after 24 and 48 hrs was recorded onto grains of SX-30N11 hybrid comparing to SX-3062, SX-Shams and 3WC-352 hybrids at 21% grain moisture content.
17- No clear differences were recorded in grain mold infections caused by F. moniliforme onto the dressed grains with fungicides at the different storage periods i.e., 15, 30 and 45 days but there were clear differences among the three tested storage periods concerning control treatment (un-dressed grains and treated with F. moniliforme). Whereas, dressing grains of yellow corn hybrids with Vitavax at 2500 ppm inhibited completely the grain mold infection caused by A. flavus onto grains of SX-3062, SX-30N11 and SX-Shams hybrids when seed dressing was achieved before or after 48 h of infestation and onto grains of SX-30N11 hybrid when seed dressing was achieved before 24 h of infestation at storage period 45 day. Also, dressing grains before 24 or 48 hrs with Vitavax at 1000 ppm inhibited completely the grain mold infection onto grains of SX-30N11 hybrid when stored for 45 day.
18- Dressing the grains of yellow corn hybrids with the two fungicides before 24 h of infestation with A. flavus was more effective than those dressed before 48 hrs of infestation. The lowest grain mold infection caused by A. flavus on dressed grains of the four tested yellow corn hybrids with the tested fungicides after 24 and 48 hrs of infestation was recorded onto grains of SX-30N11 hybrid comparing to SX-3062, SX-Shams and 3WC-352 hybrids at 21% grain moisture content.
19- Three organic acids reduced effectively the growth of the tested grain mold fungi. Also, increasing the concentrations of tested organic acids from 5 to 10 mM increased their effect in reducing the mycelial growth of tested mold fungi. Salicylic acid was the best effective one among the tested organic acids in reducing the linear growth of the tested mold fungi. Also, salicylic acid with 10 mM concentration inhibited completely the mycelial growth of all tested fungi, as well as, it inhibited completely the mycelial growth of F. moniliforme and F. oxysporum at concentration 5 mM. Meanwhile, salicylic acid at 5 mM concentration was effective in reducing the mycelial growth of A. flavus and A. ochraceus to minimum values comparing to control treatment. On the other hand, oxalic acid was also effective in reducing the mycelial growth of the four tested mold fungi at 5 and 10 mM comparing to control treatment. Also, citric acid at 5 and 10 mM concentrations was effective in reducing the mycelial growth of the four tested mold fungi comparing to the other two organic acids (salicylic acid and oxalic acid) but its effect was the least among them.
20- Treating the grains of the four tested yellow corn hybrids with some organic acids was effective in reducing the grain mold infection caused by F. moniliforme, F. oxysporum, A. flavus and A. ochraceus comparing with control treatment. Moreover, treating the grains with the tested organic acids at 10 mM was better than 5 mM concentration with superiority to salicylic acid effect than the other tested organic acids in reducing the grain mold infection at the three tested storage periods comparing to control.
21- Treating the grains with salicylic acid at 10 mM inhibited completely the grain mold infection caused by F. moniliforme, F. oxysporum, A. flavus and A. ochraceus onto the stored four yellow corn hybrids for 15 day. The least grain mold infection caused by the four tested mold fungi onto grains of yellow corn hybrids was recorded onto SX-30N11 followed by SX-3062, SX-Shams and 3WX-352 hybrids.
22- Eugenol oil was the most effective plant oil with its three tested concentrations (1, 5 and 10% conc.) in controlling the grain mold fungi i.e., F. moniliforme, F. oxysporum, A. flavus and A. ochraceus under in vitro conditions where it inhibited completely the mycellial growth of the tested fungi. Meanwhile, thymol and anisol oils with the three tested concentrations were not able to cause any reduction in growth of A. flavus and A. ochraceus while they had low effect in reducing the growth of F. moniliforme, and F. oxysporum comparing to control treatment.
23- Eugenol oil reduced the grain mold infection onto grains of the four yellow corn hybrids comparing with control treatment. Increasing the concentration of used eugenol oil from 1% to 5% have a positive effect in reducing the grain mold infections% caused by F. moniliforme, F. oxysporum, A. flavus and A. ochraceus where the infections were decreased with increasing of eugenol oil concentrations. Results indicated that eugenol oil at 5% concentration inhibited completely the infection of F. moniliforme, F. oxysporum, A. flavus, and A. ochraceus onto the stored grains of the four yellow corn hybrids for 15, 30 and 45 days.
24- Also, the efficacy of eugenol oil at 1% was decreased by increasing storage period from 15 to 45 days. It is clear that the least infection with grain molds was recorded onto grains of SX-30N11 hybrid treated with eugenol oil, followed by SX-3062 and SX Shams. Meanwhile, the highest infection was recorded onto grains of 3WX-352 hybrid.