الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 153 |  |  |
| | | from | 153 | | |
Abstract
The present study was conducted using Crimson seedless grape (Vitis vinifera
L.cv) to investigate the following points:
I. Fungicidal activity in vitro of chitosan, three natural oils (citronella, clove and neem
oils), salicylic acid, calcium chloride and their mixtures with chitosan in addition to some minerals and two standard recommended fungicides (Tecto® and Switch® ) were investigated against four decay causing pathogenic fungi as (Aspergillus niger, Botrytis cinerea, Penicillium spp and Rhizopus stolonifer).
II. The efficacy of pre and postharvest treatments on grapes quality in order to expand the storage interval as well as total soluble solids (TSS), titrable acidity (TA), shelf life of
table grapes sensors during storage period.
III. Effect of pre and postharvest treatments on some biochemical parameters as the microbial analysis, anthocyanin content, polyphenol oxidase (PPO, EC 1.10.3.1) and Peroxidase (POD, EC 1.11.1.7) enzyme activities.
The results of the experiments could be summarized as follow:
6.1 In vitro antifungal efficacy of tested treatments The fungitoxic activity of tested treatments with chitosan and natural oils and their combination as well as other treatments against grape decay disease agents were investigated using food poisoned technique. The results indicated that:
1. Salicylic acid was the most effective fungitoxic tested compound followed by chitosan against all chosen fungi. The MGI50 values of salicylic acid were the lowest values against A. niger and R. stolonifer (118.7 and 255.4 ppm respectively). While clove oil
caused higest fungitoxic activity among natural oils, neem oil was the lowest one in this respect against the four tested decay grape pathogenic fungi.
2. Mixing chitosan with other natural alternatives increased the fungitoxicity of the resulting mixtures that all MGI50 values were lower than crosponding values of either chitosan or the natural tested compound alone. 119
3. Mixing chitosan with salicylic acid increased the fungitoxic activity against all four tested fungi, that the MGI50 of the mixtures were lower than the corresponding values of chitosan alone. The fungitoxicity increased by 5.1, 1.5, 3.1 and 1.76 folds for A.
niger, B. cinerea, P. spp and R. stolonifer respectively.
4. Calcium cholride alone treatments had very weak activity against all tested fungi, mixing calcium cholride with chitosan remarkably decreased the MGI50 values of calcium cholride against the four tested fungi
5. The conventional two fungicides used Tecto® and Switch® exhibited strong fungicidal activity that inhibited competely the mycelial growth of the four tested pathogenic fungi
at very low concentrations of both compounds.
6.2 Evaluation of fruit decay in field
Samples were sprayed twice at 10 and 20 days before harvest.
1. Chitosan and salicylic acid reduced the activity of fungi at the most critical vulnerable period before harvest and formation of fruits. Salicylic acid over the two seasons had
remarkable antifungal activity. Clove oil either alone or when mixed with chitosan reduced the mycelial fungal growth too.
2. Two sprays of treatments from the beginning of the variation were effective more than one in order to inhibit decay fungal growth.
6.2.1 Evaluation of quality sensors
6.2.1.1 Evaluation of fruit decay during storage In the 2019 season: After 15 days during storage, preharvest treatments were good results
especially chitosan, clove oil, salicylic acid and mixing with chitosan.
With the passage of time it was noticed increase in the infection from (1-2) berries reached (9-12) in punnet of 50 berries. Generally preharvest treatments were much better than the postharvest ones. High degree of infection has been noticed in the control (untreated both preor postharvest treatments and without sulfur sheets ) chitosan, salicylic acid, clove oil and their
combinations were effective in this respect and they were able to prevent pathogen infections and stop their mycelial growth.