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Abstract SOJIlIARY AJID aB:LUSIOB Fruit rots caused by various fungi are considered one of the most serious troubles that reflecting considerable deterioration in both quantity and quality of pome fruits during storage and retail marketing. So, the present work was planned to study the physiological and pathological deterioration of stored fruits in order to reduce losses and increase the storage life of fruits using some fungicides such as thiabendazole a systemic or Botran a contact fungicides as well as pre storage treatments with compounds that increase the resistance of fruits to fungal invasion and fruit deterioration such as caC12 and Vapor Gard (Poly-I-methene 8-9 diyl). Moreover, evaluation some consumer packages was carried out in this respect. The present work was udnertaken during the seasons of 1985, 1986 and 1987 in order to identification the deterioration aspects of pome fruits during storage and retail marketing. In the first season, results obtained could he summarized as follows : 1. Isolation from naturally rotted fruits indicated that Penicillium expansum, Botrytis cinerea, Alternaria alternata and ASpergillus ~ were the more frequent isolates responsible for causing apple (Anna, Bercker) cultivars and pear (Le Conte, Bartlett) cultivars, fruit rots. Other fungi such as Rhiwopus ~ Cladosporium Pencillium ~ and stymphyllium sp., occurred in less frequency, while Diploida natalensis, Fusarium §.E.:...L Trichothecium roseum and Negrospora .§.E..:.. showed the least frequent rate. 2. Pathogenicity tests revealed that the degree of infection was affected by the cultivar and the kind of fungus. Le conte pear fruits showed higher vlaues of infection followed by either Anna apple or Bartlett pear fruits, but Bercker apple showed the least values of disease severity. Gray mould caused by the fungus B. cinerea was the most important causal of fruit rot followed in decreasing order by P. expansum, Alt. alternata and ASpergillus .§E. Therefore, the work was facused up on the physiology of B. cinerea and its metabolic activities on the more susceptible cultivar (Le Conte pear fruits) during cold storage. 3. Physiological studies indicate that the incidence of Botrytis rot developed on a _w___id--,e_....--------.-ranger-· of tempera.tur-e for’ either -r------ .. frui t infection or disease severity. The proper temperature ranged between 20 - While at 5°C the rot didn’t exceed. the inoculated • region of the fruit till 6 days of incubation • Under high relative humdiity (90 100 %) the highest infection with B. cinerea was obtained. No ~i-n-f--e-ction was bserved at 14.5 % R.H. ... - ~----””” The effect of different stages of fruit maturity on fruit rot development proved that there was a ..p..o.=s-i.-t-.i--v--e c~~ 19t..iPIl between the c1e9r~~_.9£ fruit maturity an,. the incidence of Botrytis rot, where maturs seemed to ’be resi$ts.nt~ Moreover, in vitro, mycelial biomass increased significantly as the maturity stage of fruit extract advanced. 4. Biochemical studies indicated that in~fectio---n------.J with B. cinerea led to a pronouncing ir:n: s_~--ill. _r~g.’p-ciM---’ ~. J:~. f;?~~ content of of mature fruits, while sugars content in inoculated riEe fruits tended to ,defter 10 days incubation Total phenols in mature green and greenhish yellow pear frai ts were. generally higher than those in fruits l\’- i - ,Ii - of other stages of maturity, where ,n.-o-----c--l-~a.x:..-..d--i.f-f” e-r-e-R---e-s were noted between inoculated and\ln-inocu But at yellow green stage, the phenolic contents of inoculated fruits were relatively higher than those in healthy ones. 5. Rnzymatic assays in B. cinerea culture filtrate resulted in detecting Peroxidase and polyphenol oxidase \>-~t a }( (’ ~ ’t> J (P. P•0) enzymes and ~th-”e”’-._m--a-x--i_m._u-m---_a.c_ti .._v-~-i” ~ was obtained at the end of incubation~iod. Peroxidase and P.P.o. enzymes activity was higher in the extracts of fruits inoculated at m~~ or gre~~w stage than other stages of maturity. Also, the levels of enzymes In addition, the activity of Peroxidase enzymes was lower in ripe fruits than that of mature green ones. Studies ’of Pectolytic and cellulolytic enzymes activity showed that B. cinerea produced Pectin methylestrase, polygalacturonase and cellulase enzymes in its culture filtrate, and its jactivities were increased by prolonging the incubation period, in vitro as well as in ~., In extracts of inoculated pear frui ts, and after 10 days incubation PMEand PG enzymes activity were as much two times as those of healthy fruits. Futhermore, ex: enzymes acti vi ty was increased in both infected and heal thy fruits and the reduction in viscosity was more pronounced in inoculated fruits than in healthy ones. Studies on rot control in vitro revealed that systemic fungicides (TBZ or Benlate) almost checked the growth at relatively lower concentrations (500 ppm.), while contact ones (Botran or Rovral) showed the same effect at higher concentrations (1000 or 2000 ppm), but caC1 2 was less effective. ~ studies, indicated that all pre inocualtion treatments at higher concentrations· gave highly protective effect against Botrytis rot. TBZ treatment showed the best values followed in decreasing order by Botran, Benlate, CaC12 and Vapor Gard, while Rovral treatment was less effective in this respect. Post inoculated treatments showed that TBZat 1500 ppm was more effective in reducing Botrytis rot followed by Benlate and Botran treatments respectively. While Rovral, CaCI Z and Vapor Gard treatments were less effective’ in this respect. Results showed that residues in peel extract reflected higher reduction in mycelial weight than that \ In .p.;e..e.-l-.- extract, Benlate at reduction effect followed in ~ CaCI Z and Botran respectivley. 1500 of flesh extract. ppm gave the highest ’\.- decreasing order by TBZ, (1500 ppm) in f.l.e.-s-h-= \ of TBZ, extract, the highest concentration 2- vJ ~ Benlate and -Botran as well However, at 2 % were statistically similar in their as~ residual effect. On the other hand, -R_ovr.al- or - .Va--p-o-r. Gard .c> _ \68 - treatments showed lower effects in either peel or flesh extract. 7. St..o.-r--a--g...e studies were carried out for two seasons (1986, 1987) on physical and chemical changes associated with inoculation. Le conte pear fruits with B. cinerea and stored t decay at Results Ztotal showed a marked increase loss in weight, c~lour total soluble -=f soluble pectin, ~ chlorophyll, solids, percentage,,.J( carotenoid (’ total nitrogen content accumulation in development, and total on the other hand a.continuous decreases in 1:- 3 ., ~ .4’ Calc~um, titratable ac~d~ty and mo~sture contents as y well as fruit firmness was obtained by increasing the (25 ± 2°C) , fruits Af~t-e--r---r--emoval to roo~ temperaturewere subjected to a sharp period of incubation. deterioration. 8. All compounds applied as a post-inoculated treatments (TBZ, Botran, CaC12 and Vapor - Gard) significantly reduced the percentage of deca.y and total loss in weight as compared with inocualted control. TBZ at 1000 ppm induced the lowest losses percentage during cold storage and extended the shelf-life of treated frui ts up to 12 days. The colour development was slower than that in inocualted control, while the total ti tratable acidity, moisture and calcium content were increased as compared with inocualted control. On contrary, total soluble solids, total soluble pectin and total nitrogen content decreased in treated fruits. 9. Botran treatment at 1000 ppm, significantly reduced the Botrytis rot during both cold storage and shelf-life, but it was less effective than other treatments in extneidng the shelf-life of treated fruits. Moreover, the effect of Botran on the physical and chemical properties of stored pears was somewhat similar to that of healthy fruits. 10. The use of calcium chloride deQreased signfiicant1y the total loss in weight, total soluble pectin and total nitrogen content, delayed chlorophyll degradation, carotenoids accumulation and subsequently colour development and reduced loss of fruit firmness. Decay percentage of inoculated fruits, was also reduced during either cold storage or shelf-life to rank the first treatment in this respect. 11. vapor Gard (V.G.) at 2 or 1 % was effective in delaying the physical and chemical changes of inocua1ted fruits, which led to fruit ripening. But when V.G. was used at -2 % (in the first season) as ~ confirmed by .i:E. vitro data, fruits were subjected to ---- internal browning. For this reason, V.G. at 2 % was ¢ ~ es;;:: replaced by the concentration of 1 % in the second I season. Moreover, V.G. treatment reduced significantly loss in fruit weight, moisture content, the degradation of either chlorophyll or pectin content and also the accumulation of either total nitrogen or carotenoids. A signficiant decrease in loss of fruit firmness, colour development and Botrytis rot were signficiantly obtained during cold storage, where the shelf-life was extended for 12 days. with 2 kg. capacity, i.e. perforated polyethylene bags, Open meshed plastic bags, carton-box (with wrapped or un-wrapped fruits) and kept at SoC, reduced signfiicantly thatotal loss in weight and Botrytis rot of packed fruits, except those packed in open meshed bags. 13. perforated bags led to higher moisture content, pronounced decrease in decay percentage during cold storage and extended the shelf-life for 6 days. Moreover, a significant increase in fruit firmness, total titratable, acidity and chlorophyll contents was obtained. On the other hand, colour development, total soluble solids, carotneoids content, total nitrogen and soluble pectin were markedly decreased. 14. Wrapping inoculated Le Conte pear fruits in tissue papers and packing in caroton box, led to a marked reduction in Botrytis rot during cold storage and extended the shelf-life up to 6 days. wrapped fruits behaved similarly as those packed in perforated bags, where the development showed a slow rate. 15. Levels of rotting and deterioration in inocualted fruits packed in open meshed plastic bags were significantly equal to those in inocualted control during cols storage and after transference to room temperature. 16. Inoculated fruits packed in c..a.r..to.-n----b-o-x-, showed a significant reduction in Botrytis rot and loss in fruit weight, and extended the shelf-life for packed fruits for only 6 days with less than 50 % sound fruits. Moreover, the physical and chemical changes in packed fruits were more or less the same as that of healthy fruits. from the previous results it could be concluded that : 1. Store mature greeen Le conte pear fruits at 50C. seems to be suitable for prolonging the storage life. _ liz - 2. Treatments with some chemicals could be considered supplementary to refrigeration of Le Conte pear fruits. 3. The application of CaCl2 at 2 % revealed a satisfactory results in reducing Botrytis rot as well as Vapor Gard at I %, where CaCl2 ranked the first in this respect. 4. post-harvest treatment with the. systemic fungicide II Thiabendazolell revealed higher reduction in frui trot, where vitro studies showed the rpesent of its residues in both peel and flesh extract in treated fruits. S. When fruits were wrapped and packed in carton box or when fruits were packed in perforated bage, as a consumer package with 2 kg. capacity and kept at SoC., led to less decay percentages. |