Postharvest quality of papaya fruit (carica papaya)associated with applications of calcium and chitosan

A study was conducted to evaluate calcium and chitosan effects on storage life, anthracnose disease incidence, quality, physiological changes and enzymes activities of papaya. Mature green papaya fruits of colour index 2 were used for conducting the experiments. In the first experiment, papaya fruits were treated with different concentrations of chitosan, 0, 0.5, 0.75 and 1%, and stored at 13±1°C for 28 days. Chitosan concentrations 0.75 and 1% showed the best effect on extending storage life by 26 and 28 days, respectively while maintaining the quality compared with 0.5% and control. However, there was no significant difference between 0.75 and 1% treatments. In the second experiment, calcium at different concentrations 1.5, 2.5 or 3.5% were applied as a postharvest treatment for papaya fruits using vacuum infiltration and dip application techniques. Calcium infiltration at 2.5% significantly extended the storage life up to 26 days and retained the quality better than other treatments. Since, chitosan with its coating ability to retard weight loss of fruits and antifungal property while alcium provides better fruit firmness, a study was conducted using calcium at different concentrations 1.5, 2.5 or 3.5% and chitosan at 0.75% or their combination. From the in vitro experiment, calcium at different concentrations had slight inhibition effects on C. gloeosporioides spore germination but did not show any significant effects on mycelial growth. Chitosan treatment significantly inhibited spore germination and mycelia growth compared to calcium treatments and their control. Calcium at 2.5 in combination with chitosan (0.75%) had significantly better effects on inhibition of spore germination and mycelial growth of C. gloeosporioides compared to calcium individual treatments. Anthracnose disease incidence (%) on papaya fruits was significantly controlled (5.6%) using calcium at 2.5% and chitosan compared with the other treatments. This combined treatment of 2.5% calcium with chitosan 0.75% extended the storage life up to 33 days while retaining the quality of fruits compared with the other treatments. To look at the effect of this combined treatment over different storage intervals, experiment has been conducted. The effectiveness of the treatments was assessed by evaluating their impacts on the quality characteristics during 35 days of storage period. Calcium 2.5% in combination with chitosan 0.75% treatment had better retention of fruits firmness, weight loss, retarding changes in color and preserving chemical characteristics during storage compared to the other treatments. Furthermore, experiment on the physiological and ultrastructures changes and enzyme activities during storage was conducted. The combined treatment of calcium 2.5% and chitosan 0.75% markedly reduced the respiration rate, ethylene production and maintaining the integrity of the waxy cuticle and epidermal cells. Polygalacutronase (PG) degrading enzyme activity was retarded and the induction of defense response of fruits against anthracnose disease was enhanced by eliciting peroxidase enzyme activities (POD)

Effects of Salinity on Yield and Postharvest Quality of Tomato (Lycopersicon Esculentum Mill.)

The effects of salinity on the yield and chemical composition of tomato (Lycopersicon esculentum Mill.) fruits produced in soilless culture under protected environment were investigated. Two experiments were carried out at Hydroponic Complex, Crop Science Department, Faculty of Agriculture, Universiti Putra Malaysia. Increasing salinity (EC) from 2 m~cm-('control) to 6 m~cm-l'i nearly reduced total yield, size, firmness and water content of tomato fruits, and dry weights of roots and shoots of plants. The incidence of blossom end rot (BER) was higher at high salinity level as a consequence of deficiency of Ca content, which was found to decrease with increasing salinity levels. On the contrary, high salinity conditions resulted in increasing total soluble solids, carbohydrates (fructose, glucose, sucrose), titratable acidity and ascorbic acid (Vitamin C) concentrations and dry matter content of tomato fruits. The redness (a*) values gradually increased with increasing salinity level from ECs 3 to 6 m~m-', whereas the lightness (L*) and yellowness (b*) values decreased. These observations indicated that it is possible to obtain a good quality tomato fruits with acceptable yield reduction at EC 4.5 m~cm-I. Salinity affected both shelf life of tomato fruits stored at ambient temperature (2 1°C) or in cool condition (15°C) with relative humidity (RH) between 48-66% and 91-92%, respectively. There was a negative relationship between salinity and fruit shelf life, probably due to an increase in polyglacturonase activity, which enhances softening and hence causes shorter shelf life. In another experiment, both high (6 m~cm- 'a)n d moderate (3 mscm-') salinities were applied at different growth stages of plants development. Saline irrigation at EC 3 m~cm- during late developmental stages (onset of ripening) improved the quality of the fruits with acceptable yield reduction (fresh weight, number and size of fruits). In general, maintaining the proper ECs 3 and 4.5 mscm-' appplied at onset of ripening and flowering stages, respectively resulted to in an acceptable yield reductions and high quality products

Formulations of Glyphosate Using Oil Based Adjuvants and their Weed Control Efficacy

The oillwater isotropic formulations of methyl oleate/water/nonionic surfactants system were obtained through phase diagram study. The results showed that surfactants Agrimul 2067, Agrimul 2069, Speedex, Pulse, Triton X-100, Tween 20, Trycol 5956 and Trycol 5944A lead the solubilization of methyl oleate in water to the formation of isotropic solutions. All surfactants except Pulse exhibited a good tolerance to waterbased isotropic solutions. The organosilicone surfactants (Pulse and Speedex) exhibited intolerant characteristic to the glyphosate isopropylamine salts. In mixed surfactant systems, Triton X- 100 extended greater isotropic regions of methyl oleate/water/Agrimul 2069 and methyl oleate/water/Agrimul 2067 systems compared to Tween 20. Six oil in water isotropic (microemulsion) formulations were selected from the phase diagram study and evaluate for their effectiveness against eight selected weeds. The efficacy of commercial glyphosate ( ~ o u n d u ~w@a)s first established against eight selected species of weeds in the glasshouse. The percentage of mortality and spray deposition significantly linearly increased with increasing rates of glyphosate. The EDso of glyphosate on the weed species indicated variable tolerance and ranked as follows: Diodia ocimifolia (0.95 kg a.e ha-') z Cyperus rotundus (0.78 kg a.e ha-') 2 Eleusine indica (0.77 kg a.e ha-') > Imperata cylindrica (0.71 kg a.e ha-') > Paspalum conjugatum (0.60 kg a.e ha-') > Asystasia gangetica (0.56 kg a.e ha-') > Mikania micrantha (0.53 kg a.e ha-') > Borreria latifolia (0.34 kg a.e ha-'). These dosages were used to compare with the performance of methyl oleate-water-nonionic surfactant glyphosate formulations. Nine glyphosate formulations, including adjuvant methyl oleate, alkyl polyglycoside, tallow amine (standard), ammonium sulfate, and Triton were prepared and used in the spread area and effectiveness study. In the study of spreading properties of spray droplet on leaf surface, the wax of the weed leaf was determined by two methods of extraction. The extraction of wax using warm chloroform at 40°C and chloroform at room temperature did not show any significant difference among weed species. However, there was a significant different of wax weight between weed species used in this experiment. The amount of wax of the weeds could be ranked as high, medium and low with I. cylindrica (49.46 pg ~ m - ~M)., m icrantha (48.14 pg ~ m - ~E). ,in dica (45.63 pg ~ m -a~nd) C . rotundus (38.69 pg ~ m -b~ein)g in the high category, A. gangetica (23.16 pg ~ m -a~nd) P . conjugatum (22.37 pg ~ m -in~ t)he medium category and D. ocimifolia (14.21 pg ~ m - a~nd) B . latifolia (15.21 pg ~ m -in~ t)he low category. In the spread area and coefficient study, E. indica, A. gangetica and D. ocimifolia were selected to represent the high, medium and low wax respectively. The presence of methyl oleate, Agrimul 2067, Agrimul 2069 and mixed with Triton X-100 in glyphosate formulations significantly increased the spread area and spread coefficient on leaf surfaces of E. indica, A. gangetica and D. ocimifolia compared to water and Roundup@. In the efficacy study, adding methyl oleate, Agrimul 2067 and Agrimul 2069 in the glyphosate formulation gave equal performance as ~ o u n d u ~fo@r th e control of C. rotsrudais, I. cyliudrica, P. conjugaturn, M. micrantha and B. latifolia. All microemulsion formulations showed significantly greater control of D. ocimifolia. In addition, the glyphosate formulation of ME4, ME5 and ME6 performed better than standard Roundupm in controlling A. gangetica and ME6 increased the efficacy of glyphosate for the control of E. indica

Effects of calcium and chitosan treatments on controlling anthracnose and postharvest quality of papaya (Carica papaya L.)

This study was conducted to evaluate the in vitro fungicidal effects of calcium and chitosan on Colletotrichum gloeosporioides and to as well determine their effects on storage life and quality of papaya. Potato Dextrose Agar (PDA) incorporated with calcium at different concentrations (1.5, 2.5 or 3.5%) or in combination with chitosan at 0.75% or chitosan alone were used as treatments for in vitro tests. Uncorporated treatments with PDA and untreated fruits as control used on papaya fruits for storage life and quality evolutions. Chitosan had the greatest effect against Colletotrichum gloeosporioides in both in vitro and in disease incidence (%) on papaya fruits compared to calcium treatment and as well as control. Calcium reduced spores germination significantly as calcium concentrations increased from 2.5 to 3.5%, compared to the 1.5% and control treatments. However, it did not show any fungicidal effects on mycelial growth. The combination of 2.5% calcium with chitosan 0.75% completely inhibited spore germinations and significantly inhibited mycelia growth compared to calcium individual treatments and as well as control. Anthracnose disease incidence (%) was significantly controlled (5.6%) using calcium at 2.5% combined with chitosan compared with the other treatments. This demonstrated the best effect on controlling anthracnose disease incidence for papaya fruits. Moreover, this treatment proved able to extend the storage life of papaya fruits up to 33 days of storage life while maintaining valuable attributes of quality

Effects of different concentrations and applications of calcium on storage life and physicochemical characteristics of papaya (Carica papaya L.)

Papaya (Carica Papaya L.) fruits index 2 were treated with 1.5, 2.5 and 3.5% solutions of calcium chloride by dipping and vacuum infiltration (-33 Kpa) or untreated (0%) as control. Effects of these treatments were evaluated on storage life and postharvest quality characteristics of papaya. After 21 days of storage at 13±1°C, the fruits were removed from storage for physicochemical analysis. Following additional five days holding in the storage condition for fruits used for evaluation of the rate of disease incidence and storage life. Postharvest dip treatments at different concentrations of calcium prolonged storage life, slowed down the ripening processes and maintained the quality of papaya. Whereas, it was effectively greater with calcium infiltration treatments than that for dip treatments. Calcium infiltration extended the storage life and retained the quality as calcium concentrations increased up to 2.5% and then declined. The desired effect was obtained at 2.5% infiltration compared with other treatments. The least disease incidence was found in those fruits infiltrated with 2.5% calcium. Hence, it can be concluded that postharvest infiltration of calcium at 2.5% has the potential to control disease incidence, prolong the storage life and preserve valuable attributes of postharvest papaya, presumably because of its effects on inhibition of ripening and senescence process and loss of the fruit firmness of papaya

Effect of different concentrations of chitosan coating on storage life and quality characteristics of Papaya (Carica Papaya L.)

Mature green stage of papaya fruits were treated with different concentrations of chitosan at 0, 0.5, 0.75 and 1%, and stored at 13±1 °C for 28 days to study the effect of these concentrations on the storage life and maintaining quality of papaya. Chitosan concentrations 0.75 and 1% showed the best control effect on decay compared with 0% (Control) and 0.5%. At 0.75 and 1% of chitosan, flesh firmness maintained resulted in prolonging in storage life of 28 and 26 days compared with 21 and 19 days, respectively for 0.5 and 0%. Furthermore, they were significantly decreased the weight loss of fruit. All of the treatments inhibited increase of soluble solid contents and pH values of pulp fruits after 21 days of storage at 13 ± 1°C. Titratable acidity and ascorbic acid were higher for coated fruits (0.5, 0.75 and 1%) compared with uncoated fruits. Concern treatments of chitosan at 0.75 and 1% improve papaya fruit quality and resistance to decay

Effects of calcium infiltration and chitosan coating on storage life and quality characteristics during storage of papaya (Carica papaya L.)

Mature green stage (Index 2) papaya cv Eksotika II fruits were treated either with 2.5% calcium chloride infiltration, 0.75% chitosan coating, calcium infiltration at 2.5% then subsequently with chitosan coating at 0.75% or untreated fruits as the control. The fruits were then stored at 13±1°C for 35 days. Calcium infiltration was observed to be effective in maintaining the firmness with a slight effect on the weight loss by 2.9 folds and 2.8%, respectively compared to the control. Chitosan coating had less effect on maintaining firmness (2 folds) but gave better effect in preventing weight loss (5.3%). Chitosan coating treatment markedly slowed the ripening of papaya as shown by their retention of weight loss, delayed changes in their external color and other quality aspects. Calcium infiltration and subsequently chitosan coating as a combined treatment further extended the storage life up to 35 days with better retention of fruits firmness and water loss control compared to the treatments mentioned