quality, due to improper harvesting maturity and handling practices (MACK, 1999; Rustenburg Co., 1999).

Transcription

1 AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA ISSN Print: , ISSN Online: , doi: /abjna , ScienceHuβ, Physico-chemical changes during growth and development of Galia cantaloupes. I. Physical changes Al Fadil Mohamed Baraka, Abu-Bakr Ali Abu-Goukh and Mustafa Mohamed Ali Elballa Department of Horticulture, Faculty of Agriculture, University of Khartoum, Shambat 13314, Sudan Corresponding author: Abu-Bakr Ali Abu-Goukh, phone number , ABSTRACT Physical changes during growth and development of fruits of three Galia melon cultivars were evaluated. Fruit growth of the three cultivars followed typical simple sigmoid curves. Fresh fruit weight and flesh and rind thickness progressively increased in the three cultivars with advancement in growth up to physiological maturity stage (44 days after anthesis) and then remained constant. The respiration curves of the three cultivars exhibited a typical climacteric pattern, with peak of respiration coinciding with physiological maturity (44 DAA) and then decreased. Rind color progressively increased during growth and development of the three cultivars. Fruit flesh firmness slightly decreased up to the mature-green stage and then sharply declined during the ripening phase (44-48 DAA). Galia cantaloupes should be harvested at least at physiological maturity, where the fruit attains maximum size and weight, rind color develops and it is still firm. Keywords: Galia cantaloupe, physical changes, growth and development. INTRODUCTION Cantaloupes (Cucumis melo L.) are among the major vegetables that are grown worldwide. The demand for fresh cantaloupes is increasing for their excellent flavor, attractive fragrance, beautiful color, delicious taste and health giving properties (Salunkhe and Desai, 1984). They are used as a dessert or breakfast fruit and are also used in fruit salads, bunches and jellied meals. Cantaloupes rank second after mango in Sudanese horticultural exports in term of revenue (AOAD, 2008). Galia is the only melon cultivar grown for export in Sudan (Baraka, 2004). Although Sudan has great potential to produce and export high quality cantaloupes, the harvesting and post-harvest practices are still not taken care of by both producers and distributors. These practices need a lot of improvement for the development of a sound cantaloupe trade, both for export and local markets. quality, due to improper harvesting maturity and handling practices (MACK, 1999; Rustenburg Co., 1999). Correct harvest maturity of cantaloupe is rather difficult to determine. Over-maturity or under-maturity affects fruit quality adversely. As the melon approaches maturity, the netting becomes fully rounded out, the color changes from dark-green to grayish-green and then to yellowish-green near maturity (Salunkhe and Desai, 1984). Many physical and chemical changes undergone by the developing fruit have been used as means of assigning harvesting maturity. None of these parameters are reliable individually for determining harvest maturity. It usually requires a combination of these physical and chemical parameters, coupled with considerable experience (Saunkhe and Desai, 1984). During the last few years, farmers failed to harvest and keep their product to comply with export requirements. About 40 % to 55 % of total yield is classified as local market grade (Abbas, 2004). This is mainly attributed to smooth or incomplete netted fruits. Importers feed-back indicated that considerable part of the product was discarded at destination for poor This study was carried out to evaluate the physical changes during growth and development of Galia cantaloupes, to provide base-line information regarding the biochemistry of the developing fruit and to assist in selection of the optimum harvesting maturity.

2 MATERIALS AND METHODS Experimental Site and Cultural Practices: A field experiment was conducted at Silate Agricultural Project-Khartoum North, during the winter season. Chicken manure and triple super phosphate (43% P 2 O 5 ) were applied during land preparation, at rates of 6.75 tons and 125 kg per hectare, respectively. Then, the soil was disc harrowed, leveled and divided into beds 1.75m wide. The field was divided into plots, 10 meters long, with four beds each and was arranged in a randomized complete block design with four replications. Seeds of Galia F 1 Standard and Galia F 1 MN-318 were provided by Pop Vriend Seed Company and seeds of Galia F 1 Solar King were obtained from Nunhem Seed Company. Two seeds per hole were sown on both sides of the bed at 25cm inter-row spacing. Fifty kilograms of urea (46%N 2 ) per hectare were applied 15 and 45 days after sowing. The crop was irrigated at seven-day intervals until flowering, and then the interval was extended to 10 days up to harvesting time. Insecticides and fungicides were used when necessary to control insect pests and powdery mildew. Experimental Material: Hundred and sixty plants were selected randomly in each of the plots for fruit sampling. Fruits were tagged at time of flowering on each selected plant. Fruits were picked at 12, 19, 26, 33, 40, 42, 44, 46 and 48 days after anthesis (DAA) for determination of physical changes during growth and development of the fruit. Ten fruits were picked at random from each replicate of the three Galia cultivars at the designated time for the determination of fruit fresh weight, pulp and rind thickness, respiration rate, peel color and fruit flesh firmness. Parameters Studied Average fruit fresh weight was determined using a digital balance and was expressed in grams. Pulp and rind thickness were determined using a Varnier caliber (Whiter-Grew Model) and were expressed in millimeters. Respiration rate was determined by the total absorption method and was expressed in mg CO 2 per kilogram per hour (Mohamed-Nour and Abu- Goukh, 2010). Peel color was determined using the following color score: mature green (= 0), trace yellow on rind (= 1), 20 % yellow (= 2), 40 % yellow (= 3), 60 % yellow (= 4), 80 % yellow (= 5) and 100% yellow (= 6). Fruit flesh firmness was measured by Magness and Taylor Firmness Tester (D. Ballauf Meg. Co.), equipped with an 8 mm diameter plunger tip. Two readings were taken from opposite sides of each fruit after the rind was removed. Flesh firmness was expressed in kilograms per square centimeter. Statistical Analysis: Analysis of variance and Fisher's protected LSD test at significance level of P 0.05 were performed on the data (Gomez and Gomez, 1984). RESULTS AND DISCUSSION The three Galia cultivars were significantly different in all parameters studied. Standard Galia and MN- 318 were closely related and quite different from Solar King in all parameters studied. The two cultivars were higher in fruit fresh weight and flesh thickness and lower in respiration rate, rind color development, rind thickness and flesh firmness, compared to Solar King. Similar variation among cultivars was reported in mango (Abu-Goukh et al., 2005), orange (Garray et al., 2002), papaya (Shattir and Abu-Goukh, 2010) and onion (Mofadal et al., 2000). Fruit Fresh Weight: Cantaloupe fruits of the three Galia cultivars followed typical simple sigmoid curves. The fresh weight progressively increased in the three cultivars with advancement in growth up to the mature-green stage, 44 (DAA), then remained constant (Fig. 1). Hadfield et al. (1995) reported that about 30 to 35 days are required from pollination to harvest for most cantaloupe cultivars. Typical full-slip was reported to be about 42 days after flowering (Agblor and Waterer, 2001). Standard Galia had significantly the highest fresh weight at maturity (1014g), followed by MN-318 (970g) and then Solar King with the least fresh weight (870g). Flesh and Rind Thickness: Flesh and rind thickness increased steadily during fruit growth and development until full maturity and then remained constant in the three 'Galia' cultivars. Solar King showed significantly the lowest flesh thickness (2.6 cm) and the highest rind thickness (0.6 cm) at all maturity stages (Figs. 2 and 3), while, Standard and MN-318 scored flesh thickness of 2.7 cm and 2.8 cm (Fig. 2), and rind thickness of 0.48 and 0.50 cm (Fig. 3), respectively. 945

3 Fruit fresh weight (g) Fig. 1. Changes in respiration rate during growth and development of Galia F 1 Fruit flesh thickness (mm) Fig. 2. Changes in fruit flesh thickness during growth and development of Galia F 1 946

4 Fruit rind thickness (mm) Fig. 3. Changes in fruit rind thickness during growth and development of Galia F 1 Respiration Rate: The respiration rate curves of the three 'Galia' cultivars exhibited a typical climacteric pattern. This is in agreement with the findings of Kitamura et al. (1975) and Pratt (1971). Kader (2002) reported that cantaloupes have a moderate rate of respiration of 10 to 20 mg CO 2 /kg-hr at 5 º C and a respiratory climacteric was observed with fruit ripening. The respiration rate progressively increased from 12 days after anthesis (DAA) reached a peak at 44 DAA and then declined in the three cantaloupe cultivars (Fig. 4). Solar King F 1 had significantly the highest respiration rate during growth and development with peak of 126 mg CO 2 /kg-hr. Standard and MN-318 exhibited almost similar respiration rates during the different stages of fruit growth and development with peaks of 90 and 86 mg CO 2 /kg-hr, respectively (Fig. 4). Rind Color: Rind color progressively increased during fruit growth and development of the three Galia cultivars. The color development started earlier during development in Solar King, compared to the other two cultivars. Solar King had reached color score 2 (20% yellow color) after 26 days from anthesis (DAA) and full yellow color after 44 days from anthesis. On the other hand MN-318 and Standard reached color score 2 after 40 and 41 DAA, respectively and the full yellow color in both, after 48 DAA (Fig. 5). These results are in line with earlier reports that the rind color of cantaloupes changes from dark-green to grayish-green and then to yellowish-green as the fruit approaches maturity (Salunkhe and Desai, 1984). The main period of fruit ripening on the plant in terms of changes of color occurred between 37 and 51 days after pollination (DAP) (Benzioni et al., 1993). During that time, absorbance of light at wave lengths of 667 and 431 nm decreased with time, indicating loss of chlorophyll, and absorbance at 442 and 470 nm increased, indicating carotene production (Benzioni et al., 1993). The carotenoids begin to increase in muskmelons, at least 10 days prior to the onset of the respiratory climacteric and chlorophyll content drops gradually with a final rapid decline coinciding with ripening (Pratt, 1971). Fruit Flesh Firmness: Fruit flesh firmness slightly decreased up to the climacteric peak of respiration (42 DAA) and then sharply declined in a similar manner in the three cultivars (Fig. 6). Solar King was more firm at all stages of growth and development, followed by Standard and MN-318 cultivar was the 947

5 least firm. At the full ripe stage (48 DAA) the flesh firmness was 0.53, 0.40 and 0.09 kg/cm 2 in Solar King, Standard and MN-318 cultivars, respectively (Fig. 6). This is in agreement with the findings of Wang (1990), who stated that in melons, fruit firmness decreases by 40% between 30 and 50 days post-anthesis. Similar pattern of changes in flesh firmness was observed in mango (Abu-Goukh et al., 2005), banana (Abu-Goukh et al., 1995), guava (Bashir and Abu-Goukh, 2003), papaya (Shattir and Abu-Goukh, 2010), tomato (Ahmed and Abu-Goukh, 2003) and date (Barrevelled, 1993). These results indicated that both MN-318 and Standard followed the same pattern, in term of flesh fruit firmness and hence their shelf-life may be shorter, compared to Solar King. Mutton et al. (1981) proposed fruit flesh firmness of 2.0 kg/cm 2 at harvest as a minimum quality grade standard for 'Rocket' melon cultivar in USA. Fig. 4. Changes in respiration rate during growth and development of Galia F 1 948

6 Fruit color score ig. 5. Changes in fruit rind color during growth and development of Galia F 1 Fruit flesh firmness ( kg / cm² ) Fig. 6. Changes in fruit flesh firmness during growth and development of Galia F 1 Standard ( ), Galia F 1 MN-318 ( ), and Galia F1 Solar King ( ) cantaloupe 949

7 CONCLUSIONS Galia cantaloupes should be harvested at least at physiological maturity, where the fruit attains maximum size and weight, rind color develops and it is still firm. REFERENCES Abbas, A. M. (2004). Exportation chances for Sudanese horticultural commodities. Symposium of European Community Standards for Horticultural Commodities. Sudanese Standards and Measurements Corporation (SSMC), Khartoum, Sudan. Abu-Goukh, A. A.; Ibrahim, K. E. and Yusuf, K. S. (1995). A comparative study of banana fruit quality and acceptability under different ripening conditions in Sudan. University of Khartoum Journal of Agricultural Sciences, 3(2): Abu-Goukh, A. A.; Mohamed, H. E. and Garray, H. E. B. (2005). Physico-chemical changes during growth and development of mango fruit. University of Khartoum Journal of Agricultural Sciences, 13(2): Agblor. S. and Waterer. D. (2001). Muskmelons Cantaloupe Post-harvest, Handling and Storage. Department of Plant Sciences, University of Saskatchewan. URL: http: // / doc/pfraarap/csidc/pdf/melons-e.pdf. Ahmed, I.H. and Abu- Goukh, A. A. (2003). Effect of maleic hydrazide and waxing on ripening and quality of tomato fruit. Gezira Journal of Agricultural Science, 1 (3): Albuquerque, B.; Lidon, C. F. ; and Barrerio, M. G. (2006). A case study on the flavor properties of melon (Cucumis melo L.) cultivars., CIRAD, EDP Sciences, 61: AOAD (2008). Arab Agricultural Statistics Yearbook. Arab Organization for Agricultural Development (AOAD), Khartoum, Sudan. Ayub, R.; Guis, M.; Amor, M. B; Gillot, L.; Roustan, P. J.; Latche, A.; Bouzayen, M. and Pech, C. J. (1996). Expression of ACC oxidase antisense gene inhibits ripening of cantaloupe melon fruit. Nature Biotechnology, 14: Baraka, A. M. (2004). Report on Melon Production in Sudan. Alzahra for Agricultural Commodities and Trade. P. O. Box Khartoum, Sudan. Barreveled, W. H. (1993). Dates Palm Products. Food and Agriculture Organization of the United Nations (FAO). Agricultural Services, Bulletin No Rome, Italy. 216 p. Bashir H. A. and Abu-Goukh, A. A., (2003). Compositional changes during guava fruit ripening. Journal of Food Chemistry, 80(4): Benzioni, A.; Mendlinger, S.; Ventura, M. and Huyskens, S. (1993). Germination, fruit development and postharvest characteristics of Cucumis metuliferrus. In: New Crops. pp J. Janick and E.W. Simon (Eds.). Willey, New York. USA. Garray, H.E.B.; Abu-Goukh, A.A.; El-Tahir, F.H. and Hamid, G.A. (2002). Physical and chemical changes in Valencia orange fruits grown in the heavy clay soils of central Sudan. JONARES, 3(1): Gomez, K. A. and Gomez, A. A. (1984). Statistical Procedures for Agricultural Research. 2 nd edition. pp John Willey and Sons. Inc. New York. Hadfield, K.; Arose, J. K. and Bennett, A. B. (1995). The respiration climacteric is present in Charentais (Cucumis melo cv. Reticulatus F 1 Alpha) melons ripened on or off the plant. Journal of Experimental Botany, 46(12): Kader, A. A. (2002). Postharvest Technology of Horticultural Crops. 3 rd. edition. Publication Cooperative Extension, Division of Agriculture and Natural Resource, University of California. Oakland, California, USA. 535 p. Kasmire, R. F.; Rappaport, L. and. May, D. (1970). Effects of 2-chloroethyl phosphonic acid on ripening of cantaloupes. Journal of the American Society for Horticultural Sciences, 95: Kitamura, T.; Umemoto, T.; Wata, T. I. and Alabamian, T. (1975). Studies on the storage of melon fruits. II. Changes of respiratory and ethylene production during ripening with reference to cultivars. Japanese Society for Horticultural Science, 44: Mack (1999).Marketing Report. Multiples Division European Companies (MACK). The Netherlands. Mohamed-Nour, I.A. and Abu-Goukh, A.A. (2010). Effect of ethrel in aqueous solution and ethylene released from ethrel on guava fruit ripening. Agriculture and Biology Journal of North America, 2010, 1(3): Mofadal, H.I.; Abu-Goukh, A.A. and Abu-Sarra, A.F. (2000). Performance, quality and yield of twenty onion cultivars in Jabal Marra area-sudan. University of Khartoum Journal of Agricultural Sciences, 8(1): Mutton, L. L.; Gullis, B. R. and Balkeney, A. B. (1981). The objective definition of eating in rocket melons (C. melo L). Science, 32: Pratt, H.K. (1971). Melons. In: The Biochemistry of Fruits and their Products. pp A. C. Hulme, (Ed.). Academic Press. London and New York. Rustenburg Co. (1999). Marketing Report. Rustenburg Company. The Netherlands. 950

8 Salunkhe, D. K. and Desai, B. B. (1984). Postharvest Biotechnology of Vegetables. Vol. 2. pp CRC Press, Inc. Boca Raton, Florida, USA. 193p. Shattir, A.E. and Abu-Goukh, A.A. (2010). Physicochemical changes during growth and development of papaya fruit. I. Physical changes. Agriculture and Biology Journal of North America, 2010, 1(5): Shellie, K. C. (1995). Enhancing ripening characteristics of netted, orange-flesh and smooth, green-flesh type melons (Cucmis melo L.) In: Proceedings of Cucurbitacae: Evaluation and Enhancement of Cucurbit Germplasm. pp G. E. Lester and J.R. Dunlap (Eds.). Gateway Printing Co., Edinburg, TX, UK. Wang, Y.M. (1990). Chilling Injury of Horticultural Crops. CRC Press, Boca Raton, Florida, U.S.A. 313 p. Watt, B.K. and Merrill, A.L.(1975). Composition of Foods. Consumer and Food Economics Institute, Agricultural Research Service, United States Department of Agriculture. Agriculture Handbook No. 8. Washington, D.C., USA.190 p. 951