C.L. George Chu, Ph.D.Associate ProfessorPostharvest Storage & Packaging TechnologyE.C. Bovey Building |
E-mail: gchu@uoguelph.ca |
Education
Degree |
University |
Year completed |
B.Sc. |
National Chung-Hsing University |
1972 |
M.Sc. |
University of Guelph |
1977 |
Ph.D. |
Washington State University |
1980 |
Awards
-
Outstanding Reviewer Award received from the American Society for Horticultural Science (1995).
- Joseph Harvey Gourley Award received from the American Society for Horticultural Science for the distinguished research paper published in the Journal of the American Society for Horticultural Science (1978).
Postharvest Fruit Physiology and Storage Program
We have studied and developed maturity indices for new apple cultivars. Our findings have indicated that internal ethylene concentration and a starch index can be useful maturity indices for commercial apple cultivars grown in Ontario. Color guide charts for determining the starch index were developed, printed and distributed to growers and storage operators.
Two major studies were performed for 'McIntosh' and 'Empire' apples to evaluate the relationship between pre-storage holding condition and post-storage fruit quality. Results from these studies were used to establish the concept of "harvest-handling-storage-marketing system for controlled atmosphere storage of apples". Different harvest, handling, storage, and packaging techniques can be employed for apples to be marketed at certain times of the year.
Low-oxygen controlled atmosphere storage research projects have been conducted to develop a new non-chemical technique for controlling scald disorder on apples. This has become a major contribution to the apple industry since the scald inhibitor DPA was withdrawn from the market.
We have also studied the potential use of low-oxygen controlled atmosphere storage techniques to control San Jose Scale on apples to be exported to foreign countries. Information was helpful to commercial CA storage operators and apple marketers to deal with the export/import regulations imposed by the foreign governments.
We have conducted controlled atmosphere storage research (including low-oxygen and low-ethylene CA storage) of fresh pears to support the Ontario pear industry. The results have provided a technique to extend the marketing window of pears for an additional two months.
Since 1997, we have started modified atmosphere packaging technology research to extend the shipping and shelf life of Ontario grown fresh fruits. Bio-control agents are studied to reduce the produce loss due to pathological infections. We have also studied the potential use of ethylene absorption materials to maintain a low-ethylene atmosphere environment in polyethylene film packages.
Significance of greenhouse floriculture to the Agri-food industry and research.
- Non-chemical height control. The use of cold water has shown to be very effective in controlling plant height when applied to the apical meristem of Easter lilies. The response has been linear, e.g. plant height increases linearly with water temperature. The response curve is very similar (same slope!) when plants are grown at different air temperatures (14, 18, or 22C). Height reduction of 50-60% has been achieved with Easter lilies, but is lower for hybrid lilies (7-15%). Early applications are more effective than late applications, and a slight delay in forcing time (4-5 days) has been noted when using very low temperatures (2d).
- Comparison of PGR's on chrysanthemums. Daminozide (B-9) at 2500 ppm was about twice as effective as uniconazole (Sumagic) at 2.5 ppm on height control of pot mums. However B-9 caused a delay in flowering, especially early and more frequent applications. Also B-9 has shown to affect the colour of the popular bronze cultivar 'Pelee', especially when applied late. Sumagic did not show any delay in flowering date.
- Photoperiod and supplemental lighting on cut gerberas. Gerbera cut flower production responded favorably to short photoperiod (8-h PP) in terms of number of stems produced to either 13-h or 18-h PP. However short photoperiod produced shorter stems with the cut gerberas. Supplemental lighting with high pressure sodium lamps at high light intensity (70 µmol/m²/sec) showed only marginal effect.
- The effect of twilight (sunrise or sunset) on plant height. The elimination of twilight at the end of day (using black-out) is a very simple and effective technique to control plant height for many crops.
- Alternative to case cooling of Easter lilies. The use of interrupted cooling for Easter lilies is a viable alternative for forcing Easter lilies compared to the previous standard cooling techniques used in the industry, such as case-cooling and controlled temperature forcing.
- Post harvest studies on Easter lilies. The use of gibberellic acid (GA4+7) has been a very effective technique in preventing yellowing of the lower leaves of Easter lilies. Also, methylcyclopropene (1-MCP) has shown to be a very effective protectant against ethylene damage in both cut flowers and potted plants during shipping and initial shelf life.
Technology transfer. A proportion of my time is spent on transferring research information to commercial greenhouse growers through meetings, workshops, and responding to growers' inquiries. Also articles are written for the Industry trade to convey research results to greenhouse growers as well as for the scientific community. I coordinate and help teaching growers night schools (10 evenings/ semester) relating to topics relevant to greenhouse production.
State of the Industry
Increasing global competition, an impetus for change in the Ontario $80 million apple industry, has resulted in more efficient production practices to be adopted, resulting in improved apple quality and decreased input costs. The result has lead toward optimism for apple exports to Europe. A quick overview of the present status of the Ontario Apple Industry can be obtained from a Web page prepared by the Apple Team, Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) in co-operation with the Policy Analysis Branch, OMAFRA and the Ontario Apple Marketing Commission.
Courses
During the winter semester I teach (in cooperation with Dr. Dennis Murr) Controlled Atmosphere Storage Theory and Technology; Postharvest Disorders; and Handling of Fruits, Vegetables and Flowers as part of two courses in Post-Harvest Physiology (HORT4300) and Post-Harvest Handling and Storage (DAGR425).
Additional Information
Research Information:
Apple Scald Threatens Quality of Fresh Market Fruit - A general discussion of non-chemical control, prediction model, and our research findings.
CA Storage Recommendations for Apples Grown in Ontario
Stretching the supply- Better stability means year-round availability
Selected Publications
Chu, C.L., S.K. Leung, and M. Kawaji. 2004. Reversibility of lychee pericarp red color in relation to pericarp pH, activity of polyphenol oxidase, and particle size of brown pigment. Fruits 59:17-23.
Lencki, R.W., M. Zhu, and C.L. Chu. 2004. Comparison of unsteady- and steady-state methods for produce respiration rate determination. 1. Model development and validation. Postharvest Biology and Technology. 31:229-238.
Skog, L. and C.L. Chu. 2003. Apples. In: Encyclopedia of Food Sciences and Nutrition. Academic Press. Elaevier Science Ltd. 290-294.
Liu, W.T., C.L. Chu, and T. Zhou. 2002. Thymol and acetic acid vapors reduce postharvest brown rot of apricots and plums. HortScience 37:151-156.
Blom, T.J., W. Brown, C.L. Chu, W.T. Liu, L. Skog. 2002. Easter lilies react differently to short- or long-term exposure of ethylene or methane at different stages of forcing. HortTechnology 12:91-94.
Skog, L. and C.L. Chu. 2001. Effect of Ozone on Qualities of Fruits and Vegetables in Cold Storage. Can. J. Plant Sci. 81:773-778
Zhou, T., C.L. Chu, W.T. Liu, and K.E. Schneider. 2001. Postharvest control of blue mold and gray mold on apples using isolates of Pseudomonas syringae. Can. J. Plant Pathology 23:246-252.
Chu, C.L., W.T. Liu, and T. Zhou. 2001. Fumigation of sweet cherries with low levels of thymol and acetic acid to reduce postharvest brown rot and blue mold rot. Fruits 56(2):123-130.
Zhu, D.M., C.L. Chu, S.L. Wang, and R. Lencki. 2001. Influence of oxygen, carbon dioxide, and degree of cutting on the respiration rate of rutabaga. Journal of Food Science 66(1):30-37.
Chu, C.L. and S.L. Wang. 2001. Effect of cutting style, low-oxygen atmosphere and cold temperature on the respiration rate of minimally processed vegetables. Acta Horticulturae 553(2):691-692.
Chu, C.L. and L. Skog. 2000. Ozone technology can reduce ethylene levels in cold rooms stored with apples, pears and broccoli. Fruit & Vegetable Magazine. 3:38
Miles, N.W., C.L. Chu, and R. Guarnaccia. 2000. ‘Venture’ - A new processing peach variety. The Tender Fruit Grape Vine. A Newsletter for Commercial Fruit Growers from OMAFRA. 4(5):5.
Chu, C.L. and F.C. Eady. 2000. Fruit quality of new cherry cultivars evaluated at harvest and after storage. The Tender Fruit Grape Vine. A Newsletter for Commercial Fruit Growers from OMAFRA. 4(3):10-12.
Chu, C.L. 1999. Effects of storage temperature, storage atmosphere and growing region on internal browning disorder of 'McIntosh' apples. HortTechnology 9(1):31-34.
Chu, C.L., W.T. Liu, T. Zhou, and R. Tsao. 1999. Sweet cherry grey mould rot may be controlled with thymol and acetic acid. Canadian Fruitgrower 55(6):1.
Chu, George. 1998. Pears, after the orchard : refining handling & storage to extend market quality. Agri-food research in Ontario 21 (1): 47.
Chu, George. 1998. Proper storage environment can help avoid internal browning disorder in 'McIntosh' apples. Canadian Fruitgrower 54(5): 14-16.
Chu, C.L. 1995. Effects of postharvest pre-storage holding temperature followed by cold or CA storage in the quality of 'Bartlett' pears. HortSci. 30:792 (Abst.)
Chu, C.L. 1993. Effects of pre-CA holding period and controlled atmosphere storage on the quality of Empire apples. Proc. 6th Intl. Controlled Atmosphere Res. Conf. Cornell University, Ithaca, New York. June 15-17. Edited by G.D. Blanpied. Vol. 2. pp. 668-676.
Chu, C.L. 1992. Postharvest control of San Jose Scale on apples by controlled atmosphere storage. Postharvest Biol. Technol. 1:361-369.
Looney, N.E., R.L. Granger, C.L. Chu, S.J. McArtney, and R.P. Pharis. 1992. Influencing apple fruit quality and tree productivity with gibberellins A4, A4+7, and A4+iso-A7. I. Effects on fruit russet and tree productivity. J. Hort. Sci. 67(5):613-618.
Looney, N.E., R.L. Granger, C.L. Chu, and R.P. Pharis. 1992. Influencing apple fruit quality and tree productivity with gibberellins A4, A4+7, and A4+iso-A7. II. Other effects on fruit quality and importance of fruit position within the tree. J. Hort. Sci. 67(6):841-847.
Blanpied, G.D., W.J. Bramlage, C.L. Chu, M. Ingle, M.M. Kushad, O.L. Lau, and P.D. Lidster. 1991. A survey study of the relationship between accumulated orchard hours below 10oC and the incidence of storage scald on 'Starkcrimson Delicious' apples. Can. J. Plant Sci. 71:605-608.
Wang, S.L. and C.L. Chu. 1991. Modified atmosphere packaging of minimally processed butternut squash. Can. Inst. Food Sci. Technol. J. 24(5):190-191.
Elfving, D.C., E.C. Lougheed, C.L. Chu, and R.A. Cline. 1990. Effects of Daminozide, Paclobutrazol, and Uniconazole treatments on 'McIntosh' apples at harvest and following storage. J. Amer. Soc. Hort. Sci. 115:750-756.
Chu, C.L. 1989. Maturity indices of 'Red Delicious' apples in Ontario. Proceedings of the 5th International Controlled Atmosphere Research Conference. Wenatchee, Washington. June 14-16. Edited by J.K. Fellman. Volume 1. pp. 91-101.
Chu, C.L. 1988. Internal ethylene concentration of 'McIntosh', 'Northern Spy', 'Empire', 'Mutsu', and 'Idared' apples during the harvest season. J. Amer. Soc. Hort. Sci. 113:226-229.
Chu, C.L. 1988. Starch-iodine test for determining maturity and harvest dates of Empire, Idared and Spartan apples. OMAF Factsheet No. 88-090. 4 pp.
Lauro, E.M., J.D. Wismer, and C.L. Chu. 1987. Temperature monitor and alarm system for cold storage rooms. Intl. J. of Refrig. 10(2):106-107.
Elfving, D.C., C.L. Chu, E.C. Lougheed, and R.A. Cline. 1987. Effects of Daminozide and Paclobutrazol treatments on fruit ripening and storage behaviour of 'McIntosh' apple. J. Amer. Soc. Hort. Sci. 112:910-915.
Chu, C.L. 1986. Poststorage application of TAL Pro-long on apples from controlled atmosphere storage. HortScience 21:267-268.
Chu, C.L., E.M. Lauro, and R.B. Smith. 1985. New CA storage research facilities at the Horticultural Research Institute of Ontario. In: Controlled Atmospheres of Storage and Transport of Perishable Agricultural Commodities. Edited by Blackenship, S.M. pp. 229-234.
Chu, C.L. and E.M. Lauro. 1984. Monitoring of controlled atmosphere storage by micro-computer. Acta Horticulturae 157:41-44.
Chu, C.L. 1984. Use of internal ethylene concentration as a maturity index of eleven apple cultivars. Acta Horticulturae 157:129-134.
Farhoomand, M.B., M.E Patterson, and C.L. Chu. 1978. The ripening pattern of 'Delicious' apples in relation to position on the tree. J. Amer. Soc. Hort. Sci. 102(6):771-774.
Internet Links
Horticultural Crop Statistics - Ontario Ministry of Agriculture, Food and Rural Affairs
Norfolk Fruit Growers' Association: E-Mail: nfgapple@nornet.on.ca, Simcoe, Ontario, Canada
Postharvest Informaiton Network - Washington State University
Postharvest Technology - Research and Information Center - University of California, Davis
Postharvest Commodity Series - Coop. Extension Service, North Carolina State University
Postharvest Horticulture - South Australian Research and Development Institute (SARDI)
