Tropentag 2005 Stuttgart-Hohenheim, October 11-13, 2005

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1 Tropentag 2005 Stuttgart-Hohenheim, October 11-13, 2005 Conference on International Agricultural Research for Development Influence of Packaging Materials and Storage Time on Seed Viability and Chemical Component of Rice Seed Rattanaporn Muangkaeo a, Sombat Srichuwong b and Suchada Vearasilp c a Postharvest Technology Institute, Graduate School, Chiang Mai University, Chiang Mai, 50200, Thailand b Department of Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200, Thailand c Department of Agronomy, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200, Thailand Abstract This research aimed to study the effects of packaging materials and storage time on seed viability and chemical component changes during storage. Seed of Rice var. Khao Dawk Mali 105 has been processed and dried to 9.65%moisture( MC). Seeds were stored in 4 different types of plastic bag i.e. Polyamide (PA), Polyethylene (PE), Metallized Polyethylene Terepthalate (MPET) and Woven Polypropylene (WP) bags for a period of 5 months under controlled temperature (16 0 C) and relative humidity (65%) at Seed Center No.7, Chiang Mai. The experiments were designed in 4 6 Factorial in RCB (Randomized Completely Block Design) consisting of 2 factors; packaging material and storage period. Changes in seed moisture content, standard germination, vigour and chemical composition (crude carbohydrate, protein and crude fat) were monthly determined. The experiment was conduct from Febuary to July, 2004 at the Postharvest Technology Institute and Department of Agronomy, Faculty of Agriculture, Chiang Mai University. From the experiment, seeds in WP bag were highly changed and gave a higher moisture content percentage (10.40%) than seeds in PA (9.81%), PE (9.83%) and MPET (9.89%) bags throughout storage periods. All treatment showed that rice seeds could maintain their germinability average % after 5 months. Rice seeds vigour showed that germination investigated by accelerated aging technique were decreased and the electrical conductivity from seed exudates were increased after 5 months storage (average % and µmhos/cm/g). The analysis of seed chemical composition showed that all the plastic bag types did not resulted significantly affecting in carbohydrate (85.56%) and protein contents (7.07%), but the fat contents decreased. After 5 months, fat contents in seeds stored in WP bag were lower than MPET, PE and PA bags (1.86, 1.90, 1.97 and 2.01, respectively). The fat contents decreased because of lipase in rice seed and gas oxygen that the main cause seed deterioration. It was concluded that rice seeds stored in PA bag which prevented water vapor and oxygen transmission could delay seed quality deteriorate followed by PE, MPET and WP bags during 5 months storage. 2 Background and Aim of the Study Rice (Oryza sativa L.) is the most important cereal crop cultivated in the world, which feeds more than half the world s population (IRRI, 1997). It grows widely and finds many uses. Commonly, it is consumed as cooked rice or used as a raw material for food and stock-feed industries. Khao Dawk Mali (KDML) 105, commonly known in food markets as Jasmine Rice or Thai Hom Mali Rice, is the most popular aromatic rice variety grown in Thailand. Because of its famous reputation in appearance, cooking quality and high aroma level, the rice has gained an increasing popularity throughout the world food market. The management of rice grain after harvesting has been reported to play an essential role in posterior maintenance of rice yield and quality. The post-harvest treatments often considered include methods and temperature of drying, storage moisture content, storage conditions and duration, while the properties of rice grains frequently reported are head rice yield, pasting properties, chemical properties and sensory quality (Daniels et al., 1998; Pearce et al., 2001). Seed health refers primarily to the presence or absence of disease-causing organisms such as fungi, nematodes, bacteria, viruses and insects associated with seed. Farmers often use seeds that have impurities and contaminants and are infected with pathogens

2 (Fujisaka et al., 1993). The importance of seed quality in realizing the full potential of a variety is well known. The three major aspects of seed quality are a) genetic and physical purity, b) high germination percentage and vigour, and c) free from seed-borne diseases and insects (Seshu and Dadlani, 1989). Seed vigour is recognized as an important seed quality parameter distinct from germinability (Seshu et al., 1988). The objectives of this study were to determine the effect of packaging materials and storage time on seed viability and chemical component in rice seed during storage. 3 Materials and Methods Seed of Rice var. Khao Dawk Mali (KDML) 105 had processed and dried to 9.65% MC. Four different types of plastic bag; Polyamide (PA), Polyethylene (PE), Metallized Polyethylene Terepthalate (MPET) and Woven Polypropylene (WP) bags were selected for the experiment. Seeds were stored for a period of 5 months under controlled temperature (16 0 C) and relative humidity (65%). Seed moisture content viability and chemical composition were monthly determined. 3.1 Seed Moisture Content In a set of 3 replicates seed samples of each treatment, the seed moisture content was determined by hot air oven method (ISTA, 1999). 3.2 Seed Viability Seed germination test Germination test was conducted by the between paper method, in 4 replicates of 100 seeds each treatment, at 25 0 C following the standard method (ISTA, 1999) Vigour Test Accelerating Aging Test; the seed is aged at 41 0 C for 72 hrs prior to planting under normal germination test conditions (ISTA, 1999). Conductivity Test; 25 seeds of rice and treatments were taken in 3 replications in each flask and 75 ml of distilled water was added with seeds. Then the flask were kept in the incubator at 25 0 C for 24 hrs (ISTA, 1999). The seed leachate was collected and the electrical conductivity (EC) was measured using a digital conductivity meter. 3.3 Chemical Analysis The crude lipid content of seed sample was measured by using soxtec system. The nitrogen content of sample was determined by the Kjeldahl method (AOAC, 1980). The protein content of sample was obtained from nitrogen by multiplying it by a nitrogen-protein conversion factor of 5. (Juliano, 1985). The crude carbohydrate content is calculated as 100 [protein + lipid + ash]. 3.4 Statistical analysis Data obtained from the study were subjected to statistical analysis in accordance with the procedures of Gomez and Gomez (1976). Significantly different treatment means were compared by the method of Least Significant Difference (LSD). 4 Result and Discussion Rice seed moisture content of 4 packages trended to increase during storage. Moisture content from WP bags were most increased and resulted in the higher moisture content percentage than from MPET, PA and PE bags throughout storage periods but the 3 last packages were not significantly (Table 1). The oxygen and vapor transmission rate of WP bag were higher than MPET, PA and PE bags (Michael et al., 2000) and the grains have a natural behavior as they had rapid moisture adsorption or desorption through the grains surface readsorption moisture from the environment and/or the grains surface adsorbing moisture from the center of the kernel (Kunze and Calder, 1980). The rice seeds could maintain their germinability over percent and all the plastic bag types did not resulted any significantly after 5 months storage (Table 1). Rice seeds vigour investigated by accelerated aging technique found that slightly decreased and the indirect electrical conductivity test was increased with time (Table 1). The vigour of

3 seeds were decreased after increasing storage periods that cause seed deterioration (Delouche and Baskin, 1973). Results presented in Table 2 indicated remarkable changes in proximate chemical composition of rice seed due to germination. As germination progressed, the amount of crude carbohydrate, protein and crude fat slightly change during 5 months storage. All the plastic bag types did not resulted any significantly affecting in crude carbohydrate and protein content, whereas the crude fat slightly decreased. During storage rice will be occur enzyme activities, oxidation and respiration that cause chemical change, the starch, protein and lipid were decreased (Ohtsubo, 2000). Mutters (2003) found that the chemical composition were highly change during storage in 3-4 months at high temperature (>15 0 C), the protein were decreased and free fatty acid were increased form oxidation and Wayne and Jame (1993) found that total protein did not change during storage. Using WP bags, the crude fat in rice seeds has decreased more than in MPET, PE and PA bags. From this experiment, indicated that seeds stored in PA, PE and MPET plastic bags could more delay seed quality deteriorate than WP bags during 5 months storage. Table 1. Means seed moisture content, germination, storability (investigated by accelerated aging technique) and vigour test (investigated by electrical conductivity) of rice seeds stored in 4 different containers after 5 months storage. Container type Moisture content (%) Germination (%) Storability (AA test) Germination (%) 93 PA PE MPET WP 9.81b * 9.83b 9.79b 10.40a 96 * Means within column followed by different letter are significantly different at < P 0.05 Vigour test (Electrical conductivity) Table 2. Means seed chemical composition; crude carbohydrate, protein and crude lipid of rice seed stored in 4 different containers after 5 months storage. Container type PA PE MPET WP Seed chemical composition Crude carbohydrate Protein (%) Crude lipid (%) (%) a b c d * Means within column followed by different letter are significantly different at < P Conclusion Rice seed qualities stored in WP bag were extremely changed and gave a higher moisture content percentage than stored in PA, PE and MPET bags throughout storage periods. The rice seeds could maintain their germinability average % after 5 months. Rice seeds vigour were decreased and the electrical conductivity from seed exudates were increased. All the plastic bag types did not resulted significantly affecting in carbohydrate and protein contents, but the fat contents decreased. After 5 months, fat contents in seeds stored in WP bag were lower than MPET, PE and PA bags. The fat contents decreased because of lipase in rice seed and gas oxygen that the main cause seed deterioration. It was concluded that rice seeds stored in PA bag which prevented water vapor and oxygen transmission could delay seed quality deteriorate followed by PE, MPET and WP bags during 5 months storage. Acknowledgements Financial support for the joint research is provided by Postharvest Technology Institute, Chiang Mai University, Thailand.

4 Reference AOAC Official methods of analysis (13th ed.). Washington, DC: Association of Official Analytical Chemists. Daniels, M.J., Marks, B.P., Siebenmorgen, T.J., Mcnew, R.W. and Meullenet, J.F Effects of long-grain rough rice storage history on end-use quality. Journal of Food Science, 63, Delouche, J.C. and Baskin, C.C Accelerated aging techniques for predicting the relative storability of seed lots. Seed Sci. and Technol. 1: Fujisaka, S., Guino, R.A., Lubigan, R.T. and Moody, K Farmers Rice Seed Management Practices and Resulting Weed Seed Contamination in the Philippines. Seed Sci. Technol. 21: International Seed Testing Association (ISTA) International Rules for Seed Testing. Seed Sci. and Technol. Volume pp. International Rice Research Institute (IRRI) Rice Alman ac (2nd ed.). Los Ba~nos, Philippines: International Rice Research Institute. Kunze, O.R. and Calder, A.L System for drying of rice. pp In Drying and Storage of Agriculture Crop. C.W. Hall, ed. Avi Publication Co., Ltd., Westetort. Connecticut. Michael, F., Karwan, E. Kim, E. and Thomas, C The Purpose of Packaging. [ Project.html]. Mutters, R.G Concept of Rice Quality. [online]. (4 January 2548) Ohtsubo, K Rice Storage and Its Quality. Group training course in post-harvest rice processing. Tsukuba International Centre Japan International Cooperation Agency. 30 p. Pearce, M.D., Marks, B.P. and Meullenet, J.F Effects of postharvest parameters on functional changes during rough rice storage. Cereal Chemistry, 78, Seshu, D.V. and Dadlani, M Role of Woman in Seed Management with Special Reference to Rice. IRTP Technical Bulletin # 5, 24 pp. Seshu, D.V., Krishnasamy, V. and Siddique, S.B Seed vigour in rice. In Rice Seed Health. International Rice Research Institute, Philippines, pp Wayne, E.M. and James, I.W Rice Science and Technology. Agricultural Research Service U.S. Department of Agriculture New Orleans, Louisiana. 470

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