Handling of rice seed for germplasm conservation and use

Rice genetic resources conservation activities are aimed to safeguard the local rice treasure from genetic erosion and extinction. The scientists travelled to the different growing areas to collect cultivated rice and wild relatives of rice. For elite breeding lines, which were generated through breeding programmes, the seeds were obtained through breeders. Foreign germplasm materials were acquired directly or through the International Rice Research Institute (IRRl) , Manila Philippines. Collection activities were started in the 50's and being continued till the present. The germplasm seed is preserved under cold storage facility at The Rice Genebank, MARDI Research Station, Seberang Perai, Penang. The facility provides ideal storage conditions for short-term (12-15°C; and 40-45% R.H), medium-term (3-5·C and 35-40 % R.H) and long-term storage (-10 to -20·C). Currently, the genebank's registered holdings total 10,730 accessions of cultivated rice and 150 accessions for wild rices of which 74% are of local origin. For long-term storage, a total of 18-20 gram seeds per accession at 6-7% moisture content were vacuumed-sealed in aluminium foil bags. The foil bags were then stored in deep freezers and freezer cabinets. The expected seed longevity is 30 years. For medium-term storage, seeds at 8-9% moisture content were vacuumed -sealed in aluminium foil bags and preserved in medium-term room. Germination tests, which were carried out on randomly selected accessions from medium -term storage revealed that the seed longevity is maintained at an acceptable level of more than 80% germination even after 13 years of storage; the expected seed longevity is 15 years. However, to prevent possible genetic erosion in storage, the accessions are considered due for seed renewal after 7 years in storage for all rice types except for japonica, which is 5 years. For short-term storage, seeds were stored in brown paper envelopes in short-term storage room. To prevent possible genetic erosion while in medium-term storage, regular and timely monitoring are carried out. Only accessions meeting the set criteria will be considered for seed rejuvenation. To prevent from possible seed contamination or admixture and seed damage during the seed rejuvenation cycle, various precautionary measures were followed through out the process i.e. from seed retrieval for seeding to seed packing for storage. The planted germplasm materials were subjected to systematic characterization procedures for not less than 35 morpho-agronomic traits using standard descriptors for rice evaluated for their reaction to common diseases and pests. The combinations ofprocesses ofgood planning, scheduling, crop husbandry, timely harvestingandscientificunderstandings ofgeneticdiversityhaveaccountedfor thesuccess ofobtaining seeds with the highest quality and potential. High quality seed can be maintained through excellent drying and cold-room preservation. Information and data handling through computerization and internal linking speeds up execution ofgermplasm conservation relatedactivities anddissemination ofinformation and seed to potential users. This paper has two objectives. Firstly, to report on the overall progress of rice genetic resources conservation programmes in Malaysia. Secondly, to present practical aspects of seed handling procedures being adopted in handling rice germplasm at the Rice Genebank.