Relationship between Rate of Laticifer Differentiation, Number ofLaticifer Rows and Rubber Yield among 1981 IRRDB Germplasm Collections of Hevea brasiliensis

摘要

Early selection based on parameters related to yield is important in the Hevea breeding program. In an attempt to characterise such parameters, we investigated the variation in TNLD (time needed for laticifer differentiation) of the 1981 IRRDB germplasm collections by means of an experimental system for the induction of secondary laticifer differentiation in relation to RLCL (ratio of laticifer rows to the cell layers of the functional phloem) and rubber yield of the corresponding mature germplasm collections. The results demonstrated that TNLD varied among the 63 germplasm collections examined and was correlated to RLCL (r=0.5795, highly significant) and rubber yield (r=0.4558, significant level) of the mature plants. TNLD is expected to be a parameter candidate for early selection, which is better than the leaflet latex method in that it is related to the secondary laticifer differentiation and also better than test-tapping yield method in that early selection can be carried out with one-year-old epicormic shoot in the nursery. Large scale experiment is necessary to confirm this conclusion.