| Natural rubber is playing an important role in the construction of national economic construction and national security. Our demand for natural rubber has increased and the gap between supply and demand is increasing year by year. Species improvement and update of the rubber tree was hindered by the long time breeding period. Long time related crossbreeding narrowed the genetic basis, hindered the breeding and selection. In this study, two aspects, one was early-stage prediction about the dry rubber yield and girth growth in rubber tree from different hybrid offspring, yield investigation at seedling stage, elite cross and generations were selected, and part of the key parents were described which provided reference for the selection of the better parent and with appropriate hybrid combinations, the second was the construction of the genetic linkage map for Reyan88-13×IAN873and their offsprings, then the preliminary QTL location for these traits relevant with the latex production,, the results were as follows:The girth growth at1m from the ground for the3rd (before test tapping) and5instars (after test tapping) of rubber tree from9pairs of hybrid combinations progeny were investigated. The results showed the girth growth of3rd and5th instars of the progeny were in line with normal distribution basically, fewer variations happened among the offspring. The coefficient of variation varied from18.24%to22.87%, more variation happened slightly among the offspring at5th instars, up to58.22%except cross e, and the coefficient of variation for other combination varied from26.35%to35.80%. The girth growth of cross D was at the annual average of9.51cm, which was the biggest one. The germplasm of’81IRRDB, which was introduced from Brazil, as one of the parents, appeared the more girth growth and the fast-growing characters were good. The annual average girth growth of cross g, h and f was9.45cm、9.21cm and8.54cm respectively.Totally1235generations from9hybrid combinations and CK were investigated the dry rubber yield via3rd test tapping. The results showed, there were high significant difference among different combination, and more variations happened within the cross. The average yield of test tapping of cross a and b, were higher than ck, RRIM600, with high significant difference, which were26.01g per plant and3.38g per plant respectively. The average yield of cross g, which had of the parent of the germplam, was14.17g per plant. The coefficient of variation of the dry rubber yield at test tapping within cross was ranged from51.87%to100.1%, of which, cross g had the most variations that was proved that, the further relationship between the hybrid parents, the more separations among the off springs. 9crossed were divided into two groups, one was high dry rubber yield and the other was both good on rubber and wood (wild germplasm utilization), and the shortest distance method was used to cluster grouping according to the average yield of test tapping, the annual girth growth of before and after test tapping, also the dry rubber yield per tapping cut. They were cluster into7and8types respectively. The elite generations were cluster into1,5,6and7area, the same things happened in the both groups. The ratio of the high dry rubber yield in1,5,6and7area was0.11%、0.22%、0.44%and4.15%respectively, they were totally4.92%, the ratio of the group of both good on rubber and wood was0.31%、1.25%、1.88%and3.13%respectively, they were totally6.57%.The primary generation of clones PR107, PB86and Tjirl were the important materials for rubber tree breeding currently. The yield of the group was higher when the value of genetic contribution was0.5, at the same time, the fast-growing germplasm of’81IRRDB’ appeared better among its generations. The germplasm of’XJA05664’, who was crossed with Reyan88-13, appeared the best performance, the annual average girth growth of the generations before and after test tapping were9.45cm and5.89cm respectively. And the coefficient of variation of the dry rubber yield was higher than100, which proved the potential of selection the high yield and fast growing species.Reyan7-33-97and Reyan87-6-47, which were selected from the3rd and4th high yield clones, as the parents of the different cross, appeared variations obviously between different crosses, the offspring maybe not inherited the parents’elite characters. The reasonable selection for the parents of the crosses should be considered by the key parent’s contribution.An SSR and AFLP molecular marker genetic linkage map was constructed using the cross Reyan88-13, IAN873and their offspring, which was composed with31groups,88SSR markers and140AFLP markers. The map covered rubber tree genome1484.28cM, and the average length of the linkage group was47.88cM. Each linkage group contained2to66markers, and the average distance between markers was6.51cM. The longest group was the8th linkage group containing11markers and the shortest group was the22nd linkage group, containing4markers. The maximum distance was49.26cM in13th linkage groups, and the minimum distance was0.042cM located on1st linkage group.These traits, yield per plant, dry rubber yield, size of laticifer, line of laticifer and number of laticifer were used to QTL using CIM method. Under the confidence LOD2.5, three QTLs were related to yield per plant, located in the10th,21st and25th groups, the greatest phenotypic variation explained (PVE) of the QTL was47%near rx51. Four QTLs were related to dry rubber yields, all of them located in the6th group, the greatest PVE was41.8%near rx70. Six QTLs were related to size of laticifer, located in the6th,7th and8th groups, the greatest PVE was39.5%near HBE045. Only one QTL was related to line of laticifer, the PVE was26.5%, located in the6th group near rx113. Ten QTLs were related to number of laticifer, located in1st,2nd,6th,7th,19th and25th groups, the greatest PVE was40.9%near rx81. |
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