Effect of seed quantity on growth performance of rubber seedling plants and quality of planting material

High-quality rubber seeds ensure high seedling performance and successful production of planting materials in the nursery management. An experiment was conducted at Moneragala Sub Station of RRISL in 2020 to investigate the performance of seedling plants raised from different seed quantities to determine the growth and bud-grafting success. Treatments were setup as two times of seed quantity taken and harvested in three rounds (T1-control), three times seed quantity taken and harvested in two rounds (T2), four and five times of seed quantities harvested in one round (T3 and T4). Seed beds of each treatment were arranged according to Randomized Complete Block Design (RCBD) with five replications. Germinated seeds were transferred to the rootstock nursery as soon as the tip of the radical has forced its way through the seed coat. Once the establishment was completed, the growth of seedling plants was evaluated under nursery condition. The seedling plants which were raised from four and five times of seed quantity have significantly increased stem diameter when compared with the control treatment (T1). It was also revealed that dead plant percentage of seedlings raised from control (T1) treatment was high when compared with T3 and T4 treatments. Increasing the number of fresh seeds to four to five times of the required quantity gives more opportunities to select early germinators with high vigor. Therefore, plants that were raised by T3 and T4 treatments have shown a significantly higher bud grafting success (about 80%) as compared to that of T1 and T2 treatments. The overall results revealed that a higher productivity can be achieved with one-time harvested seedlings from four to five times of required seed quantities. However, the seed availability and cost effectiveness of producing planting materials should also be considered in application of suggested method.