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Studies on Seed Germination, Bud Activation, and Early Budshoot Growth of Uevea brasiliensis (Muell. Arg.)
Dissertation Abstract:
Studies to reduce the uneven early growth of Hevea buddings were done to overcome the low percentage of tappable trees during the early years of tapping. These included experiments on Hevea seed germination - bud activation of budded stumps to induce early bud-break using growth regulators, other techniques, and other growth-regulating materials; and the manipulation of early growth of Hevea budshoot under various bud activation treatments.
Research on seed germination revealed that Hevea seeds (RRIM 600) gathered during the early seedfall had very low percentage of germination compared with seeds gathered during the peak seedfall. However, partial cracking of the seed coat improved the percentage of germination in both groups of seeds. Moreover, the heavier seeds (4-5 g) germinated earlier (before 14 days from sowing) and their seedlings were more vigorous than those from the lighter seeds. Seedlings from the early germ ina ted seeds reached buddable girth size for young budding two months after planting.
Studies on bud activation using benzyladenine at 3,500- 4,000 ppm revealed that 40-60 percent early bud-break could be obtained in green and young buddings. This was significantly higher than the result from the untreated control. A similar response was obtained when different clonal materials were used in green buddings.
Early bud-break was also induced by dipping the budded stumps in melted paraffin wax with temperatures between 60°C and 85°C. This technique resulted in 40-50 percent bud-break three weeks after treatment.
The early shoot growth of Hevea buddings was not affected by any of the growth regulators applied on the dormant buds. However, after bud emergence, brushing gibberellin preparation on the shoot at bud stage stimulated rapid growth of the shoot. Significant rapid growth of shoot in height, particularly the first internode, was very evident 15 to 30 days after regulator application.
An anatomical study of the bud patches showed that the effectiveness of the different treatments to induce bud-break was closely associated with early cambial activity and callus formation in stock and scion.
The studies on seed germ ination, bud activation, and early budshoot growth in Hevea revealed that variations in early growth of Hevea buddings could be minimized through selection and appropriate treatments of seeds, use of growth regulators, and other horticultural techniques and manipulations on the young and green buddings.
