(22) Clonal gardens have the principal objective of obtaining plant buds for grafting using the same technology adopted for commercial seedling production. Those gardens have an approximate 5-year longevity with an objective to obtain “brown stalk” buds and a 12-year longevity for obtaining “green stalk” buds.
The selection of the best material for grafting is essential since vigorous buds
affect rubber yield and rootstock development. (24) “Green stalk” buds are preferred because of their success in grafting, earliness of bud formation and longevity in the clonal garden.
(25) Vigorous seedlings are essential for adequate crop establishment, productivity and longevity.
(26) Seed Production
Grafted seedlings are transplanted to the field after sufficient rainfall or on cloudy days in 7.0 m - 8.0 m rows with 2.5 m – 3.0 m plant spacing to obtain an optimum population of approximately 500 plants/ha. The recommended hole size is at least 0.4x0.4x0.5 m. It is common to replant 20% of the seedlings to obtain the correct plant population.
Soil fertility is closely related to crop yield and proper NPK and other essential mineral elements must be provided. Pest control is also necessary and Erinnys ello, a worm called Mandorova is the most common insect attacking rubber tree leaves during leaf exchanging, flowering and fruit development periods.
Foliar diseases are not common in regions with moderate relative humidity such as in the Brazilian southeast, except for coastal locations. The incidence of the fungus Oidium hevea is detrimental to seed production.
Mature seeds are shed from dehiscent fruits to the soil. As a consequence, the area must be cleaned before seed collection to avoid picking up old seeds because rubber tree seeds are shot-lived, recalcitrant seeds. It is recommended that harvest occurs as soon as possible after shedding to prevent seed deterioration. Normal seed production yields vary from 70 to 500 kg/ha/year.
(27) In the Brazilian southeast, seeds are commonly harvested from February to April following weed control and “old” seed removal from the forest floor. Daily harvests