Initial development of IAC rubber clones in Sao Jose do Rio Preto, Sao Paulo State, Brazil/Desenvolvimento inicial de clones IAC de seringueira em Sao Jose do Rio Preto, SP

In this study the development of four clones (IAC 35; 40; 300 e 301) of rubber tree [Hevea brasiliensis (Willd. ex A. Juss.) Muell. Arg.] selected by Instituto Agronomico de Campinas were evaluated during the first 24 months of cultivation. The experiment was laid out in randomized block design with three replications and four plants for parcel following the 1.5mx1.0m spacing at Sao Jose do Rio Preto, SP. The clone RRIM 600 was used as check. The variables analyzed were the trunk girth, the number of matured whorl, the photosynthesis rate and the concentrations of chlorophyll a, b, total and carotenoids. At the end of the experiment the values of trunk girth at 0.5m above the budgrafting union varied from 5.85 cm (IAC 301) to 10.53 cm (IAC 300) and the mean number of matured whorl varied from 2.58 (IAC 301) to 3.91 (RR1M 600). During the dry season, when the plants were 22 month old, the mean value of photosynthesis rate of IAC 40 and IAC 301 (12 [micro]mol [m.sup.2] [s.sup.-1]) were lower compared to the other clones (15 [micro] mol [m.sup.2] [s.sup.-1]). The chlorophyll a, b and total carotenoids concentrations were equal or superior to the check, never lower. Considering the variables analyzed, excluding the IAC 301, the other clones show performance comparable to RRIM 600.