Comparação entre folhas sombreadas de sete clones adultos de seringueira

Comparisons among shade leaves of seven adult rubber tree plants In rubber trees the raw material for latex synthesis becomes, in short term, from the photosynthetic process performed mostly by leaves under sub-saturate radiation. In this study were evaluated and compared the following parameters in six clones selected by Instituto Agronômico de Campinas (IAC) with one another and with the traditional RRIM 600 (control): (1) photosynthetic pigment concentrations (chlorophyll a, b and total carotenoids); (2) total leaflet, palisade and spongy chlorenchyma thickness; and (3) area and dry mass weight of shade leaves. The mean values of total chlorophyll (a+b) and total carotenoid concentration were, respectively, 3.14 and 1.04 mg.g-1 fresh weight, always superior or equal to the control. The mean leaflet thickness was 119.62 μm and varied between clones and control. The mean leaf area was 219.17 cm2 and nearly equivalent for all clones. The specific mean leaf area was 198.08 cm2g-1, and IAC 56 showed the greater value, with values from other clones inferior or equal to the control. For all the characters analyzed, the clones IAC 302 and IAC 303 were statistically similar to RRIM 600 and a relationship with productivity was suggested for IAC 303.