PHYSIOLOGICAL-RESPONSE OF SOLANUM-CRINITUM LAM TO CONTRASTING LIGHT ENVIRONMENTS

During a 66-day period, a study was made in controlled environment cha mbers, under high (800-1000 mu mol m(-2) s(-1)) and low (200-350 mu mo l m(-2) s(-1)) light regimes on the physiology, morphology and growth of Solanum crinitum, a pioneer medium-sized woody species known to inv ade forest gaps, active pastures and abandoned agricultural areas in t he Brazilian Amazonia. The objective was to investigate the sun-shade acclimation characteristics of this species. High-light grown plants ( HL) had higher light saturated rates of photosynthesis than low-light plants (LL). No significant difference in dark respiration was observe d between light regimes. Relative growth rate was initially (at 22 d) higher for HL, becoming similar between treatments in the last two har vests (44 and 66 d). Leaf area ratio and specific leaf area were highe r for LL. Allocation of biomass to leaves was similar between treatmen ts, while biomass allocated to roots was higher in HL. Allocation of b iomass to stems was higher in LL. Leaves grown under high irradiance h ad less nitrogen per unit of mass and more per unit of area than leave s developed at low irradiance. These results suggest that light is imp ortant to the performance of this species and that the differential re sponses to light conditions may contribute to or detract from its abil ity to succeed in natural and agricultural environments or to endure c ontrol strategies.