Revista Facultad Nacional de Agronomía, Medellín
versão impressa ISSN 0304-2847
MEDINA CANO, Clara Inés et al. BIOCHEMICAL BEHAVIOR AND GASS EXCHANGE OF LULO (Solanum quitoense LAM.) UNDER FULL SUNSHINE CONDITIONS IN THE LOW MOUNTAIN RAIN FORESTS OF EASTERN ANTIOQUIA, COLOMBIA. Rev.Fac.Nal.Agr.Medellín [online]. 2006, vol.59, n.1, pp. 3123-3146. ISSN 0304-2847.
The study was carried out with two lulo, Solanum quitoense, accessions, namely NM, with spines (CE), botanical variety septentrionale (adapted to understory) and SV80, spineless (SE), botanical variety quitoense (selected for tolerance to certain sunlight adaptation). Population CE exhibited higher contents of total protein and Rubisco and PEP carboxilase activity than population SE. Chlorophyll a, b, total and a/b levels were higher in the vegetative phase (V) in comparison with those obtained in the productive period (P: 252 days after transplanting); but, in the stage P a greater chlorophyll a and total concentration was noted in ecotype SE than in genotype CE at the middle and top canopy strata without significant differences between genotypes in the bottom canopy strata. Population CE exhibited greater chlorophyll b than ecotype SE genotype during the V stage. During the P stage, there was differential content between strata at the population CE, with higher profiles in the bottom strata, in contrast with the accession SE in which no differences were detected between canopy strata. This also was true for the chlorophyll ratio a/b. In the V period both genotypes presented high photosynthesis values (F), but at the beginning of the R stage, F decayed significantly for both ecotypes without differences between strata; but at the end of this period the botanical varieties septentrionale and quitoense exhibited photosynthetic activity at the top and middle canopy strata while the bottom canopy was only respiring. For transpiration there was a declining tendency throughout phase V and at the beginning of stage R, without differences among strata in the material CE, but in the genotype SE a bigger T was expressed in the middle and bottom strata. During the phase R, an increase in T was observed in material CE, with significant differences between the medium stratum and the bottom and top canopy portions; in this phase the material SE exhibited maximum values for T in the middle and bottom canopy strata. The high profile for a and b chlorophyll as well as for the ratio a/b at planting time indicates that the plants of both ecotypes, with a relatively reduced photosynthetic area at that time, presented high pigment density which agrees with the obtained photosynthetic activity. With the development of a larger photosynthetic area, the pigments were distributed in the foliage, with a decrease in the concentration for the different types of chlorophylls. Photosynthetic variability was observed between the medium and top canopy strata along the different ontogenetic stages; and it was noted that the bottom canopy was only respiring which characterizes senescent foliage. Based on the net photosynthesis rates it was concluded that lulo is an underestory plant with C3 behavior.
Palavras-chave : Lulo; rubisco; PEP carboxilase; chlorophyll; photosynthesis; transpiration.