Seasonal changes in vegetative growth and photosynthesis of Arabica coffee trees

Alterações morfofisiológicas em folhas de Coffea arabica L. cv. "Oeiras" sob influência do sombreamento por Acacia mangium Willd

“…Esses resultados estão de acordo com SILVA et al (2004), que mostram que a fotossíntese do cafeeiro é amplamente controlada pela abertura estomática. Quando há maior disponibilidade de água (estação chuvosa), a condutância estomática é maior, conseqüentemente, observaram-se maiores valores de taxa fotossintética (Figura 1B).…”

Trocas gasosas e fluorescência da clorofila em seis cultivares de cafeeiro sob estresse de alumínio

“…Os valores observados de A, gs e E estão dentro da faixa de variação constante na literatura para cafeeiros (FAHL et al, 2001;SILVA et al, 2004;ALFONSI et al, 2005). Em todas as cultivares submetidas ao estresse de Al ocorreu queda significante em A (p<0,05) quando comparadas com o controle (Figura 1A).…”

Ecophysiology of coffee growth and production

“…Values for A have been averaged at 7.2 and 8.3 µmol m -2 s -1 , and maximum stomatal conductance at 108 and 148 mmol m -2 s -1 , respectively for arabica and conilon coffee (see Figure 3 for details). In contrast, the photosynthetic capacity for both species, determined under saturating light and CO 2 (~5 kPa), reaches values as high as 30-40 µmol m -2 s -1 (Almeida and Maestri, 1997;Campostrini and Maestri, 1998;Silva et al, 2004). The low values of in situ A has been associated with diffusive (stomatal and mesophyll), rather than biochemical, limitations to photosynthesis DaMatta, 2003;Araujo, 2006;Cavatte et al, 2008).…”

“…They also found a parallelism between stomatal conductance and shoot growth accompanying the onset of the declining growth phase, and thus hypothesized that photosynthesis might to some extent modulate the growth of the coffee tree. However, according to Silva et al (2004), declining air temperature appears to be the factor directly responsible for depressions in both growth and photosynthesis, and these depressions would simply run in parallel, rather than being related to each other. It should be emphasized, however, that air temperatures of September in Viçosa (resumption of growth rates) are similar to, or even lower than, those of March and April (start of declining growth rates) and thus the decline in growth rates from mid-March onwards is likely to be related, if any relation does really exist, to decreasing minimal temperatures rather than to the minimal temperatures themselves.…”