Photosynthetic responses of apricot (Prunus armeniaca L.) to photosynthetic photon flux density, leaf temperature, and CO2 concentration

Abstract

Two cultivars (Katy and Erhuacao) of apricot (Prunus armeniaca L.) were evaluated under open-field and solar-heated greenhouse conditions in northwest China, to determine the effect of photosynthetic photon flux density (PPFD), leaf temperature, and CO2 concentration on the net photosynthetic rate (PN). In greenhouse, Katy registered 28.3 μmol m-2 s-1 for compensation irradiance and 823 μmol m-2 s-1 for saturation irradiance, which were 73 and 117 % of those required by Erhuacao, respectively. The optimum temperatures for cvs. Katy and Erhuacao were 25 and 35°C in open-field and 22 and 30°C in greenhouse, respectively. At optimal temperatures, PN of the field-grown Katy was 16.5 μmol m-2 s-1, 21 % less than for a greenhouse-grown apricot. Both cultivars responded positively to CO2 concentrations below the CO2 saturation concentration, whereas Katy exhibited greater PN (18 %) and higher carboxylation efficiency (91 %) than Erhuacao at optimal CO2 concentration. Both cultivars exhibited greater photosynthesis in solar-heated greenhouses than in open-field, but Katy performed better than Erhuacao under greenhouse conditions. © 2007 Institute of Experimental Botany, ASCR.