RESUMO
Development of the photosynthetic electron transport system, under the influence of hormones and nitrate-nutrition, in greening cucumber cotyledon was investigated. Both photosystems, PS I measured as DCPIP â MV, and PS II as H2O â pBQ, were significantly promoted by GA and kinetin with kinetin being more effective. PS II/PS I ratio, though increased in control, did not change significantly with GA or kinetin treatment. Other partial reactions (H2O â MV/K3Fe(CN)6/NADP) were also promoted. Addition of KNO3 showed concentration-dependent effects on growth and photosynthetic electron transport reactions (H2O â MV/K3Fe(CN)6/NADP). It is concluded that both hormones and nutritional status influence development of the photosynthetic electron transport system in greening cucumber cotyledons.
