Photosynthetic response of Plukenetia volubilis L. to light intensity and soil water availability in young plants

The development of species depends on its physiology and its relationship with the environment. We wanted to determine the response to light intensity and the effect of soil water availability on the rate of photosynthesis of P. volubilis. The seedlings were propagated by seeds and grown in bags, under normal environmental conditions. Two water treatments were imposed: half of the plants continued with irrigation under normal environmental conditions, and the other half was irrigated every five days for six weeks. The available water was calculated with the volumetric humidity values obtained through the ECH2O EC-5 sensor. A photosynthetic light response curve showed that the species hads a high capacity for light utilization, since there was no photoinhibition. Plants also exhibited tolerance to drought, that allowed them to still be alive for several weeks with a reduced water level in the soil (0.033 m(3) m(-3)) since it presented significant differences in the PSII and the Fv/Fm ratio. For the six week of being subjected to water stress under normal environmental conditions, the plants presented photoinhibition as a resistance mechanism. These results show that the species exhibited adaptability to dry seasons, also resistance to water deficit, and a suitable reaction of the photoinhibition mechanism to prevent the photosynthetic apparatus from being damaged.