Shade delayed flowering and decreased photosynthesis, growth and yield of Sacha Inchi ( Plukenetia volubilis) plants

Abstract

We examined variation in the flowering phenology of Sacha Inchi ( Plukenetia volubilis) plants monitored during an 8-month period with reference to a light gradient (20%, 52%, 75% and 100% of full sunlight), and related these results to photosynthetic features, growth and fruit yield. With strong phenotypically plastic response to light, relative growth rate and photosynthetic capability continually increased with increasing irradiance and their maximum values were much similar to those of the pioneer species. Shade did not increase the apparent quantum yield and reduce the light saturation point and respiration rate. Thus, it was suggested that P. volubilis is a high-light demanding species. Shade delayed initial flowering date and decreased flower and fruit parts. An earlier initiation of flowering was associated with higher flower biomass and plant total biomass, in turn; the latter was positively correlated with fruit biomass across light gradients. These results suggested that an optimized crop management practice should be adopted to ensure that P. volubilis be grown under conditions with minimal shading.