Photochemical efficiency of photosystem II and growth in banana passionfruit plants (Passiflora tripartita (Juss.) var. mollissima (Kunt) L.H. Bailey under salt stress

Banana passionfruit (Passiflora tripartita (Juss.) var. mollissima (Kunth)) is an important crop in Colombia, with Boyacá Department contributing over half of national production. Osmotic stress is a major hindrance to production of this crop, but there exists little information on banana passionfruit responses to soil salinity. The present study aimed to evaluate growth and chlorophyll fluorescence in banana passionfruit under salt stress. A completely randomized block design was used. Plants were exposed to concentrations of 20, 40, 60, and 80 mmol NaCl kg-1 soil. Leaf area was reduced by 20.89, 42.91, 58.37, and 76.40%, respectively, compared to control plants in non saline conditions. Total stem length showed a reduction of 9.97, 27.28, 42.79, and 55.77%, and total dry weight per plant was reduced by 23.89, 31.49, 39.60, and 61.26%. Maximum quantum yield of photosystem II (Fv/Fm) was reduced by 11.29, 14.23, 38.89, and 92.25% under the respective treatments. Salinity thus affected all measured growth factors and photosynthesis drastically. Leaf area reduction was closely correlated to reduction in photosynthesis. Dry matter reduction also closely followed the trend in Photosystem II maximum quantum yield (Fv/Fm), which suggests that the major impact of salinity on the banana passionfruit plants was due to negative effects on photosynthesis.