Effect of temperature on growth, flowering and nutrient uptake of three passionfruit cultivars under low irradiance

Abstract

High day/night temperatures (2015,2520 and 3025 degrees celcius compared to 1510 degrees celcius) increased vegeta growth in Passiflora edulis f. edulis × P. edulis f. flavicarpa hybrids (cultivars ‘Lacey’, ‘E-23’ and ‘Purple Gold’) grown under low solar radiation levels (9.8 MJ m−2 day−1). For ‘E-23’ and ‘Purple Gold’, increased vegetative growth at 2520 and 3025 degrees celcius was associated with a reduction in the number of floral buds and open flowers. Flowering in ‘Lacey’ was completely suppressed at all temperatures. The greatest numbers of floral buds and open flowers were obtained in ‘Purple Gold’ at 2015 degrees celcius.
The greatest uptake of nutrients into the shoots occurred at
2520 degrees celcius for all cultivars. Tissue concentrations of P, Ca, Fe, Mn, Cu, B and Al were also greatest at the same temperature. In contrast, the concentrations of K rose at higher temperatures, while those of N, S and Mg declined with an increase of temperature.
These results show that potential yield will be reduced by either low temperatures which restrict vegetative growth or by high temperatures which prevent flower production. Selection criteria for new passionfruit cultivars should include both cold and heat tolerance.