Photoperiod and temperature interaction on inflorescence architecture and receptacle size of everbearing 'Capri' strawberry

Flower induction and differentiation processes of everbearing strawberry occur throughout a long period and are therefore naturally subjected to variable environmental conditions. Thus, it is fundamental to understand the influence of photoperiod and temperature on the development of the inflorescence architecture and on the receptacle morphometrics, which together determine the potential crop load. Hence, a trial was set up growing one-leaf runner cuttings of 'Capri' strawberry in natural environmental condition and in two controlled climatic chambers, set respectively at 15 and 25°C with two photoperiods: 10 h (SD) or 24 h (LD) a day with fixed light intensity. On August 23, 2013, plants grown in natural environment were transplanted in soilless culture in Pergine Valsugana (525 m a.s.l.), Italy. Temperature had the strongest influence on inflorescence architecture: 15°C produced more primary branches and a higher total flower number. However, the plants that reached the highest value, with 4 secondary flowers, were those grown in natural environment. Finally, the 15°C LD resulted in trusses with the highest hierarchical flower order, being the only treatment that produced a significant quinary flower number, and the highest total flower number. Temperature strongly affected also the receptacle size: flowers developed at 15°C had both larger diameters and heights than those at 25°C. SD decreased receptacle diameter. The environmental-growing treatment showed an intermediate behaviour, in a different way for flower number and receptacle size, and produced the largest receptacle diameters. The trial highlighted both the strong influence of the temperature and the minor effect of the photoperiod on the truss architecture and on receptacle morphometric response. However, the variability of these conditions in the natural environment could result in a more complex plant response