The effect of nitrogen on fruit shape and production in short day 'Opera' strawberry trayplants
The timing of nitrogen application during flower initiation and differentiation and its subsequent effect on plant performance and fruit shape was examined in three successive experiments. From planting (in mid-July) until the end of flower differentiation (beginning of November) different nitrogen (N) rates were applied to container-grown plants of the short day cultivar 'Opera'. In the first trial, rates of 68 and 100 kg N ha-1 were compared. The higher rate of N was applied mainly in the long day period from mid-July until early September. In a second trial trayplants received 86 and 158 kg N ha-1 during the nursery period. The highest N rate was applied from planting onwards and increased in the short day period from early September until end of October. In a third experiment N-application was kept low in July and August and increased from mid-September until mid-October. The trayplants received respectively 70 and 140 kg N ha-1. Following cold storage the trayplants were grown on substrate and data relating to fruit number, fruit size, fruit shape and yield was collected. High N applied during the nursery period promoted vegetative growth and resulted in more stolons and daughter-plants per plant. In all trials high rates of N delayed harvest by 3 to 4 days. In both trials following early high application of N primary flowers developed significantly more grooved (10.8 vs. 3%) and split fruits (2.4 vs. 0%). Later N application, from mid-September, resulted in a significant higher percentage of conical fruits (95%). Strawberry trusses of 'Opera' were simple dichasial bearing a primary, two secondary and one or two tertiary fruits. A higher rates of N first and second trusses branched. This resulted in a significantly higher fruit number per truss and yield per plant.
Lieten, P. and Gallace, N. (2017). The effect of nitrogen on fruit shape and production in short day 'Opera' strawberry trayplants. Acta Hortic. 1156, 255-262
Fragaria × ananassa, nutrition, flower differentiation, fruit set