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ISHS Acta Horticulturae 1156: VIII International Strawberry Symposium

The effect of nitrogen on fruit shape and production in short day 'Opera' strawberry trayplants

Authors:   P. Lieten, N. Gallace
Keywords:   Fragaria ananassa, nutrition, flower differentiation, fruit set
DOI:   10.17660/ActaHortic.2017.1156.39
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.

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