High Microplant Densities in Greenhouses – Are they Always Efficient in Small Potato Minituber Production Systems?

Four microplant planting densities (PD) for greenhouse production of minitubers of three varieties were used to assess the agronomic and economic efficiencies of increased PD compared to the baseline density (63 microplants m⁻²). The field performance of minitubers was also included in the agronomic (yield formation) efficiency assessment of minitubers production. The concept of a field value (FV) of greenhouse area and of microplant was introduced. Economic assessment of PD changes was based on partial budget analysis and the marginal rate of return between PDs in ascending order. Agronomic efficiency assessment, as an efficient utilization of greenhouse space, revealed that the number of minitubers per m² increased gradually with increasing PD and the magnitude of the increase was up to 2.6 times between PD 63 and 184 microplants m⁻² making this PD the most effective of the studied. The change in minituber number per microplant due to the increased PDs was closely related to the economic efficiency assessment. In the baseline scenario (microplant cost of 0.54 € and minituber cost of 0.41 €), only the shift from PD63 to PD95 was efficient without trade-offs for only one of three varieties.