Vapor pressure deficit control and mechanical vibration techniques to induce self-pollination in strawberry flowers

Abstract

Background Pollination strategies to supplement or replace insect pollinators are needed to produce marketable strawberry fruits in indoor vertical farms. To ensure the self-pollination of strawberry flowers, we investigated the anther dehiscence and pollen attachment under different vapor pressure deficit (VPD) conditions and external mechanical sine wave vibrations. Results The proportion of dehisced anthers was examined under VPDs of 2.06, 1.58, and 0.33 kPa, and the projected area of pollen clumps was assessed under VPDs of 2.06 and 0.33 kPa. After exposing flowers to a VPD of 0.33 kPa, vibrations with various frequency (Hz) and root mean square acceleration (m s⁻²) combinations were used to evaluate pollination effectiveness. The anthers underwent complete dehiscence at VPDs of 2.06, 1.58, and 0.33 kPa. The projected area of the pollen clump was larger at a VPD of 0.33 than that at 2.06 kPa. Pollen clump detachment was effective at 100 and 800 Hz with 40 m s⁻², while pollen attachment to the stigma was most effective at 100 Hz. Conclusions These findings suggest that environmental control strategies and specific vibration characteristics can successfully aid strawberry flower pollination. This study provides fundamental insights into mechanical vibration pollination systems for fruit production in indoor vertical farming.