The interactive effect of seed spacing and orientation influences the time to germination and physiological response in tomato (Lycopersicon esculentum Mill.)

Several environmental stimuli are recognized to impact seed germination, However, very little is known about how different stimuli interact to optimize germination over time. In this study, we conducted an in vitro investigation in agar media to examine the combined effect of seed density and different seed orientation conditions on the relative seedling emergence of Lycopersicon esculentum Mill. Plants sense gravity as a directional environmental cue for controlling growth orientation and growth architecture for survival. We observed that the seedling emergence was faster in horizontally oriented seeds under limiting seed spacing conditions and, in vertical orientation with greater spacing conditions. We also found that the radicle length was comparatively higher in seeds oriented vertically than horizontally. This study also revealed that seedlings under limiting spacing conditions showed higher MDA, a physiological indicator of elevated stress. From this study, it can be concluded that seed spacing and the gravitational stimulus influence seed germination and seedling growth characteristics in tomato.