Impact of the orientation of seed placement and depth of its sowing on germination: A review

Abstract

Seed orientation and its impacts on germination and seedling establishment mainly depend on the type of germination (hypogeal (or) epigeal), seed size and shape. Higher germination per cent is noticed when seeds are sown in the horizontal position. Planting seeds in a downward position can lead to a variety of physiological, chemical and morphological changes in seedlings. Consequences are usually manifested as noticeable modifications in their development. Vigorous seeds have strong, resilient seedlings due to their well-balanced metabolism and coordinated subcellular activity, making them well-suited for tough environments. Proper plumule and radicle growth require additional hormones and energy to ensure seedling survival. Four necessary factors must be considered while deciding the sowing depth viz., soil moisture, optimum soil temperature, soil aeration and atmospheric humidity required for seed germination, emergence and seedling growth. Variations are observed in germination behaviour and seedling growth for different sowing depths. The necessary factors are very much important for efficient nursery seedlings production. This review looks at the effects of seed depth and orientation on the germination and growth of important agricultural, horticultural and silvicultural crops.