Corkscrewed mesocotyls & failed corn emergence
Restricted Emergence: Corkscrewed mesocotyl/coleoptile development can result when the coleoptile encounters resistance as the mesocotyl elongates. Severe soil crusting or otherwise dense soil surface and cloddy soil surfaces can cause such resistance. A combination of severe sidewall compaction plus press wheel compaction over the furrow can also restrict coleoptile emergence and force the mesocotyl to elongate in unusual directions.
Herbicide Injury: Certain herbicides, notably cell growth inhibitors like acetochlor, can affect seedling shoot development especially if weather or soil conditions are not conducive for rapid seedling growth. However when herbicide injury is suspected to be a contributing factor, cool soils and dense soil crusting are often also contributing factors, so is difficult to pin the blame completely on the herbicide injury.
Cold Soils: Cold soils and/or wide fluctuations in soil temperatures throughout the day during the emergence process are also thought to be major contributing factors for the development of corkscrewed mesocotyl development (Buckle & Grant, 1974). The exact minimum soil temperatures that can cause such corkscrewed development are not clearly documented, but clearly it is not uncommon in Indiana for daily soil temperatures to dip as low as 40F during April and early May. Furthermore, bright sunny days can elevate bare soil temperatures quite high but still drop quite low the following night and thus result in a wide diurnal fluctuation in soil temperatures. Dry soils would be more prone than wetter soils to wide swings in daily soil temperatures.
Corny Trivia: Cold temperature injury that results in corkscrewed mesocotyls is not exactly the same as that which is referred to as "imbibitional chilling" injury. The latter refers to cold injury to the seed during the first 24 to 72 hours after planting when the seed is imbibes (aka absorbs) water. Imbibition of water causes the seed to swell. If seed cell tissue is very cold, it may become less elastic and thus may rupture during the swelling process. The most common symptom of such imbibitional chilling damage to seed cell tissue is often simply swollen seed with little to no evidence of germination progress. Conversely, seedlings with corkscrewed mesocotyls germinated successfully. The cold temperature damage occurred slightly later, during the early stages of mesocotyl elongation and affected the mesocotyl tissue, not the seed tissue.
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