Anomalies or a return to the sources
The wild ancestor of corn, teosinte, is a strongly branching plant with many panicles and many ears. Along with the domestication and improvement of corn as we know it today, morphological changes occurred. Plants showing apical dominance, building a single shoot and a single, well-developed ear, were preferred. Sometimes, however, we observe deviations from the habit of corn, developed over hundreds of years of breeding work.
As a result of stress factors, such as frost or hail, anomalies such as tillering or the development of multiple ears often appear. In a sense, corn then resembles its wild ancestor. This can be explained as follows: plants "understand" unfavourable conditions as a threat to producing offspring and activate mechanisms (such as the previously mentioned creation of an additional ear) that are supposed to compensate for developmental disorders and increase the chance of survival of the species.
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Multi-columbar and multi-digitation. What do they consist of?
The aforementioned anomalies, which we are also observing this year on many plantations, are multi-cob and multi-fingeredness. Multi-cobedness involves the development of additional cobs at different heights of the stem in addition to the main cob. This can be one, two or even five more cobs. Multi-fingeredness is a similar condition. It also involves the development of a greater number of cobs, but they all grow from one cob base, creating a characteristic "bouquet".
Very often, additional cobs on corn are formed as a natural response of the plant to problems at the pollination stage. Multi-fingeredness and multi-cob are also the result of stresses that occurred at early stages of plant development, and become visible much later. It should be remembered that corn cob buds are formed already in the 4-6 leaf phase. Plant stress caused by, for example, frost, hail, temperature fluctuations, pest feeding, phytotoxicity of applied herbicides – all this can disrupt apical dominance and stimulate plants to produce additional, "rescue" cobs. The scale of the occurrence of anomalies depends on the sensitivity of a given variety to a given stress factor. The formation of additional cobs can also be the result of too high nitrogen fertilization or inappropriate plant population.
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How does extra corn cobs affect yield?
Of course, in favorable conditions, the plant will be able to pollinate well and fill the second ear with good-sized grains. The condition is a sufficient supply of water and nutrients. If it is met, the additional ear on the plant can have its beneficial effect on the yield of corn for grain.
Unfortunately, additional cobs do not always benefit the crop. They usually appear a little later than the main cob, which may result in a lack of pollen for its pollination, especially in conditions of water shortage and high temperatures. As a result, such a cob is small and poorly seeded.
Building additional cobs on the stem takes away valuable energy, nutrients and water from the plant, the resources of which are often limited at this time due to unfavourable external conditions. This is done at the expense of the main cob, which is less filled and less impressive. Losses on the main cob in such conditions will not be compensated by additional cobs. That is why in maize cultivation we strive to obtain plants with a single, but large, well-developed cob.
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