Maize: Short Cycle, but Huge Potential
Maize: Short Cycle, but Huge Potential
As a plant of multiple uses (grains, corn-cob-mix, whole plant silage, biogas, first/second generation biofuel, etc), maize is characterised by its enourmous potential, the result of thousands of years of selection – first done by farmers and later on, by specialised companies. The reason why seed production companies in France invest considerable amounts in maize breeding is the plant’s high potential for genetic progress, enabled by its great natural genetic variability, which is an important source of heterosis during hybrid development. Farmers also play a part in this process through their activities – whether past or present. This is first of all because half of the progress made in agriculture comes from the growing practices implemented by the farmers themselves, as well as from their variety choices. Thus paradoxically, this hybrid plant that needs to be re-planted every year depends, in the first place, on the farmer’s ability to best combine genotype and farm specifics. Moreover, the farmers’ interest in new developments spurs the production of genetic material. For the past fifteen years, the lead time (from the development of lines and hybrids to the market) has shortened considerably. This has helped to accelerate maize genetic progress and has led to yield increases throughout the world. To-date, in countries with reasonable growing conditions, national yields reach as much as 10 tons per hectare. In 2010, the famous NCGA (National Corn Growers Association) yield contest – the NCYC (National Corn Yield Contest) reported yields of 478 bushels/acre (32.1 tons/hectare) for irrigated maize and of 318 bushels/acre (21,4 tons/hectare) for non-irrigated maize. Also, since biodiversity is a common topic nowadays, it is worth noting that a plot planted to a single cultivar presents more genetic variation than what the 19th-century native maize populations (that were grown before the development of hybrids) did in a single production region.
The maize plant has an intense, but short growth cycle. The development and growth of its various morphological and biochemical components go hand in hand with the progress of the various criteria related to quality, yield, earliness, and energy content.
A High-production System
The potential of maize, as enabled by genetic progress, is first of all due to the plant’s specific characteristics, as well as to its biochemical system, which is particularly efficient.
As all plants in the C4 category (such as sorghum and sugar cane), maize has a highly-efficient biochemical system, which enables it to harness solar radiation, absorb carbon, and produce dry matter. Maize can remain functional at higher summer temperatures than most other C3 plants (up to 40°C) and can continue to function at night, as well. The maize growth cycle consists of two successive stages.
The first stage lasts from planting to flowering/pollination (consisting in silking and pollen emission). It is characterized by the development of the plant’s components that capture solar radiation, water, and minerals (the leaves and roots) and by the development of the male and female flowers (the tassels and the ears, respectively). The second stage consists in grain filling, followed by the grain growth and ending with the harvest. One should also remember that the plant’s growth rate, its morphology, size, and yield components (one ear per plant) are such that they allow little room for correcting the effects of possible adverse factors. The key to a successful corn crop is planting. Its timing and the crop establishment conditions constitute decisive criteria for the crop outcome, but also represent the crop’s core production and operating costs: hybrid choice, applying “slow-release” organic fertilizers, planting density, basic weed control, and protection against soil-borne pests. One may say that maize yield is what is left after the weather/growing/agronomic hazards are “subtracted” from its initial genetic potential. Thus as soon as the planting is over, producers should seek to limit the impact of biotic and abiotic stressors on the crop.