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  1. MANUAL FOR MAIZE PRODUCTIONByDennis Owusu Boateng (Technical Officer)Bunso Cocoa College (COCOBOD)
  2. Introduction• Maize is a tropical grass that is well adapted to many climates and hence has wide-ranging maturities from 70 days to 210 days.• Maize plants are erect and may grow as tall as 3 m, with little tillering capacity.• The scientific name for maize is Zea mays; it is also commonly known as corn.• White (or waxy) maize is the dominant type of maize grown in Ghana.
  3. • Maize fits well in an upland crop rotation when grown in combination with mungbeans in the early wet season.• Maize has been identified as having a large potential for growth in production and profit for most farmers• Maize is the most widely grown crop in the Americas with 332 million metric tons grown annually in the United States alone (although 40% of the crop - 130 million tons - is used for corn ethanol.• Maize is one of the world’s most important cereal crops after rice and wheat, and because of increasing global demand for stockfeed.• In order to achieve better yields and profitability, farmers may need to adopt other agronomic methods and technology
  4. Morphology of maize• Seedling – The seed of a maize plant is called the kernel and consists of three major parts: the fruit wall, endosperm and embryo. – The kernel is made up of approximately 10% protein, 70% carbohydrate, 2.3% crude fibre and 1.4% ash. – It is also a source of Vitamins A and E, riboflavin and nicotinic acid. – Once the seed absorbs water, germination commences. – The seedling uses seed starch reserves in the endosperm to germinate and a root, called the radicle, sprouts from the kernel. – At the same time or soon after, a shoot emerges at the other end of the kernel and pushes through the soil surface.
  5. – This breaking through the soil surface is called emergence. When the tip of the shoot breaks through the soil surface, elongation of the middle section of the shoot, called the mesocotyl, ceases, and the first leaf, which is termed the plumule, emerges– The primary roots develop at the depth at which the seed is sown.– The first adventitious roots (roots other than those growing from the radicle) start developing from the first node at the mesocotyl, which occurs just below the soil surface.– These adventitious roots continue to develop into a thick web of fibrous roots and are the main anchorage for the maize plant; they also facilitate water and nutrient uptake.
  6. • Maize vegetation morphology – In the early growth stages, the leaves and stem are not readily distinguishable. That is because the growing point (whorl) remains underground until the first five leaves have emerged – series of enlargements that encircle the stem are called nodes. – The space between two nodes is called an internode. – The earliest internodes elongate only slightly, so that the space between internodes is only small. – However, internodes of older plants elongate much more and account for height in maize – Leaves are made up of a blade which extends from the stem at a node.
  7. – The stem has two functions: to support the leaves and flowers and to transport water and nutrients.– Nutrients are carried in vessels, called xylem and phloem, which are connected to the roots.– The xylem transports water and mineral nutrients from the roots and flow one way whiles the phloem flows in both directions and transports organic nutrients in a water based solution– The major function of the leaves is to carry out photosynthesis for grain production.– New leaves arise from the growing point, Depending upon the variety.– Maize farmers should check the crop for symptoms of these problems by observing the colour, growth, and development of the leaves.
  8. • Reproductive structures – Maize is a monoecious plant, which means that each individual plant has both male and female flowers. – Male flowers produce pollen and are on the tassel. – The tassel arises from the growing point of the plant. – When the tassel becomes visible, the innermost leaf in the growing point is the last leaf produced. – The female flowers receive the pollen and are carried in the ears. – The pollinated female flowers develop into the kernels.
  9. • Pollen grain and silk – The tassel has a central spike and several lateral branches, each of which has many flowers. – The flower, called a spikelet, consists of a pair of functional florets with three anthers, which produce pollen, borne on filaments. – The round, slightly sculptured pollen grains begin dropping from the anther two or three days before the silks (styles) on the female flower are ready to receive them. – However, the process continues after female receptivity as pollen is shed from the anthers over a five to eight day period. – The functional ear floret partly encloses the ovule, which contains the embryo sac with the egg inside it. – Pollen from the tassel passes down the silk to fertilise the egg. – The embryo sac eventually becomes a maize seed.
  10. A maize ear with emerging silks A maize tassel during pollination
  11. Growth stages of maize• Flowering – During Pollination and fertilisation there is a high demand for water, and the uptake of N and P is rapid, although K uptake is almost complete. – If maize is flowering during hot, dry weather this places extra stress on the plant’s resources and the silks may wither and burn off before the pollen reaches the ear. – Hence fertilisation does not occur for all kernels and seed set is greatly reduced. – This is commonly referred to as pollen blasting.
  12. • Cob and kernel development – Cobs, husks and shanks are fully developed by day 7 after silking. – The plant is now using significant energy and nutrients to produce kernels on an ear. – Initially the kernels are like small blisters containing a clear fluid; this is referred to as the kernel blister stage. – As the kernels continue to fill, the fluid becomes thicker and whiter in colour. This is called the ‘milk stage’. – Denting of the grain occurs around 20 days after silking; this is an indicator that the embryos are fully developed. – Initially at denting a line can be seen which slowly moves to the tip of the kernel through until physiological maturity. – This line is called the ‘milk line’ and marks the boundary between the liquid (milky) and solid (starchy) areas of the maturing kernels.
  13. • Maturity – Approximately 30 days after silking the plant hasreached the maximum dry weight, a stage called physiological maturity. – This is where a ‘black layer is noticeable at the tip of each kernel, where cells die and block further starch accumulation into the kernel. – At this stage the milk line has completely disappeared. Kernel moisture at physiological maturity is around 30%. – The grain and husks begin losing moisture while healthy stalks remain green. – Eventually the leaves will dry off. – Harvesting can commence when grain moisture is below 20%. – The grain is dried down to 14% for delivery to storage or market.
  14. Maize cob cross section showing milk line at mid development
  15. Varieties• Many forms of maize are used for food, sometimes classified as various subspecies related to the amount of starch each had: – Flour corn — Zea mays var. amylacea – Popcorn — Zea mays var. everta – Dent corn — Zea mays var. indentata – Flint corn — Zea mays var. indurata – Sweet corn — Zea mays var. saccharata and Zea mays var. rugosa – Waxy corn — Zea mays var. ceratina – Amylomaize — Z

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