Everything you need to learn about maize cultivation, harvest and growth.
Introduction to Maize:
It is generally admitted that maize is a native of the Americas and the species probably originated in the tropical South America. Although there is difference of opinion as to the date of introduction of maize into India, recent evidences available indicate that its introduction took place before the time of Columbus.
Maize is considered to be one of the most important cereals of the world. Taking its world average-yield into consideration, it is the highest yielder among the cereals. In regard to acreage and production, India ranks fifth and eleventh respectively among the maize- growing countries of the world. The other important maize-growing countries are USA, Brazil, China, Mexico, USSR, Argentina, South Africa and Rumania.
Area and production of maize in India, where it is regarded as an important cereal, have increased during the last twenty years or more and are around 6 million hectares and 7 million tonnes respectively. Among the states, only five, namely, UP, Bihar, MP, Rajasthan and Punjab together account for more than three-fourths of the total area and production of the crop in the country.
Maize (Zea mays L.) belongs to the family Gramineae. The plant is a tall annual monoecious herb with a stout stem, which is solid and jointed at the nodes. Leaves are alternate, distichous, simple, linear-lanceolate and acuminate; margin entire and ciliate; sheaths overlapping. The male inflorescence is a terminal panicle and the pistillate, an axillary spadix.
The panicle has a central axis with several rows of paired spikelets, and a few lateral branches with only 2 rows of paired spikelets. One of each pair of spikelets has a pedicel, while the other is sessile. Each spikelet consists of 2 flowers subtended at the base by a pair of glumes.
Glumes almost equal in size, densely covered with minute hairs, the outer or lower one more or less overlapping the other. Each flower has 2 opposite bracts, the lemma and the palea. Two lodicules are present at the base of the lemma. Stamens3 are filament long, with 2-lobed versatile another.
The spadices or cobs are borne in the axils of the lower leaves and are enclosed by a number of large bracts or spathes. The axis of the cob is thick and spongy. Spikelets arranged on the cob in vertical rows. Rows of female spikelets present all-round the axis. Each female spikelet is 2-flowered and has 2 glumes at the base; the lower flower barren and the upper fertile.
Like the male flower, the female one has a lemma and a palea. The sterile flower has 2 lodicules, 3 rudimentary stamens and a rudimentary carpel. The fertile flower has a well-developed carpel, but the lodicules and staminodes are not recognizable. Ovary 1-celled with 1 campylotropous ovule, style is filiform with long hairy stigma. Caryopsis is subglobose, hard and shining.
Climate and Soil Required for Maize Cultivation:
Although maize is essentially a crop of the warm weather, it is cultivated under very different climatic conditions in different parts of the world. It is grown at various altitudes, from the sea level up to 2,500 metres. The crop can be grown throughout the year, in areas where the night temperature does not fall below 15°C.
It cannot withstand frost. So far as India is concerned, its cultivation extends from the hot and dry plains of Rajasthan and Gujarat to the wet hills of Assam and West Bengal, where the annual rainfall may be more than 400 cm. Maize can be grown without irrigation if 60 cm of well-distributed rainfall is received in the area in question.
Fertile, deep and well-drained soil is ideally suited for maize cultivation. The crop can, however, be grown on soils, ranging from deep heavy clays to light sandy ones. In hilly tracts, it is commonly raised in coarse gravel soils. The pH of the soil should be within the range, from 7.5 to 8.5. As the crop is badly affected by flood and salinity, proper drainage is essential. Soils with adequate water-holding capacity and good drainage are quite suitable for maize.
Rotation of Maize Crops:
Maize is a short-duration crop and as such it can be fitted into various crop rotations. In northern India, it is commonly rotated with wheat, potato, barley, etc., in a one-year rotation under irrigated conditions. It is also included in a two-year rotation with cotton and sugarcane. Although maize is usually grown as a pure crop, mung, arhar or beans and certain quick-growing vegetables, like pumpkins and gourds, are sometimes taken as subsidiary crops.
Cultivation of Maize:
A fine, compact seedbed is very good for maize; Different types of tillage are required for different types of soil. The primary objective in preparation of seedbed is to obtain a good tilth. Adequate drainage is essential for kharif cultivation. Heavy manuring is necessary for obtaining high yields of the crop, and hence before sowing, 25 to 30 cartloads of farmyard manure or compost should be applied per hectare, and thoroughly mixed with the soil.
Season and Sowing:
There are three distinct seasons for cultivation of maize, of which the main one is kharif; the other two are Rabi in Peninsular India and Bihar, and spring in northern India. Higher yields have been obtained from Rabi and spring crops, primarily because of better water management and lower incidence of diseases and insect pests.
Maize is sown in rows running 60-75 cm apart, the plants in each row being spaced at 20-25 cm. sowing in rows is generally done with a drill and seeds are dropped behind the plough. Broadcasting is still in vogue in several parts of the country. This method of sowing is adopted particularly under rain-fed conditions and also for raising the crop for purposes of fodder. The quantity of seed required for the grain crop is 17-20 kg per hectare and that for the fodder crop 35-40 kg.
Manuring and Fertilization:
Maize is a heavy feeder and as such a heavily manured field is necessary for good yields. If taken after potato, it requires little manuring, because there is sufficient residual effect of heavy doses of cow dung and castor cake applied to the former crop. Likewise, little manuring of maize is necessary if it follows pulse crops.
In the case of other rotations, heavy doses of manures and fertilizers are required for maize. About 70-80 kg of nitrogen per hectare should be applied to Indian varieties of maize. For hybrid and composite varieties of maize, 110-120 kg of nitrogen, 60 kg of phosphorus and 40 kg of potassium per hectare are necessary, the exact doses of the second and the third elements being determined on the basis of the results of soil analysis.
The total quantity of nitrogen is to be applied in three equal doses, the first one before sowing along with the total quantities of phosphorus and potassium, and the other two at the knee- high and the tasselling stages of the plants.
Irrigation and Weeding:
Irrigation is not required in regions where the rainfall is about 60 cm and the same is well-distributed during the growing season. If the soil-moisture is inadequate during the time of grain filling, which is the most susceptible stage, the crop should be irrigated. The number of irrigations in the case of the spring and the Rabi crops, which are entirely grown under irrigation, may vary from 5-10.
Weeding is very necessary particularly during the initial stage, when the growth of plants is suppressed by weeds. First weeding is generally undertaken when the seedlings are 2 weeks old. Weeding between the rows of the crop may be done by bullock- or tractor-drawn implements, whereas within the rows, hand-weeding is done. Two or three weeding may be done, after which the crop is earthed up. Weedicides may also be used for weed control. Spraying Simazine or Atrazine before germination of the crop is effective.
It is a very important operation in connection with the cultivation of maize and it consists of placing earth near the roots of plants. The object is to provide anchorage to the lower whorls of adventitious roots above the soil to enable them to function as absorbing roots and also to prevent lodging of plants. Besides, during the rains, it facilitates draining away of water through the channels made in this way.
Harvesting and Yield:
The grain crop is harvested when the moisture content of the grain is 20 per cent or less. Ears are collected from the standing crop and dried in the sun before shelling. So far as the late-sown crop is concerned, whole plants are harvested and piled up and ears are removed later.
The fodder maize is to be harvested in the milk to early-dough stage of the grain. While shelling of grains may be done by hand or by beating with sticks, as is common in northern India, it may be conveniently and efficiently done by power- and hand-operated maize shellers. These shellers are cheap and are indigenously available.
Grain yield of maize varies considerably. It depends particularly on the variety, the amount of fertilizer applied, the pattern of rainfall, etc. The crop raised under irrigated conditions and with the recommended cultural practices yields, on an average, 4 tonnes of grain per hectare in the Indo-Gangetic plains. In Peninsular India and also at higher altitudes, an average yield of 5-7 tonnes per hectare is commonly obtained.
Uses of Maize Crop:
A large portion of the produce in the country is consumed directly as food in different forms, particularly as chapatis. Roasted ears, pop-corn and porridge are some of the other forms in which maize is consumed. There has, of late, been an increase in its use in animal feed and starch industry. Green maize plants are also used as a succulent fodder during spring and monsoon.
Varieties of Maize Crop:
Maize varieties may be grouped into dent, flint, floury, waxy, amylose, pop and sweet, on the basis of endosperm type. In India, cream-yellow to orange coloured, early-maturing flint varieties are commonly grown.
On the basis of maturity, maize varieties can be grouped into three classes, very early, medium-early and late. Among the superior germplasm in Indian varieties, mention may be made of Jaunpur, Rudrapur, Basi, Malan, H M 1 etc.
As a result of the breeding work, which is being carried out in India, many high- yielding hybrids and composites have been developed during the last thirty years or so. The seeds of composites, unlike those of hybrids, can be saved by cultivators for their own use in the following year.
Since rapid and large-scale production of seeds of composites is easy, the difficulties faced with in connection with availability of quality seeds of high- yielding varieties have been removed considerably. An isolation distance of 300 m is to be maintained between seed – fields of different composites.
Besides high-yielding maize varieties, a few nutritionally superior composites, like Shakti, Rattan and Protina, were also developed and released some years ago. They have the Opaque-2 gene and are rich in essential amino-acids, particularly in lysine and tryptophan. The genetic make-up of these composites makes it necessary to cultivate them in isolation from normal maize in order to eliminate chances of contamination.
The hybrids and composites, which are now on the recommended lists for kharif cultivation in different states, particularly in the eastern, central and north-eastern parts of the country, are indicated below:
For rabi cultivation, the recommended hybrids/composites are Hi-Starch, Ganga 5 and Deccan 103 for Orissa and West Bengal, Ganga 5, Deccan and Deccan 103 for MP, Hi- Starch, Deccan 103, Ganga 5 and Ganga 9 for UP, and Hi-Starch, Lakshmi, Hemant, Deccan 103, Ganga 5, Ganga 9 and Diara MFS 4 for Bihar.
Diseases of Maize Crop:
Maize is attacked by quite a few diseases, the important among them are:
(i) Brown spot caused by Physoderma maydis, which can be controlled by practicing crop rotation and sanitation.
(ii) Head smut caused Sphacelotheca reiliana, which can be controlled by practising crop rotation and sanitation, and also by roguing out and destroying diseased plants.
(iii) Smut caused by Ustilago zeae, which can be controlled by growing resistant varieties and by practising crop rotation and sanitation.
(iv) Downy mildew and brown stripe caused by Sclerophthora rayssiae Var. zeae, S. philippinensis and S. sacchari, which can be controlled by spraying with Bordeaux mixture or any other copper fungicide, such as Fytolan, Perenox etc., roguing out diseased plants, and by growing resistant varieties.
(v) Leaf rust caused by Puccinia sorghi, which can be controlled by growing resistant varieties.
(vi) Bacterial stalk rot caused by Erwinia dissplvens, E. carotovora f. sp. zeae. Pseudomonas lapsa, which can be controlled by roguing out affected plants, by spraying Streptomycin and by growing resistant varieties.
(vii) Leaf spot caused by Cercospora sorghi, for which no control measure is known.
(viii) Charcoal rot caused by Macrophomina phaseoli, which can be controlled by avoiding water stress after the flowering of the crop.
(ix) Mossaic caused by virus, which can be controlled by growing resistant varieties.
(x) Turcicum leaf blight caused by Trichometasphaeria turcica, which can be controlled by spraying 0.2% Zineb, Maneb or 0.3% fixed copper and by growing resistant varieties.
Insect Pests of Maize:
The important insect pests are:
(i) Stem borers (Chilo zonellus and Sesamia inferrens), which can be controlled by ploughing and destroying all the stubble after harvest, by applying 4% Endosulfan or Carbaryl granules or spraying 0.05% Lindane.
(ii) Hairy caterpillar (Amsacta moorei and A. albistriga), which can be controlled by dusting 10% BHC.
(iii) Aphid (Rhopalosiphum maidis), which can be controlled by spraying 0.02% Phosphamidon, 0.04% Diazinon or Dimethoate.
(iv) Phadka grass hopper (Hieroglyphus nigrorepletus), which can be controlled by destroying eggs in the soil by deep ploughing soon after harvest and by dusting hoppers and adults with 5% and 10% BHC, respectively.
(v) Shoot fly (Atherigona spp.), which can be controlled by applying 10% Phorate or 5% Disulfotan granules in seed furrows at the time of sowing.
(vi) Termites (Odontotermes obesus and Microtermes obesi), which can be controlled by mixing 5% Aldrin or Chlordane dust with the soil at the time of sowing or during preparation of the land.