Classification Of Field Crops

It is well known that there are more than 600 cultivated plant species, from which there are about 100- 200 species play important role in the world trade. However, only fifteen plant species represent the most important economic crops. Therefore, these crop species must be classified or grouped in a convenient way to facilitate communication, dissemination and retrieval of scientific information as well as promotes the conservation, and improvement of certain plants. Generally, classification of these species is important for these reasons:

1. To get acquainted with crops.

2. To understand the requirement of soil & water different crops.

3. To know adaptability of crops.

4. To know the growing habit of crops.

5. To understand climatic requirement of different crops.

6. To know the economic produce of the crop plant & its use.

7. To know the growing season of the crop

8. Overall to know the actual condition required to the cultivation of plant.

The grown field crops are classified according to different stand points as follows:

1. Botanical classification.
2. Agronomic classification
3. Special- purpose classification.
4. Classification according to life span.
5. Classification according to root depth.
6. Classification according to growth habit.
7. Classification according to Co2 fixation.
8. Classification according to mode of pollinations.

1- Botanical Classification

Botanical classification is based upon similarity of plant parts and flower structure. This is the most important way of classification because it determines to what extent the plants are relatives. Field crops belong to the “spermatophyte”, or seed plant, division of “plant kingdom”, which includes plants reproduced by seeds. Within this division, the common crop plants belong to the subdivision of “Angiosperm”, which are characterized by producing seeds with coats (covered seed). The “angiosperm”, are then divided into two classes, namely, monocotyledons and the dicotyledons. All the grasses, which include the cereals and sugar cane are monocotyledons. The legumes and other plants except the grasses are classified as dicotyledons. Each of these two classes is still further divided into orders, familes, genera, species and varieties.
For example, maize crop (corn) which is monocotyledons belongs to the order “herbaceous”; family “Gramineae”; genus Zea; species mays; varieties; S.C. 10 as follows:

Plant Kingdom

Division–> Spermatophyte

Subdivision–> Angiosperms

Class–> monocotyledons

Order–> Herbaceous

Family–> Gramineae

Genus–> Zea

Species–> mays

Variety–> S.C. 10

1- Monocotyledons:

– Gramineae: includes the following crops: wheat, barley, rice, maize, oat, sugar cane, sorghum, rye grass, and sudan grass.

–Liliaceae: includes onion and garlic.

2- Dicotyledons:

– Leguminosae: includes: field bean, lupine, check pea, lentil, fenugreek, Egyptian clover, alfalfa, soybean, peanut, grass pea, caster bean, red clover and white clover.

– Malvaceae: includes: cotton.

– Linaceae: includes: flax.

– Solanceae: includes: potato, tomato, and tobacco.

– Pedaliaceae: includes: sesame.

– Composite: includes: sunflower, and safflower.

It is well known that the most important field crop families belong to two botanical families, the grass family (gramineae) and the legume family (Legumioseae). Therefore, we have to get an idea about the characteristics of both families.

Characteristics of grass family:

This family includes about three fourths of the cultivated forage crops and all the cereals. They have the following characters:

They are winter annuals or perennials.
They are almost herbaceous plants.
Stems are usually hollow, cylindrical and made up of nodes and internodes.
Leaves are alternative with parallel veins. The basal portions of the leaf sheath, encloses the stem, the sheath being open on the side opposite the blade. Where the blade of the leaf joins the sheath, there is usually found a peculiar appendage known as the “ligule”.
The roots are fibrous and new roots are formed each year.
The flowers are perfect and collected in inflorescence at the top of plant.
The grain may be free (wheat) or enclosed (oats).

Characteristics of legume family:

It ranks next in importance to grass family.
Legumes may be annual, biennial, or perennial.
The leaves are alternate compound, stipulate, with netted veins.
The flowers are buttery- like.
The fruit in a pod that contains one to several seeds. The seeds are usually without an endosperm, the two cotyledons being thick and full of stored food.
Legumes have relatively large taproot. The roots bear enlargements called “nodules” caused by the activities of a bacterium Rhizobium, which has the ability to fix atmospheric nitrogen in their bodies and eventually in the plant residues.

2- Agronomic classification

Field crops can be classified according to their economic importance as follows:

1- Cereal or grain crops: Cereals are grasses grown for their edible seeds such as wheat, oats, barley, rye, rice, maize, and grain sorghum,

2- Legumes of seeds such as faba bean, pea nuts, fenugreek, lupine, cowpea, soybean, chick pea, and lentil.

3- Sugar crops: they include sugar beet and sugar cane.

4- Oil crops: they include: flax, soybean, peanut, sunflower, safflower, sesame, caster bean and rape.

5- Fiber crops: they include cotton. Flax, jute, sisal, and ramie.

6- Fodder crops: they include alfalfa, Egyptian clover, sorghum, Suddan grass, grass pea, lablab, Napier grass, millet, white clover, and red clover.

7- Rubber crops: including para rubber, Castilla rubber, and guayule.

8- Tuber crops: such as potatoes and Jerusalem artichoke.

9- Root crops: such as sweet potatoes and sugar beet.

10- Medical plants: such as caster bean and others.

11- Stimulates such as tobacco, tea and coffee.

3- Special- purpose classification

These classifications are used to refer to plants having special advantages to the farmer himself in relation to his farming practices, and include

1- Catch or emergency crops: These crops are used to substitute crops that have failed on account of unfavourable conditions. They are usually quick-growth crops, such as rye, millet and clover. In Egypt. Clover can be grown and one cut can be obtained before planting cotton crop.

2- Cash crop: any short maturing crop which is grown to generate income while the main crop is still in its vegetative stage of growth; any crop grown to generate cash rather than for subsistence. Some crops may be cash crops one year but not the next, or for one farmer but not another.

3- Cover crops: these crops are planted to provide a cover for the soil and to prevent erosion such as clover and rye.

4- Green manure crops: these crops are turned under while still green in order to improve the soil properties and increase organic matter content. Several field crops can be used such as Egyptian clover, lupine and cowpea.

5- Companion crops: in this case a crop can be intercropped with another one and each crop is harvested separately. For example, onion and garlic can be intercropped with cotton crop, or soybean with maize.

6- Silage crops: these crops are preserved in a succulent condition by partial fermentation in a tight receptacle. They include corn, sorghum, forage grasses and legumes.

4- Classification according to life span.

All field crops can be divided into three categories according to the length of their life cycle as follows:

1- Annual crops: plants of this category complete their entire life cycle from seed to seed in a single growing season and then die. Most field crops are considered annual crops such as wheat, barely, rice, maize, sorghum, faba bean, lentil, check pea, lupine, flax, soybean, sesame, sunflower, safflower, and others.

2- Biennial crops: these plants complete their life cycle in two seasons. Vegetative growth occurs during the first season resulting in a rosette form but plants don’t start flowering (blooming). In the second season, the green plants give flowers and seeds. The crops of this category are onion, sweet clover, and sugar beet. If you expose sugar beet plants, grown in the first year to low temperature they can start blooming and flowering and behaved as annual crops.

3- Perennial crops: these crops are grown in the soil for more than two years (they can persist for more than two years). They may either produce seed or not every year. In other words, they have and indefinite life period. They do not die after reproduction but continue to grow indefinitely from year to year. Sugar cane, white clover, and alfalfa are examples of perennial crops.

5- Classification according to root depth

It is clear that the root system of field crops differ in structure, function and extent. Therefore, field crops can be classified according to the depth of their roots as follows: 1- Hallow root crops: the root system of these crops extends in the soil to a depth of one meter such as wheat, barley and rye. 2- Intermediate crops: the depth of the root system of these crops ranges from 1- 1.5 meter in the case of faba bean and sugar beet. 3- Deep root crops: the root system of these plants extends in the soil to a depth more than 1.5 meter as in alfalafa.

6- Classification according to growth habit

Determining the best time of planting of any field crop is a very important task. That is because planting date must be in suitable time which ensure the best environmental conditions throughout the growing season of the crop. Crops need optimum levels of light, temperature, moisture and other environmental conditions to grow well and produce the highest productivity. Therefore, when field crops are classified according to growing season this means that the environmental requirements of such crop are prevail in such season. Accordingly, field crops can be classified as follows:

1. The Kharif Season: Crops are sown at the beginning of south-west monsoon and harvested at the end of the south-west monsoon.

Sowing Season: May to July.

Harvesting Season: September to October.

Important Crops: Jowar, Bajra, Rice, Maize, Cotton, Groundnut, Jute, Hemp, Tobacco etc.

2. The Rabi Season: Crops need cool climate during growth period but warm climate during the germination of seed and maturation.

Sowing Season: October to December

Harvesting Season: February to April

Important Crops: Wheat, Barley, Gram, Linseed, Mustard, Masoor & Peas.

3. The Zaid Season: These Crops are raised throughout the year due to artificial irrigation.

1. Zaid Rabi Crops:

Sowing Season: August to September

Harvesting Season: December-January

Important Crops: Rice, Jowar, Rapeseed, Cotton, Oilseeds.

2. Zaid Rabi Crops:

Sowing Season: February to March.

Harvesting Season: April-May.

Important Crops: Watermelon, Tori, Cucumber & other vegetables.

Cereal Crops

Rice, Wheat and millets are consumed as important staple food all over the world. Cereals provide essential carbohydrates which are important source of energy for working. Cereals are monocotyledonous plants and are grown on large scale by Indian farmers. The economy of huge number of Indian farmers is largely dependent on cereals.

Pulse Crops

Pulse crops are legumes. The word legume is derived from the Latin word ‘legere’, with means ‘to gather’. Pulses are important in crop rotations and crop mixtures practiced by farmers, as they help in maintaining the soil fertility. Pulses are rich in protein and they meet the major share of the protein requirements of the predominantly vegetarian population of India.

Oil seed crops

Importance of oilseeds crop in Indian farming:-

• They can be grown on all kinds of soil.

• Important constituent of the crop rotation with millets and pulses.

• Valuable cash crops and bring ready cash to the farmers.

• They are a source of foreign exchange.

• They provide raw material for many industries e.g. paints, varnishes,

• Soaps, lubricating oils etc.

• They contribute vegetable oils and fats to Indian diet.

• The edible oil cakes provide concentrates for the cattle.

• The non-edible oil cakes are used as manures and some oil cakes like

Cash, fiber and spice corps

Sugarcane is the important cash crop grown in India. Sugarcane is cultivated in UP, Bihar, Maharashtra, Karnataka and AP. on large scale. Sugarcane is the most important source of sugar and jaggery. The sugar factories have transformed the total scenario in the sugarcane tracts. Cotton is the most extensively grown commercial crop and the most important of all fibre crops of the world. Likewise turmeric is an important spice crop grown on commercial scale as a source of farm income. It is cultivated in the states of AP, Tamilnadu, Maharashtra, Orissa, Kerala and Assam.

7- Classification according to Co2 fixation

C3 Plants
C4 Plants
Cam Plants

8- Classification according to mode of pollination

1. Naturally self-pollinated crops: – the predominant mode of pollination in these plants is selfpollination in which both pollen and embryo sac are produced in the same floral structure or in different flowers but within the same plant. Examples: rice, most pulses, okra, tobacco, tomato.

2. Naturally cross-pollinated crops: pollen transfer in these plants is from the anther of one flower to the stigma of another flower in a separate plant, although self-pollination may reach 5 percent or more. Examples: corn and many grasses, avocado, grape, mango, many plants with unisexual or imperfect flowers.

3. Both self- and cross-pollinated crops: these plants are largely self-pollinated but varying amounts of cross-pollination occur. Examples: cotton and sorghum.

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