Introduction

Botanical Description

• Scientific Name: Triticum aestivum (common wheat)
• Family: Poaceae (Gramineae)
• Chromosome Number: Hexaploid (2n = 6x = 42) for common wheat
• Growth Habit: Annual grass
• Root System: Fibrous
• Stem: Hollow, cylindrical, and jointed (tillering capacity varies by variety)
• Leaves: Long, narrow, parallel-veined
• Flowers: Inflorescence is a spike with multiple florets
• Grain: Caryopsis (rich in starch, protein, and minerals)

Types of Wheat

Based on Growing Conditions

1. Winter Wheat: Requires vernalization (cold period) to flower and is grown in temperate regions.
2. Spring Wheat: Grown in regions with shorter growing seasons, does not require vernalization.

Based on End Use

1. Bread Wheat (Triticum aestivum): Used for making chapati, bread, and biscuits.
2. Durum Wheat (Triticum durum): Used for making pasta, macaroni, and semolina.
3. Emmer Wheat (Triticum dicoccum): A traditional wheat type used in some regions of India.

Chemical Composition of Wheat Grain

Wheat grains are rich in essential nutrients, including carbohydrates, proteins, fats, and minerals:

• Starch: 60-68%
• Protein: 8%
• Fat: 1.5-2%
• Cellulose: 2-2.5%
• Minerals: 1.5-2%

Origin of Wheat

Wheat has played a crucial role in the development of human civilization since ancient times. The exact origin of cultivated wheat is unknown, but it is believed to have originated in Southwest Asia before spreading to European countries. Wheat cultivation was known along the Atlantic Coast in the 17th century and was introduced to India by the Aryans.

Important Species of Wheat

The most commonly cultivated wheat species include:

• Triticum aestivum (Common Bread Wheat) – Hexaploid (2n = 42) The most widely grown wheat species, covering 85% of the total wheat area. Adapted to diverse climatic conditions, from sea level to 3658 meters in the Himalayas.
• Triticum durum (Macaroni or Suzi Wheat) – Tetraploid (4n = 28) The second most important wheat species, occupying 14% of the total wheat area. Mainly cultivated in Central and Southern India. Previously grown in Punjab and West Bengal, but now replaced by T. aestivum.
• Triticum sphaerococcum (Indian Dwarf Wheat) – Hexaploid (2n = 42) Has gone out of cultivation due to low productivity and high susceptibility to diseases.
• Triticum dicoccum (Emmer Wheat) Grown on a limited scale in Gujarat, Maharashtra, Andhra Pradesh, and Tamil Nadu. Locally known as Popatya (Gujarat), Khapli (Maharashtra), Ravva Godhumalu (A.P.), and Samba (Tamil Nadu). Preferred for making granular preparations like Upma.

Global Wheat Production and Area India ranks second among wheat-growing nations after China. Other major wheat-producing countries include the USA, USSR, Canada, and Australia.

Climate Requirements for Wheat Cultivation Wheat is primarily a winter crop and requires specific climatic conditions for optimal growth:

• Temperature
  • Germination: 2.2°C to 26.4°C
  • Optimum growth: 21.1°C
• Rainfall
  • Moderate soil moisture with low humidity is essential for early ripening and rust prevention.
  • Annual rainfall requirement: 750-1000 mm (optimal)
  • Grows in areas with annual rainfall ranging from 125-1125 mm in India.
  • Grown at high altitudes, up to 2000-3000 meters in Kashmir.
• Growing Period
  • 180 days in North Indian hills.
  • 100 days in Peninsular India.
• Tolerance
  • Can withstand severe cold and snow and resumes growth with warm weather.
  • Best wheat is produced under cool, moist weather during the growing phase, followed by dry, warm weather during grain ripening.

Soil Requirements

Wheat grows well in different types of soil, but it performs best in:

• Well-drained loam and clay loam soils.
• Alluvial soils of the Gangetic plains.
• Black cotton soils of Central India.

Wheat Growing Seasons in India

• Wheat is a Rabi (winter) crop in India.
• High temperatures at the beginning and end of the season limit its cultivation.
• High temperatures in September prevent good tillering and promote diseases like root rot and seedling blight.
• Hot summers during the grain ripening period lead to poor-quality wheat.
• In Telangana and Rayalaseema, wheat is sown in mid-November and harvested by late February to early March.

Field Preparation for Wheat Cultivation

A well-prepared seedbed ensures good and uniform germination:

• For dryland wheat (alluvial soils):
  • 3-4 ploughings in summer.
  • Repeated harrowing during the rainy season.
  • 3-4 cultivator workings before sowing.
• For black cotton soils:
  • Blade harrow instead of plough.
  • 1-3 ploughings with an iron plough before using the blade harrow.
• For irrigated wheat:
  • Pre-sowing irrigation.
  • Fewer ploughings required.
• For areas with termite problems:
  • Application of Aldrin or BHC 10% @ 25 kg/ha.

Methods of Wheat Sowing

1. Broadcasting – Seeds are scattered manually, followed by ploughing/harrowing. Cheap but inefficient and requires a high seed rate.
2. Sowing behind plough by hand – Common in irrigated lands.
3. Sowing with seed drill – Used in rainfed (barani) lands. Ensures uniform depth and spacing.
4. Dibbling – Manual placement of 2-3 seeds at 4-6 cm depth and 22.5 cm row spacing. Time-consuming but good for pure seed multiplication.
5. Transplanting – Raising seedlings in nurseries and transplanting 3-4-week-old seedlings. Labor-intensive but useful for late sowing.

Optimum Sowing Time

• First fortnight of November (ideal time).
• End of October for early sowing with varieties like Kalyan Sona.

SEED RATE

The seed rate is crucial for achieving optimal plant population and ensuring good crop establishment. The required seed rate varies based on the variety and sowing conditions:

• Bold-seeded & shy tillering varieties (e.g., Sonalika) require a higher seed rate of 100-125 kg/ha to compensate for lower tillering capacity.
• Medium-sized grain varieties (e.g., Kalyan Sona) need a moderate seed rate of 75-100 kg/ha.
• Late-sown crops require a higher seed rate of 125-140 kg/ha to compensate for shorter vegetative growth and to achieve an adequate plant population.
• Rainfed conditions: A seed rate of 100 kg/ha is recommended to ensure uniform plant density despite limited moisture availability.

In Andhra Pradesh (AP), wheat does not tiller profusely, so farmers should use the recommended seed rate to ensure proper yield.

SEED TREATMENT

Seed treatment is essential to protect the crop from seed- and soil-borne diseases. The recommended treatment includes:

• Thiram @ 0.2% (or Captan @ 1:300 parts by weight of seed) to control seedling blight.
• The application rate is 10 g per 3 kg of wheat seed, ensuring uniform coverage to prevent early-stage infections.

INTERCULTIVATION

Intercultural operations help in weed control and aeration of soil for better root growth:

• Weed control should be done in the early growth stages to minimize competition for nutrients and moisture.
• Light earthing up helps in root establishment.
• A light plough or Danthi can be used for inter-row cultivation to control weeds and improve soil aeration.

FERTILIZATION

Nutrient management is vital for maximizing wheat yield. The recommendations vary based on irrigation conditions:

For Rainfed Wheat:

• Farmers often do not fertilize rainfed wheat due to economic constraints.
• 2-3 tonnes of FYM/ha should be applied 5-6 weeks before sowing to improve soil fertility.
• 40 kg N + 20 kg P₂O₅ per ha should be applied 10 cm deep (3-4 cm below the seed) before sowing to enhance yield.

For Irrigated Wheat:

• 120-60-40 kg NPK/ha is recommended.
• Application method:
  • Full dose of P & K and half of N should be applied 5 cm below the seed at sowing.
  • The remaining half of N should be applied at CRI stage (21 DAS).

For Zinc Deficiency:

• 25-50 kg ZnSO₄/ha should be applied as a basal dose to prevent micronutrient deficiencies.

STAGES OF CROP GROWTH

1. Crown Root Initiation (CRI) Stage (20–25 DAS)

• Most critical stage for irrigation
• Roots start developing and absorbing nutrients
• Moisture stress at this stage can reduce yield by 25–30% Irrigation Requirement: First irrigation (4–5 cm water) is essential.

2. Tillering Stage (40–45 DAS)

• Active tiller formation occurs, increasing the number of productive shoots.
• Water stress can lead to fewer tillers and reduced yield.
• Irrigation Requirement: Second irrigation is needed to support tiller growth.

3. Jointing/Stem Elongation Stage (60–65 DAS)

• Rapid stem growth and internode elongation occur.
• Water stress reduces stem height and affects nutrient uptake.
• Irrigation Requirement: Third irrigation is applied.

4. Booting Stage (80–85 DAS)

• The wheat ear (spike) develops inside the flag leaf sheath.
• Water shortage can reduce spike size and grain number.
• Irrigation Requirement: Fourth irrigation is given.

5. Heading & Flowering Stage (90–95 DAS)

• Most sensitive stage for irrigation after CRI.
• Pollination and grain setting occur, so water stress reduces grain formation.
• Irrigation Requirement: Fifth irrigation is necessary to ensure proper grain setting.

6. Milk Stage (105–110 DAS)

• Grains are filled with a milky liquid containing starch.
• Moisture stress leads to shriveled grains and lower yield.
• Irrigation Requirement: Sixth irrigation is applied.

7. Dough Stage (120–125 DAS) (Optional)

• Grains harden as they mature.
• Irrigation is needed only if dry conditions persist.
• Irrigation Requirement: Seventh irrigation (if necessary).

WEED CONTROL

Weeds compete for nutrients and moisture, reducing yield. Control measures include:

For Broad-Leaved Weeds:

• 2,4-D @ 0.4 kg a.i./ha mixed in 750 liters of water.
• Applied 4-6 weeks after sowing.

For Graminaceous Weeds (Wild Oats, Phalaris minor):

• Pre-emergence application of Tribunal @ 1.5 kg a.i./ha in 750 liters of water.
• Alternatively, a mixture of 2,4-D ethyl ester with isoproturon/tribunal can be used.

IRRIGATION

Irrigation is essential for proper growth and yield formation. Total water requirement is 300-400 mm.

Sowing Techniques Based on Soil Type:

• Light soils: Pre-sowing irrigation is essential for uniform germination.
• Heavy soils: Sowing in dry soil followed by irrigation is preferred.

Critical Irrigation Stages:

1. CRI Stage (15-21 DAS)
2. Jointing Stage (45 DAS)
3. Heading Stage (65 DAS)
4. Dough Stage (85-90 DAS)

Limited Water Supply Strategies:

• If only one irrigation is available → Apply at CRI Stage.
• If two irrigations are available → Apply at CRI + Dough Stage.
• If three irrigations are available → Apply at CRI + Heading + Dough Stage.

The timing of irrigation is more important than the number of irrigations.

Soil-Specific Irrigation Strategy:

• Light soils → Frequent irrigation is required.
• Heavy soils (Black soils) → Fewer irrigations are needed due to high moisture storage capacity.

Storage of Wheat

• The grain should be thoroughly dried before storage, as its storage life is closely related to moisture content.
• Grains with less than 10% moisture store well.
• In Eastern India, storing wheat grains without losing viability for the next crop is a major challenge due to high humidity.

Storage Structures

• Storage pits, bins, or godowns should be moisture-proof and fumigated to prevent damage from stored grain pests, including rats.
• Zinc Phosphide (Zn₃P₂) is highly effective against rats.

Mixed Cropping with Wheat

• Across India, wheat is commonly mixed with barley, mustard, gram, lentil, and safflower.
• Farmers often plant a row of mustard or safflower for every 8-12 rows of wheat, ensuring diversified farm output and protection against pests, diseases, and natural calamities.
• In North-Western India and the Terai region of UP, wheat is grown alongside row crops like sugarcane, producing 3-4 tons of wheat as a bonus yield without reducing sugarcane productivity.

By-Product Utilization of Wheat

Food Uses

1. Wheat is ground into flour for making leavened bread (chapati), puris, and parathas.
2. It is used in the production of bread, pastries, biscuits, and semolina (for macaroni and breakfast foods).
3. Durum wheat (large white kernels) is often used for puffed wheat products.

Animal Feed & Industrial Uses

1. Wheat straw serves as an important fodder for livestock.
2. By-products from wheat flour mills, especially bran, are used in cattle feed.
3. Wheat starch is a key industrial product used in the paper industry.

Average Wheat Yield in India

• National Average Yield: 3.5–4.5 tonnes per hectare (t/ha)
• Irrigated Areas Yield: 4.5–6.5 t/ha
• Rainfed Areas Yield: 1.5–2.5 t/ha