Cultivation and improvement of Wheat

Origin of Wheat:-

1. Introduction:-

·   Common Name:- Wheat

·    Botanical Name:- Triticum aestivum

·    Family:- Poaceae or Gramineae

2. Species and Chromosome Numbers:- According to Feldman and Sears (1981) wheat has 13 diploid, 12 tetraploid and 5 hexaploid species. Some of the main species are given in the table below -

Note:- 3 species of wheat are cultivated in India -

i. Triticum aestivum:- 95%

ii. Triticum durum:- 4%

iii. Triticum dicoccum:- 1%

3. Center of Origin:-

·   Primary Center of Origin:- Near East (Asia Minor)

·   Secondary Center of Origin:- Ethiopia

4. Genetic Evolution of Wheat:- Today, hexaploid wheat Triticum aestivum is the most cultivated species in the world. It has been artificially developed by distant hybridization. For this, the following 2 steps were used -

i. Firstly, the cross of the diploid wheat Triticum monococcum is made with the diploid species Triticum searsii, which results in the production of tetraploid wheat Triticum turgidum.

ii. Now the cross of this tetraploid wheat Triticum turgidum is made with diploid Triticum tauschii, which results in the production of hexaploid wheat Triticum aestivum.

Cultivation of Wheat:-

1. Climate Requirements:-

> Optimum Temperature Range:- 

i. 20 – 25°C (Ideal germination of wheat seed)

ii. 3.5 – 35°C (Seed germination Temperature range)

iii. 14 – 15°C (Optimum average temperature at the time of maturity)

> Rainfall:- 25 – 150cm/year

> Humidity:- 50-60%

2. Season for Wheat Cultivation in India:- Wheat, in India, is best grown as a rabi or winter season crop since the conditions during that time are conducive for growth and ensures maximum yield.

3. Soil Requirements:- Wheat needs soil with a moderate amount of water holding capacity. Well drained loams and clayey loams are considered to be a good for wheat.

> Salinity level (EC) 6ds/m, Yield is reduced by about 50% at 14ds/m.

> pH 6-8

4. Sowing time:- 

> The normal time of sowing of high-yielding cultivars in irrigated areas start in the beginning of November. 

> Under specific circumstances, wheat is also sowing in December. 

> When wheat is sown beyond December there is a drastic reduction in yield. 

> After November, delay in sowing by each day causes reduction of 5kg/ha/day in northeastern parts of the country and 41kg/ha/day in north-western and central parts of the country.

5. Sowing:-

i. Seed treatment:- The seed of loose smut-susceptible varieties should be given solar or hot-water treatment. If the wheat seed is used only for sowing, it can be treated with Vitavax,thyram 2.5 gm/kg seed.

ii. Seed rate:- 90-100 Kg/ha

iii. Row spacing:- 15 - 22.5cm

iv. Depth:- 5-6cm

vi. Method:- Wheat is sown by the following 4 methods:

- Broadcast method

- Behind the plough method

- Drilling method

- Dibbling method

6. Mannures and Fertilizer:- It is desirable that 2 to 3 tonnes of farmyard manure per hectare or some other organic matter is applied 5 or 6 weeks before sowing. The NPK fertilizer requirement of the irrigated wheat crop is as follows:

Nitrogen (N) = 80-120 kg/ha

Phosphorus (P2O5) = 40- 60 kg/ha

Potash (K2O) = 40 kg/ha

Total quantity of Phosphorus and potash and half the quantity of nitrogen should be applied at the time of sowing. Remaining quantity of Nitrogen should be applied at the time of crown root initiation.

7. Water Management:- In wheat cultivation, irrigation requirement depends on various factors viz.

type of soil, variety grown etc. The critical stages of wheat are described below:

8. Plant Protection:-

a. Weed control:- Generally weeding is done after 1 ½ to 2 months after sowing or weedicides like 2,4 D, Avadex or Nitrofen (Tok E-25) for controling Chenopodium sp, Angallis sp. Asphodelus sp. Phalaris sp. of weeds.

b. Disease control:- DiseasesWheat crops suffer from several diseases causing reduced yield and quality. The major diseases and their chemical control are given below:

c. Insect pest control:- Wheat is attacked by a number of insects- pests and rodents both in the fields

and in storage. Some insets-pests and their control are following:

9. Harvesting:- The time of harvesting of wheat depends on the type and variety grown. The wheat crop is usually harvest when the grains become hard and the leaves become dry and brittle. General time for wheat harvesting in different zones is given in table:

10. Yield:- 40-45 q grain and 70-80 q straw/ha may be obtained from dwarf wheat varieties under irrigated areas. Under rainfed condition, 20-25 q grain and 30- 35 q straw/ha may be obtained. From Deshi wheat varieties, 20-30 q grain and 60-70 q straw/ha may be obtained.

Improvement of Wheat:-

1. Pollination:-

Ø  Wheat exhibit wind pollination, so versatile anthers are found in its flowers.

Ø  Wheat is a self-pollinated crop. It show less than 1% cross pollination. But sometimes 3–4% cross pollination may also occur.

2. Breeding Objectives:-

a. Higher Yield:- The yield in wheat depends on the following factors -

i. Number of ears in unit area

ii. Number of grains per ear

iii. Average weight of grains

Note:- In the 1960s, two varieties of wheat are considered responsible for bringing Green Revolution -

i. Sonora – 64

ii. Lerma rojo

b. Water Lodging Resistance:-

Ø  For this, dwarf varieties are developed in wheat.

Ø  3 dwarf varieties of wheat were developed by incorporating Norin - 10 gene into the genome of wheat -

i. Sonora – 63

ii. Sonora – 64

iii. Kalyan sona

c. Disease Resistance:-

Ø  Rust disease:- By Puccinia

Ø  Smut disease:- By Ustilago

d. Insect Resistance:-

Ø  Shoot fly

Ø  Hessian fly

Ø  Aphids

Ø  Termites

e. Quality:-

Ø  Quality in wheat is represented by the following factors -

i. Colour of grains

ii. Hardness of grains

iii. Size of grains

iv. Protein content

v. Gluten content

vi. Protein quality

vii. Quality of dough

Ø  High amounts of gluten are good for making chapati.

Ø  Lysine amino acid is deficient in wheat protein.

Ø  Types of Wheat:- 3 main types are -

i. Hard Wheat:- This is normal wheat which is also known as bread wheat. It contains high amounts of Gluten. It is used in making bread or chapati.

ii. Soft Wheat:- It is used in making cakes and pastries.

iii. Durum Wheat:- It is used in making Macaroni and Biscuit.

3. Breeding Methods:-

·   A project is underway at DWR (Directorate of Wheat Research), Karnal, Haryana -

AICWBIP = All India Coordinated Wheat and Barley Improvement Project

·   There are 4 main breeding methods used in wheat -

a. Introduction

b. Pure line Selection

c. Hybridization

d. Mutation Breeding

a. Introduction:-

Ø  Two varieties of wheat were brought to India by the primary introduction -

i. Sonora – 64

ii. Lerma rojo

Ø  Two varieties of wheat were developed in India by secondary introduction -

i. Kalyan Sona

ii. Sonalika

b. Pure line Selection:- Many varieties of wheat were developed by this method -

Ø  NP – 4, 6, 12

Ø  Pb – 8, 9, 11

Ø  K – 46, 53, 54

c. Hybridization:-

Ø  By the pedigree method, 3 varieties of wheat have been developed-

i. K – 65

ii. WL – 711

iii. Malviya – 12

Ø  2 varieties of wheat have been developed by back cross method -

i. IWP – 72

ii. MLKS – 11

d. Mutation Breeding:-

Ø  Sonora - 64 is a red-grained variety. By mutation through gamma rays the Sharbati Sonara variety has been developed. which is a amber grained variety.

Ø  Lerma rojo is also a red-grained variety. By mutation through gamma rays the Pusa Lerma variety has been developed. which is a amber grained variety.