Seed Production: Maize (Zea Mays L.)

Introduction:

1. Maize: Zea mays L.

2. Family: Poaceae

3. Crop is cultivated in Central and South America, Africa, Central Europe and Asia

4. In India, Uttar Pradesh, Bihar, Rajasthan, Madhya Pradesh, Punjab, Himachal Pradesh

5. Maize types: Flints (with round seed), dent (with flat seeds)

6. Crop follows C4 photosynthetic pathway

7. Origin: Central America (Mexico)

Reproduction and Pollination

1. Maize is monoecious plant. Male and female flowers are separate on same plant.

2. Male inflorescence is tassel and female flower is silk.

3. Maize is cross pollinated (Dichogamy)

4. Seed propagated crop

5. Maize is non-tillering cereal.

6. Isolation seed: Foundation seed – 400 m / Breeder seed – 200 m

Breeding Objectives:

1. Higher yield: Ear length, Kernels per row, Kernels per ear, Size of kernel and Number of ears per kernel

2. Seed quality: Seed colour, protein content, Lysine and Tryptophan. Gene (Opaque 2) source of high lysine content, protein found in endosperm is zein

3. Disease resistance: Root rot, stalk and ear rot, leaf blight, leaf spot, downy mildew, mosaic virus

4. Insect resistance: Stem borer, Fall armyworm

Breeding Methods:

A) Population Improvement Approaches

1. Mass Selection

2. Progeny Selection

3. Ear to Row Selection

4. Recurrent Selection

5. Disruptive and Bi-parental Mating

B) Inbred Improvement Approaches

1. Backcross Breeding

2. Convergent Improvement

3. Gamete Selection

C) Cultivar Development Approaches:

1. Mass Selection

2. Heterosis Breeding

3. Synthetics and Composites

4. Tissue Culture

Classification of Maize:

A) Two close relatives:

1. Gamma grass: Tripsacum spp

2. Teosinate: Zea Mexicana

B) Seven groups based on characteristics of endosperm (Sturtevant, 1899):

1. Dent Corn: Zea mays var. indentata

2. Flint Corn: Zea mays var. indureta

3. Sweet Corn: Zea mays var. saccharata

4. Flour Corn: Zea mays var. amylaceae

5. Popcorn: Zea mays var. everta

6. Podcorn: Zea mays var. tunicate

7. Waxy Corn: Zea mays var. certaina

Types of Hybrids in Maize:

1. Single Cross Hybrid (A x B)

2. Modified Single Cross Hybrid (A x A1) x B

3. Double Cross Hybrid (A x B) (C x D)

4. Three Way Cross Hybrid (A x B) x C

5. Modified Three Way Cross Hybrid (A x B) (C x C1)

6. Top Cross Hybrid (a Inbred x Open Pollinated Variety)

Factors Affecting Hybrid Maize Seed Production:

1. Planting ratio

2. Non-synchronization of flowering

3. Genetic drift

4. Detasseling

5. Mechanical Admixture

6. Rouging

7. Physiological Maturity of Crop

8. Harvest Seed Crop

9. Post Harvest Operation