HORMA - 302
Breeding of Fruit Crops
Breeding of Fruit Crops
UNIT II: Citrus, Grapes, Guava, and Sapota
📚 Contents
1. CITRUS (Citrus spp.)
1. Origin, Distribution & Taxonomical Status
- Family: Rutaceae (Subfamily: Aurantioideae).
- Origin:
- South East Asia (Indo-China region).
- Mandarins: China.
- Limes/Lemons: India.
- Taxonomy (Complex): Classification is controversial due to frequent hybridization and polyembryony.
- Swingle (1943): Recognized 16 species.
- Tanaka (1954): Recognized 162 species (Splitter).
- Important Species:
C. reticulata: Mandarin/Santra (Loose jacket).
C. sinensis: Sweet Orange (Mosambi/Malta).
C. aurantifolia: Acid Lime (Kagzi lime).
C. grandis / C. maxima: Pummelo (Monoembryonic).
C. paradisi: Grapefruit.
2. Cytogenetics
Chromosome Number: 2n = 18 (Diploid).
- Ploidy: Triploids (3n=27) occur naturally (e.g., Tahiti lime) and are seedless.
- Polyembryony: A unique feature where seeds contain multiple embryos (one sexual/zygotic + many nucellar/asexual). Nucellar seedlings are true-to-type (clones of mother), while zygotic are hybrids. This is a barrier to hybridization but excellent for rootstock propagation.
3. Blossom Biology
- Inflorescence: Cymes (axillary).
- Flowers: Hermaphrodite, white, scented.
- Pollination:
Mandarin/Sweet Orange: Self-pollinated (Facultative cross-pollination).
Pummelo: Cross-pollinated
Entomophilous (Honey bees). - Self-Incompatibility: Present in Pummelo and some Mandarin hybrids (Clementines).
4. Breeding Objectives & Ideotypes
Ideotype: Dwarf tree (<2.5m), viral disease resistant, seedless fruits, high juice content.
- Rootstocks: Resistance to Phytophthora (root rot), nematodes, and salinity. Dwarfing habit.
- Scion:
- Seedlessness (e.g., in Mandarins like Kinnow).
- Resistance to Citrus Tristeza Virus (CTV) and Greening.
- Easy peeling, good blend of TSS/Acid.
5. Breeding Approaches
A. Introduction
- Kinnow: Introduced from USA (California) to Punjab. It is a hybrid of King x Willow Leaf mandarin.
- Grapefruit: Introduced varieties like Marsh Seedless.
B. Selection (Clonal Selection)
- Selecting superior nucellar seedlings to rejuvenate old clones (free from viruses).
- Examples: Nagpur Santra (selection), Kagzi Lime selections (Vikram, Pramalini)
C. Hybridization
- Difficulties: Nucellar embryony masks the hybrid embryo.
- Solution: Use monoembryonic females (e.g., Pummelo) or use pollen from specific males on emasculated flowers.
- Intergeneric Hybrids:
- Citrange = C. sinensis x Poncirus trifoliata (Rootstock).
- Citrumelo = C. paradisi x Poncirus trifoliata.
D. Mutation Breeding
- Used for seedlessness (by inducing sterility).
- Achievements: Red fleshed grapefruits (Star Ruby, Rio Red).
E. Biotechnological Interventions
- Protoplast Fusion: To create somatic hybrids between sexually incompatible species (e.g., for rootstocks).
- Embryo Rescue: To recover seedless triploids (2n X 4n crosses)
6. Achievements
| Crop | Variety/Hybrid | Remarks |
|---|---|---|
| Mandarin | Kinnow | High yield, but seedy. (Breeding now focused on seedless Kinnow). |
| Acid Lime | Vikram (Sai Sharbati) | Off-season fruiting, cluster bearing. |
| Pramalini | High yield, canker tolerant. | |
| Rootstocks | Troyer Citrange | Phytophthora tolerant, cold hardy. |
| Rangpur Lime | Virus tolerant, salinity tolerant. |
2. GRAPES (Vitis spp.)
1. Origin & Taxonomy
- Family: Vitaceae.
- Origin:
- Vitis vinifera: Black Sea / Caspian Sea region (Old World).
- Vitis labrusca: North America (Fox grape, "Slip skin").
- Sub-genera:
Euvitis: True grapes (2n=38), forked tendrils.
Muscadinia: Muscadine grapes (2n=40), simple tendrils, Phylloxera resistant.
2. Cytogenetics
- Chromosome Number: 2n=38 (Vinifera).
- Seedlessness
- Parthenocarpy: Fruit without fertilization (Corinth).
- Stenospermocarpy: Fertilization occurs, but embryo aborts (berries are normal size, e.g., Thompson Seedless).
3. Blossom Biology
- Inflorescence: Panicle
- Flower Types:
- Wild vines: Dioecious (Male and Female on separate plants).
- Cultivated: Hermaphrodite (Self-fertile).
- Anthesis: Morning (7-9 AM). Cap (calyptra) falls off ("Capfall").
- Pollination: Self-pollinated (Cleistogamy often seen).
4. Breeding Objectives
- Table: Large berry size, seedless, attractive bunch, crispy pulp (Muscat flavor)
- Raisin: High TSS (>22° Brix), thin skin, Seedless.
- Wine: high acidity/sugar balance, specific aroma.
- Resistance: Downy mildew, Anthracnose, Salinity.
5. Breeding Approaches
A. Introduction
Thompson Seedless, Flame Seedless (USA).
B. Selection
Clonal Selection: Tas-A-Ganesh, Sonaka, Manik Chaman are all mutants/selections of Thompson Seedless in Maharshtra.
C. Hybridization
- Challenge: Seedless x Seedless crosses are impossible naturally (no seeds to plant).
- Solution (Biotech): Embryo Rescue. Crossing two seedless varieties (Stenospermocarpic) and rescuing the embryo in vitro before it aborts.
- Rootstocks: Utilizing wild species (V. rupestris, V. champinii) for nematode/salt tolerance.
D. Mutation Breeding
- Extensively used for berry elongation and color.
- Pusa Seedless is a distinct mutant.
6. Achievements
| Institute | Hybrid/Variety | Parentage | Key Traits |
|---|---|---|---|
| IIHR (Bengaluru) |
Arkaavati | Black Champa x Thompson Seedless | High yield, white wine. |
| Arka Soma | Anab-e-Shahi x Queen of Vineyards | White wine, vigorous. | |
| IARI (New Delhi) |
Pusa Urvashi | Hur x Beauty Seedless | Extra early, seedless. |
| Rootstocks | Dogridge | (V. champinii) | Salinity & Drought tolerant. |
| 1613 | (V. solonis x Othello) | Nematode resistant. |
3. GUAVA (Psidium guajava)
1. Origin & Taxonomy
- Family: Myrtaceae.
- Origin: Tropical America (Mexico to Peru).
- Related Species:
- P. cattleianum (Strawberry Guava),
- P. friedrichsthalianum (Chinese Guava - Dwarf/Wilt resistant).
2. Cytogenetics & Blossom Biology
- Chromosome Number: 2n = 22
- Triploids (3n=33): Produced naturally or by crossing. They are seedless but have irregular fruit shape and low yield (shy bearing).
3. Blossom Biology
- Inflorescence: Cyme (solitary or 2-3 flowers) in leaf axils of current season growth.
- Anthesis: Early morning.
- Pollination: Cross-pollination (bees) is common (approx 35%), though self-compatible.
4. Breeding Objectives
- Guava Wilt: The most devastating disease (Fusarium). Need resistant rootstocks.
- Quality: Low seed content (soft seeds), pink/red flesh (Lycopeine rich), high pectin (for jelly).
- Growth: Dwarf canopy for high density.
5. Breeding Approaches
A. Selection
- Allahabad Safeda and Lucknow-49 (Sardar) are superior chance seedlings selected in Uttar Pradesh.
- L-49 is semi-dwarf and heavy bearer.
B. Hybridization
- Used to combine soft seeds and colour.
- Heterosis: F1 hybrids often show increased vigour and fruit size.
C. Polyploidy Breeding
Developed Seedless Guava (Triploid). However, due to fruit ridges and low yield, it is not commercially hit.
D. Resistance Breeding (Rootstocks)
- Interspecific hybridization attempts: P. molle x P. guajava shows incompatibility.
- Psidium molle is immune to wilt but not graft compatible.
6. Achievements
| Institute | Variety | Parentage | Features |
|---|---|---|---|
| IIHR | Arka Mridula | Selection from open pollinated seedlings of Allahabad Safeda. | Soft seeds, good keeping quality. |
| Arka Amulya | Seedless x Allahabad Safeda | Heavy yielder, white flesh. | |
| Arka Kiran | Kamsari x Purple Local | Red flesh (Lycopene), soft seeds. | |
| CISH | Lalit | Selection from Apple Color | Red flesh, high yield. |
| Shweta | Selection from Apple Color | White flesh, pink blush. | |
| HAU | Hisar Safeda | Allahabad Safeda x Seedless | Less seeds. |
4. SAPOTA (Manilkara achras)
1. Origin & Taxonomy
- Family: Sapotaceae.
- Origin: Tropical America (Mexico/Guatemala).
- Synonyms: Achras sapota.
- Note: Also source of 'Chicle' gum (chewing gum base)
2. Cytogenetics
- Chromosomes: 2n = 26.
3. Blossom Biology
- Flowering: Throughout the year (peak: Sept-Oct, Feb-March).
- Protogyny: Female reproductive organs mature before male.
- Pre-anthesis: Stigma becomes receptive 2 days before flower opening.
- Problem: High flower drop and poor fruit set due to heterozygosity
4. Breeding Objectives
- Yield: Higher fruit retention.
- Quality: Less granular (gritty) texture, sweet pulp, thin skin.
- Ideotype: Spreading branches, high fruit set, vertically oval fruits (preferred in market).
5. Breeding Approaches
A. Selection
- Most Indian varieties are clonal selections.
- Kalipatti: Dark leaves, oval fruit, high quality (Maharashtra/Gujarat).
- Cricket Ball: Large round fruit, granular pulp.
B. Hybridization
- To combine large size of Cricket Ball with medicinal/sweet quality of Oval types.
- Crossing techniques involve early morning emasculation (before 5 AM) as anthesis is at 4 AM.
4. Achievements
| Institute | Hybrid | Parentage | Key Features |
|---|---|---|---|
| TNAU (Coimbatore) |
CO-1 | Cricket Ball x Oval | Long oval, sweet, no granules. |
| CO-2 | Clonal selection from Baramasi | High yield. | |
| Periyakulam (TNAU) |
PKM-1 | Guthi x Cricket Ball | High yielding, dwarf, suitable for high density. |
| UAS (Dharwad) |
DHS-1 | Kalipatti x Cricket Ball | Sweet, high TSS, tolerant to leaf spot. |
📚 References & Sources
Bose T.K., Mitra S.K. & Sanyol D. (2002). Fruits of India – Tropical and Sub-tropical. Naya Udyog.
Janick J. & Moore J.N. (1996). Fruit Breeding. Vols I-III. John Wiley & Sons.
Chadha K.L. (2001). Handbook of Horticulture. ICAR.
Nijjar G.S. (1977). Fruit Breeding in India. Oxford & IBH.
Radha T. & Mathew L. (2007). Fruit Crops. New India Publ. Agency.