Breeding & Genetics in Vegetable Crops

• Tomato is a self-pollinated crop but cross-pollination may occur up to 5%.
• Male sterility in onion is used for hybrid seed production.
• Cytoplasmic male sterility (CMS) is most widely used in onion and carrot.
• Gynoecious lines are used in cucumber breeding to increase yield.
• Polyploidy breeding is used in watermelon for developing seedless varieties.
• Male sterility in chilli is governed by cytoplasmic-genetic system.
• Single seed descent method is often used in self-pollinated vegetable crops.
• Recurrent selection is used to improve cross-pollinated vegetables like cabbage and cauliflower.
• Mutation breeding in vegetable crops led to the development of Pusa Lal Meerch (chilli).
• Heterosis breeding is extensively used in tomato, brinjal, and chilli.

Nutrient Disorders in Vegetables

• Blossom end rot in tomato and chilli – due to calcium deficiency.
• Bitter pit in tomato – due to calcium deficiency.
• Whiptail in cauliflower – caused by molybdenum deficiency.
• Button formation in cauliflower – due to boron deficiency.
• Cracking of fruits in tomato – due to irregular irrigation and boron deficiency.
• Hollow heart in potato – due to boron deficiency.
• Brown heart in turnip – caused by boron deficiency.
• Interveinal chlorosis – typical symptom of magnesium deficiency.
• Marginal leaf burn – due to potassium deficiency.
• Pale yellow leaves – due to nitrogen deficiency.

Physiological Disorders

• Cracking of cabbage heads – caused by irregular watering.
• Greening of potato tubers – due to exposure to sunlight (solanine accumulation).
• Pithiness in radish – caused by rapid growth due to excess nitrogen.
• Black heart in celery – caused by calcium deficiency.
• Forking of carrot roots – caused by undecomposed organic matter.
• Sunscald in chilli fruits – due to high temperature and intense sunlight.
• Hen and chicken disorder in grape – due to boron deficiency.
• Hollow stem in broccoli – caused by boron deficiency.
• Tip burn in cabbage – due to calcium deficiency.
• Frost injury in tomato – results in water-soaked lesions and wilting.

Seed Production & Technology

• Seed rate of tomato – 400–500 g/ha for transplanting.
• Seed rate of brinjal – 500–750 g/ha.
• Seed rate of chilli – 1–1.5 kg/ha.
• Seed rate of okra – 8–10 kg/ha.
• Seed rate of onion (rabi) – 8–10 kg/ha (for bulb crop).
• Seed rate of cucumber – 1–2 kg/ha.
• Seed rate of pea – 75–100 kg/ha.
• Seed rate of French bean – 80–100 kg/ha.
• Seed rate of bottle gourd – 2.5–3 kg/ha.
• Seed rate of pumpkin – 2.5–3.5 kg/ha.

Seed Certification & Standards

• Tomato isolation distance – 50 m (foundation), 25 m (certified).
• Brinjal isolation distance – 200 m (foundation), 100 m (certified).
• Chilli isolation distance – 400 m (foundation), 200 m (certified).
• Okra isolation distance – 400 m (foundation), 200 m (certified).
• Onion isolation distance – 1000 m (foundation), 500 m (certified).
• Cabbage and cauliflower isolation – 1000 m (cross-pollinated).
• Pea isolation – 10 m (foundation), 5 m (certified).
• Tomato germination standard – 70% minimum.
• Brinjal and chilli germination standard – 70% minimum.
• Onion germination standard – 70% minimum (validity 1 year only).

Diseases of Vegetable Crops

Tomato

• Early blight – Alternaria solani; causes concentric ring spots on leaves and fruits.
• Late blight – Phytophthora infestans; develops water-soaked lesions on leaves and fruits.
• Bacterial wilt – Ralstonia solanacearum; sudden wilting without yellowing.
• Leaf curl – caused by Tomato Leaf Curl Virus (TLCV); transmitted by whitefly (Bemisia tabaci).
• Damping-off – Pythium aphanidermatum; affects seedlings in nursery.
• Fruit cracking – physiological disorder due to uneven irrigation or boron deficiency.

Brinjal (Eggplant)

• Phomopsis blight – Phomopsis vexans; causes fruit rot and stem cankers.
• Bacterial wilt – Ralstonia solanacearum; same as in tomato.
• Little leaf – caused by mycoplasma-like organism (phytoplasma), transmitted by Hishimonus phycitis.
• Fruit and shoot borer – Leucinodes orbonalis; major pest of brinjal.

Chilli

• Leaf curl – Chilli leaf curl virus (transmitted by whitefly).
• Anthracnose or fruit rot – Colletotrichum capsici.
• Powdery mildew – Leveillula taurica.
• Dieback – Colletotrichum capsici.
• Root-knot nematode – Meloidogyne incognita.

Cucurbits (Cucumber, Bottle Gourd, Pumpkin, etc.)

• Downy mildew – Pseudoperonospora cubensis; yellow spots on upper leaf surface.
• Powdery mildew – Erysiphe cichoracearum and Sphaerotheca fuliginea.
• Anthracnose – Colletotrichum lagenarium.
• Mosaic disease – caused by Cucumber Mosaic Virus (CMV); transmitted by aphids.
• Fruit fly – Bactrocera cucurbitae; maggots feed inside fruit.

Onion & Garlic

• Purple blotch – Alternaria porri; concentric purple spots on leaves.
• Downy mildew – Peronospora destructor.
• Stemphylium blight – Stemphylium vesicarium.
• Basal rot – Fusarium oxysporum f. sp. cepae.
• Twister disease – caused by Fusarium oxysporum and nematodes.

Cole Crops (Cabbage, Cauliflower, Broccoli)

• Black rot – Xanthomonas campestris pv. campestris; V-shaped yellow lesions on leaf margins.
• Downy mildew – Peronospora parasitica.
• Club root – Plasmodiophora brassicae; swelling of roots.
• Alternaria leaf spot – Alternaria brassicae.
• Diamondback moth (Plutella xylostella) – serious pest of cabbage & cauliflower.

Root Vegetables

• Cavity spot of carrot – Pythium violae.
• Alternaria leaf blight of carrot – Alternaria dauci.
• Black rot of radish – Xanthomonas campestris.
• Root-knot nematode – affects most root vegetables.
• Aster yellows – Mycoplasma-like organism disease of carrot.

Potato

• Late blight – Phytophthora infestans; led to Irish famine (1845).
• Early blight – Alternaria solani.
• Black scurf – Rhizoctonia solani.
• Common scab – Streptomyces scabies.
• Bacterial wilt – Ralstonia solanacearum.
• Potato virus X & Y – cause mosaic symptoms.

Pea & Beans

• Powdery mildew – Erysiphe pisi.
• Downy mildew – Peronospora viciae.
• Rust – Uromyces pisi.
• Fusarium wilt – Fusarium oxysporum f. sp. pisi.
• Pod borer – Helicoverpa armigera; attacks flowers and pods.

Common Management Practices

• Seed treatment with Trichoderma viride (4 g/kg) helps control soil-borne fungi.
• Roguing is essential to maintain disease-free seed crops.
• Use of yellow sticky traps helps control whitefly and aphids.
• Neem-based pesticides (azadirachtin) are effective against sucking pests.
• Crop rotation with non-host crops reduces nematode population.
• Soil solarization controls damping-off pathogens in nursery beds.
• Copper oxychloride (0.3%) – effective against bacterial leaf spot.
• Carbendazim (0.1%) – used for control of fungal diseases.
• Imidacloprid (0.3 ml/l) – systemic insecticide for whiteflies and aphids.