Brinjal

Morphology


Introduction

  • The growth and development of brinjal comprises several sequential changes from germination to maturity.
  • Knowledge of plant structure and growth and development is essential to improve management practices and yield.

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Morphology

Plant

  • The brinjal is a much branched, perennial usually grown as an annual under cultivation.
  • It is characterized by a bush, indeterminate erect plant, attaining a height of 0.5- 1.5 m. and some plants develop spines.
  • The leaves are large and alternate on the stem and are more or less oval in shape.
  • Stems are erect and branching and covered with fine grey hairs.
  • Brinjal has a strong tap root, penetrating to a depth of about one metre within 6-7 weeks. The mature plant has an extensive root system.

Germination

  • The brinjal seed is covered by a leathery seed coat.
  • Germination involves mobilization and utilization of food and energy reserves.
  • The environmental factors which affect germination are soil moisture, temperature and oxygen supply.
  • A moisture content of about 60% is required for germination of brinjal seed.
  • Brinjal fails to germinate if the soil moisture tension exceeds 7.0 atm.
  • The optimum germination temperature is around 30-35oC.
  • Brinjal germination is epigeal and under favourable conditions, seedlings emerge 5-6 days after sowing.

Root

  • Roots are important growth components, because they anchor the plant and supply water and mineral nutrients.
  • The brinjal root system is characterised by a tap root that consists of lateral roots arising from the upper portion of the primary root.
  • During the period before true leaves begin expansion, the primary root is penetrating into the soil and branch of roots are being formed.
  • The brinjal root system continues to grow throughout the life cycle of the plant, but the rate of root proliferation is more rapid during early flowering.
  • The major portion of the roots is concentrated in the top 30 cm of the soil profile, but brinjal roots have been observed as deep as 1.0-1.5 m. below the soil surface under field conditions.
  • The rate at which root systems grow downward depends on the soil fertility status and moisture availability.

Shoot

  • The main stem of the brinjal is monopodial, with leaves and branches but no flowers.
  • There are usually two axillary buds at each main stem node.
  • Normally, only one bud develops out of it.
  • At lower nodes the first bud remain vegetative and may develop into a vegetative branch of monopodium.
  • Usually the vegetative branch occurs in a definite zone near the base of the plant, and the fruiting branches occur farther up the stem.
  • The number of nodes from the base of the main stalk to the first fruiting branches varies among the brinjal cultivars and is affected by cultural practices.
  • Vegetative shoot growth ceases at about the last fruit picking.

Leaves

  • The leaves are usually large lobed, ovate, thin and relatively hairy on the under surface.
  • The leaves occasionally bear sharp spines.
  • It's surface contains many stomata through which gases are exchanged between plant and the atmosphere.
  • Most of the stomata are on the underside of the leaf.
  • The petiole is about one fourth as long as the leaf blade.
  • At the point where it joins the stem or branch, is enlarged.

Flowers

  • The flowers are large, violet colored solitary or form cluster of two or more borne in lateral cymes, having a deeply lobbed and toothed calyx (bearing a few prickles) and a rotate purplish corolla.
  • On most varieties, flowers are borne singly and opposite of leaves.
  • The pedicel is erect, thick and upto 6.0 cm long.
  • The large fleshy calyx is persistent, usually five lobed, enlarging and enclosing the base of the fruit.
  • The expanded purple corolla is bright in appearance, about 5 cm in diameter, having five partite lobes.
  • The anthers are yellowish, arranged in a cone around the style and dehisce (discharge) the pollen longitudinally through terminal pores.
  • The style is simple, yellowish and the stigma is capitate.
  • Stigma often projects beyond the anthers.
  • Following pollination, the fruit, which is a berry is formed.

Pollination

  • Self-pollination is more common than cross pollination in brinjal.
  • The cone-like shape of anthers favours self-pollination, but since stigma ultimately projects beyond the anthers, there is ample opportunity for cross pollination.
  • The extent of cross pollination in brinjal may vary from 0.2 to 46.8%, averaging about 6.75 per cent.

Fruits

  • The brinjal fruit is a fleshy berry and forms in a pendant position.
  • It is held by the calyx, which after the corolla has withered, enlarges considerably, enclosing the entire basal portion of the mature fruit.
  • The fruit is usually borne singly at the nodes.
  • The fruits are large (up to 500g), and may extremely variable in shape (oval to oblong) and colour (purple, purple-black, white, green and red).
  • The ripe fruits are usually pale to bright yellow in colour
  • The seeds are scattered through the fruit, embedded in a firm placenta.
  • Many seeds are formed in a single fruit (800-1000 in long brinjal and 1000-1500 in round brinjal).
  • The seeds are small (about 2-3 mm diameter), flattened, pale brown, kidney shaped with leathery seed coat.

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Taxonomy

  • The brinjal belongs to the family Solanaceae or nightshade.
  • The cultivated species of brinjal Solanum melongena L. differ in shape and colour of fruits.
  • The fruit is a large, smooth, glossy, firm-fleshed, pendent berry (upto 15 cm long) usually oblong or somewhat pear-shaped, ovoid, or obovoid, ranging from white or yellow to deep purple or black, or even striped and with a shining surface.
  • There are only 3 main botanical varieties under S. melongena.
  • The round or egg-shaped cultivars are grouped under var. esculentum.
  • The long, slender types are included under var. serpentinum.
  • The dwarf brinjal plants are grouped under var. depressum
  • Other species of Solanum are as follows

S. aculeatissimum S. nodiflorum
S. aethiopicum S. ocranthum
S. americanum S. petinatum
S. anguivi S. Pseudocapsicum
S. atropurpureum S. quinquangulare
S. aviculare S. repandum
S. capense S. rickii
S. capsicoides S. rigescentoides
S. ciliatum S. rostratum
S. eleagnifolium S. sepium
S. ferox S. sessiliflorum
S. juglandifolium S. spinosissimum
S. laciniatum S. stramonifolium
S. linnaeanum S. suaveolens
S. lycopersicoides S. surattense
S. mammosum S. viarum

  • Besides, the following wild species of Solanum genus have been recognised and studied in varietal development of brinjal.
  • S. gilo S. macrocarpon
  • S. incanum S. nigrum
  • S. indicum S. sisymbriifolium
  • S. integrifolium S. torvum

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Growth phases

Seedling Stage

  • Brinjal is a tender perennial grown as annual
    • .
  • It is raised in nursery beds and seedling age for transplantation is 40-45 days.

Vegetative Stage

  • Vegetative development starts from 20 days after sowing and ends with the start of flowering i.e. from 45-50 days after transplanting.
  • The vegetative growth supports the photosynthetic capacity of the plant, which supports the yield.
  • During vegetative growth, roots, leaves and stems may compete for photosynthetic products.
  • The partitioning of products may be controlled by plant hormones or by environmental factors.
  • If there is water stress, plant shoots are affected more than roots.

Flowering stage

  • Initiation of flowering varies with cultivar and environmental factors.
  • Flowering may be visible at 65 or 70 days or may be delayed until 80 days when certain genotypes or environments interact.
  • Flowering may occur over a period of 6 -10 weeks after start of flowering, depending on the environment and cultivar.

Fruiting and Maturity

  • Fruits are normally visible about two weeks after the start of flowering.
  • After fertilization of the flower, the fruits develop slowly for the first few days; then the rate of development increases until the fruit reaches maximum size.
  • The number of fruits varies from 15-35 in a single plant.
  • At maturity, fruit may contain 800-1500 seeds approximately. The 1000 seed weight is approximately 5 grams.
  • A chronology of phenological development of brinjal plant is presented in Table.

Phenological Phase
Duration (in days)
Seed germination
4-7
Seedling
40-45
Vegetative
45-75
Flowering
75-100
Fruiting and Maturity
100-150

  • The sequence of events remain the same regardless of cultivar or environmental condition, but the absolute times between events may vary by several days as a function of cultivar and environment.

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Tamilnadu

Brinjal

Brinjal Management