- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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
- 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
- Brinjal is a tender perennial grown as annual.
- It is raised in nursery beds and seedling age for transplantation is 40-45
- 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.
- 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.
Duration (in days)
Fruiting and Maturity
- 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.