About Lesson
1. Climatic factors
a. Temperature:
- The optimum mean temperature controls the mechanism of seed formation and development.
Effect of high temperature:
- High night temperature alone can cause flower fall in chilly and tomatoes, that is due to rapid formation of abscission tissue at the peduncle base that prevent seed set.
- In late planted wheat, forced maturity is a problem that is due to effect of high temperature. In such condition, milk is quickly dried and formed shrinked seeds.
Effect of low temperature:
- Trigger development of mature embryo from dormant stage.
- Winter cereals will not flower unless subjected to a period of chilling early in their development.
- In very cold situation, the pollen mortality is a serious problem in rice, wheat, maize etc.
b. Light:
- It directly influenced the plant to pass from vegetative to reproductive stage.
- In absence of bright sunlight, the mobilization of carbohydrate from source to sink and condensation to starch is impaired producing unfilled grains in rice.
- It also disturbs the normal pathway of flower development, anthesis and ultimately the seed set.
c. Rainfall:
- Flowering, seed set and seed development is directly affected due to reduction in the rate and duration of seed development.
d. wind:
- If the wind velocity is very high during the growth period of any crop it results in higher transpiration, flower dropping and desiccation.
- Gentle wind, however, is better for pollination, seed set and seed development.
- Soil factor:
- It effects the chemical composition and boldness of the seed. Soil containing more amount of N produces seeds with higher protein content.
- Example: rice varieties adapted to alluvial soils will be very poor seed producers in gravelly, saline or sodic soils.
- Agronomic factors
- The growth and development of seed is directly influenced by agronomic practice like timely planting, irrigation, drainage, intercultural operation, harvesting etc.
- Genetic factor
- The effective breeding and selection techniques used by the plant breeders are able to manipulate the chemical composition as well as the growth and development of seed.