Effect of Seed Size on Seedling Vigour and Seed Yield
Seed size is an important physical indicator of seed quality that affects vegetative growth and is frequently related to yield, market grade factors and harvest efficiency. Genetic variation is the cause for variation in size of seed between varieties. Based on size, the seeds are classified as very large, large, medium, small and very small. The variation is due to flow of nutrients into the seed at the mother plant. Seed size is considered as the components of seed quality which affects the performance of crop ( Ojo, 2000; Adebasi et al., 2011).
The size of seed is known to affect the fitness of the plant growing from it, larger seeds often have the higher fitness. Generally large seed has better field performance than small seed. Seedling vigour and germination rate increases with the increase in size of seed in rice and wheat. Variation in seed size has been observed in many species among populations, among plants within populations and within single plants. While seeds of particular sizes appear to be favoured in particular environments, seed size has also been observed to affect the time and probability of germination, seedling survival and adult reproductive output within the same environment.
Many scientists has shown that use of large seed size and increased seedling rates can improve wheat competitiveness and provide an effective means to reduce wild oat biomass and seed production. The seed size often controls the germination and initial seedling growth in many species. Different seed size having different levels of starch and other food storage may be one factor which influences the expression of germination and growth of the plants. Seed grading based upon their size and weight is a common practice to regulate the germination and subsequent seedling growth.
For a successful crop production, the use of good quality seed is very essential which increase the yield by 15-20%. The extent of this increase is directly proportional to the quality of seed that is being sown. The seeds of the seed lot may differ by size, weight and density due to production environment and cultivation practices. Size is a widely accepted measure of seed quality and large seeds have high seedling survival growth and establishment. A wide array of different effects of seed size has been reported foe seed germination, emergence and related agronomical aspects in many crop species.
Effect of large seed on seedling vigour:
In wheat, seed size is positively correlated with seed vigour, larger seeds tend to produce more vigorous seedlings. Germination rate and seedling vigour index values increased with the increase of seed size suggesting that selection of larger seeds for good stand establishment in rice.
Effect of large seed on seed yield:
Larger seed of spring wheat produce higher yield than smaller seeds under late shown conditions but not under optimum management conditions. It is reported that in wheat, seed size not only influences emergence and establishment but also affected yield components and ultimately grain yield.
Effect of small seeds on seedling vigour:
Small to medium sized ones produced better germination and seedling vigour than those of bigger ones. Small seeds germinated faster and grow higher under saline conditions and that they could be preferred for use in saline soils to achieve better stands.
Writer: Dikshya Pandey (Student, Bsc Ag 4th semester, IAAS, Paklihawa)