S – U

S phase
Part of interphase in which replication of DNA and synthesis of histone proteins occurs is called as S phase.
Appendages of chromosome either round, elongated or knob like are called as satellite.
Satellite DNA
DNA with short, repeating base sequences is called as satellite DNA .
Secondary constriction
Secondary constriction is a constriction present at any point on chromosome and constant in position and extent.
Botanically seed is defined as matured (after fertilization) and ripened ovule which contains an embryo with food reserve and protective coat.
Seed coat
Seed coat is a three-layered outer covering of seed.
Seed dormancy
Seed dormancy is the failure of fully developed, mature, viable seed to germinate even under favorable physical conditions (like moisture and temperature).
Seed Germination
Seed germination is the resumption of growth of the embryo plant inside the seed.
Seed technology
Seed technology is the science dealing with the methods of improving physical and genetical characteristics of seed.
Seed Viability
Seed viability is the capability of plant structure (seed, cuttings etc.) to show living properties like germination and growth.
Selection is a process either natural or artificial, by which individual plants or group of plants are sorted out from mixed population, primarily aiming at the removal of undesirable types.
Self pollination
Self pollination is the phenomenon in which pollen grains are transferred from anthers to stigma of the same flower or another flower of same plant.
Self-incompatibility is a phenomenon with which a plant with functional pollen fails to set seed when self pollinated.
Semi conservative replication
Each of two daughter helices conserves only one of the parental strands hence the process is called as semi conservative replication.
Sometimes in a heterozygote, dominant allele does not completely masks or hide the phenotypic expression of the recessive allele; as a result of this heterozygote has intermediate phenotype. This is called as semidominance.
Single Seed Descent
Single seed descent is a method of plant breeding in which instead of bulking whole seed lot of selected plants, a single seed is selected randomly from each selected plant to make bulk.
Somatic crossing over
When crossing over occurs in chromosomes of somatic cells of an organism during mitotic cell division, it is called as somatic crossing over.
Somatic Embryogenesis
Somatic embryogenesis is the process by which embryo forms and develops from bipolar structures from somatic cells that parallel the developmental path of zygotic embryos.
Specific combining ability
Specific combining ability is a performance of a parent under consideration, in a specific cross.
Sporic meiosis
Meiosis which occurs at some intermediate time between fertilization and the formation of gametes is called as sporic meiosis.
Meiocytes of plant sporangium are called as sporocytes i.e. micro and mega sporocytes.
Sporophytic self-incompatibility
Sporophytic Self-incompatibility is a type of self-incompatibility which is governed by genotype of pollen producing plant i.e. diploid genotype of the sporophyte generation.
Standard heterosis
When heterosis is estimated over standard commercial hybrid it is called as standard heterosis.
Sub-metacentric chromosome
Chromosome with centromere near the center is called as sub-metacentric chromosome.
Synapsis or syndesis
Synapsis or syndesis is the pairing of two homologous chromosomes.
Synaptonemal complex
The synaptonemal complex is a tripartite, protein structure. It forms between two homologous chromosomes during meiotic division in all animal and plant nuclei.
Synthetic seed
Synthetic seed is encapsulated plant propagule (somatic embryo / shoot bud) in a suitable matrix, containing substances like nutrients, growth regulators, herbicides, insecticides, fungicides and mycorrhizae which will allow and help it to grow into a complete plantlet.
Synthetic variety
Synthetic variety is a variety developed by selecting a number of inbred lines with good general combining ability (gca) , intercrossing them in all possible combinations and mixing the seeds of all the crosses conducted, in equal quantity.
The inner, thin part (layer) of seed coat is called as tegmen
Telocentric chromosome
Chromosome with terminal centromere is called as telocentric chromosome
At the ends of chromosome long stretches of non-coding DNA are present, these are telomers.
Terminal meiosis
Meiosis which occurs before formation of gametes is called as terminal meiosis.
Movement of chaismata towards end of chromosome is called as terminalization.
The outer, thick part (layer) of seed coat is called as testa.
Test cross
Cross of progeny with its recessive parent is called as test cross.
When somatic cell of an organism contain one pair of chromosome in addition to the somatic complement it is called as tetrasomy.
Tissue culture
Plant tissue culture is a technique with which plant cells, tissues or organs are grown on artificial nutrient medium, either static or liquid, under aseptic and controlled conditions.
Ability of a plant cell to divide and differentiate, give rise to develop a particular organ or a whole plantlet is called as totipotency.
Transcription is the process of synthesis of molecule of mRNA from a DNA template.
Transgenic Male Sterility
When the male sterility is induced by the technique of genetic engineering, it is called as transgenic male sterility.
Tricentric chromosome
Chromosome with three cetromeres is called as tricentric chromosome.
Trisomy is a condition where somatic cell of an organism contain three copies of any one chromosome of the haploid complement.
Truthful Seed
Truthful seed is the category of seed produced by private seed companies and is sold under truthful labels.
Useful heterosis
When heterosis is estimated over standard commercial hybrid it is called as useful heterosis.