• Plant Breeding is the science that helps change the genetic makeup of plants for maximum economic output for human use.
  • The basic chromosome/genomic number is X.
  • The genetic chromosome number is denoted as n.
  • The haploid number of Triticum aestivum is n = 21.
  • Aneuploid refers to a heteroploid condition where one or few chromosomes are missing from 2n.
  • Monosomic hypoploid is represented as 2n - 1.
  • Double monosomic is represented as 2n - 1 - 1.
  • Nullisomic is represented as 2n - 2.
  • A hyperploid has one extra chromosome, termed trisomic (2n + 1).
  • Double trisomic is represented as 2n + 1 + 1.
  • The polyploidy level in the embryo and endosperm of seed is 3n.
  • The polyploidy level of the testa and pollen mother cell of seed is 2n.
  • The polyploidy level in the endosperm of Triticum aestivum is 63.
  • Triploids are useful for producing seedless fruits.
  • Wheat, cotton, tobacco, and oat are classified as allopolyploids.
  • The term “primary centres of origin” was proposed by Vavilov.
  • Apomixis refers to the development of vegetative embryos without fertilization.
  • Parthenocarpy is the development of fruit without fertilization.
  • Parthenogenesis describes when an embryo originates from an unfertilized egg.
  • The progeny of a single cross-fertilized heterozygous individual is called an inbred.
  • A male sterile line is referred to as an A-line.
  • The progeny of a single plant obtained by asexual reproduction is known as a clone.
  • A single gene that affects more than one character is known as pleiotropy.
  • Back cross involves repeated crossing of hybrid progeny back to one of its parents.
  • An F1 x homozygous recessive parent is called a test cross.
  • Intra-specific hybridization occurs between two plants of different varieties.
  • Self-pollination occurs when pollen grains from another flower fall on the receptive stigma of the same flower.
  • Self-pollinated species are also known as autogamous species.
  • Cross pollination or allogamy occurs when pollen from one plant is transferred to the receptive stigmas of another plant.
  • Rice, wheat, buckwheat, and oat are examples of self-pollinated crops.
  • Maize, pearl millet, black mustard, and sunflower are examples of cross-pollinated crops.
  • Commonly cross-pollinated crops include safflower, arhar, cotton, and sorghum.
  • Continuous inbreeding (selfing) leads to homozygosity.
  • The single seed descent method is a method of self-pollination.
  • Mass selection is always based on phenotype.
  • The oldest selection method of crop improvement is mass selection.
  • The concept of a pure line was given by Johnson.
  • The progeny of a single homozygous self-pollinated crop is known as a pure line.
  • The pure line selection method is used for breeding wheat.
  • Bulk refers to the selection procedure where the segregating population of self-pollinated species is grown without selections.
  • The most commonly used method for selection from segregating generations of crosses in self-pollinated crops is the pedigree method.
  • The method that does not handle segregating populations is the bulk method.
  • The pedigree method is used for improving specific traits such as plant height and disease resistance.
  • Multiline breeding is widely exploited in the crop wheat.
  • The method that does not provide an opportunity to practice selection for superior plants until F5 generations is the single seed descent method.
  • The commonly used method for transferring disease resistance from one variety to another is the back cross method.
  • Clonal selection is mostly used in the crop ginger.
  • The parent used only once in back cross breeding is referred to as the donor.
  • The bulk method was first used by Nilson Ehle in 1908.
  • Progeny selection is also known as the ear-to-row method of selection.
  • The methods used for handling the segregating generation are pedigree, bulk, and single seed descent method.
  • A breeding method appropriate for improving a good variety is the back cross method.
  • The method in which desirable scattered favorable genes are selected in different plants in each generation is called recurrent selection.
  • The breeding method that is not appropriate for cross-pollinated crops is pure line selection.
  • A cross between two genetically different homozygous plants is known as a hybrid or F1.
  • A x B = F1 refers to a single cross hybrid.
  • (A x B) x (C x D) represents a double cross hybrid.
  • The equation selected variety/line/clone x open pollinated variety results in a top cross.
  • The equation (A x B) x OP variety results in a double top cross.
  • A variety produced by crossing all combinations of several lines that combine well with each other is called a synthetic variety.
  • A synthetic variety is maintained by self-pollination.
  • A variety produced by mixing the seeds of several phenotypically outstanding lines (varieties) is known as a composite variety.
  • A composite variety is developed through cross-pollination.
  • The hybrid variety was first exploited in maize.
  • Chasmogamy is a mechanism of self-pollination in which flowers open only after pollination has taken place.
  • Chasmogamy is found in rice, moong, and oat.
  • Pollination and fertilization that occur before the opening of a flower is termed cleistogamy.
  • Cleistogamy is found in wheat and barley.
  • When male and female flowers of a hermaphrodite flower mature at different times, it is referred to as dichogamy.
  • Protogyny occurs when the female matures before the male.
  • Gaitonogamy is when pollen from a flower of one plant falls on the stigmas of other flowers of the same plant.
  • A plant with both male and female flowers is termed monoecious.
  • A plant with male and female flowers occurring on different plants is termed dioecious.
  • Maize is classified as a monoecious plant.
  • Papaya is classified as a dioecious plant.
  • The first intergeneric hybrid was Raphino brassica (Radish x Cabbage).
  • The hybrid variety of rice is developed using GMS and CGMS lines.
  • Double cross hybrids of maize are developed using CGMS lines.
  • The exploitation of hybrids in tobacco was carried out by Koelreuter.
  • The superiority of F1 hybrids over both of its parents is termed as heterosis.
  • The term “heterosis” was given by Shull.
  • The average value for a character of the two parents of the concerned hybrid is called mid parent or average heterosis.
  • When heterosis is estimated over the superior or better parent, it is called heterobeltiosis.
  • When the superiority of the hybrid is compared to the standard commercial check variety, it is termed as economic heterosis.
  • The exchange of chromatin between non-sister chromatids of homologous chromosomes is known as crossing over.
  • Inbreeding depression refers to the loss or decrease in vigor and fitness as a result of inbreeding.
  • Highly inbreeding depression is found in alfalfa and carrot.
  • A sudden heritable change in any characteristics of an organism is known as a mutation.
  • X-rays were first used as a mutagen by Müller.
  • The unit in which mutation occurs is called a muton.
  • A mutagen is a chemical or physical agent that greatly enhances the frequency of mutation.
  • Triticale is a man-made cereal.
  • The cultivated banana is classified as an autotriploid.
  • The removal of the entire tassel (male inflorescence of maize) before pollen to initiate cross hybridization is called detasseling.
  • A condition where either pollen is absent or non-functional in flowering plants is known as male sterility.
  • When pollen sterility is caused by cytoplasmic genes, it is termed cytoplasmic male sterility (CMS).
  • An important male sterility source of sorghum is Tift 60.
  • Ethrel is used as a gametocide for wheat, rice, and sugarbeet.
  • Wheat is classified as an allohexaploid.
  • Sugarcane, cotton, and Brassica are classified as autopolyploids.
  • Potato is classified as an autotetraploid.
  • Brassica nigra evolved from B. compestris x B. oleracia.
  • Brassica juncea evolved from B. compestris x B. nigra.
  • Polygenic traits are characters governed/controlled by several genes, each having a small individual effect.
  • The natural genetic engineer is Agrobacterium.