Botany : Plant Breeding
Choose the Correct Answers
1. Assertion: Genetic variation provides the raw material for selection
Reason: Genetic variations are differences in genotypes of the individuals.
a) Assertion is right and reason is wrong.
b) Assertion is wrong and reason is right.
c) Both reason and assertion is right.
d) Both reason and assertion is wrong.
2. While studying the history of domestication of various cultivated plants _______ were recognized earlier
a) Centres of origin
b) Centres of domestication
c) Centres of hybrid
d) Centres of variation
3. Pick out the odd pair.
a) Mass selection – Morphological characters
b) Purline selection - Repeated self pollination
c) Clonal selection - Sexually propagated
d) Natural selection - Involves nature
4. Match Column I with Column II
Column I : Column II
i) William S. Gaud I) Heterosis
ii) Shull II) Mutation breeding
iii) Cotton Mather III) Green revolution
Muller and Stadler IV) Natural hybridization
a) i – I, ii – II, iii – III, iv – IV
b) i – III, ii – I, iii – IV, iv – II
c) i – IV, ii – II, iii – I, iv – IV
d) i – II, ii – IV, iii – III, iv – I
5. The quickest method of plant breeding is
d) Mutation breeding
6. Desired improved variety of economically useful crops are raised by
a) Natural Selection
7. Plants having similar genotypes produced by plant breeding are called
8. Importing better varieties and plants from outside and acclimatising them to local environment is called
9. Dwarfing gene of wheat is
a) pal 1
b) Atomita 1
c) Norin 10
d) pelita 2
10. Crosses between the plants of the same variety are called
b) inter varietal
c) intra varietal
d) inter generic
11. Progeny obtained as a result of repeat self pollination a cross pollinated crop to called
a) pure line
b) pedigree line
c) inbreed line
12. Jaya and Ratna are the semi dwarf varieties of
13. Which one of the following are the species that are crossed to give sugarcane varieties with high sugar, high yield, thick stems and ability to grow in the sugarcane belt of North India?
a) Saccharum robustum and Saccharum officinarum
b) Saccharum barberi and Saccharum officinarum
c) Saccharum sinense and Saccharum officinarum
d) Saccharum barberi and Saccharum robustum
14. Match column I (crop) with column II (Corresponding disease resistant variety) and select the correct option from the given codes.
Column I Column II
I) Cowpea i) Himgiri
II) Wheat ii) Pusa komal
III) Chilli iii) Pusa Sadabahar
IV) Brassica iv) Pusa Swarnim
a) I:iv, II:iii, III:ii, IV:i
b) I:ii, II:i, III:iii, IV:iv
c) I:ii, II:iv, III:i, IV:iii
d) I:i, II:iii, III:iv, IV:ii
15. A wheat variety, Atlas 66 which has been used as a donor for improving cultivated wheat, which is rich in
16. Which one of the following crop varieties correct matches with its resistance to a disease?
Variety Resistance to disease
a) Pusa Komal - Bacterial blight
b) Pusa Sadabahar - White rust
c) Pusa Shubhra - Chilli mosaic virus
d) Brassica - Pusa swarnim
17. Which of the following is incorrectly paired?
a) Wheat - Himgiri
b) Milch breed - Sahiwal
c) Rice - Ratna
d) Pusa Komal - Brassica
18. Match list I with list II
List I : List II
i) Free living N2 a) Aspergillus
ii) Symbiotic N2 b) Amanita
iii) P Solubilizing c) Anabaena azollae
iv) P Mobilizing d) Azotobactor
a. ic, iia, iiib, ivd
b. id, iic, iiia, ivb.
c. ia, iic, iiib, ivd
c. ib, iia, iiid, ivc.
Answer the following questions
19. Differentiate primary introduction from secondary introduction.
Introduced variety is well adapted to the new environment without any alternation to the original genotype.
Introduced variety is subjected to selection to isolate a superior variety and hybridized with a local variety to transfer one or a few characters to them.
Example : Tea varieties collected from China and North East India initially grown in Botanical Garden of Kolkata and then introduced to different parts of india.
20. How are microbial innoculants used to increase the soil fertility?
Answer: (i) Biofertilizers are defined as preparations containing living cells or latent cells of efficient strains of microorganisms that help crop plants uptake of nutrients by their interactions in the rhizosphere when applied through seed or soil.
(ii) Biofertilizers are also called as microbial cultures, bioinoculants, bacterial inoculants or bacterial fertilizers.
(i) They are efficient in fixing nitrogen, solubilising phosphate and decomposing cellulose.
(ii) They are designed to improve the soil fertility, plant growth, and also the number and biological activity of beneficial microorganisms in the soil.
(iii) They are ecofriendly organic agro inputs and are more efficient and cost effective than chemical fertilizers.
(i) Bio-fertilisers containing rhizobium bacteria are called rhizobium bio-fertilizer culture.
(ii) They are symbiotic bacteria living inside the root nodules and convert the atmospheric nitrogen into a bio available form to the plants.
(iii) This nitrogen fixing bacterium when applied to the soil undergoes multiplication and fixes the atmospheric nitrogen in the soil.
(iv) Rhizobium is best suited for the paddy fields which increase the yield by 15 - 40%.
Azolla is a free-floating water fern that fixes the atmospheric nitrogen in association with nitrogen fixing blue green alga Anabaena azolla. It is used as a bio-fertilizer for wetland rice cultivation and is known to contribute 40 - 60 kg/ha/crop.
(i) Arbuscular mycorrhizae (AM) is formed by the symbiotic association between certain phycomycetous fungi and angiosperm roots.
(ii) They have the ability to dissolve the phosphates found in abundance in the soil and provides necessary strength to resist disease, germs and unfavourable weather conditions. It also assures water availability.
21. What are the different types of hybridization?
Answer: According to the relationship between plants hybridization is divided into.
(i) Intravarietal hybridization - The cross between the plants of same variety. Such crosses are useful only in the self-pollinated crops.
(ii) Intervarietal hybridization - The cross between the plants belonging to two different varieties of the same species and is also known as intraspecific hybridization. This technique has been the basis of improving self-pollinated as well as cross pollinated crops
(iii) Interspecific hybridization - The cross between the plants belonging to different species belonging to the same genus is also called intragenic hybridization. It is commonly used for transferring the genes of disease, insect, pest and drought resistance from one species to another.
Example: Gossypium hirsutum x
(iv) Intergeneric hybridization - The crosses are made between the plants belonging to two different genera. The disadvantages are hybrid sterility, time consuming and expensive procedure.
Example: Raphanobrassica, Triticale.
22. Explain the best suited type followed by plant breeders at present?
Answer: Conventional plant breeding methods resulting in hybrid varieties had a tremendous impact on agricultural productivity over the last decades. It develops new plant varieties by the process of selection and seeks to achieve expression of genetic material which is already present within the species.
The following are the types of conventional plant breeding methods :
(i) Plant Introduction method
(ii) Selction method
(iii) Hybridization method
(iv) Heterosis method
(v) Mutation Breeding method
(vi) Green Revolution method
23. Write a note on heterosis.
Answer: (i) Heterosis (hetero – different, sis – condition ) G.H. Shull was the first scientist to use the term heterosis in 1912.
(ii) The superiority of the F1 hybrid in performance over its parents is called heterosis or hybrid vigour.
(iii) Vigour refers to increase in growth, yield, greater adaptability of resistance to diseases, pest and drought.
(iv) Vegetative propagation is the best suited measure for maintaining hybrid vigour, since the desired characters are not lost and can persist over a period of time.
Depending on the nature, origin, adaptability and reproducing ability heterosis can be classified as :
(i) Euheterosis : This is the true heterosis which is inherited and is further classified as :
(a) Mutational Euheterosis - Simplest type of euheterosis and results from the sheltering or eliminating of the deleterious, unfavourable often lethal, recessive, mutant genes by their adaptively superior dominant alleles in cross pollinated crops.
(b) Balanced Euheterosis - Well balanced gene combinations which is more adaptive to environmental conditions and agricultural usefulness.
(ii) Psuedoheterosis: Also termed as luxuriance. Progeny possess superiority over parents in vegetative growth but not in yield and adaptation, usually sterile or poorly fertile.
24. List out the new breeding techniques involved in developing new traits in plant breeding.
Answer: In the milestones of plant breeding methods Genetic Engineering, Plant tissue culture, Protoplasmic fusion or somatic hybridisation, Molecular marking and DNA finger printing are some of the modern plant breeding tools used to improve the crop varieties.
NBT - New Breeding Techniques.
NBT are a collection of methods that could increase and accelerate the development of new traits in plant breeding. These techniques often involve genome editing, to modify DNA at specific locations within the plants to produce new traits in crop plants. The various methods of achieving these changes in traits include the following.
(i) Cutting and modifying the genome during the repair process by tools like CRISPR / Cas.
(ii) Genome editing to introduce changes in few base pairs using a technique called Oligonucleotide-directed mutagenesis (ODM).
(iii) Transferring a gene from an identical or closely related species (cisgenesis).
(iv) Organising processes that alter gene activity without altering the DNA itself (epigenetic methods).
Acclimatization : The adaptation of an individual to a changed climate or the adjustment of a species or a population to a changed environment over a number of generations.
Agronomy : Science of farming
Anthesis : Period of opening of flower.
Certified seed : Seed produced from the foundation or certified seed under the regulation of a legally constituted agency.
Germplasm Collection : The entire collection (of plants / seeds) having all the diverse alleles for all genes in a given crop is called germplasm collection.
Non recurrent parent : The parent of a hybrid that is not again used as a parent in backcrossing
Pure-Line: Progeny of a single self-fertilised homozygous individual.
Quarantine : Strict isolation imposed to prevent the spread of disease
Strain : A group of similar individuals from a common origin.