Method of Plant Breeding Questions in English

(A) The development of high-yielding and disease-resistant wheat varieties in India,such as the semi-dwarf varieties introduced during the Green Revolution,was primarily achieved through plant breeding techniques.
Specifically,the process involved $Hybridisation$ (crossing genetically different parents) to combine desirable traits and $Mutation$ breeding (using physical or chemical mutagens) to induce genetic variation,which was then selected for superior characteristics.

(D) $Triticale$ is the first man-made cereal crop.
It is produced by crossing wheat ($Triticum$ $aestivum$) with rye ($Secale$ $cereale$).
This intergeneric hybridization combines the high yield and grain quality of wheat with the hardiness and disease resistance of rye.

(A) Breeding for disease resistance is primarily carried out using conventional breeding techniques or mutation breeding.
$1$. Conventional breeding techniques involve hybridization and selection to introduce resistance genes into crop varieties.
$2$. Mutation breeding is the process of inducing mutations artificially using physical agents (like gamma radiation) or chemical agents (like ethyl methanesulfonate) to create genetic variation.
$3$. Radiation breeding is a specific type of mutation breeding where radiation is used as the mutagen. Therefore,$II$ and $III$ are essentially the same category of breeding method.
Since the question asks for the methods,both conventional breeding $(I)$ and mutation breeding ($II$ and $III$) are valid approaches. However,in standard textbook contexts,$I$ and $II$ are often cited as the primary categories. Given the options provided,$I$ and $II$ is the most appropriate choice.

(A) Selection is the oldest method of crop improvement.
Hybridization is the process of crossing two genetically different individuals to produce a hybrid with desirable traits.
Polyploidy involves the presence of more than two sets of chromosomes,which is used to develop new crop varieties,such as $Triticale$.
Mutation breeding is the process of exposing seeds or plant tissues to physical or chemical mutagens to create genetic variability.
Genetic engineering involves the transfer of specific genes from one organism to another to create transgenic plants with desired characteristics.
All the listed methods $(I, II, III, IV, V)$ are standard techniques used in modern plant breeding and crop improvement.

(D) Haploids contain only one set of chromosomes $(n)$.
When these haploid cells are subjected to diploidisation (doubling the chromosome number,often using chemicals like colchicine),they produce individuals that are completely homozygous for all traits.
This is highly advantageous in plant breeding programmes because it allows for the rapid development of pure lines,eliminating the need for multiple generations of self-pollination to achieve homozygosity.
Therefore,the correct option is $D$.

(D) The conventional breeding method for disease resistance involves a systematic series of steps:
$1$. Screening germplasm for resistant sources: Identifying plants that naturally possess resistance genes.
$2$. Hybridization of selected parents: Crossing the resistant plant with a high-yielding or otherwise desirable variety.
$3$. Selection and evaluation of the hybrids: Identifying the progeny that possess both the desired traits and the resistance.
$4$. Testing and release of new varieties: Evaluating the selected hybrids in research fields and farmers' fields before official release.
Since all four steps are essential components of the conventional breeding process,the correct option is $I, II, III$ and $IV$.

(D) Host crop plants can exhibit resistance to insect pests through various mechanisms,including morphological,biochemical,and physiological characteristics.
$(i)$ Morphological characteristics: For example,hairy leaves in cotton provide resistance to jassids,and in wheat,they provide resistance to cereal leaf beetles.
$(ii)$ Biochemical characteristics: For example,in maize,high aspartic acid content,low nitrogen,and low sugar content provide resistance against stem borers.
$(iii)$ Physiological characteristics: Certain physiological traits can also influence the preference or survival of pests on the host plant.
Therefore,all three factors ($I$,$II$,and $III$) contribute to the resistance of crop plants against insect pests.

(A) Sugarcane is an important cash crop. For better yield and economic profit,a sugarcane farmer looks for specific desirable traits in the crop.
These traits include a thick stem (to increase biomass),long internodes (to increase the length of the stalk where sugar is stored),high sugar content (for better quality),and disease resistance (to prevent crop loss).
Therefore,the combination of thick stem,long internodes,high sugar content,and disease resistance is the most ideal for a farmer.

(C) Several South Indian states are able to cultivate $2-3$ crops of rice annually due to the development and use of early-yielding rice varieties. These varieties have a shorter growth cycle,allowing farmers to harvest the crop quickly and plant the next one within the same year,thereby maximizing agricultural productivity.

(C) Cross hybridization is a time-consuming and tedious process because it involves the careful and manual techniques of emasculation (removal of anthers) and bagging (covering the stigma) to ensure that only the desired pollen grains are transferred to the stigma of the selected female parent plant.

(D) Air layering,also known as $gootee$,is a method of vegetative propagation used for woody plants.
In this process,a portion of the bark is removed from a stem,covered with moist moss or soil,and wrapped to encourage root development while the stem is still attached to the parent plant.
$Litchi$ $(Litchi chinensis)$ is a classic example of a plant where air layering is commonly practiced to produce new,genetically identical plants.
Bamboo is typically propagated by rhizome division,while grapevines are often propagated by stem cuttings.

(B) Grafting is a horticultural technique where tissues of plants are joined so as to continue their growth together.
In this process,the upper part of the grafted plant is called the $Scion$,and the lower part (which has the root system) is called the $Stock$.
The $Scion$ determines the characteristics of the aerial parts of the plant,including the flowers,leaves,and fruits.
Therefore,the genotype of the $Scion$ is responsible for the quality,size,and type of fruits produced by the grafted plant.

(C) In grafting,two different plants are joined together so that they grow as a single plant.
An improved method of grafting involves making oblique cuts on both the stock and the scion to increase the surface area for cambial contact.
Additionally,in certain advanced techniques like approach grafting,both the scion and the stock plants are allowed to remain intact with their own root systems until the union is successful.
Therefore,both the preparation of oblique cuts and the technique of keeping plants intact are considered features of improved grafting methods.

(D) Outbreeding usually takes place between members of different varieties or strains and in certain plants of closely related species. The resulting progeny is known as a hybrid. When the hybrid exhibits phenotypes showing characteristics that are superior to either of the parental stocks,this phenomenon is known as hybrid vigour or heterosis (as defined by Shull).

(A) Hybrid vigour or heterosis is the phenomenon where the progeny of a cross between two genetically different inbred lines shows superior traits compared to the parents.
Maize $(Zea \, mays)$ is the classic model organism used extensively in plant breeding to study hybrid vigour due to its high degree of cross-pollination and the ease of creating inbred lines.

(C) Green manure is prepared by incorporating green leguminous plants into the soil to improve soil fertility.
$Crotalaria$ $juncea$ (sunnhemp) is a well-known leguminous crop used for green manuring.
Other examples include $Sesbania$ $aculeata$ (daincha) and $Cyamopsis$ $tetragonoloba$ (cluster bean).

(B) Disease resistance in crops is primarily achieved through plant breeding techniques.
One of the most effective methods is crossing cultivated crop varieties with their wild relatives.
Wild varieties often possess natural resistance genes against various pathogens,pests,and environmental stresses.
By hybridizing these wild varieties with high-yielding cultivated varieties,breeders can introduce these beneficial resistance genes into the new crop lines.

(A) Wonder wheat is a high-yielding variety of wheat that can produce up to $18$ tonnes per hectare. It is characterized by having approximately $200$ grains per stalk. This variety was developed by the International Maize and Wheat Improvement Center $(CIMMYT)$ located in Mexico.

(D) Plant breeding is the purposeful manipulation of plant species in order to create desired plant types that are better suited for cultivation,give better yields,and are disease resistant.
Modern plant breeding is primarily carried out by using the method of $Hybridization$ followed by $Selection$.
In this process,two genetically different parents are crossed to produce hybrids,and then the best-performing individuals are selected from the progeny to develop new and improved varieties.

(C) Traditional hybridisation is a conventional plant breeding method. It involves the crossing of two genetically different individuals to produce offspring with desirable traits. However,a major limitation of this method is that it often leads to the inclusion and multiplication of undesirable genes along with the desired genes,as it involves the transfer of large segments of $DNA$. Therefore,option $C$ is incorrect because it describes a feature of modern biotechnology (recombinant $DNA$ technology) rather than traditional hybridisation.

(B) Biofortification is the process of breeding crops to increase their nutritional value.
This includes improving protein content,vitamin content,and micronutrient and mineral content.
Improving resistance to diseases is an objective of plant breeding for disease resistance,not specifically biofortification.
Therefore,the correct answer is $B$.

(N/A)

Cutting	Grafting
$(1)$ Cut pieces of root or stem are planted in moist soil.	$(1)$ $A$ union of two different plants is established.
$(2)$ They can be transplanted to other locations.	$(2)$ No need for transplantation of the combined unit.
$(3)$ Cut pieces of stem or root develop adventitious roots.	$(3)$ It is practiced in plants that have a poor or weak root system.
$(4)$ Aerial parts of the cut stem or root sprout.	$(4)$ The rooted part is the stock and the grafted part is the scion.
$(5)$ The resulting plant maintains the same genetic characters as the parent.	$(5)$ The resulting plant exhibits the characters of the scion plant.

(A) The process of plant breeding for a genetically diverse crop variety follows a specific sequence:
$1.$ $\text{Collection of variability}$ $(IV)$: The first step is to collect all the available alleles of all the genes in a given crop.
$2.$ $\text{Evaluation and selection of parents}$ $(V)$: The germplasm is evaluated to identify plants with desirable traits, and these are selected as parents.
$3.$ $\text{Cross-hybridization among the selected parents}$ $(I)$: The selected parents are cross-hybridized to combine the desired traits into a single progeny.
$4.$ $\text{Selection and testing of superior recombinants}$ $(III)$: The progeny is evaluated to select plants that show the desired combination of traits.
$5.$ $\text{Testing, release, and commercialization of new cultivars}$ $(II)$: The selected lines are tested in research fields and then in farmers' fields before being released as a new variety.
Therefore, the correct sequence is $IV \rightarrow V \rightarrow I \rightarrow III \rightarrow II$.

(C) The collection of variability is the first and fundamental step in plant breeding.
Genetic variability is the root cause of all variations in plants.
By collecting germplasm (the entire collection of plants/seeds having all the diverse alleles for all genes in a given crop),breeders can identify and utilize the desired traits.
Therefore,the collection of variability serves as the foundation for genetic variation.

(A) The entire collection of plants or seeds having all the diverse alleles for all genes in a given crop is known as the germplasm collection. This collection serves as the fundamental resource for plant breeding programs,allowing breeders to select and incorporate desirable traits into new crop varieties.

(D) The process of plant breeding involves several steps to develop new crop varieties.
$1$. Selection and testing of superior recombinants is a crucial step.
$2$. During this phase,the progeny obtained from hybridization are evaluated to identify those that possess the desired combination of traits.
$3$. This evaluation is conducted scientifically to ensure the reliability of the results.
$4$. The ultimate goal is to select individuals that exhibit traits superior to both parents (heterosis or hybrid vigor).
Therefore,all the given statements are correct.

(A) The semi-dwarf varieties of wheat developed during the Green Revolution in India include Sonalika and Kalyan Sona. Thus,$P$ matches with $I$ and $IV$.
The semi-dwarf varieties of rice developed include $IR-8$,Jaya,Taichung Native-$I$,and Ratna. Thus,$Q$ matches with $II, III, V,$ and $VI$.
Therefore,the correct matching is $(P - I, IV)$ and $(Q - II, III, V, VI)$.

(A) During the period from $1960$ to $2000$,wheat production in India increased from $11$ million tonnes to $75$ million tonnes due to the Green Revolution. This significant increase was primarily driven by the development and introduction of high-yielding varieties of wheat and rice.

(D) Norman $E$. Borlaug,an American agronomist,is known as the 'Father of the Green Revolution'. He developed semi-dwarf wheat varieties at the International Maize and Wheat Improvement Center $(CIMMYT)$ in Mexico. These varieties,such as $Sonalika$ and $Kalyan Sona$,were high-yielding and disease-resistant,which significantly increased wheat production globally.

(C) The acronym $IRRI$ stands for the $International$ $Rice$ $Research$ $Institute$.
This institute is a non-profit agricultural research and educational organization,headquartered in $Los$ $Baños$,$Laguna$,in the $Philippines$.
It was established in $1960$ with the goal of improving the well-being of rice farmers and consumers,and protecting the rice-growing environment.

(B) The International Maize and Wheat Improvement Center,commonly known by its Spanish acronym $CIMMYT$ (Centro Internacional de Mejoramiento de Maíz y Trigo),is a non-profit research and training institution dedicated to the development of improved varieties of wheat and maize. It is headquartered in El Batán,Texcoco,which is located in Mexico.

(B) The high-yielding varieties of rice,known as $Jaya$ and $Ratna$,were developed in India during the Green Revolution.
These varieties were bred to increase agricultural productivity and ensure food security.
Therefore,the correct option is $B$.

(C) Sonalika and Kalyan Sona are semi-dwarf, high-yielding varieties of wheat $(Triticum \text{ } aestivum)$.
These varieties were introduced in India during the mid-$1960$s as part of the Green Revolution to increase food production.
They are known for their disease resistance and high productivity, which significantly contributed to the success of the Green Revolution in India.

(D) The correct option is $D$. All the given statements regarding disease-resistant plants are correct:
$1$. Disease-resistant plants help in reducing the dependence on the use of chemical fungicides and bacteriocides,which is beneficial for the environment.
$2$. Resistance of the host plant is defined as the ability of the plant to prevent the disease from occurring by inhibiting the growth or entry of the pathogen.
$3$. This resistance is primarily determined by the genetic constitution (genotype) of the host plant,which can be improved through plant breeding techniques.

(D) Traditional plant breeding has been practiced for thousands of years,since the beginning of human civilization.
These methods primarily rely on the selection of plants with desirable traits and the hybridization (crossing) of these selected plants to produce offspring with improved characteristics.
Mutation breeding is considered a modern technique used when desired traits are not available in the existing germplasm.
Therefore,traditional breeding methods involve both hybridization and selection.

(A) Pusa Shubhra and Pusa Snowball $K-1$ are well-known disease-resistant varieties of cauliflower ($Brassica$ $oleracea$ var. $botrytis$).
These varieties were developed through plant breeding techniques to provide resistance against black rot and curl blight black rot diseases.

(C) Mutation breeding is a technique used to induce genetic variation in crops. In the case of mung bean ($Vigna$ $radiata$),mutation breeding was successfully used to induce resistance to yellow mosaic virus and powdery mildew. This is a classic example of crop improvement mentioned in the $NCERT$ textbook under the topic of plant breeding.

(C) Parbhani Kranti is a specific variety of Okra (Abelmoschus esculentus) developed through mutation breeding. It is known for its resistance to the yellow vein mosaic virus. Therefore,it is associated with Okra.

(A) Plant breeding for developing resistance to insect pests is a crucial strategy in agriculture. In maize,resistance to stem borer insects is specifically associated with high aspartic acid,low nitrogen,and low sugar content. These biochemical characteristics make the plant less attractive or unsuitable for the pests to feed on or thrive,thereby providing natural resistance.

(D) Insect resistance in host crop plants is the result of a combination of morphological,biochemical,and physiological characteristics.
$1$. Morphological characteristics: For example,hairy leaves in cotton plants are associated with resistance to jassids.
$2$. Biochemical characteristics: For example,high aspartic acid,low nitrogen,and sugar content in maize lead to resistance against maize stem borers.
$3$. Physiological characteristics: Internal plant processes that inhibit the growth or survival of insects.
Therefore,the correct option is $D$.

(B) In wheat,the development of solid stems leads to non-preference by the stem sawfly. This is a classic example of morphological resistance in plant breeding where specific structural traits prevent pest infestation. Therefore,the correct answer is $B$.

(A) The variety 'Parbhani Kranti' of okra (Abelmoschus esculentus) was developed through mutation breeding. It was specifically bred to provide resistance against the yellow mosaic virus. Therefore,the correct option is $A$.

(B) Mutation breeding is a technique used to induce genetic variation in crops by exposing them to physical or chemical mutagens.
Among physical mutagens,ionizing radiations such as Gamma rays are most commonly and effectively used to induce mutations in plant breeding programs.
Gamma rays have high penetrating power,which allows them to reach the plant tissues effectively to cause $DNA$ damage,leading to mutations.
Therefore,Gamma rays are the primary choice for inducing mutations in crops.

(C) Hybridisation is the process of crossing two genetically different individuals to produce a hybrid.
When the crossing occurs between two different species of the same genus,it is called interspecific hybridisation.
When the crossing occurs between two different genera of the same family,it is called intergeneric hybridisation.
Therefore,the correct answer is intergeneric.

(D) $Jagannath$ is a mutant variety of $Rice$.
$NP \ 836$ is a mutant variety of $Wheat$.
$Indore \ 2$ is a mutant variety of $Cotton$.
$Regina \ II$ is a mutant variety of $Cabbage$,not $Cauliflower$.
Therefore,the pair $Regina \ II$ - $Cauliflower$ is mismatched.

(D) In plant breeding for disease and pest resistance,biochemical characteristics are often used to develop resistant varieties.
In maize,high levels of aspartic acid,low nitrogen,and low sugar content are known to provide resistance against the attack of stem borers.
These biochemical traits make the plant less attractive or unsuitable for the larvae of stem borers to feed and survive.