Tag: improvement if crop varieties

The cochineal insect are introduced into the (Opuntia) prickly pear. The insect destroy the weeds without harming the crop plants. Its one of the biological method as well.

Yeast ferments the sugar present in the dough into carbon dioxide. The ${ CO } _{ 2 }$ released from the yeast fills the dough and increases its volume. Once, the bread has baked, the heat causes the bubbles to break and makes the bread light and fluffy.

• Triticale is a man-made crop developed by crossing wheat and cereal rye. It is probably the only new man-made crop in commercial production. 
• Triticale was found to be more efficient than wheat in utilizing and absorbing nitrogen from the soil. 
• It also produces a 30% higher yield on acid soils and is superior to wheat on copper-deficient soil.

• Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
• Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 

Pure breeding varieties are the one that carries same allele for a particular character and pass the trait without change from one generation to next upon selfing (for example, pure breeding tall (TT) plant carries two copies of “T” allele). Hybrids are the one which carries contrasting allele of a particular gene e.g., hybrid tall plant’s genotype is “Tt”. Incomplete dominance refers to the conditions where none of factors of a gene is dominant; the phenotype of heterozygous dominant individual is blend of dominant and recessive traits. Thus, it is an exception to Mendel’s principle of dominance. Heredity is genetic transmission of characters from parent generation to progeny. Alternative forms of a gene are called alleles e.g., alleles for gene for plant height are “T” and “t”. Thus, the correct answer is option A.

• Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. 
• Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular techniques. 
• Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
• Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 
• Generally, a successful variety is one with a total balance of traits that makes it more profitable for growers. 
• Quality characters vary from one crop to another, e.g., grain size, colour, milling and baking qualities in wheat (Triticum aestivum), cooking quality in rice (Oryza sativa), malting quality in barley (Hordeum vulgare), size, colour, and flavour of fruits, keeping quality of vegetables, protein content in cereals and legumes, lysine content in cereals, methionine and tryptophan contents in pulses, etc.

• Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
• Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 

Presence of three or more sets of chromosomes in an organism is called polyploidy. It is often seen in plants and very rare in animals. It is caused due to the non disjunction of the sister chromatids during the recombination (at meiosis). It can be induced in plants and cell cultures with the help of some chemicals like colchicine. Polyploidy causes variation, as it adds new genomes into a species. It has been widely used in producing hybrids of wheat. Ploidy level also effects some characteristics of plants. For example, higher ploidy leads to the larger cell size. So, the correct answer is B.