Understanding Traditional Plant Breeding Steps

Traditional plant breeding is a method used to improve crops by selecting and breeding plants with desirable traits. It involves several sequential steps aimed at developing new and improved varieties.

The question asks for the correct sequence of the given steps in traditional plant breeding:

• (A) Evaluation of hybrids
• (B) Emasculation of selected parents
• (C) Screening of germplasm
• (D) Hybridization of selected parents
• (E) Release of hybrid variety

Sequencing Traditional Plant Breeding Processes

Let's analyze the typical flow of traditional plant breeding activities to determine the correct order of these steps.

The general steps involved are:

1. Collection of variability (Germplasm collection and screening).
2. Evaluation and selection of parents.
3. Cross hybridization among the selected parents.
4. Selection and testing of superior recombinants/hybrids.
5. Testing, release, and commercialization of new cultivars.

Now, let's map the given steps to this general sequence:

• (C) Screening of germplasm: This is the very first step. It involves collecting and evaluating genetic material (germplasm) to identify plants with useful traits. This corresponds to step 1.
• (B) Emasculation of selected parents: Emasculation is the removal of anthers from a flower before pollen is shed. This is done to prevent self-pollination and facilitate cross-pollination with pollen from the desired male parent. This step is part of the preparation for cross hybridization and happens after selecting parents but before the actual cross.
• (D) Hybridization of selected parents: This is the process of crossing two selected parents to produce hybrids (the first generation, F\(_1\)). This is step 3. Emasculation (B) must occur before hybridization (D) if required for the specific plant species.
• (A) Evaluation of hybrids: After hybridization, the resulting hybrid plants (F\(_1\) generation and subsequent generations) are grown and evaluated for the presence of desired traits. Superior plants are selected. This is part of step 4. This happens after the cross is made.
• (E) Release of hybrid variety: Once a hybrid variety is proven to be stable, superior, and suitable for cultivation through extensive testing, it is released for commercial farming. This is the final step, corresponding to step 5.

Based on this understanding, the logical sequence of the given steps is:

1. Begin by screening the available germplasm (C) to find desirable traits and select suitable parents.
2. Prepare the selected female parent for crossing, which involves emasculation (B) if necessary to avoid self-pollination.
3. Perform the hybridization (D) between the selected and prepared parents by transferring pollen.
4. Grow the resulting offspring (hybrids) and conduct thorough evaluation of hybrids (A) over generations to select the best ones.
5. Finally, after successful testing, proceed with the release of the hybrid variety (E) for commercial use.

Therefore, the correct sequence is (C), (B), (D), (A), (E).

Revision Table: Plant Breeding Sequence

Additional Information on Plant Breeding

Germplasm: Germplasm refers to the sum total of all the genes and their variations present in a crop species and its related wild relatives. Screening germplasm helps breeders find sources of resistance to diseases, pests, tolerance to environmental stresses, and improved yield or quality traits.

Emasculation: This step is crucial in bisexual flowers where self-pollination is likely. Removing the anthers before they mature ensures that the flower will only be pollinated by the desired pollen from the male parent in a controlled cross.

Hybridization: The process of combining desirable traits from two different parents by crossing them. The first generation hybrid (F\(_1\)) often exhibits hybrid vigor or heterosis.

Evaluation and Selection: This involves growing the hybrid generations (F\(_1\), F\(_2\), etc.) and carefully observing them for the desired traits. Selection involves choosing the best individuals or families for further breeding or testing. This often takes multiple generations to achieve stable lines.

Release of Variety: Before a new variety is released to farmers, it undergoes extensive testing in multiple locations and over several seasons to ensure its performance is consistent and superior to existing varieties. It must also meet regulatory requirements.