29978 - Breeding of Herbaceous crops

Learning outcomes

At the end of the course the student gains the knowledge for planning a breeding program aimed at the selection of new varieties. In particular, the student can identify the breeding objectives and the most suitable breeding procedure in relation to the genetic structure of the source populations and to the environmental conditions in which the new varieties will be grown.

Course contents

At the end of the course the student gains the knowledge for planning a breeding program aimed at the selection of new varieties. In particular, the student can identify the breeding objectives and the most suitable breeding procedure in relation to the genetic structure of the source populations and to the environmental conditions in which the new varieties will be grown.

Course contents

A) Prerequisites

The students attending this course have to know the basic aspects of agricultural genetics, herbaceous crops, botany, statistics, entomology and plant pathology. Such a knowledge is provided by the courses followed in the previous three-years degree and by the courses held in the first year, first cycle of this two-years degree.

B) Teaching units

1. Reproductive systems of plants (Total of the teaching unit 5 hours)

Flower characteristics of self-pollinated and cross-pollinated species. Monoecism and dioecism. Self-incompatibility. Agamic propagation.

Knowledge obtained in the teaching unit 1

· The student knows the floral structures and the self-incompatibility mechanisms causing self- and cross-pollination.

2. Response to selection and heritability of quantitative traits (Total of the teaching unit 9 hours)

Response to selection for qualitative and quantitative traits. Analysis of variance applied to quantitative traits. Components of the phenotypic variance: genetic and environmental variances. Components of genetic variance due to additive and dominance effects. Heritability in the broad and in the narrow sense; heritability on an individual and on a mean basis. Utilization of heritability in plant breeding. Selection differential and expected response to selection. Realized heritability.

Knowledge obtained in the teaching unit 2

· The student can apply the analysis of variance in the study of quantitative traits and can partition the phenotypic variance into its components.

· The student can estimate the heritability value and properly utilize this estimate in a breeding work.

3. Breeding procedures for self-pollinated species (Total of the teaching unit 12 hours)

Genetic structure of the natural populations of self-pollinated species. Selfing and homozygosity. Selections within natural populations. Mass and pure line selections. Development of new genetic variation by cross. Choice of the parents and of the selection procedures. Methods of pedigree, bulk and single seed descent. Achievement of pure lines by production of doubled haploids. Use of colchicine and doubling of the chromosome number in the haploids. Backcross: transfer of the dominant and of the recessive alleles. Resistance to pathogens; selection for horizontal and vertical resistances. Utilization of molecular markers in plant breeding. Marker assisted selection (MAS).

Knowledge obtained in the teaching unit 3

· The student can choose and apply the most suitable breeding procedure for a given self-pollinated crop in relation to the source material and the objectives.

4. Breeding procedures for cross-pollinated species (Total of the teaching unit 12 hours)

Genetic structure of the natural populations in relation to the Hardy-Weinberg law. Ecotypes. Recurrent selections to improve populations. Intra-population selections: mass selection, selection for families obtained by selfing and by crossing (test-cross families). Inter-populations selection: reciprocal recurrent selection. Synthetic varieties. Hybrids. Selection of the parental lines and estimate of their general and specific combining ability. Choice of the tester. Production of the commercial hybrid seed. Genetic, cytoplasmic and genetic-cytoplasmic male-sterility.

Knowledge obtained in the teaching unit 4

· The student can choose and apply the most suitable breeding procedure for a given cross-pollinated crop in relation to the source material and the objectives.

· The student knows the various aspects concerning the commercial production of the hybrid seed.

5. Breeding procedures for agamic species (Total of the teaching unit 4 hours)

Clonal selection; cross between clones and selection.

Knowledge obtained in the teaching unit 5

· The student can choose and apply the most suitable breeding procedure for a given agamic crop in relation to the source material and the objectives.

6. Exercises (Total of the teaching unit 18 hours)

The practical exercises mainly concern the analysis of variance for estimating the heritability and the visits to the fields in which the materials under selection are grown. The phenotypic values to be used for the analysis of variance are obtained by measures directly made by the students on plants of populations expressly produced by the teacher; these plants are grown in the didactic field of via Fanin. This direct approach allows the students to appreciate the meaning of genetic variability which is typical for those populations used to carry out selection. The visits to the fields mainly concern populations under selection and the lines or crosses tested in comparative trials, so as to allow the students to understand how, in practice, a selection work is carried out. Two visits will be organized: one to the selection nursery at the experimental farm of UNIBO and one of a seed company near Bologna.

Readings/Bibliography

G. Barcaccia, M. Falcinelli. Genetica e genomica. Volume II. Miglioramento genetico. 2005. Liguori editore, Napoli.

Teaching methods

The course includes lectures and practical exercises. Lectures deal with the aspects concerning the reproductive biology of the herbaceous crops, the estimate and utilization of heritability in plant breeding, and the main breeding procedures which can be used in relation to the available genetic variability and to the objectives. The practical exercises deal with the analysis of variance applied to data obtained by the students and with the calculation of heritability. Moreover, students will visit fields in which materials under selection are grown and comparative trials are made, so as to get a better comprehension of the breeding procedures described during the lectures.

Assessment methods

The final exam is oral and includes 3 questions aimed at ascertaining the knowledge of the theoretical and applied aspects of plant breeding described during the lectures and the practical exercises. The exam is expected to last about 45 minutes.

Teaching tools

For lectures, overhead projector, PC and projector can be used. For practical exercises, the teacher will produce experimental populations to be grown in the field for analysis of the genetic variability.

Office hours

See the website of Roberto Tuberosa

See the website of Marco Maccaferri