Plant Science 446/546

Plant Science 446/546

Exam #3, 1994

Ag.Sci Room 339

9:30 am to 10:20 am

Name :

Answer all 10 questions

A total of 100 points are available

Points available from each question are shown in bold parenthesis

try to be as brief and concise as possible

Please write in a lodgeable form

Show all necessary working and calculations

Make sure that any additional paper used is

inclosed along with the test paper

1a. The greenhouse committee at the College of Agriculture has just received $1,000,000 to build additional greenhouses. As you might expect, there has been tremendous demand made from faculty wanting space in the new facility. As a result you have been asked to list five breeding operations you intend to use the area requested for plant breeding [5 points].

1b. Parental selection can generally be divided into two different types. List the types and, briefly, indicate differences between types [2 points].

1c. Describe the main features of North Carolina I, North Carolina II and Diallel crossing designs [3 points].

NC(I) :

NC(II) :

Diallel :

1d. Explain the terms in the model for the analysis of a Griffing Diallel:

Yijk = μ + gi + gj + sij + eijk

and indicate the importance of these terms and Griffing analysis in selecting superior parental lines [5 points].

2a. Briefly, outline the main objective behind growing field trials in a plant breeding program [2 points].

2b. In 1995, the Plant Science Farm Parker Farm is to be sold for housing development. To replace this research facility, the College of Agriculture has purchased a farm near Genesee called the Allroks Farm. Neither you, nor anyone else, has ever grown research plots on this previously commercial farm. List four factors that you would look for to identify an area to plant your 1995 breeding plots [4 points].

2c. Briefly outline the major reason for multiple location trials in a plant breeding program [1 point].

List four problems that may be encountered in organizing and carrying out `off station' trials [2 points].

3a. What is the most important advantage of employing good experimental design in a plant breeding program [2 points].

3b. Identify one aspect of a plant breeding selection scheme where unreplicated designs (UR), randomized complete block designs (RCB) and split plot (SP) designs could be the appropriate experimental design of choice [3 points].

UR :

RCB :

SP :

3c. The yield performance of ten spring barley breeding lines were assessed in 15 different environments. After correcting the yield data to Kg/plot adjusted to 10% moisture content, a "Finley and Wilkins" style joint regression analysis was carried out. Results of genotype mean yield (MEAN) and environmental sensitivity (SENS) of the 10 cultivars are shown below:

Genotypes MEAN SENS

BJ.14.2.45 34.5 1.45

BJ.15.23.15 19.1 0.04

BJ.35.11.21 25.5 1.35

BJ.35.11.23 29.3 1.11

BJ.65.12.7 44.2 1.72

BJ.72.33.47 29.4 0.76

BJ.99.34.1 33.6 0.22

BJ.101.34.26 32.8 1.66

BJ.113.1.36 27.4 0.77

BJ.121.33.91 34.1 0.73

You need to select two lines for entry into the Western Regional Barley Trial next year. Based on the above results, which would you select and explain, briefly, your choice [4 points].

First Choice :

Second Choice :

4a. You have been appointed as Assistant Professor/Plant Breeder in the Crops Division of McDonalds University in Frysville, MD. It appears that the breeding program has been trying to select improved genotypes with decreased sugar content in the tubers. However, in the 10 years previous to your appointment, there appears to have been no genetic improvement resulting from breeding. Outline three reasons that could individually, or in combination, have caused this non-response [6 points].

4b. Briefly, explain the main features of the three stages of selection, early generation selection (EGS), intermediate generation selection (IGS) and advanced generation selection (AGS) [6 points].

EGS :

IGS :

AGS :

4c. In a Douglas Fir breeding program you have only sufficient resources to screen segregants from two cross each year. However, in 1995, you have been provided data of family mean (MEAN), phenotypic variance (VAR), and narrow-sense heritability (h2) from six crosses. From these three statistics determine which two crosses you will put your efforts in 1995 assuming that you will select at only the 10% level (Hint : i = 1.13 + 0.73 x log10(1/k)) and explain, briefly, your choices [8 points].

Cross code MEAN VAR h2

DF.33.111 22.3 16.7 0.45

DF.66.123 24.6 14.3 0.51

DF.97.37 28.1 6.3 0.47

DF.97.332 26.1 15.3 0.11

DF.99.1 22.5 10.2 0.84

DF.99.131 18.9 26.1 0.75

Choice #1 :

Choice #2 :

4d 4000 F3 lentil breeding lines were evaluated for yield and the highest yielding 500 genotypes selected. The average yield of the 500 selection was 1429 lb/a while the average yield of the discard genotypes was 1204 lb/a. A random sample from the discards and the 500 selected lines were grown in a properly designed F4 trial where the average yield of the random genotypes was 1199 lb/a and the yield of the selected 500 lines was 1362 lb/a. Determine the narrow-sense heritability for yield at the F3 in lentil [4 points].

5. "Costalot", the new University of Idaho computer store has a giant 1% off sale on computer software and particularly plant breeding software. You therefore decide to purchase a package to handle and help manage your breeding program. Indicate five operations you would like the software to perform or features included in the new software [6 points].

6a. At least four types of mutation can occur in plants. Name four types and briefly describe the features of each type [4 points].

6b. Briefly, outline two difficulties that might be problematical when using mutagenesis in a plant breeding program [2 points].

7a. Interspecific and intergeneric hybridization can sometimes be useful technique in plant breeding by introgression of characters and genes from different species. In an interspecific cross between Brassica napus and B.campestris, there was no evidence that any B.napus egg cells had been fertilized. List three reasons that could have caused this non-fertilization [3 points].

7b. Producing homozygous lines using haploidy can also be a useful tool in plant breeding. Outline four reasons why using haploidy techniques as a routine procedure in a practical barley breeding program may not be feasible [4 points].

7c. A cross is made between two barley lines. One parent is tall and mildew resistant and the other is short and mildew susceptible. Height and mildew resistance are each controlled by single genes. If 200 doubled haploids were produced from heterozygous F1 plants from a cross between a tall resistant and a short susceptible, how many of the doubled haploids would you expect to be short and mildew resistance [1 point].

8. List three reasons why new cultivars in the year 2024 might not all have been developed using only genetic transformation techniques [5 points].

9a. In a high diastase barley breeding program it is known that the correlation between yield and diastatic power is r = 0.60. In this breeding program 3000 doubled haploids are evaluated for yield and diastatic power in a properly designed field trial. If you which to retain approximately the "best" 150 lines what proportion would your discard based on yield and what proportion would you discard based on diastase to achieve this selected number [4 points].

% selected for yield

% selected for diastase

9b. Margaret McThatcher, the famous Scottish potato breeder who did all her selection based only on government policy, has finally (after 45 years of breeding) developed a genotype that might be suitable as a new cultivar. List three things that Maggie must ensure before making a variety submission [3 points].

9c. Maggie is hoping to have a prosperous retirement after working 45 years for a miserly British Civil Service. Outline two methods that Maggie could use to protect his cherished cultivar from being stolen by Hilary Clinton to pay for proposed health care [2 points].

9d. Although Maggie has never actually seen her new wonder cultivar, her political advisors have told her that the clone a good Conservative, is early maturing, has very long, red skinned and yellow flesh tubers and produced wonderful french frys. Help Maggie by suggesting a suitable name for this cultivar and explain your choice [1 point].

Plant Science 446/546

Final Exam May 9, 1994

Ag.Sci Room 323

10.00am to 12.00 noon

Name :

Answer all 10 questions

A total of 100 points are available

Points available from each question are shown in bold parenthesis

try to be as brief and concise as possible

Please write in a lodgeable form

Show all necessary working and calculations

Make sure that any additional paper used is

inclosed along with the test paper

1. Artificial/controlled hybridization.

2. Seed increase, either to produce pre-breeders seed or to accelerate inbreeding through single seed descent.

3. Small scale disease or pest testing where either expensive or unreliable field testing is not possible.

4. Transfer of planting material from in vitro to in vivo, i.e. in a anther culture haploidy system.

5. Growing plants out of season, for a multitude of reasons.

1b. Parental selection can generally be divided into two different types. List the types and, briefly, indicate differences between types [2 points].

1. Phenotypic selection where parental lines are evaluated based on the performance of the parental genotype grown in different environments.

2. Genotypic selection, where the progeny of specific parental lines are evaluated to determine general combining abilities or to identify specific combining ability cross combinations.

1c. Describe the main features of North Carolina I, North Carolina II and Diallel crossing designs [3 points].

NC(I) : A number of different genotypes are hybridized to a number of "tester genotypes", with known general combining ability and the progeny are evaluated to determine general and specific combing ability of the non-tester genotypes. In these designs it is not necessary to hybridize all non-tester lines to a common set of tester genotypes.

NC(II) : These designs are similar to NC(I) crossing designs but in NC(II)'s all non-tester genotypes are hybridized to each of the tester lines (i.e. a balanced design). Again progeny from crosses are evaluated to determine general and specific combing ability.

Diallel : Diallel designs involve crossing a set number of genotypes in all possible combinations. Diallel designs may or may not include either parental (selfs) or reciprocal crosses. Diallel designs can serve as an extremely powerful tool in choosing parents in a breeding program and in understanding the heritability of polygenic traits.

1d. Explain the terms in the model for the analysis of a Griffing Diallel:

Yijk = μ + gi + gj + sij + eijk

and indicate the importance of these terms and Griffing analysis in selecting superior parental lines [5 points].

Yijk = the observation from the cross between the ith parent and the jth parent in the kth replicate;

μ = the average performance of all crosses;

gi = the general combing ability of the ith parent;

gj = the general combing ability of the jth parent;

sij = the specific combing ability between the ith parent and the jth parent;

eijk = the error term due to replication.

These terms are important as they predict the performance of hybrid progeny without making specific crosses. In plant breeding the general aim is to select parents which have high general combing ability (i.e. progeny from crosses with this parent will have high expression) and to chose high general combing ability parents to maximize specific combing ability.

2a. Briefly, outline the main objective behind growing field trials in a plant breeding program [2 points].

The main object of growing field trials is to predict how specific genotypes will respond if they were to be grown commercially, i.e. mimic commercial production.

1. What was the previous crop;

2. Past history of the land, i.e. has it been drained, what is the potential of waterlogging;

3. Has the land previously been graded, i.e. removal of fertile soil from hilltops;

4. Identify possible shading from trees or buildings, avoid trees if there is potential for bird damage to the crop.

2c. Briefly outline the major reason for multiple location trials in a plant breeding program [1 point].

To determine general and specific adaptability parameters on breeding lines.

List four problems that may be encountered in organizing and carrying out `off station' trials [2 points].

1. Time and cost involved in travel to and from the off station locations;

2. Need to haul small plot machinery (i.e. planters, harvesters, rota-tillers, etc.);

3. Lack of inexperienced staff on site to make day to day decisions on trial management;

4. Lack of on site storage or lab. facilities;

3a. What is the most important advantage of employing good experimental design in a plant breeding program [2 points].

To estimate error variance and to minimize this component. Minimum error variance will result in greatest selection response as it will increase heritability (i.e. genetic variance/(genetic variance + error variance).