Plant Science 446/546
Exam #3, 1996
9:30 am to 10:20 am
Name :
Answer all 10 questions
A total of 100 points are available
Try to be as brief and concise as possible
Please write in a legible form
Show any working/calculations
Make sure that any additional paper used
is attached to the questionnaire
1a.Selection in a plant breeding program can be divided into three different stages: early generation selection (EGS); intermediate generation selection (IGS) and advanced generation selection (AGS). Briefly, state the major differences between the three stages. [3 points]
EGS:
IGS:
AGS:
1b.After the Presidential election in 1996, it is noted that "White water" has bankrupt the Whitehouse Estate and it is offered to the University of Idaho as a research farm. Neither you (nor Bill or Hilary for that matter) has ever grown research plots on this estate. List four factors that you would look for to identify an area to plant your 1997 breeding plots [4 points].
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4.
List three problems that may be encountered in organizing and carrying out `off station' trials [3 points].
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2.
3.
2a.In chickpea breeding it is known that the correlation between yield performance of F4 families in one year and F5 families in the following year is r = 0.57. 4000 F4 breeding lines of chickpea were evaluated for seed yield in a properly designed field trial. All 4000 lines were re-evaluated at the F5 stage the following year. If the highest yielding 10% were selected based on F4 performance and the highest yielding 15% were selected based on their F5 performance, many of the original 4000 lines would you expect to be selected both on F4 and F5 performance [3 points].
2b.Briefly explain what Type I and Type II error means in the context of selection. Estimate the Type I and Type II errors expected by selecting F4 families for yield at the 10% level and selecting F5 families at the 15% level (i.e. from question 2a (above)) [4 points].
2c.Independent culling can be a very effective means to select for two or more characters simultaneously and can be easily applied to breeding data. Under what circumstances would independent culling not be very effective? [2 points].
If index selection is used list two methods that could be used to weight variates. [4 point]
1.
2.
3a.In 1994, 10,000 F3 head rows were grown in an unreplicated, but randomized, design from Bobby Z's Wheat Breeding Program. At harvest, seed from all rows were thrashed and weighed. The average yield of all 10,000 lines was found to be 164.24 kg. After weighing, 200 rows were taken at random and retained irrespective of their yield performance. From the remaining lines the "best" 1000 rows were selected for further evaluation in the breeding scheme. The average yield of these selected lines was of course higher than the whole population at 193.74 kg.
In 1995, the bulk F4 seed from the 200 random lines and the 1000 selected lines were grown in a randomized complete block design. At harvest, each plot was harvested separately and the yield recorded.
From this 1995 trial it was found that the average yield of the selected lines was 168.11 kg, while the average yield of the 200 randomly chosen lines was 133.41 kg.
Determine the narrow-sense heritability for yield using the above information. [6 points]
3b.Explain how this value of heritability found might influence your selection strategy at future F3 head row selection stages [4 points]
4a.You have been employed as Senior Breeder at the Hass Bean Breeding Co. for several years and have had to carry out your breeding operation with very few funds. Due to a recent takeover of the company by the Human Bean Seed Association, you have been given a vast sum of money from the takeover. You have decided to use this money to upgrade the computer facilities used by your breeding group. To achieve this goal you have appointed a computer programmer to develop a computer plant breeding management.
List the five main features that you would request from the computer package to perform and help increase the efficiency of breeding future new cultivars. [5 points]
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2.
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5.
4b.Having successfully updated the computer system you realize that you still have thousands of dollars left in your budget (isn't working for a commercial company wonderful?) and have been asked to design a glasshouse complex (that is similar to a greenhouse complex) suitable for your breeding program. List five features you would like to include in the new facility [5 points].
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5.
5a.A half diallel crossing design is carried out involving 25 homozygous parents from the world famous Rapeseed Breeding Program at the illustrious University of Idaho. Progeny from each of the 300 F3 families possible from the half diallel cross combinations were raised and grown in a four replicate yield trial (i.e., planting F3 and harvesting F4 seed). Also grown within the trial were all 25 parental lines.
Based on the yield results from the trial it was found that the regression of mid-parent value (x) onto progeny performance (y) was:
y = 0.632 x + 0.012
Also from this trial, the phenotypic variance of the F3 families was found to be σ2p = 255.16 and the average yield of the F3 families was 1700 lbs/acre.
What would be the expected gain from selection if the F3 families were selected at the 10% level (i.e. discard 90% of families) according to yield performance and what would be the expected yield at F4 of the selected families (Hint: i = 1.13 + 0.73 x (log(1/k), where k is the proportion selected) [5 points]
5b.If you selected the F4 families from question 5a (above) at the same 10% selection intensity would you expect to have a smaller response, the same response or a larger response from selection? Briefly, explain your answer [5 points].
6.In a series of properly designed experiments, a team of plant breeders produced estimates of narrow-sense heritabilities (h2n) for plant height and plant yield from two different segregating families of spring barley (95.BAR.31 and 95.BAR.69). Both families were grown on two farms (Moscow and Boise, in Idaho) in three successive years (1993, 1994 and 1995). The h2n values from each year and site are summarized below.
95.BAR.3195.BAR.69
CharacterYearMoscowBoiseMoscowBoise
Plant19930.200.220.830.86
height19940.010.210.310.74
19950.210.300.520.79
Plant19930.110.250.520.57
yield19940.020.150.120.46
19950.210.240.210.48
Which family is likely to give better responses in a breeding program to equivalent selection intensities, and why? [2 points]
In such a breeding program, which of the two characters (plant height or plant yield) is likely to give the better response to equivalent selection intensities, and why? [2 points]
Consistently higher average values of h2n were obtained at the farm near Boise. Which site, if either, is likely to provide the most accurate estimate of h2n, and why? [2 points]
Some of the heritability estimates (particularly those for plant height for 95.BAR.69 in Moscow) varied greatly over the 3 year period. What could be the cause? [4 points].
7.25 progeny from 10 winter wheat crosses were evaluated for yield in a properly designed F3 cross prediction study under field conditions. From the results the following cross means and additive genetic standard deviations (σA) for seed yields were obtained:
MeanσA
92.WW.46236.60127.34 =
92.WW.53199.33191.40 =
92.WW.54241.82 91.43 =
92.WW.61142.00119.10 =
92.WW.71133.11125.46 =
92.WW.74236.73102.14 =
92.WW.93233.55281.77 =
92.WW.108201.22106.63 =
92.WW.111229.37299.39 =
92.WW.116169.11119.32 =
Also grown in the same trial were 5 commercial cultivars. The average performance of the commercial cultivars was 211.10 and the standard deviation was 41.93.
Using univariate cross prediction procedures determine which three crosses should be used in breeding for cultivars which would need to produce yields. Rank your choices as first, second and third and include the probabilities used for your decision:
(i)Greater than average controls plus one control standard deviation. [6 points]
1st.
2nd.
3rd.
(ii)Greater than the average control plus twice the control standard deviation. [4 points]
1st.
2nd.
3rd.
8a.The yield performance of eight water melon breeding lines and two named cultivars (controls) were assessed in 15 different environments. After harvest melons from each line were weighed (Kg/plot), and a "Finley and Wilkins" style joint regression analysis was carried out. Results of genotype mean yield (MEAN) and environmental sensitivity (SENS) of the eight cultivars are shown below:
GenotypesMEANSENS
Big'n'juicy167.50.88
Yielder279.21.04
WM.69.34.2248.51.35
WM.35.23.67329.21.91
WM.12.7.16144.20.27
WM.72.33.47301.90.46
WM.1.45.68193.20.22
WM.A.BIG.1269.81.66
WM.2.LATE295.41.27
WM.O.2.IT264.10.67
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 [5 points].
8b.Mutation breeding and doubled haploidy have promised to be useful tools for plant breeders for creating genetic diversity and producing homozygous lines, respectively. List three problems that could be encountered when using mutagenesis in your program [3 points]
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and, list two reasons why doubled haploids are not used more routinely by plant breeders [2 points]
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10a.You are at the advanced stage of evaluating lines from your sugar beet breeding scheme and have decided that in 1996 you would like to release one (or more) of your advanced lines as a new cultivar. Indicate three aspects that you consider will need to be considered to ensure successful release of the new variety. [3 points]
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10b.Having decided to release a new of these sugar beet cultivars, you wish to have control of several aspects of production and also receive some financial reward for the 12 years of work that have been involved. Briefly explain how you might be able to achieve some kind of proprietary rights on a new cultivar. [6 points]
1.
2.
3.
10c.Your plant breeding teacher (a world famous potato breeder) has just bred a potato cultivar which has great yield, very attractive tuber appearance, stores for months without sprout suppressants and is a lovely red color. However this potato cultivar tastes like soap. Nonetheless, your teacher has decided to release the cultivar and has asked you to suggest a possible name. What is your choice of name and very briefly, why. [1 point]
Name :
Reason: