Jana U'Ren
Jana (Sweet) U'Ren & Matt (Krn-Dog) Krna with their Nicotiana seedlings in the greenhouse that they called "home" for many long months in spring & summer of 2000.
Jana U'Ren
Jana (Sweet) U'Ren & Matt (Krn-Dog) Krna with their Nicotiana seedlings in the greenhouse that they called "home" for many long months in spring & summer of 2000.
Jana is an undergraduate
researcher who has been supported by NSF REU and MU-LSUROP (Life
Sciences Undergraduate Research Opportunity) funds. Her LSUROP
project is outlined below. For the REU, Jana is helping us develop
microsatellite
markers for Nicotiana.
Environmental Effects on F3 hybrid plants of Nicotiana alata
and N. forgetiana.
We examined the effect of two environmental stresses, crowding and nutrient availability, on phenological and morphological traits of F3 hybrid plants with different genetic architectures. F2 hybrid plants were planted in Brazil under natural conditions and allowed to be visited by natural pollinators (F3 open), and the same F2 plants were hand-pollinated to randomly-chosen mates to produce a F3 control group (F3 random). To examine the effects of crowding, F3 open and F3 random plants were each planted in three densities: high, 4 plants/pot, medium, 2 plants/pot, and low, 1 plant/pot. Half of the plants from each density treatment were supplemented weekly with 200 PPM of aqueous fertilizer with an NPK ratio of 20:10:20 to examine the effect of nutrient availability. The other half were supplemented biweekly (they needed this much fertilizer just to keep them alive!) with the same concentration of fertilizer. All plants were watered with equal quantities twice a day.
The experimental design is diagrammed below. One replicate of this design was randomly arranged on each of two greenhouse benches (blocks).
F3-open pollinated low fertilizer high fertilizer F3-random pollinated low fertilizer high fertilizer
10 pots X 2 populations X 6 treatments X 2 blocks = 240 pots; 560
plants
The floral traits measured were:
Phenological traits measured were:
Table 1. Environmental effects on phenology. Summary of
ANOVA -- independent variables & interaction effects are listed
in the left-most column. Column and row indicate positions on the
greenhouse benches. Response (dependent) variables are listed across
the top row. D(N)bolt and D(N)flower indicate the days to bolt or
flower of the Nth plant per pot, e.g. D1bolt is the number of days
required for the first plant in a pot to bolt.
Significance is abbreviated as follows: ~: 0.1>p>0.05; *:
p<0.05; **: p<0.01; ***: p<0.001
Source of
variation D1bolt D2bolt D3bolt D4bolt D1flower D2flower D3flower D4flower block . . . . . . . . column . . . . . . . . row . . ~ . *** ** ~ . population . . . . . . . . fertilizer *** *** *** *** *** *** *** *** pop*fertilizer . . . ** . . . * crowding *** . . . *** . . ~ population*crowding . . . . . . . . fertilizer*crowding ~ ~ . . * . . . pop*fert*crowd . . . . . . . .
Both F3 open and F3 random plants were affected by crowding
and by nutrient availability. Plants that were fertilized bolted and
flowered sooner than unfertilized plants at all densities. Plants at
the low density bolted and flowered sooner than plants at the medium
and high density but . Plants at the medium density bolted and
flowered sooner than plants at the high density. Fertilizer effects
were significant for all plants per pot while crowding only affected
the first plant to flower in each pot. Fertilizer*crowding
interactions were significant only for the fourth plants to bolt or
flower in the 4 plants/pot treatment.
The population effects were not significant for phenological traits -- the mating structure applied to their F2 parents (random versus naturally-pollinated) did not affect the propensity of the F3s to bolt or flower earlier or later. Analysis of variance indicates that there is no interaction between population (open vs. random) and the environment for most traits. However, population* fertilizer interactions were evident for the fourth plant to bolt and flower in the 4plants/pot treatment. F3 plants that descended from open pollination responded to fertilizer treatment (shortened their time to bolting and flowering) more than randomly-pollinated plants -- but this interaction was only significant for the last plant to flower in the most crowded treatment.
Spaital variation in the glasshouse was evident for 2 traits. While block and column (North-to-South) effects were not significant for any variables, row (East-to-West) affected days to flower for the first and second plants to flower per pot. The row effects were likely the result of a shade gradient, east-most positions receiving less sun than more westerly positions.
Significance denoted as follows: ~: 0.1>p>0.05; *: p<0.05; **: p<0.01; ***: p<0.001
Source of variation stigma insertion anther-stigma distance corolla tube length limb width mouth width color block . . . . . . column . . . . * ~ row . . * ~ . . population . . . . . . fertilizer *** * . . *** . pop*fertilizer . . . . . . crowding ** . . *** *** . population*crowding . . . . . . fertilizer*crowding . . . . ~ . pop*fert*crowd . . . . . .
Fertilizer and crowding had significant effects on three
floral traits each. Although block effects were not significant,
position within blocks (row, column) were evident for one trait each,
probably due to gradients of light and temperature, respectively.
Fertilizer and crowding effects acted independently; their
interaction was not significant for any trait. Population main
effects and population interactions were not significant for any
trait.
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