Explanations and Research Ideas, for students working with professor Mione

Link to Jaltomata home page
professor Thomas Mione, Central Connecticut State University
Biology Department, Copernicus Hall, 1615 Stanley Street, New Britain, CT 06050-4010

Questions students and I are asking, using plants grown either outdoors or in the greenhouse:

1) How long does the female (pistillate) phase last? During this phase flowers are open but anthers are closed (undehisced). Most but not all Jaltomata species have a pistillate phase.

2) How long does the hermaphroditic phase last? During this phase flowers are open and both the stigma is receptive and one or more anthers have dehisced (are presenting pollen).

3) How long does a flower last?
Tag flowers a day before they look like they will open, and then visit flowers at the same time every day (morning) and score the flower each day as open or not. It is better to make observations twice a day. The corolla and androecium will drop together when the flower is done.

4a) Is the plant self-compatible (SC)?  
To answer this question, apply pollen to the stigma using pollen from the same plant (it can be but does not have to be from the same flower) and if you get fruit, then the plant is SC.  No need to remove the anthers (emasculate flowers) for this question. If you are growing more than one plant flowers need to be bagged to exclude cross pollination. Bagging is done with a see-through mesh light-weight fabric that can be purchased from a fabric store. If you grow a single plant you don't need to bag.

4b) Is the stigma receptive during the pistillate phase?
Gently and carefully remove the undehisced anthers with forceps (emasculate flowers) making sure you don't bump the style, and then pollinate by hand. Pollinate the flower while all anthers are undehisced (not yet open); for most Jaltomata species this is the first and only the first day the flower is open. Carefully bag flowers to exclude any pollination by insects, remove bag after corolla-androecium drops off, and if pollinated flowers produce fruit, you can then state with certainty that the flower is protogynous and does not just appear to be protogynous. Even if you grow a single plant you do need to bag flowers to exclude pollinators, so pollen is not moved to the flower you pollinated and emasculated after its pistillate phase.

5) Does the flower close at night (or in the late afternoon) and reopen again the next day? If yes, what time of day is it closing? Does the flower close for rain too? Make several observations: for example it is possible that flowers close for rain and clouds but not at night, and it is possible they close each night but don't close for rain and clouds.

6) Does the flower change size? (pistillate phase compared with hermaphroditic phase)?  Measure corolla during both phases (afternoon of day one vs. same time on either day two or day three). We will do a paired T-test, so keep the two observations for each flower together in the same row of your data sheet. Gently flatten corolla to ruler while taking measurements.

7)  What color is the nectar? Transfer nectar from the flower on to something white that does not absorb liquid (a white plastic ruler, for ex). Record the phase of the flower and the color of the nectar. At least in the genus Jaltomata, some nectars change color as the flower ages, so make several observations during the pistillate phase and several observations during the hermaphrodic phase.

8) If the flower has a pistillate phase, is nectar produced during this phase? Make sure you are looking at the flower during its pistillate phase (anthers closed), and simply score the flower as having or not having visible nectar. Or, is nectar only noticeable during the hermaphroditic phase? If nectar is present during both phases, is there more nectar during the hermaphroditic phase (this is going to depend in part on visitation by insects)?

9) Do the anthers dehisce simultaneously or do one or two dehisce and then if you visit a couple of hours later one or two different anthers are then dehiscing? Do the anthers of a flower appear to be of equal size prior to dehiscence?

10) How many days does it take to go from flower to ripe fruit? For this question you can tag flowers as soon as they open.

11) Do the ripe fruits drop off and land on the ground? Or, do the ripe fruits remain attached to the parent plant? If ripe fruits drop as soon as they become ripe, do they drop with the calyx attached to the fruit or do they drop without the calyx? If ripe fruits remain attached to the plant, for how many days do they remain attached before they finally drop? To answer this question, if you are growing plants outdoors you will need to make observations in September.

12) If you manually self-pollinate a flower, how many seeds per fruit do you get?
If you are answering this question, a) take notes as to whether the plant is or is not growing vigorously, b) tag flower, c) use a hand lens and make sure, when you look at the stigma after you manually pollinate it, that the stigma is coated with pollen.

13) Does the style elongate while the flower is open? Take measurements twice a day every day, starting the morning a flower opens. Use 10 flowers.

12) Can you get three or more refractometer readings on the nectar? You may have to combine the  nectar of many flowers to get a reading (combine nectar of only pistillate phase flowers or only hermaph phase flowers).

13) Does the stigma protrude from the corolla before it opens for the first time? If yes, is it receptive at this stage?  
If it protrudes, apply pollen from a different flower of the same species while it is protruding. As soon as the flower opens carefully emasculate before anthers dehisce, bag flower to exclude pollinators, and see if that flower sets fruit. If you get fruit, your flowers was functionally pistillate before the corolla even opened!

14) If you remove flowers and put them in a vial, and you have an identical vial that is empty, and you blind test someone, can they tell which jar or vial contains the flowers?  Both vials have to be cleaned at the same time with the same soap and then very thoroughly rinsed, and have the caps removed the same number of seconds before the blindfolded person takes a whiff. Flip a coin to decide if you will first give the person a smell of the empty vial or the vial containing flowers.  If yes, and if you use at least five people (more if you get inconsistent results) you can report that the flowers have a detectable-by-human scent.

15) Do flowers that get pollinated during their first day of being open last as long as flowers that don't get pollinated at all? In other words, if you pollinate a flower, does the corolla drop off sooner than flowers left unpollinated? Tag and handle the unpollinated (control) flowers as much as you handle the flowers you are manually pollinating so that you don't introduce another variable, amount of handling.

16) Do plants that only make a few fruits make bigger fruits, have larger seeds, or have more seeds per fruit than plants that make many fruits? Experimental Plants: As soon as you see fruits beginning to form (small green, expansion of ovary of flower) remove from each inflorescence all but one fruit, leaving one developing fruit.  Use a small pair of scissors to cut pedicels.  Be very careful to not damage the peduncle (stalk of the inflorescence). Control Plants: No manipulation, same amount of water, same intensity and duration of sunshine, same size pot if you are using pots, same soil.

August, September.  Harvest 20 fruits from each plant when ripe (dark purple/black).  Measure each fruit with calipers, 1) pole to pole (one pole is where the pedicel/calyx was attached, the other pole is the opposite end), and 2) perpendicular to previous measurement.  Put your measurements in a spreadsheet.  To obtain fruit volume I have two ideas: a) average of the two measurements used as diameter, and b) consult a reference for a formula for the volume of an oblate spheroid. 

We will do statistical tests: fruit volume control vs. experimental, seed size control vs. experimental, seeds per fruit control vs. experimental. The null hypothesis is no difference.

To count seeds per fruit: smash a fruit on its own piece of paper towel, being careful to number the towel so you know whether the fruit came from the experimental or the control.

Seed Size.  We may or may not get to this, but save seeds separately (one envelope per plant) so we can do this if we have time.  I will show you how to measure seeds with a dissecting microscope

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For some studies you may need pollinator exclusion netting and poles. I have tags you can use. You will need to go to a fabric store and pick a light mesh that has pores large enough for plenty of air flow but small enough to exclude pollinators. If you have any trouble with this contact me immediately and I will go to the fabric store and get the exact name of material that will work. If you grow numerous showy flowers near the Jaltomata plants, the bees will (from my experience) ignore Jaltomata, and if the bees ignore Jaltomata you will not need pollinator exclusion netting for an indep study but would need to use the netting if you plan to publish. You can buy showy annuals 6 for less than $2.50, and plant 18 or 24 of them, and then you may be able to completely omit the pollinator exclusion tent. If you want to try to publish your results, use the net, but not using the net will be OK with me if you make frequent observations and do not see insects visiting your research plants.

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How to grow Jaltomata outdoors in Connecticut

Plant seeds indoors in early April. Use a heat mat under the cup holding the seeds and keep the seeds moist not wet. Seeds of some species need our outdoor June weather to get a high percentage to germinate.

In May, put Jaltomata plants outside during day, in at night, for a few days to a week. Keep in mind that while in small cups they dry out easily.

Try some of your plants in the ground and some in pots. If grown in pots outdoors try about 2/3 top soil and 1/3 potting mix. I can give you the potting mix, and top soil is inexpensive at garden centers. Thoroughly mix these components.

It is best to gradually transition plants as they enlarge to larger and larger pots. In other words from a 4" pot as it gets too big move it to a 6" pot. Then when it gets too big for the 6" pot move it up to a larger pot.

If the the plants get used to an environment with no wind and indirect sun (indoors) and then you abruptly move them to outside, they may die. To gradually transition them to the outside put them out for a few hours a day for a week or so. The next week leave them out all day and bring them in for the night if nights are not yet warm. Next, leave them out all the time.

Return all pots you borrowed to the CCSU greenhouse in the fall. You don't need to wash them, just place them to the left edge of the sink.