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 (if any) last? During this phase flowers are open but anthers are closed (undehisced). If you are working with J. grandiflora follow this link, and note that the flower on the left is in the pistillate phase, and the flower on the right is in the hermaphroditic phase.

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

3) How long does a flower last?
To answer this question we simply tag flowers a day or two before they look like they are going to open, and then visit flowers at the same time every day (morning) and score the flower each day as open or not. It is much better to make observations twice a day.

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 see-through mesh light weight fabric that can be purchased from the fabric store.

4b) Is the stigma receptive during the pistillate phase?
Same as 4a but flower must have its anthers shut (not yet open, undehisced); this is the first and only the first day the flower is open. Gently and carefully remove the undehisced anthers with forceps (emasculate flowers), and then pollinate by hand. Carefully bag flowers to exclude any pollination by insects, remove bag after corolla drops off, and if pollinated flowers produce fruit, you can then say with certainty that the flower is protogynous and does not just look protogynous.

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?

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.

7)  What color is the nectar? To answer this question, simply look into flowers and look for liquid that is present even when it has not rained directly on flowers. J. grandiflora's nectar should be translucent, but check me on this because some nectars change color as the flower ages.

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 are 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) How many days does it take to go from flower to ripe fruit?

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?

10) If you manually self-pollinate a flower, exactly how many seeds per fruit do you get?
If you are answering this question, a) take notes as to whether the plant is happy vs not growing vigorously, b) 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.

11) Does the style, or do the filaments, 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?  
to answer this auestion: 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, have caps, 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 or the vial containing flowers.  If yes, and if you use at least five people (more if you get inconsist results) you can report that the flowers have a detectable-by-human scent.

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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 on flowers left completely unpollinated? Handle the unpollinated flowers as much as you handle the flowers you are manually pollinating to make this a valid comparison.

Acquire materials. We may need pollinator exclusion netting and poles. I have tags and a hand lens you can use/borrow. I will pay for the pollinator exclusion fabric; bring me a receipt. 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 etc. of material that will work. I have seen fabric that would work well being sold in a store with a name something like JoAnn Fabric. 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. You can buy showy annuals 6 for less than $1.50, 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.

Your experiment involves three treatments, all (or none) under pollinator exclusion netting. If you use two or three plants, divide treatment 1 among all plants, divide treatment 2 among all plants, and do the same with treatment 3. To exclude pollinators from a plants you could pound in four vertical stakes around the plants, and then staple gun the netting to the stakes, so that the plant(s) is essentially inside a net tent. The netting has to cover the top and sides, and touch the ground at the bottom of the sides. You are going to need to get in and out of the "tent" so you will need to somehow fashion a door on one side. One possibility is to use velcro, but attaching it to the fabric and the stakes might take some creativity and patience.

Treatment 1. No manipulation. Tag these, giving each one a number, right before they open. How many days do these last? Use 20 or so flowers, starting with number 1, 2, 3, .....

Treatment 2. No pollination with emasculation during day 1 (while anthers are undehisced). Look at the stigma with a lens, getting the stigma in perfect focus. If you see any pollen it means that pollinators are getting inside your exclusion net (or neighboring flowers at a later stage are bumping into your stigma). Do not use if you see pollen on the stigma. Use 20 or so flowers, so you may want to start numbers (on the tags) at 21, 22, 23....

Treatment 3. Pollination and emasculation on day 1. You will know that the flower is a "day 1" flower if you see short filaments and undehisced anthers. You will have to transfer pollen from a different flower that is in its day 2 or day 3 stage. Right before you pollinate these flowers, emasculate them. To do this carefully pinch/cut (with forceps) the filament so that the anther drops off, without disturbing the style. If you accidentally injure the style do not use the flower. Use 20 or so flowers, so you may want to start these numbers (on the tags) at 41, 42, 43,...

Number a tag before you hang it on the plant. Tag each flower, give the flower a number, and in a notebook keep track of how many days the flower lasts. For example, if you pollinate it on a Monday (thus it was closed Sunday), and you see it open on Tues, Wed. and Thurs., but when you check on it on Fri you see that the corolla-androecium dropped, you score this flower as having lasted 4 days. Obviously, if you can check your flowers at the same time every day, all the better.

All three treatments must be done during the same stretch of the summer. For example, if you were to do all of treatment 2 in June and then do all of treatment 1 in July, if we see a difference in floral longevity we will not know if the hotter temps in July were the cause of the difference. I don't think you should do one treatment on one plant and another treatment on another. Perhaps you will need three plants and then you will have 7 or so flowers of each treatment on each plant.

Consider the problem of how to keep track of all your tags (hanging off plants). When I have had this many tags hanging off plants at the same time I have, in the process of recording data, wasted valuable time finding the right tag. Consider color coding, so that red tags are treatment 1, white are treatment 2, and yellow are treatment 3 (or whatever colors you may want to use). Color code with a thick marker (prior to hanging the tag on a plant).

It is difficult to tag an individual flower, because its individual stalk (called a pedicel) is so fine. You may remove all flowers of the inflorescence except one or two, so that you can hang the tag on the stalk of the inflorescence (peduncle) instead of hanging the tag on the pedicel. This may be better, because I flowers will be less likely to be damaged (a tag is kind of heavy for a pedicel). To remove flowers use a small pair of scissors, leaving only the one or two flower(s) of the inflorescence you are interested in. This method will require you to have 30 to 60 inflorescences, and so I will give you four plants (three would probably do it). When you are done with a tag, because the corolla-androecium has dropped) remove it (with scissors).

Return forceps, unused tags and hand lens in September.

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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 to 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.

July, August, September.  Harvest 20 fruits from each plan 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 pole to pole.  Put your measurements in a spreadsheet.  To obtain fruit volume I have two ideas at the moment: 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 scope

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How to grow Jaltomata outdoors here in Connecticut

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. Plant as you would a tomato.