Dear Dhanashri,

I am assuming you want to hybridise. If that is the plan, you have to emasculate flowers before pollen is shed and you can pollinate on the same day if you have the stigma receptive (you can understand if you open few flowers of different maturity). If you are aiming to get more seeds per flower, you can pollinate over three days from the day of emasculation. Alternately you can hybridise more flowers and get the same number of seeds (without repeating on the same flower).

If you are growing tomato indoors and worried about pollination for seed production, you can pollinate for two days. Morning hours are always better.

Good luck!. 

If you perform the artificial pollination at the right time (i.e. when stigma is receptive) only one pollination could be sufficient. Just note that when you perform the artifical pollination, plants receive much higher number of pollen grains than what happen naturally.

what is the reason for your pollination? if your plants are mature enough then you can do it in the same day by:

1. collect pollins.

 2. emasculate the flower which has a receptive stigma.

3. do the pollination then tag it or remove the sepals in order to recognize the pollinated flower later on. 

4. cover it if it is in outdoor to avoid contamination by other pollins.

Note: Sometimes pollin collection is hard in early morning because they are a bit wet so you should have collected in advance. 

In modern Technics breeders use electric tooth brush to collect pollins, I have used and still use it in tomatoes it really works! 

The more you repeat the process the more seeds you get. but normally in tomatoes one time is more than enough if you have enough pollin.

good luck! 

If your aim is hybrid,

1. Take immature buds to emasculate, ensuring no pollen bursting.

2. Preferably emasculate in evening and pollinate next day morning for more success. 

Once you have your pollen, apply it generously to a fresh stigma (fresh stigmas are found on new flowers at any time of day).  Remember that one grain of pollen produces one fruit and only one seed.  However, more pollen on a stigma will give more seed and it will be limited by the number of eggs in the ovary of the flower.  If the pollen is good, if the stigma is fresh, and if the pollen and eggs are genetically compatible, then one pollination attempt per flower will be sufficient.

1. How many times a week?-- It depends on your research and how many lines you want to cross. Basically, as long as there are flowers, you can do hand-pollination. For my project, if the 'pollen flow' (direction) is not restricted, I hand-pollinate reciprocal directions: pollen from line A to line B, then pollen from line B to line A, just to compare.

2. When to do pollination?-- usually in the morning, but I also see some successful fertilization cases from afternoon operation.

3. Attached an article, hope it is helpful to you.

Good luck on your research.

I only worked on tomato for one season. Initially I did not succeed in getting any crosses as I pollinated only once as in cereals. Success was obtained only after repeating pollination to the same female stigmas for 2-3 times. Good luck.

Tomato is a self pollinating crop. Therefore, the anthers must be removed before they begin to release the pollen grains. Artificial pollination can be done either in the morning or in the evening depending on your location. In extreme hot environments, emasculation and pollination will be better in the evening to take advantage of the cool night temperature for recuperation. The more the pollen grains on a receptive stigma the higher the number of seeds so you can do repeated pollination on the same  or different flowers in one day. Goodluck colleague.

Dear Dhanashri Shinde,

I would like to thank you for your question. First, you must have 2-3 sowing dates intervals (10-14 days) to get more flowers and hybrid seeds if you need to study plant breeding to estimate type of gene action, heterosis, combining ability. 

You must know your plant or crop very well (as their different kind of pollination and the crop can be divided depend on the type of pollination. 

Tomato is self or often pollinated crops (if you have bees or insect that can do pollination)

the steps of artificial crosses is as following:

1- You must select the female flower first (it must be closed and not turn yellow) and do the emasculation this must be morning and evening if you work in the field as pollination happened when the sun rise. 

2- after emasculation you must write the name of the female parent in lapel and the date 

3- after 2-3 days try select yellow flowers as male parent for pollination and you could check after 7-10 days if their is some fruits 

you must repeated this things as your study need F1 seeds

I wish to ask one more thing in this regard. In many papers regarding using electric vibrator its mentioned that thrice in a month we should pollinate. But what is all tomato flowers did not get bloomed in that week. should we remove the buds or do the pollination again in next week.

Dear Dhanashri,

from past experience, when I worked with dwarf tomato cultivars within a closed environment (growth room and growth chambers). I used an electric toothbrush to agitate active open flowers in each plant manually twice a week. It is a simple and efficient way of conducting artificial pollination within a small space if you don't have a very large plant population (less than 200 plants).

Kind Regards.